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• How many video chats can an Amazon instance handle?

  - by cute

  How many simultaneous tete-a-tete video chats of reasonable quality can an Amazon instance handle? How do you think? How would I find out? How would I test?

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• how do one determine the number of concurrent users that a web application can handle?

  - by lakshmiiyer

  As far as what I know , I think apache web server handles multiple requests through a combination of multi-processing and multi-threading. Want to know for a php application running a webserver is it just the apache which decides the concurrent users it can handle or it also depends on the php application. If yes, then to what extent?

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• How many Tomcat instances can one application server handle?

  - by NetworkUser

  My network engineer states I am part of a cluster where two apache application servers(512G RAM each) have 142 instances each of Tomcat (of which my company represents 6 each with 2G RAM). This seems like a lot and my latency issues move with the hour of the day - 7AM CST software functions fine, 10AM CST - system slows significantly this slowness continues until 6PM CST. My question is how many Tomcat instances can one application server handle?

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• Fatal error: Call to a member function getAttribute() on a non-object in C:\xampp\htdocs\giftshoes\s

  - by Sadiqur Rahman

  I am getting following error message when using Doctrine ORM in Codeigniter. Please help me... ------------------Doctrin Table Defination------------- abstract class BaseShoes extends Doctrine_Record { public function setTableDefinition() { $this-setTableName('shoes'); $this-hasColumn('sku', 'integer', 11, array('primary' = true, 'autoincrement' = false)); $this-hasColumn('name', 'string', 255); $this-hasColumn('keywords', 'string', 255); $this-hasColumn('description', 'string'); $this-hasColumn('manufacturer', 'string', 20); $this-hasColumn('sale_price', 'double'); $this-hasColumn('price', 'double'); $this-hasColumn('url', 'string'); $this-hasColumn('image', 'string'); $this-hasColumn('category', 'string', 50); } public function setUp() { } } ------------------------Doctrin Table Code ------------------- class ShoesTable extends Doctrine_Table { function getAllShoes($from = 0, $total = 15) { $q = Doctrine_Query::create() -from('Shoes s') -limit($total) -offset($from); return $q->execute(array(), Doctrine::HYDRATE_ARRAY); } } -----------------Model Code----------------- class Shoes extends BaseShoes { function __construct() { $this-table = Doctrine::getTable('shoes'); } public function getAllShoes() { $this-table-getAllShoes(); } } -------------------ERROR I am getting-------------------- ( ! ) Fatal error: Call to a member function getAttribute() on a non-object in C:\xampp\htdocs\giftshoes\system\database\doctrine\Doctrine\Record.php on line 1424 Call Stack Time Memory Function Location 1 0.0011 327560 {main}( ) ..\index.php:0 2 0.0363 3210720 require_once( 'C:\xampp\htdocs\giftshoes\system\codeigniter\CodeIgniter.php' ) ..\index.php:116 3 0.0492 3922368 Welcome-Welcome( ) ..\CodeIgniter.php:201 4 0.0817 6234096 CI_Loader-model( ) ..\welcome.php:14 5 0.0824 6248376 Shoes-__construct( ) ..\Loader.php:184 6 0.0824 6248424 Doctrine_Core::getTable( ) ..\Shoes.php:5 7 0.0824 6248424 Doctrine_Connection-getTable( ) ..\Core.php:1080 8 0.0824 6254304 Doctrine_Table-__construct( ) ..\Connection.php:1123 9 0.0841 6396128 Doctrine_Table-initDefinition( ) ..\Table.php:249 10 0.0841 6397472 Shoes-__construct( ) ..\Table.php:301 11 0.0841 6397680 Doctrine_Access-__set( ) ..\Access.php:0 12 0.0841 6397680 Doctrine_Record-set( ) ..\Access.php:60

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• How do I make a jQuery POST function open the new page?

  - by ciclistadan

  I know that a submit button in HTML can submit a form which opens the target page, but how do I cause a jQuery ajax call POST information to a new page and display the new page. I am submitting information that is gathered by clicking elements (which toggle a new class) and then all items with this new class are added to an array and POSTed to a new page. I can get it to POST the data but it seems to be working functioning in an ajax non-refreshing manner, not submitting the page and redirecting to the new page. how might I go about doing this? here's the script section: //onload function $(function() { //toggles items to mark them for purchase //add event handler for selecting items $(".line").click(function() { //get the lines item number var item = $(this).toggleClass("select").attr("name"); }); $('#process').click(function() { var items = []; //place selected numbers in a string $('.line.select').each(function(index){ items.push($(this).attr('name')); }); $.ajax({ type: 'POST', url: 'additem.php', data: 'items='+items, success: function(){ $('#menu').hide(function(){ $('#success').fadeIn(); }); } }); }); return false; }); any pointers would be great!! thanks

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• jQuery, unable to store data returned by $.get function.

  - by Deepak Prasanna

  I am trying to turn div#sidebar into a sidebar in my app. My code looks like the one below. $('#sidebar').userProfile(); jQuery.fn.userProfile = function() { $.get('/users/profile', function(data){ $(this).html(data); }); }; It didnt work because, I found the this (inside the $.get function) here contexts to the get request and not $('#sidebar'). Then I tried something like below. $('#sidebar').userProfile(); #This doesnot work jQuery.fn.userProfile = function() { var side_bar = null; $.get('/users/profile', function(data){ side_bar = data; }); $(this).html(side_bar); console.log(side_bar); }; This doesnt work either. In firebug console I see Null which I am setting on top when I am declaring the variable.Atlast I made it work by changing my code to something like below by hardcoding the selector. #This works, but I cannot turn any element to a sidebar which is sick. jQuery.fn.userProfile = function() { $.get('/users/profile', function(data){ $('#sidebar').html(data); }); }; But this is not I wanted because I wanted to turn any element to a sidebar. Where am I goin wrong or which is the correct way of doing it?

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• Move <option> to top of list with Javascript

  - by Adam

  I'm trying to create a button that will move the currently selected OPTION in a SELECT MULTIPLE list to the top of that list. I currently have OptionTransfer.js implemented, which is allowing me to move items up and down the list. I want to add a new function function MoveOptionTop(obj) { ... } Here is the source of OptionTransfer.js // =================================================================== // Author: Matt Kruse // WWW: http://www.mattkruse.com/ // // NOTICE: You may use this code for any purpose, commercial or // private, without any further permission from the author. You may // remove this notice from your final code if you wish, however it is // appreciated by the author if at least my web site address is kept. // // You may *NOT* re-distribute this code in any way except through its // use. That means, you can include it in your product, or your web // site, or any other form where the code is actually being used. You // may not put the plain javascript up on your site for download or // include it in your javascript libraries for download. // If you wish to share this code with others, please just point them // to the URL instead. // Please DO NOT link directly to my .js files from your site. Copy // the files to your server and use them there. Thank you. // =================================================================== /* SOURCE FILE: selectbox.js */ function hasOptions(obj){if(obj!=null && obj.options!=null){return true;}return false;} function selectUnselectMatchingOptions(obj,regex,which,only){if(window.RegExp){if(which == "select"){var selected1=true;var selected2=false;}else if(which == "unselect"){var selected1=false;var selected2=true;}else{return;}var re = new RegExp(regex);if(!hasOptions(obj)){return;}for(var i=0;i(b.text+"")){return 1;}return 0;});for(var i=0;i3){var regex = arguments[3];if(regex != ""){unSelectMatchingOptions(from,regex);}}if(!hasOptions(from)){return;}for(var i=0;i=0;i--){var o = from.options[i];if(o.selected){from.options[i] = null;}}if((arguments.length=0;i--){if(obj.options[i].selected){if(i !=(obj.options.length-1) && ! obj.options[i+1].selected){swapOptions(obj,i,i+1);obj.options[i+1].selected = true;}}}} function removeSelectedOptions(from){if(!hasOptions(from)){return;}for(var i=(from.options.length-1);i=0;i--){var o=from.options[i];if(o.selected){from.options[i] = null;}}from.selectedIndex = -1;} function removeAllOptions(from){if(!hasOptions(from)){return;}for(var i=(from.options.length-1);i=0;i--){from.options[i] = null;}from.selectedIndex = -1;} function addOption(obj,text,value,selected){if(obj!=null && obj.options!=null){obj.options[obj.options.length] = new Option(text, value, false, selected);}} /* SOURCE FILE: OptionTransfer.js */ function OT_transferLeft(){moveSelectedOptions(this.right,this.left,this.autoSort,this.staticOptionRegex);this.update();} function OT_transferRight(){moveSelectedOptions(this.left,this.right,this.autoSort,this.staticOptionRegex);this.update();} function OT_transferAllLeft(){moveAllOptions(this.right,this.left,this.autoSort,this.staticOptionRegex);this.update();} function OT_transferAllRight(){moveAllOptions(this.left,this.right,this.autoSort,this.staticOptionRegex);this.update();} function OT_saveRemovedLeftOptions(f){this.removedLeftField = f;} function OT_saveRemovedRightOptions(f){this.removedRightField = f;} function OT_saveAddedLeftOptions(f){this.addedLeftField = f;} function OT_saveAddedRightOptions(f){this.addedRightField = f;} function OT_saveNewLeftOptions(f){this.newLeftField = f;} function OT_saveNewRightOptions(f){this.newRightField = f;} function OT_update(){var removedLeft = new Object();var removedRight = new Object();var addedLeft = new Object();var addedRight = new Object();var newLeft = new Object();var newRight = new Object();for(var i=0;i0){str=str+delimiter;}str=str+val;}return str;} function OT_setDelimiter(val){this.delimiter=val;} function OT_setAutoSort(val){this.autoSort=val;} function OT_setStaticOptionRegex(val){this.staticOptionRegex=val;} function OT_init(theform){this.form = theform;if(!theform[this.left]){alert("OptionTransfer init(): Left select list does not exist in form!");return false;}if(!theform[this.right]){alert("OptionTransfer init(): Right select list does not exist in form!");return false;}this.left=theform[this.left];this.right=theform[this.right];for(var i=0;i

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• how to create an function using jquery live? [Solved]

  - by Mahmoud

  Hey all i am trying to create a function that well keep the user in lightbox images while he adds to cart, for a demo you can visit secure.sabayafrah.com username: mahmud password: mahmud when you click at any image it well enlarge using lightbox v2, so when the user clicks at the image add, it well refresh the page, when i asked about it at jcart support form they informed me to use jquery live, but i dont know how to do it but as far as i tried this code which i used but still nothing is happening jQuery(function($) { $('#button') .livequery(eventType, function(event) { alert('clicked'); // to check if it works or not return false; }); }); i also used jQuery(function($) { $('input=[name=addto') .livequery(eventType, function(event) { alert('clicked'); // to check if it works or not return false; }); }); yet nothing worked for code to create those images http://pasite.org/code/572 Update 1: i have done this function adding(form){ $( "form.jcart" ).livequery('submit', function() {var b=$(this).find('input[name=<?php echo $jcart['item_id']?>]').val();var c=$(this).find('input[name=<?php echo $jcart['item_price']?>]').val();var d=$(this).find('input[name=<?php echo $jcart['item_name']?>]').val();var e=$(this).find('input[name=<?php echo $jcart['item_qty']?>]').val();var f=$(this).find('input[name=<?php echo $jcart['item_add']?>]').val();$.post('<?php echo $jcart['path'];?>jcart-relay.php',{"<?php echo $jcart['item_id']?>":b,"<?php echo $jcart['item_price']?>":c,"<?php echo $jcart['item_name']?>":d,"<?php echo $jcart['item_qty']?>":e,"<?php echo $jcart['item_add']?>":f} }); return false; } and it seems to add to jcart but yet it still refreshes

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• FindWindowEx from user32.dll is returning a handle of Zero and error code of 127 using dllimport

  - by puretechy

  I need to handle another windows application programatically, searching google I found a sample which handles windows calculator using DLLImport Attribute and importing the user32.dll functions into managed ones in C#. The application is running, I am getting the handle for the main window i.e. Calculator itself, but the afterwards code is not working. The FindWindowEx method is not returning the handles of the children of the Calculator like buttons and textbox. I have tried using the SetLastError=True on DLLImport and found that I am getting an error code of 127 which is "Procedure not found". This is the link from where I got sample application: http://www.codeproject.com/script/Articles/ArticleVersion.aspx?aid=14519&av=34503 Please help if anyone knows how to solve it. UPDATE: The DLLImport is: [DllImport("user32.dll", SetLastError = true)] public static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string className, string windowTitle); The Code that is not working is: hwnd=FindWindow(null,"Calculator"); // This is working, I am getting handle of Calculator // The following is not working, I am getting hwndChild=0 and err = 127 hwndChild = FindWindowEx((IntPtr)hwnd,IntPtr.Zero,"Button","1"); Int32 err = Marshal.GetLastWin32Error();

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• How to handle window closed in the middle of a long running operation gracefully?

  - by Marek

  We have the following method called directly from the UI thread: void DoLengthyProcessing() { DoStuff(); var items = DoMoreStuff(); //do even more stuff - 200 lines of code trimmed this.someControl.PrepareForBigThing(); //someControl is a big user control //additional 100 lines of code that access this.someControl this.someControl.Finish(items); } Many of the called methods call Application.DoEvents() (and they do so many times) (do not ask me why, this is black magic written by black magic programmers and it can not be changed because everyone is scared what the impact would be) and there is also an operation running on a background thread involved in the processing. As a result, the window is not fully nonresponsive and can be closed manually during the processing. The Dispose method of the form "releases" the someControl variable by setting it to null. As a result, in case the user closes the window during the lengthy process, a null reference exception is thrown. How to handle this gracefully without just catching and logging the exception caused by disposal? Assigning the someControl instance to a temporary variable in the beginning of the method - but the control contains many subcontrols with similar disposal scheme - sets them to null and this causes null reference exceptions in other place put if (this.IsDisposed) return; calls before every access of the someControl variable. - making the already nasty long method even longer and unreadable. in Closing event, just indicate that we should close and only hide the window. Dispose it at the end of the lengthy operation. This is not very viable because there are many other methods involved (think 20K LOC for a single control) that would need to handle this mechanism as well. How to most effectively handle window disposal (by user action) in the middle of this kind of processing?

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• How should I handle expected errors? eg. "username already exists"

  - by Pheter

  I am struggling to understand how I should design the error handling parts of my code. I recently asked a similar question about how I should go about returning server error codes to the user, eg. 404 errors. I learnt that I should handle the error from within the current part of the application; seem's simple enough. However, what should I do when I can't handle the error from the current link in the chain? For example, I may have a class that is used to manage authentication. One of it's methods could be createUser($username, $password). Within that function, I need to determine if the username already exists. If this is true, how should I alert the calling code about this? Returning null instead of a user object is one way. But how do I then know what caused the error? How should I handle errors in such a way that calling code can easily find out what caused the error? Is there a design pattern commonly used for this kind of situation?

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• Inline function v. Macro in C -- What's the Overhead (Memory/Speed)?

  - by Jason R. Mick

  I searched Stack Overflow for the pros/cons of function-like macros v. inline functions. I found the following discussion: Pros and Cons of Different macro function / inline methods in C ...but it didn't answer my primary burning question. Namely, what is the overhead in c of using a macro function (with variables, possibly other function calls) v. an inline function, in terms of memory usage and execution speed? Are there any compiler-dependent differences in overhead? I have both icc and gcc at my disposal. My code snippet I'm modularizing is: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = AttractiveTerm * AttractiveTerm; EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); My reason for turning it into an inline function/macro is so I can drop it into a c file and then conditionally compile other similar, but slightly different functions/macros. e.g.: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = pow(SigmaSquared/RadialDistanceSquared,9); EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); (note the difference in the second line...) This function is a central one to my code and gets called thousands of times per step in my program and my program performs millions of steps. Thus I want to have the LEAST overhead possible, hence why I'm wasting time worrying about the overhead of inlining v. transforming the code into a macro. Based on the prior discussion I already realize other pros/cons (type independence and resulting errors from that) of macros... but what I want to know most, and don't currently know is the PERFORMANCE. I know some of you C veterans will have some great insight for me!!

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• Alter a function as a parameter before evaluating it in R?

  - by Shane

  Is there any way, given a function passed as a parameter, to alter its input parameter string before evaluating it? Here's pseudo-code for what I'm hoping to achieve: test.func <- function(a, b) { # here I want to alter the b expression before evaluating it: b(..., val1=a) } Given the function call passed to b, I want to add in a as another parameter without needing to always specify ... in the b call. So the output from this test.func call should be: test.func(a="a", b=paste(1, 2)) "1" "2" "a" Edit: Another way I could see doing something like this would be if I could assign the additional parameter within the scope of the parent function (again, as pseudo-code); in this case a would be within the scope of t1 and hence t2, but not globally assigned: t2 <- function(...) { paste(a=a, ...) } t1 <- function(a, b) { local( { a <<- a; b } ) } t1(a="a", b=t2(1, 2)) This is somewhat akin to currying in that I'm nesting the parameter within the function itself. Edit 2: Just to add one more comment to this: I realize that one related approach could be to use "prototype-based programming" such that things would be inherited (which could be achieved with the proto package). But I was hoping for a easier way to simply alter the input parameters before evaluating in R.

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• About Web service ,how to use Ajax to call a specific member function of a class?

  - by Liu chwen

  I'm trying to build a web service by PHP. In my case, I called the getINFO(), but the return value on client side always null. Have no idea to solve this problem.. Here's the SOAPserver code(WS.WEB_s.php): require("WEB_s.php"); ini_set("soap.wsdl_cache_enabled", 0); $server = new SoapServer('wsdl/WEB_s.wsdl'); $server->setClass("WEB_s"); $server->handle(); Where the main Class is(WEB_s.php): final class WEB_s { public function getINFO(){ $JsonOutput = '{"key":"value",...}'; return $JsonOutput; } public function setWAN($setCommand,$newConfigfilePath){ $bOutput; return $bOutput; } } And Client side: $(document).ready(function(){ $('#qqq').button().click(function(){ var soapMessage = LoginSoap($('#uid').val(),$('#pwd').val()); alert('soapMessage'); $.ajax({ //url: 'libraries/WS.WEB_s.php/WEB_s/getINFO',//success , return null //url: 'libraries/WS.WEB_s.php/', //success , return null url: 'libraries/WS.WEB_s.php/getINFO',//success , return null type: 'GET', timeout: (10* 1000), contentType: "text/xml", dataType: "xml", success: function( data,textStatus,jqXHR){ alert('Server success(' + data+')('+ textStatus + ')(' + jqXHR + ')'); }, error: function (request, status, error) { alert('Server Error(' + status+')->'+error); }, complete: function (jqXHR, textStatus) { alert('Server success(' + jqXHR+')('+ textStatus + ')'); } }); }); }); The following is the corresponding WSDL file : http://codepaste.net/95wq9b

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• How to handle javascript & css files across a site?

  - by Industrial

  Hi everybody, I have had some thoughts recently on how to handle shared javascript and css files across a web application. In a current web application that I am working on, I got quite a large number of different javascripts and css files that are placed in an folder on the server. Some of the files are reused, while others are not. In a production site, it's quite stupid to have a high number of HTTP requests and many kilobytes of unnecessary javascript and redundant css being loaded. The solution to that is of course to create one big bundled file per page that only contains the necessary information, which then is minimized and sent compressed (GZIP) to the client. There's no worries to create a bundle of javascript files and minimize them manually if you were going to do it once, but since the app is continuously maintained and things do change and develop, it quite soon becomes a headache to do this manually while pushing out new updates that features changes to javascripts and/or css files to production. What's a good approach to handle this? How do you handle this in your application?

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• How to use a variable in a function expression which is injected in a page?

  - by anonymous

  I'm trying to inject a function into a webpage via Chrome extension content script by: function inject(code) { var actualCode = '(' + code + ')();'; var script = document.createElement('script'); script.textContent = actualCode; (document.head||document.documentElement).appendChild(script); script.parentNode.removeChild(script); } var myObj = person; // myObj/person is passed in from elsewhere var fn = function() { alert(myObj.name); }; inject(fn); // myObj undefined My issue is, since fn is a function expression, I can't pass in myObj.personName. So my question is, how can I construct a function expression that includes a variable? Do I do some sort of string concatenation instead? I also tried to pass the object to the function, as follows: function inject(code, myObj) { var actualCode = '(' + code + ')(' + myObj +');'; ... But this did not work, and caused a "Uncaught SyntaxError: Unexpected identifier" error. Related: Building a Chrome Extension - Inject code in a page using a Content script

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• How to handle exceptions from an image-generating Servlet?

  - by ssahmed555

  I have a simple (Servlet, JSP, and JSTL) web app whose main functionality is displaying images retrieved from a back-end server. The controller servlet forwards the user to a JSP that in turn uses another Servlet to display the resulting image on that same JSP. Further down, the JSP has a line similar to: <a href="<c:out value='${imageURL}'/>"><img src="<c:out value='${imageURL}'/>" alt="image view" border="1"></a> which invokes a GET request on the image-generating servlet causing it to generate the image. My question is: how do I handle Exceptions thrown by this image-generating servlet? I already have an error page defined (in web.xml) to handle ServletException within my web app but this doesn't work for this image-generating Servlet, and results in the following errors showing up in my Tomcat server logs: SEVERE: Exception Processing ErrorPage[exceptionType=javax.servlet.ServletException, location=/WEB-INF/ExceptionPage.jsp] java.lang.IllegalStateException: Cannot reset buffer after response has been committed What's my recourse in this situation? I'd like to be able to handle Exceptions thrown from this image-generating Servlet, and display some error on the main UI or forward the user to another error page.

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• Understanding C# async / await (2) Awaitable / Awaiter Pattern

  - by Dixin

  What is awaitable Part 1 shows that any Task is awaitable. Actually there are other awaitable types. Here is an example: Task<int> task = new Task<int>(() => 0); int result = await task.ConfigureAwait(false); // Returns a ConfiguredTaskAwaitable<TResult>. The returned ConfiguredTaskAwaitable<TResult> struct is awaitable. And it is not Task at all: public struct ConfiguredTaskAwaitable<TResult> { private readonly ConfiguredTaskAwaiter m_configuredTaskAwaiter; internal ConfiguredTaskAwaitable(Task<TResult> task, bool continueOnCapturedContext) { this.m_configuredTaskAwaiter = new ConfiguredTaskAwaiter(task, continueOnCapturedContext); } public ConfiguredTaskAwaiter GetAwaiter() { return this.m_configuredTaskAwaiter; } } It has one GetAwaiter() method. Actually in part 1 we have seen that Task has GetAwaiter() method too: public class Task { public TaskAwaiter GetAwaiter() { return new TaskAwaiter(this); } } public class Task<TResult> : Task { public new TaskAwaiter<TResult> GetAwaiter() { return new TaskAwaiter<TResult>(this); } } Task.Yield() is a another example: await Task.Yield(); // Returns a YieldAwaitable. The returned YieldAwaitable is not Task either: public struct YieldAwaitable { public YieldAwaiter GetAwaiter() { return default(YieldAwaiter); } } Again, it just has one GetAwaiter() method. In this article, we will look at what is awaitable. The awaitable / awaiter pattern By observing different awaitable / awaiter types, we can tell that an object is awaitable if It has a GetAwaiter() method (instance method or extension method); Its GetAwaiter() method returns an awaiter. An object is an awaiter if: It implements INotifyCompletion or ICriticalNotifyCompletion interface; It has an IsCompleted, which has a getter and returns a Boolean; it has a GetResult() method, which returns void, or a result. This awaitable / awaiter pattern is very similar to the iteratable / iterator pattern. Here is the interface definitions of iteratable / iterator: public interface IEnumerable { IEnumerator GetEnumerator(); } public interface IEnumerator { object Current { get; } bool MoveNext(); void Reset(); } public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IDisposable, IEnumerator { T Current { get; } } In case you are not familiar with the out keyword, please find out the explanation in Understanding C# Covariance And Contravariance (2) Interfaces. The “missing” IAwaitable / IAwaiter interfaces Similar to IEnumerable and IEnumerator interfaces, awaitable / awaiter can be visualized by IAwaitable / IAwaiter interfaces too. This is the non-generic version: public interface IAwaitable { IAwaiter GetAwaiter(); } public interface IAwaiter : INotifyCompletion // or ICriticalNotifyCompletion { // INotifyCompletion has one method: void OnCompleted(Action continuation); // ICriticalNotifyCompletion implements INotifyCompletion, // also has this method: void UnsafeOnCompleted(Action continuation); bool IsCompleted { get; } void GetResult(); } Please notice GetResult() returns void here. Task.GetAwaiter() / TaskAwaiter.GetResult() is of such case. And this is the generic version: public interface IAwaitable<out TResult> { IAwaiter<TResult> GetAwaiter(); } public interface IAwaiter<out TResult> : INotifyCompletion // or ICriticalNotifyCompletion { bool IsCompleted { get; } TResult GetResult(); } Here the only difference is, GetResult() return a result. Task<TResult>.GetAwaiter() / TaskAwaiter<TResult>.GetResult() is of this case. Please notice .NET does not define these IAwaitable / IAwaiter interfaces at all. As an UI designer, I guess the reason is, IAwaitable interface will constraint GetAwaiter() to be instance method. Actually C# supports both GetAwaiter() instance method and GetAwaiter() extension method. Here I use these interfaces only for better visualizing what is awaitable / awaiter. Now, if looking at above ConfiguredTaskAwaitable / ConfiguredTaskAwaiter, YieldAwaitable / YieldAwaiter, Task / TaskAwaiter pairs again, they all “implicitly” implement these “missing” IAwaitable / IAwaiter interfaces. In the next part, we will see how to implement awaitable / awaiter. Await any function / action In C# await cannot be used with lambda. This code: int result = await (() => 0); will cause a compiler error: Cannot await 'lambda expression' This is easy to understand because this lambda expression (() => 0) may be a function or a expression tree. Obviously we mean function here, and we can tell compiler in this way: int result = await new Func<int>(() => 0); It causes an different error: Cannot await 'System.Func<int>' OK, now the compiler is complaining the type instead of syntax. With the understanding of the awaitable / awaiter pattern, Func<TResult> type can be easily made into awaitable. GetAwaiter() instance method, using IAwaitable / IAwaiter interfaces First, similar to above ConfiguredTaskAwaitable<TResult>, a FuncAwaitable<TResult> can be implemented to wrap Func<TResult>: internal struct FuncAwaitable<TResult> : IAwaitable<TResult> { private readonly Func<TResult> function; public FuncAwaitable(Func<TResult> function) { this.function = function; } public IAwaiter<TResult> GetAwaiter() { return new FuncAwaiter<TResult>(this.function); } } FuncAwaitable<TResult> wrapper is used to implement IAwaitable<TResult>, so it has one instance method, GetAwaiter(), which returns a IAwaiter<TResult>, which wraps that Func<TResult> too. FuncAwaiter<TResult> is used to implement IAwaiter<TResult>: public struct FuncAwaiter<TResult> : IAwaiter<TResult> { private readonly Task<TResult> task; public FuncAwaiter(Func<TResult> function) { this.task = new Task<TResult>(function); this.task.Start(); } bool IAwaiter<TResult>.IsCompleted { get { return this.task.IsCompleted; } } TResult IAwaiter<TResult>.GetResult() { return this.task.Result; } void INotifyCompletion.OnCompleted(Action continuation) { new Task(continuation).Start(); } } Now a function can be awaited in this way: int result = await new FuncAwaitable<int>(() => 0); GetAwaiter() extension method As IAwaitable shows, all that an awaitable needs is just a GetAwaiter() method. In above code, FuncAwaitable<TResult> is created as a wrapper of Func<TResult> and implements IAwaitable<TResult>, so that there is a  GetAwaiter() instance method. If a GetAwaiter() extension method  can be defined for Func<TResult>, then FuncAwaitable<TResult> is no longer needed: public static class FuncExtensions { public static IAwaiter<TResult> GetAwaiter<TResult>(this Func<TResult> function) { return new FuncAwaiter<TResult>(function); } } So a Func<TResult> function can be directly awaited: int result = await new Func<int>(() => 0); Using the existing awaitable / awaiter - Task / TaskAwaiter Remember the most frequently used awaitable / awaiter - Task / TaskAwaiter. With Task / TaskAwaiter, FuncAwaitable / FuncAwaiter are no longer needed: public static class FuncExtensions { public static TaskAwaiter<TResult> GetAwaiter<TResult>(this Func<TResult> function) { Task<TResult> task = new Task<TResult>(function); task.Start(); return task.GetAwaiter(); // Returns a TaskAwaiter<TResult>. } } Similarly, with this extension method: public static class ActionExtensions { public static TaskAwaiter GetAwaiter(this Action action) { Task task = new Task(action); task.Start(); return task.GetAwaiter(); // Returns a TaskAwaiter. } } an action can be awaited as well: await new Action(() => { }); Now any function / action can be awaited: await new Action(() => HelperMethods.IO()); // or: await new Action(HelperMethods.IO); If function / action has parameter(s), closure can be used: int arg0 = 0; int arg1 = 1; int result = await new Action(() => HelperMethods.IO(arg0, arg1)); Using Task.Run() The above code is used to demonstrate how awaitable / awaiter can be implemented. Because it is a common scenario to await a function / action, so .NET provides a built-in API: Task.Run(): public class Task2 { public static Task Run(Action action) { // The implementation is similar to: Task task = new Task(action); task.Start(); return task; } public static Task<TResult> Run<TResult>(Func<TResult> function) { // The implementation is similar to: Task<TResult> task = new Task<TResult>(function); task.Start(); return task; } } In reality, this is how we await a function: int result = await Task.Run(() => HelperMethods.IO(arg0, arg1)); and await a action: await Task.Run(() => HelperMethods.IO());

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• Convert ddply {plyr} to Oracle R Enterprise, or use with Embedded R Execution

  - by Mark Hornick

  The plyr package contains a set of tools for partitioning a problem into smaller sub-problems that can be more easily processed. One function within {plyr} is ddply, which allows you to specify subsets of a data.frame and then apply a function to each subset. The result is gathered into a single data.frame. Such a capability is very convenient. The function ddply also has a parallel option that if TRUE, will apply the function in parallel, using the backend provided by foreach. This type of functionality is available through Oracle R Enterprise using the ore.groupApply function. In this blog post, we show a few examples from Sean Anderson's "A quick introduction to plyr" to illustrate the correpsonding functionality using ore.groupApply. To get started, we'll create a demo data set and load the plyr package. set.seed(1) d <- data.frame(year = rep(2000:2014, each = 3),         count = round(runif(45, 0, 20))) dim(d) library(plyr) This first example takes the data frame, partitions it by year, and calculates the coefficient of variation of the count, returning a data frame. # Example 1 res <- ddply(d, "year", function(x) {   mean.count <- mean(x$count)   sd.count <- sd(x$count)   cv <- sd.count/mean.count   data.frame(cv.count = cv)   }) To illustrate the equivalent functionality in Oracle R Enterprise, using embedded R execution, we use the ore.groupApply function on the same data, but pushed to the database, creating an ore.frame. The function ore.push creates a temporary table in the database, returning a proxy object, the ore.frame. D <- ore.push(d) res <- ore.groupApply (D, D$year, function(x) {   mean.count <- mean(x$count)   sd.count <- sd(x$count)   cv <- sd.count/mean.count   data.frame(year=x$year[1], cv.count = cv)   }, FUN.VALUE=data.frame(year=1, cv.count=1)) You'll notice the similarities in the first three arguments. With ore.groupApply, we augment the function to return the specific data.frame we want. We also specify the argument FUN.VALUE, which describes the resulting data.frame. From our previous blog posts, you may recall that by default, ore.groupApply returns an ore.list containing the results of each function invocation. To get a data.frame, we specify the structure of the result. The results in both cases are the same, however the ore.groupApply result is an ore.frame. In this case the data stays in the database until it's actually required. This can result in significant memory and time savings whe data is large. R> class(res) [1] "ore.frame" attr(,"package") [1] "OREbase" R> head(res)    year cv.count 1 2000 0.3984848 2 2001 0.6062178 3 2002 0.2309401 4 2003 0.5773503 5 2004 0.3069680 6 2005 0.3431743 To make the ore.groupApply execute in parallel, you can specify the argument parallel with either TRUE, to use default database parallelism, or to a specific number, which serves as a hint to the database as to how many parallel R engines should be used. The next ddply example uses the summarise function, which creates a new data.frame. In ore.groupApply, the year column is passed in with the data. Since no automatic creation of columns takes place, we explicitly set the year column in the data.frame result to the value of the first row, since all rows received by the function have the same year. # Example 2 ddply(d, "year", summarise, mean.count = mean(count)) res <- ore.groupApply (D, D$year, function(x) {   mean.count <- mean(x$count)   data.frame(year=x$year[1], mean.count = mean.count)   }, FUN.VALUE=data.frame(year=1, mean.count=1)) R> head(res)    year mean.count 1 2000 7.666667 2 2001 13.333333 3 2002 15.000000 4 2003 3.000000 5 2004 12.333333 6 2005 14.666667 Example 3 uses the transform function with ddply, which modifies the existing data.frame. With ore.groupApply, we again construct the data.frame explicilty, which is returned as an ore.frame. # Example 3 ddply(d, "year", transform, total.count = sum(count)) res <- ore.groupApply (D, D$year, function(x) {   total.count <- sum(x$count)   data.frame(year=x$year[1], count=x$count, total.count = total.count)   }, FUN.VALUE=data.frame(year=1, count=1, total.count=1)) > head(res)    year count total.count 1 2000 5 23 2 2000 7 23 3 2000 11 23 4 2001 18 40 5 2001 4 40 6 2001 18 40 In Example 4, the mutate function with ddply enables you to define new columns that build on columns just defined. Since the construction of the data.frame using ore.groupApply is explicit, you always have complete control over when and how to use columns. # Example 4 ddply(d, "year", mutate, mu = mean(count), sigma = sd(count),       cv = sigma/mu) res <- ore.groupApply (D, D$year, function(x) {   mu <- mean(x$count)   sigma <- sd(x$count)   cv <- sigma/mu   data.frame(year=x$year[1], count=x$count, mu=mu, sigma=sigma, cv=cv)   }, FUN.VALUE=data.frame(year=1, count=1, mu=1,sigma=1,cv=1)) R> head(res)    year count mu sigma cv 1 2000 5 7.666667 3.055050 0.3984848 2 2000 7 7.666667 3.055050 0.3984848 3 2000 11 7.666667 3.055050 0.3984848 4 2001 18 13.333333 8.082904 0.6062178 5 2001 4 13.333333 8.082904 0.6062178 6 2001 18 13.333333 8.082904 0.6062178 In Example 5, ddply is used to partition data on multiple columns before constructing the result. Realizing this with ore.groupApply involves creating an index column out of the concatenation of the columns used for partitioning. This example also allows us to illustrate using the ORE transparency layer to subset the data. # Example 5 baseball.dat <- subset(baseball, year > 2000) # data from the plyr package x <- ddply(baseball.dat, c("year", "team"), summarize,            homeruns = sum(hr)) We first push the data set to the database to get an ore.frame. We then add the composite column and perform the subset, using the transparency layer. Since the results from database execution are unordered, we will explicitly sort these results and view the first 6 rows. BB.DAT <- ore.push(baseball) BB.DAT$index <- with(BB.DAT, paste(year, team, sep="+")) BB.DAT2 <- subset(BB.DAT, year > 2000) X <- ore.groupApply (BB.DAT2, BB.DAT2$index, function(x) {   data.frame(year=x$year[1], team=x$team[1], homeruns=sum(x$hr))   }, FUN.VALUE=data.frame(year=1, team="A", homeruns=1), parallel=FALSE) res <- ore.sort(X, by=c("year","team")) R> head(res)    year team homeruns 1 2001 ANA 4 2 2001 ARI 155 3 2001 ATL 63 4 2001 BAL 58 5 2001 BOS 77 6 2001 CHA 63 Our next example is derived from the ggplot function documentation. This illustrates the use of ddply within using the ggplot2 package. We first create a data.frame with demo data and use ddply to create some statistics for each group (gp). We then use ggplot to produce the graph. We can take this same code, push the data.frame df to the database and invoke this on the database server. The graph will be returned to the client window, as depicted below. # Example 6 with ggplot2 library(ggplot2) df <- data.frame(gp = factor(rep(letters[1:3], each = 10)),                  y = rnorm(30)) # Compute sample mean and standard deviation in each group library(plyr) ds <- ddply(df, .(gp), summarise, mean = mean(y), sd = sd(y)) # Set up a skeleton ggplot object and add layers: ggplot() +   geom_point(data = df, aes(x = gp, y = y)) +   geom_point(data = ds, aes(x = gp, y = mean),              colour = 'red', size = 3) +   geom_errorbar(data = ds, aes(x = gp, y = mean,                                ymin = mean - sd, ymax = mean + sd),              colour = 'red', width = 0.4) DF <- ore.push(df) ore.tableApply(DF, function(df) {   library(ggplot2)   library(plyr)   ds <- ddply(df, .(gp), summarise, mean = mean(y), sd = sd(y))   ggplot() +     geom_point(data = df, aes(x = gp, y = y)) +     geom_point(data = ds, aes(x = gp, y = mean),                colour = 'red', size = 3) +     geom_errorbar(data = ds, aes(x = gp, y = mean,                                  ymin = mean - sd, ymax = mean + sd),                   colour = 'red', width = 0.4) }) But let's take this one step further. Suppose we wanted to produce multiple graphs, partitioned on some index column. We replicate the data three times and add some noise to the y values, just to make the graphs a little different. We also create an index column to form our three partitions. Note that we've also specified that this should be executed in parallel, allowing Oracle Database to control and manage the server-side R engines. The result of ore.groupApply is an ore.list that contains the three graphs. Each graph can be viewed by printing the list element. df2 <- rbind(df,df,df) df2$y <- df2$y + rnorm(nrow(df2)) df2$index <- c(rep(1,300), rep(2,300), rep(3,300)) DF2 <- ore.push(df2) res <- ore.groupApply(DF2, DF2$index, function(df) {   df <- df[,1:2]   library(ggplot2)   library(plyr)   ds <- ddply(df, .(gp), summarise, mean = mean(y), sd = sd(y))   ggplot() +     geom_point(data = df, aes(x = gp, y = y)) +     geom_point(data = ds, aes(x = gp, y = mean),                colour = 'red', size = 3) +     geom_errorbar(data = ds, aes(x = gp, y = mean,                                  ymin = mean - sd, ymax = mean + sd),                   colour = 'red', width = 0.4)   }, parallel=TRUE) res[[1]] res[[2]] res[[3]] To recap, we've illustrated how various uses of ddply from the plyr package can be realized in ore.groupApply, which affords the user explicit control over the contents of the data.frame result in a straightforward manner. We've also highlighted how ddply can be used within an ore.groupApply call.

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• Self-referencing anonymous closures: is JavaScript incomplete?

  - by Tom Auger

  Does the fact that anonymous self-referencing function closures are so prevelant in JavaScript suggest that JavaScript is an incomplete specification? We see so much of this: (function () { /* do cool stuff */ })(); and I suppose everything is a matter of taste, but does this not look like a kludge, when all you want is a private namespace? Couldn't JavaScript implement packages and proper classes? Compare to ActionScript 3, also based on EMACScript, where you get package com.tomauger { import bar; class Foo { public function Foo(){ // etc... } public function show(){ // show stuff } public function hide(){ // hide stuff } // etc... } } Contrast to the convolutions we perform in JavaScript (this, from the jQuery plugin authoring documentation): (function( $ ){ var methods = { init : function( options ) { // THIS }, show : function( ) { // IS }, hide : function( ) { // GOOD }, update : function( content ) { // !!! } }; $.fn.tooltip = function( method ) { // Method calling logic if ( methods[method] ) { return methods[ method ].apply( this, Array.prototype.slice.call( arguments, 1 )); } else if ( typeof method === 'object' || ! method ) { return methods.init.apply( this, arguments ); } else { $.error( 'Method ' + method + ' does not exist on jQuery.tooltip' ); } }; })( jQuery ); I appreciate that this question could easily degenerate into a rant about preferences and programming styles, but I'm actually very curious to hear how you seasoned programmers feel about this and whether it feels natural, like learning different idiosyncrasies of a new language, or kludgy, like a workaround to some basic programming language components that are just not implemented?

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• Qt : crash due to delete (trying to handle exceptions...)

  - by Seub

  I am writing a program with Qt, and I would like it to show a dialog box with a Exit | Restart choice whenever an error is thrown somewhere in the code. What I did causes a crash and I really can't figure out why it happens, I was hoping you could help me understanding what's going on. Here's my main.cpp: #include "my_application.hpp" int main(int argc, char *argv[]) { std::cout << std::endl; My_Application app(argc, argv); return app.exec(); } And here's my_application:hpp: #ifndef MY_APPLICATION_HPP #define MY_APPLICATION_HPP #include <QApplication> class Window; class My_Application : public QApplication { public: My_Application(int& argc, char ** argv); virtual ~My_Application(); virtual bool notify(QObject * receiver, QEvent * event); private: Window *window_; void exit(); void restart(); }; #endif // MY_APPLICATION_HPP Finally, here's my_application.cpp: #include "my_application.hpp" #include "window.hpp" #include <QMessageBox> My_Application::My_Application(int& argc, char ** argv) : QApplication(argc, argv) { window_ = new Window; window_->setAttribute(Qt::WA_DeleteOnClose, false); window_->show(); } My_Application::~My_Application() { delete window_; } bool My_Application::notify(QObject * receiver, QEvent * event) { try { return QApplication::notify(receiver, event); } catch(QString error_message) { window_->setEnabled(false); QMessageBox message_box; message_box.setWindowTitle("Error"); message_box.setIcon(QMessageBox::Critical); message_box.setText("The program caught an unexpected error:"); message_box.setInformativeText("What do you want to do? <br>"); QPushButton *restart_button = message_box.addButton(tr("Restart"), QMessageBox::RejectRole); QPushButton *exit_button = message_box.addButton(tr("Exit"), QMessageBox::RejectRole); message_box.setDefaultButton(restart_button); message_box.exec(); if ((QPushButton *) message_box.clickedButton() == exit_button) { exit(); } else if ((QPushButton *) message_box.clickedButton() == restart_button) { restart(); } } return false; } void My_Application::exit() { window_->close(); //delete window_; return; } void My_Application::restart() { window_->close(); //delete window_; window_ = new Window; window_->show(); return; } Note that the line window_->setAttribute(Qt::WA_DeleteOnClose, false); means that window_ (my main window) won't be deleted when it is closed. The code I've written above works, but as far as I understand, there's a memory leak: I should uncomment the line //delete window_; in My_Application::exit() and My_Application::restart(). But when I do that, the program crashes when I click restart (or exit but who cares). (I'm not sure this is useful, in fact it might be misleading, but here's what my debugger tells me: a segmentation fault occurs in QWidgetPrivate::PaintOnScreen() const which is called by a function called by a function... called by My_Application::notify()) When I do some std::couts, I notice that the program runs through the entire restart() function and in fact through the entire notify() function before it crashes. I have no idea why it crashes. Thanks in advance for your insights! Update: I've noticed that My_Application::notify() is called very often. For example, it is called a bunch of times while the error dialog box is open, also during the execution of the restart function. The crash actually occurs in the subfunction QApplication::notify(receiver, event). This is not too surprising in light of the previous remark (the receiver has probably been deleted) But even if I forbid the function My_Application::notify() to do anything while restart() is executed, it still crashes (after having called My_Application::notify() a bunch of times, like 15 times, isn't that weird)? How should I proceed? Maybe I should say (to make the question slightly more relevant) that my class My_Application also has a "restore" function, which I've not copied here to try to keep things short. If I just had that restart feature I wouldn't bother too much, but I do want to have that restore feature. I should also say that if I keep the code with the "delete window_" commented, the problem is not only a memory leak, it still crashes sometimes apparently. There must surely be a way to fix this! But I'm clueless, I'd really appreciate some help! Thanks in advance.

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• Conversion from YUV444 to RGB888

  - by Abhi

  I am new in this field and i desperately need some guidance from u all. I have to support yuv444 to rgb 888 in display driver module. There is one test which i have done for yv12 → rgb565 in wince 6.0 r3 which is mentioned below. //------------------------------------------------------------------------------ // // Function: PP_CSC_YV12_RGB565Test // // This function tests the Post-processor // // // // Parameters: // uiMsg // [in] Ignored. // // tpParam // [in] Ignored. // // lpFTE // [in] Ignored. // // Returns: // Specifies if the test passed (TPR_PASS), failed (TPR_FAIL), or was // skipped (TPR_SKIP). // // TESTPROCAPI PP_CSC_YV12_RGB565Test(UINT uMsg, TPPARAM tpParam, LPFUNCTION_TABLE_ENTRY lpFTE) { LogEntry(L"%d : In %s Function \r\n",++abhineet,__WFUNCTION__); UNREFERENCED_PARAMETER(tpParam); UNREFERENCED_PARAMETER(lpFTE); DWORD dwResult= TPR_SKIP; ppConfigData ppData; DWORD iInputBytesPerFrame, iOutputBytesPerFrame; UINT32 iInputStride, iOutputStride; UINT16 iOutputWidth, iOutputHeight, iOutputBPP; UINT16 iInputWidth, iInputHeight, iInputBPP; int iOption; PP_TEST_FUNCTION_ENTRY(); // Validate that the shell wants the test to run if (uMsg != TPM_EXECUTE) { return TPR_NOT_HANDLED; } PPTestInit(); iInputWidth = PP_TEST_FRAME_WIDTH; //116 iInputHeight = PP_TEST_FRAME_HEIGHT; //160 iInputBPP = PP_TEST_FRAME_BPP; //2 iInputStride = iInputWidth * 3/2; // YV12 is 12 bits per pixel iOutputWidth = PP_TEST_FRAME_WIDTH; iOutputHeight = PP_TEST_FRAME_HEIGHT; iOutputBPP = PP_TEST_FRAME_BPP; iOutputStride = iOutputWidth * iOutputBPP; // Allocate buffers for input and output frames iInputBytesPerFrame = iInputStride * iInputHeight; pInputFrameVirtAddr = (UINT32 *) AllocPhysMem(iInputBytesPerFrame, PAGE_EXECUTE_READWRITE, 0, 0, (ULONG *) &pInputFramePhysAddr); iOutputBytesPerFrame = iOutputStride * iOutputHeight; pOutputFrameVirtAddr = (UINT32 *) AllocPhysMem(iOutputBytesPerFrame, PAGE_EXECUTE_READWRITE, 0, 0, (ULONG *) &pOutputFramePhysAddr); if ((NULL == pInputFrameVirtAddr) || (NULL == pOutputFrameVirtAddr)) { dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } //----------------------------- // Configure PP //----------------------------- // Set up post-processing configuration data memset(&ppData, 0 , sizeof(ppData)); // Set up input format and data width ppData.inputIDMAChannel.FrameFormat = icFormat_YUV420; ppData.inputIDMAChannel.DataWidth = icDataWidth_8BPP; // dummy value for YUV ppData.inputIDMAChannel.PixelFormat.component0_offset = 0; ppData.inputIDMAChannel.PixelFormat.component1_offset = 8; ppData.inputIDMAChannel.PixelFormat.component2_offset = 16; ppData.inputIDMAChannel.PixelFormat.component3_offset = 24; ppData.inputIDMAChannel.PixelFormat.component0_width = 8-1; ppData.inputIDMAChannel.PixelFormat.component1_width = 8-1; ppData.inputIDMAChannel.PixelFormat.component2_width = 8-1; ppData.inputIDMAChannel.PixelFormat.component3_width = 8-1; ppData.inputIDMAChannel.FrameSize.height = iInputHeight; ppData.inputIDMAChannel.FrameSize.width = iInputWidth; ppData.inputIDMAChannel.LineStride = iInputWidth; // Set up output format and data width ppData.outputIDMAChannel.FrameFormat = icFormat_RGB; ppData.outputIDMAChannel.DataWidth = icDataWidth_16BPP; ppData.outputIDMAChannel.PixelFormat.component0_offset = RGB_COMPONET0_OFFSET; ppData.outputIDMAChannel.PixelFormat.component1_offset = RGB_COMPONET1_OFFSET; ppData.outputIDMAChannel.PixelFormat.component2_offset = RGB_COMPONET2_OFFSET; ppData.outputIDMAChannel.PixelFormat.component3_offset = RGB_COMPONET3_OFFSET; ppData.outputIDMAChannel.PixelFormat.component0_width = RGB_COMPONET0_WIDTH -1; ppData.outputIDMAChannel.PixelFormat.component1_width = RGB_COMPONET1_WIDTH -1; ppData.outputIDMAChannel.PixelFormat.component2_width = RGB_COMPONET2_WIDTH -1; ppData.outputIDMAChannel.PixelFormat.component3_width = RGB_COMPONET3_WIDTH; ppData.outputIDMAChannel.FrameSize.height = iOutputHeight; ppData.outputIDMAChannel.FrameSize.width = iOutputWidth; ppData.outputIDMAChannel.LineStride = iOutputStride; // Set up post-processing channel CSC parameters // based on input and output ppData.CSCEquation = CSCY2R_A1; ppData.inputIDMAChannel.UBufOffset = iInputHeight * iInputWidth + (iInputHeight * iInputWidth)/4; ppData.inputIDMAChannel.VBufOffset = iInputHeight * iInputWidth; ppData.FlipRot.verticalFlip = FALSE; ppData.FlipRot.horizontalFlip = FALSE; ppData.FlipRot.rotate90 = FALSE; if (!PPConfigure(hPP, &ppData)) { dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } //----------------------------- // Read first input buffer //----------------------------- // Read Input file for new frame if (!ReadImage(PP_TEST_YV12_FILENAME,pInputFrameVirtAddr,iInputBytesPerFrame,PP_TEST_FRAME_WIDTH,PP_TEST_FRAME_HEIGHT)) { g_pKato->Log(PP_ZONE_ERROR, (TEXT("fail to ReadImage()!\r\n"))); dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } //----------------------------- // Start PP //----------------------------- if (!PPStart(hPP)) { dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } if (!PPInterruptEnable(hPP, FRAME_INTERRUPT)) { dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } //----------------------------- // Queue Input/Output Buffers //----------------------------- UINT32 starttime = GetTickCount(); // Add input and output buffers to PP queues. if (!PPAddInputBuffer(hPP, (UINT32) pInputFramePhysAddr)) { dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } if (!PPAddOutputBuffer(hPP,(UINT32) pOutputFramePhysAddr)) { dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } if (!PPWaitForNotBusy(hPP, FRAME_INTERRUPT)) { dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } RETAILMSG(1, (TEXT("===========FLIP TIME: %dms====== \r\n"), GetTickCount()-starttime)); //----------------------------- // Stop PP //----------------------------- if (!PPStop(hPP)) { dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } if (!PPClearBuffers(hPP)) { dwResult = TPR_FAIL; goto PP_CSC_YV12_RGB565Test_clean_up; } ShowRGBContent((UINT8 *) pOutputFrameVirtAddr, PP_TEST_FRAME_WIDTH, PP_TEST_FRAME_HEIGHT); iOption = MessageBox( NULL,TEXT("After CSC(YV12->RGB565). Is it correct?"),TEXT("Test result"),MB_YESNO ); if ( IDNO == iOption ) { dwResult = TPR_FAIL; } else { dwResult = TPR_PASS; } PP_CSC_YV12_RGB565Test_clean_up: if(NULL != pInputFrameVirtAddr) { FreePhysMem( pInputFrameVirtAddr ); pInputFrameVirtAddr = NULL; } if(NULL != pOutputFrameVirtAddr) { FreePhysMem( pOutputFrameVirtAddr ); pOutputFrameVirtAddr = NULL; } PPTestDeInit(); LogEntry(L"%d :Out %s Function \r\n",++abhineet,__WFUNCTION__); return dwResult; } The below is the flow for this function. It tells the start and end of this test. *** vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv *** TEST STARTING *** *** Test Name: PP CSC(YV12-RGB565) Test *** Test ID: 500 *** Library Path: pp_test.dll *** Command Line: *** Kernel Mode: Yes *** Random Seed: 24421 *** Thread Count: 0 *** vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv *******Abhineet-PPTEST : 338 : In ShellProc Function *******Abhineet-PPTEST : 339 : In Debug Function PP_TEST: ShellProc(SPM_BEGIN_TEST, ...) called *******Abhineet-PPTEST : 340 :Out Debug Function BEGIN TEST: "PP CSC(YV12-RGB565) Test", Threads=0, Seed=24421 *******Abhineet-PPTEST : 341 :Out ShellProc Function *******Abhineet-PPTEST : 342 : In PP_CSC_YV12_RGB565Test Function PP_CSC_YV12_RGB565Test *******Abhineet-PPTEST : 343 : In PPTestInit Function *******Abhineet-PPTEST : 344 : In GetPanelDimensions Function *******Abhineet-PPTEST : 345 :Out GetPanelDimensions Function GetPanelDimensions: width=1024 height=768 bpp=16 *******Abhineet-PPTEST : 346 :Out PPTestInit Function *******Abhineet-PPTEST : 347 : In ReadImage Function RELFSD: Opening file flags_112x160.yv12 from desktop *******Abhineet-PPTEST : 348 :Out ReadImage Function ===========FLIP TIME: 1ms====== *******Abhineet-PPTEST : 349 : In ShowRGBContent Function *******Abhineet-PPTEST : 350 :Out ShowRGBContent Function *******Abhineet-PPTEST : 351 : In PPTestDeInit Function *******Abhineet-PPTEST : 352 :Out PPTestDeInit Function *******Abhineet-PPTEST : 353 :Out PP_CSC_YV12_RGB565Test Function *******Abhineet-PPTEST : 354 : In DllMain Function *******Abhineet-PPTEST : 355 :Out DllMain Function *******Abhineet-PPTEST : 356 : In ShellProc Function *******Abhineet-PPTEST : 357 : In Debug Function PP_TEST: ShellProc(SPM_END_TEST, ...) called *******Abhineet-PPTEST : 358 :Out Debug Function END TEST: "PP CSC(YV12-RGB565) Test", PASSED, Time=6.007 *******Abhineet-PPTEST : 359 :Out ShellProc Function *** ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ *** TEST COMPLETED *** *** Test Name: PP CSC(YV12-RGB565) Test *** Test ID: 500 *** Library Path: pp_test.dll *** Command Line: *** Kernel Mode: Yes *** Result: Passed *** Random Seed: 24421 *** Thread Count: 1 *** Execution Time: 0:00:06.007 *** ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Please help me out to make changes to the above function for yuv444-rgb888.

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• More Animation - Self Dismissing Dialogs

  - by Duncan Mills

  In my earlier articles on animation, I discussed various slide, grow and  flip transitions for items and containers.  In this article I want to discuss a fade animation and specifically the use of fades and auto-dismissal for informational dialogs.  If you use a Mac, you may be familiar with Growl as a notification system, and the nice way that messages that are informational just fade out after a few seconds. So in this blog entry I wanted to discuss how we could make an ADF popup behave in the same way. This can be an effective way of communicating information to the user without "getting in the way" with modal alerts. This of course, has been done before, but everything I've seen previously requires something like JQuery to be in the mix when we don't really need it to be.  The solution I've put together is nice and generic and will work with either <af:panelWindow> or <af:dialog> as a the child of the popup. In terms of usage it's pretty simple to use we  just need to ensure that the popup itself has clientComponent is set to true and includes the animation JavaScript (animateFadingPopup) on a popupOpened event: <af:popup id="pop1" clientComponent="true">   <af:panelWindow title="A Fading Message...">    ...  </af:panelWindow>   <af:clientListener method="animateFadingPopup" type="popupOpened"/> </af:popup>   The popup can be invoked in the normal way using showPopupBehavior or JavaScript, no special code is required there. As a further twist you can include an additional clientAttribute called preFadeDelay to define a delay before the fade itself starts (the default is 5 seconds) . To set the delay to just 2 seconds for example: <af:popup ...>   ...   <af:clientAttribute name="preFadeDelay" value="2"/>   <af:clientListener method="animateFadingPopup" type="popupOpened"/>  </af:popup> The Animation Styles  As before, we have a couple of CSS Styles which define the animation, I've put these into the skin in my case, and, as in the other articles, I've only defined the transitions for WebKit browsers (Chrome, Safari) at the moment. In this case, the fade is timed at 5 seconds in duration. .popupFadeReset {   opacity: 1; } .popupFadeAnimate {   opacity: 0;   -webkit-transition: opacity 5s ease-in-out; } As you can see here, we are achieving the fade by simply setting the CSS opacity property. The JavaScript The final part of the puzzle is, of course, the JavaScript, there are four functions, these are generic (apart from the Style names which, if you've changed above, you'll need to reflect here): The initial function invoked from the popupOpened event,  animateFadingPopup which starts a timer and provides the initial delay before we start to fade the popup. The function that applies the fade animation to the popup - initiatePopupFade. The callback function - closeFadedPopup used to reset the style class and correctly hide the popup so that it can be invoked again and again.   A utility function - findFadeContainer, which is responsible for locating the correct child component of the popup to actually apply the style to. Function - animateFadingPopup This function, as stated is the one hooked up to the popupOpened event via a clientListener. Because of when the code is called it does not actually matter how you launch the popup, or if the popup is re-used from multiple places. All usages will get the fade behavior. /**  * Client listener which will kick off the animation to fade the dialog and register  * a callback to correctly reset the popup once the animation is complete  * @param event  */ function animateFadingPopup(event) { var fadePopup = event.getSource();   var fadeCandidate = false;   //Ensure that the popup is initially Opaque   //This handles the situation where the user has dismissed   //the popup whilst it was in the process of fading   var fadeContainer = findFadeContainer(fadePopup);   if (fadeContainer != null) {     fadeCandidate = true;     fadeContainer.setStyleClass("popupFadeReset");   }   //Only continue if we can actually fade this popup   if (fadeCandidate) {   //See if a delay has been specified     var waitTimeSeconds = event.getSource().getProperty('preFadeDelay');     //Default to 5 seconds if not supplied     if (waitTimeSeconds == undefined) {     waitTimeSeconds = 5;     }     // Now call the fade after the specified time     var fadeFunction = function () {     initiatePopupFade(fadePopup);     };     var fadeDelayTimer = setTimeout(fadeFunction, (waitTimeSeconds * 1000));   } } The things to note about this function is the initial check that we have to do to ensure that the container is currently visible and reset it's style to ensure that it is.  This is to handle the situation where the popup has begun the fade, and yet the user has still explicitly dismissed the popup before it's complete and in doing so has prevented the callback function (described later) from executing. In this particular situation the initial display of the dialog will be (apparently) missing it's normal animation but at least it becomes visible to the user (and most users will probably not notice this difference in any case). You'll notice that the style that we apply to reset the  opacity - popupFadeReset, is not applied to the popup component itself but rather the dialog or panelWindow within it. More about that in the description of the next function findFadeContainer(). Finally, assuming that we have a suitable candidate for fading, a JavaScript  timer is started using the specified preFadeDelay wait time (or 5 seconds if that was not supplied). When this timer expires then the main animation styleclass will be applied using the initiatePopupFade() function Function - findFadeContainer As a component, the <af:popup> does not support styleClass attribute, so we can't apply the animation style directly.  Instead we have to look for the container within the popup which defines the window object that can have a style attached.  This is achieved by the following code: /**  * The thing we actually fade will be the only child  * of the popup assuming that this is a dialog or window  * @param popup  * @return the component, or null if this is not valid for fading  */ function findFadeContainer(popup) { var children = popup.getDescendantComponents();   var fadeContainer = children[0];   if (fadeContainer != undefined) {   var compType = fadeContainer.getComponentType();     if (compType == "oracle.adf.RichPanelWindow" || compType == "oracle.adf.RichDialog") {     return fadeContainer;     }   }   return null; }  So what we do here is to grab the first child component of the popup and check its type. Here I decided to limit the fade behaviour to only <af:dialog> and <af:panelWindow>. This was deliberate.  If  we apply the fade to say an <af:noteWindow> you would see the text inside the balloon fade, but the balloon itself would hang around until the fade animation was over and then hide.  It would of course be possible to make the code smarter to walk up the DOM tree to find the correct <div> to apply the style to in order to hide the whole balloon, however, that means that this JavaScript would then need to have knowledge of the generated DOM structure, something which may change from release to release, and certainly something to avoid. So, all in all, I think that this is an OK restriction and frankly it's windows and dialogs that I wanted to fade anyway, not balloons and menus. You could of course extend this technique and handle the other types should you really want to. One thing to note here is the selection of the first (children[0]) child of the popup. It does not matter if there are non-visible children such as clientListener before the <af:dialog> or <af:panelWindow> within the popup, they are not included in this array, so picking the first element in this way seems to be fine, no matter what the underlying ordering is within the JSF source.  If you wanted a super-robust version of the code you might want to iterate through the children array of the popup to check for the right type, again it's up to you.  Function -  initiatePopupFade  On to the actual fading. This is actually very simple and at it's heart, just the application of the popupFadeAnimate style to the correct component and then registering a callback to execute once the fade is done. /**  * Function which will kick off the animation to fade the dialog and register  * a callback to correctly reset the popup once the animation is complete  * @param popup the popup we are animating  */ function initiatePopupFade(popup) { //Only continue if the popup has not already been dismissed    if (popup.isPopupVisible()) {   //The skin styles that define the animation      var fadeoutAnimationStyle = "popupFadeAnimate";     var fadeAnimationResetStyle = "popupFadeReset";     var fadeContainer = findFadeContainer(popup);     if (fadeContainer != null) {     var fadeContainerReal = AdfAgent.AGENT.getElementById(fadeContainer.getClientId());       //Define the callback this will correctly reset the popup once it's disappeared       var fadeCallbackFunction = function (event) {       closeFadedPopup(popup, fadeContainer, fadeAnimationResetStyle);         event.target.removeEventListener("webkitTransitionEnd", fadeCallbackFunction);       };       //Initiate the fade       fadeContainer.setStyleClass(fadeoutAnimationStyle);       //Register the callback to execute once fade is done       fadeContainerReal.addEventListener("webkitTransitionEnd", fadeCallbackFunction, false);     }   } } I've added some extra checks here though. First of all we only start the whole process if the popup is still visible. It may be that the user has closed the popup before the delay timer has finished so there is no need to start animating in that case. Again we use the findFadeContainer() function to locate the correct component to apply the style to, and additionally we grab the DOM id that represents that container.  This physical ID is required for the registration of the callback function. The closeFadedPopup() call is then registered on the callback so as to correctly close the now transparent (but still there) popup. Function -  closeFadedPopup The final function just cleans things up: /**  * Callback function to correctly cancel and reset the style in the popup  * @param popup id of the popup so we can close it properly  * @param contatiner the window / dialog within the popup to actually style  * @param resetStyle the syle that sets the opacity back to solid  */ function closeFadedPopup(popup, container, resetStyle) { container.setStyleClass(resetStyle);   popup.cancel(); }  First of all we reset the style to make the popup contents opaque again and then we cancel the popup.  This will ensure that any of your user code that is waiting for a popup cancelled event will actually get the event, additionally if you have done this as a modal window / dialog it will ensure that the glasspane is dismissed and you can interact with the UI again.  What's Next? There are several ways in which this technique could be used, I've been working on a popup here, but you could apply the same approach to in-line messages. As this code (in the popup case) is generic it will make s pretty nice declarative component and maybe, if I get time, I'll look at constructing a formal Growl component using a combination of this technique, and active data push. Also, I'm sure the above code can be improved a little too.  Specifically things like registering a popup cancelled listener to handle the style reset so that we don't loose the subtle animation that takes place when the popup is opened in that situation where the user has closed the in-fade dialog.

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• Is this a reasonable way to handle getters/setters in a PHP class?

  - by Mark Biek

  I'm going to try something with the format of this question and I'm very open to suggestions about a better way to handle it. I didn't want to just dump a bunch of code in the question so I've posted the code for the class on refactormycode. base-class-for-easy-class-property-handling My thought was that people can either post code snippets here or make changes on refactormycode and post links back to their refactorings. I'll make upvotes and accept an answer (assuming there's a clear "winner") based on that. At any rate, on to the class itself: I see a lot of debate about getter/setter class methods and is it better to just access simple property variables directly or should every class have explicit get/set methods defined, blah blah blah. I like the idea of having explicit methods in case you have to add more logic later. Then you don't have to modify any code that uses the class. However I hate having a million functions that look like this: public function getFirstName() { return $this->firstName; } public function setFirstName($firstName) { return $this->firstName; } Now I'm sure I'm not the first person to do this (I'm hoping that there's a better way of doing it that someone can suggest to me). Basically, the PropertyHandler class has a __call magic method. Any methods that come through __call that start with "get" or "set" are then routed to functions that set or retrieve values into an associative array. The key into the array is the name of the calling method after get or set. So, if the method coming into __call is "getFirstName", the array key is "FirstName". I liked using __call because it will automatically take care of the case where the subclass already has a "getFirstName" method defined. My impression (and I may be wrong) is that the __get & __set magic methods don't do that. So here's an example of how it would work: class PropTest extends PropertyHandler { public function __construct() { parent::__construct(); } } $props = new PropTest(); $props->setFirstName("Mark"); echo $props->getFirstName(); Notice that PropTest doesn't actually have "setFirstName" or "getFirstName" methods and neither does PropertyHandler. All that's doing is manipulating array values. The other case would be where your subclass is already extending something else. Since you can't have true multiple inheritance in PHP, you can make your subclass have a PropertyHandler instance as a private variable. You have to add one more function but then things behave in exactly the same way. class PropTest2 { private $props; public function __construct() { $this->props = new PropertyHandler(); } public function __call($method, $arguments) { return $this->props->__call($method, $arguments); } } $props2 = new PropTest2(); $props2->setFirstName('Mark'); echo $props2->getFirstName(); Notice how the subclass has a __call method that just passes everything along to the PropertyHandler __call method. Another good argument against handling getters and setters this way is that it makes it really hard to document. In fact, it's basically impossible to use any sort of document generation tool since the explicit methods to be don't documented don't exist. I've pretty much abandoned this approach for now. It was an interesting learning exercise but I think it sacrifices too much clarity.

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• Metro: Declarative Data Binding

  - by Stephen.Walther

  The goal of this blog post is to describe how declarative data binding works in the WinJS library. In particular, you learn how to use both the data-win-bind and data-win-bindsource attributes. You also learn how to use calculated properties and converters to format the value of a property automatically when performing data binding. By taking advantage of WinJS data binding, you can use the Model-View-ViewModel (MVVM) pattern when building Metro style applications with JavaScript. By using the MVVM pattern, you can prevent your JavaScript code from spinning into chaos. The MVVM pattern provides you with a standard pattern for organizing your JavaScript code which results in a more maintainable application. Using Declarative Bindings You can use the data-win-bind attribute with any HTML element in a page. The data-win-bind attribute enables you to bind (associate) an attribute of an HTML element to the value of a property. Imagine, for example, that you want to create a product details page. You want to show a product object in a page. In that case, you can create the following HTML page to display the product details: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <h1>Product Details</h1> <div class="field"> Product Name: <span data-win-bind="innerText:name"></span> </div> <div class="field"> Product Price: <span data-win-bind="innerText:price"></span> </div> <div class="field"> Product Picture: <br /> <img data-win-bind="src:photo;alt:name" /> </div> </body> </html> The HTML page above contains three data-win-bind attributes – one attribute for each product property displayed. You use the data-win-bind attribute to set properties of the HTML element associated with the data-win-attribute. The data-win-bind attribute takes a semicolon delimited list of element property names and data source property names: data-win-bind=”elementPropertyName:datasourcePropertyName; elementPropertyName:datasourcePropertyName;…” In the HTML page above, the first two data-win-bind attributes are used to set the values of the innerText property of the SPAN elements. The last data-win-bind attribute is used to set the values of the IMG element’s src and alt attributes. By the way, using data-win-bind attributes is perfectly valid HTML5. The HTML5 standard enables you to add custom attributes to an HTML document just as long as the custom attributes start with the prefix data-. So you can add custom attributes to an HTML5 document with names like data-stephen, data-funky, or data-rover-dog-is-hungry and your document will validate. The product object displayed in the page above with the data-win-bind attributes is created in the default.js file: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { var product = { name: "Tesla", price: 80000, photo: "/images/TeslaPhoto.png" }; WinJS.Binding.processAll(null, product); } }; app.start(); })(); In the code above, a product object is created with a name, price, and photo property. The WinJS.Binding.processAll() method is called to perform the actual binding (Don’t confuse WinJS.Binding.processAll() and WinJS.UI.processAll() – these are different methods). The first parameter passed to the processAll() method represents the root element for the binding. In other words, binding happens on this element and its child elements. If you provide the value null, then binding happens on the entire body of the document (document.body). The second parameter represents the data context. This is the object that has the properties which are displayed with the data-win-bind attributes. In the code above, the product object is passed as the data context parameter. Another word for data context is view model.  Creating Complex View Models In the previous section, we used the data-win-bind attribute to display the properties of a simple object: a single product. However, you can use binding with more complex view models including view models which represent multiple objects. For example, the view model in the following default.js file represents both a customer and a product object. Furthermore, the customer object has a nested address object: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { var viewModel = { customer: { firstName: "Fred", lastName: "Flintstone", address: { street: "1 Rocky Way", city: "Bedrock", country: "USA" } }, product: { name: "Bowling Ball", price: 34.55 } }; WinJS.Binding.processAll(null, viewModel); } }; app.start(); })(); The following page displays the customer (including the customer address) and the product. Notice that you can use dot notation to refer to child objects in a view model such as customer.address.street. <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <h1>Customer Details</h1> <div class="field"> First Name: <span data-win-bind="innerText:customer.firstName"></span> </div> <div class="field"> Last Name: <span data-win-bind="innerText:customer.lastName"></span> </div> <div class="field"> Address: <address> <span data-win-bind="innerText:customer.address.street"></span> <br /> <span data-win-bind="innerText:customer.address.city"></span> <br /> <span data-win-bind="innerText:customer.address.country"></span> </address> </div> <h1>Product</h1> <div class="field"> Name: <span data-win-bind="innerText:product.name"></span> </div> <div class="field"> Price: <span data-win-bind="innerText:product.price"></span> </div> </body> </html> A view model can be as complicated as you need and you can bind the view model to a view (an HTML document) by using declarative bindings. Creating Calculated Properties You might want to modify a property before displaying the property. For example, you might want to format the product price property before displaying the property. You don’t want to display the raw product price “80000”. Instead, you want to display the formatted price “$80,000”. You also might need to combine multiple properties. For example, you might need to display the customer full name by combining the values of the customer first and last name properties. In these situations, it is tempting to call a function when performing binding. For example, you could create a function named fullName() which concatenates the customer first and last name. Unfortunately, the WinJS library does not support the following syntax: <span data-win-bind=”innerText:fullName()”></span> Instead, in these situations, you should create a new property in your view model that has a getter. For example, the customer object in the following default.js file includes a property named fullName which combines the values of the firstName and lastName properties: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { var customer = { firstName: "Fred", lastName: "Flintstone", get fullName() { return this.firstName + " " + this.lastName; } }; WinJS.Binding.processAll(null, customer); } }; app.start(); })(); The customer object has a firstName, lastName, and fullName property. Notice that the fullName property is defined with a getter function. When you read the fullName property, the values of the firstName and lastName properties are concatenated and returned. The following HTML page displays the fullName property in an H1 element. You can use the fullName property in a data-win-bind attribute in exactly the same way as any other property. <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <h1 data-win-bind="innerText:fullName"></h1> <div class="field"> First Name: <span data-win-bind="innerText:firstName"></span> </div> <div class="field"> Last Name: <span data-win-bind="innerText:lastName"></span> </div> </body> </html> Creating a Converter In the previous section, you learned how to format the value of a property by creating a property with a getter. This approach makes sense when the formatting logic is specific to a particular view model. If, on the other hand, you need to perform the same type of formatting for multiple view models then it makes more sense to create a converter function. A converter function is a function which you can apply whenever you are using the data-win-bind attribute. Imagine, for example, that you want to create a general function for displaying dates. You always want to display dates using a short format such as 12/25/1988. The following JavaScript file – named converters.js – contains a shortDate() converter: (function (WinJS) { var shortDate = WinJS.Binding.converter(function (date) { return date.getMonth() + 1 + "/" + date.getDate() + "/" + date.getFullYear(); }); // Export shortDate WinJS.Namespace.define("MyApp.Converters", { shortDate: shortDate }); })(WinJS); The file above uses the Module Pattern, a pattern which is used through the WinJS library. To learn more about the Module Pattern, see my blog entry on namespaces and modules: http://stephenwalther.com/blog/archive/2012/02/22/windows-web-applications-namespaces-and-modules.aspx The file contains the definition for a converter function named shortDate(). This function converts a JavaScript date object into a short date string such as 12/1/1988. The converter function is created with the help of the WinJS.Binding.converter() method. This method takes a normal function and converts it into a converter function. Finally, the shortDate() converter is added to the MyApp.Converters namespace. You can call the shortDate() function by calling MyApp.Converters.shortDate(). The default.js file contains the customer object that we want to bind. Notice that the customer object has a firstName, lastName, and birthday property. We will use our new shortDate() converter when displaying the customer birthday property: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { var customer = { firstName: "Fred", lastName: "Flintstone", birthday: new Date("12/1/1988") }; WinJS.Binding.processAll(null, customer); } }; app.start(); })(); We actually use our shortDate converter in the HTML document. The following HTML document displays all of the customer properties: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> <script type="text/javascript" src="js/converters.js"></script> </head> <body> <h1>Customer Details</h1> <div class="field"> First Name: <span data-win-bind="innerText:firstName"></span> </div> <div class="field"> Last Name: <span data-win-bind="innerText:lastName"></span> </div> <div class="field"> Birthday: <span data-win-bind="innerText:birthday MyApp.Converters.shortDate"></span> </div> </body> </html> Notice the data-win-bind attribute used to display the birthday property. It looks like this: <span data-win-bind="innerText:birthday MyApp.Converters.shortDate"></span> The shortDate converter is applied to the birthday property when the birthday property is bound to the SPAN element’s innerText property. Using data-win-bindsource Normally, you pass the view model (the data context) which you want to use with the data-win-bind attributes in a page by passing the view model to the WinJS.Binding.processAll() method like this: WinJS.Binding.processAll(null, viewModel); As an alternative, you can specify the view model declaratively in your markup by using the data-win-datasource attribute. For example, the following default.js script exposes a view model with the fully-qualified name of MyWinWebApp.viewModel: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { // Create view model var viewModel = { customer: { firstName: "Fred", lastName: "Flintstone" }, product: { name: "Bowling Ball", price: 12.99 } }; // Export view model to be seen by universe WinJS.Namespace.define("MyWinWebApp", { viewModel: viewModel }); // Process data-win-bind attributes WinJS.Binding.processAll(); } }; app.start(); })(); In the code above, a view model which represents a customer and a product is exposed as MyWinWebApp.viewModel. The following HTML page illustrates how you can use the data-win-bindsource attribute to bind to this view model: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <h1>Customer Details</h1> <div data-win-bindsource="MyWinWebApp.viewModel.customer"> <div class="field"> First Name: <span data-win-bind="innerText:firstName"></span> </div> <div class="field"> Last Name: <span data-win-bind="innerText:lastName"></span> </div> </div> <h1>Product</h1> <div data-win-bindsource="MyWinWebApp.viewModel.product"> <div class="field"> Name: <span data-win-bind="innerText:name"></span> </div> <div class="field"> Price: <span data-win-bind="innerText:price"></span> </div> </div> </body> </html> The data-win-bindsource attribute is used twice in the page above: it is used with the DIV element which contains the customer details and it is used with the DIV element which contains the product details. If an element has a data-win-bindsource attribute then all of the child elements of that element are affected. The data-win-bind attributes of all of the child elements are bound to the data source represented by the data-win-bindsource attribute. Summary The focus of this blog entry was data binding using the WinJS library. You learned how to use the data-win-bind attribute to bind the properties of an HTML element to a view model. We also discussed several advanced features of data binding. We examined how to create calculated properties by including a property with a getter in your view model. We also discussed how you can create a converter function to format the value of a view model property when binding the property. Finally, you learned how to use the data-win-bindsource attribute to specify a view model declaratively.

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