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• Altering an embedded truetype font so it will be useable by Windows GDI

  - by Ritsaert Hornstra

  I am trying to render PDF content to a GDI device context (a 24bit bitmap to be exact). Parsing the PDF stream into PDF objects and rendering the PDF commands from the content dictionary works well, inclduing font rendering. Embedded fonts are decompressed from their FontFile streams and "loaded" using AddFontMemResourceEx. Now some embedded fonts remove some TrueType tables that are needed by GDI, like the NAME table. Because of this, I tried to modify the font by parsing the TrueType subset font into it's tables and modify those tables that have data missing / missing tables are regenerated with as correct information as possible. I use the Microsoft Font Validator tool to see how "correct" the generated font is. I still get a few errors, like for the maxp table the max values are usually too large (it is a subset) or The xAvgCharWidth field does not equal the calculated value of the OS/2 table is not correct but this does not stop other embedded fonts to be useable.The fonts embedded using PDFCreator are the ones that are problematic. Question: - How can I determine what I need to change to the font file in order for GDI to be able to use it? - Are there any other font validation tools that might give me insight into what is still wrong with the fontfile? If needed: I can make an original fontfile and an altered fontfile available for download somewhere.

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• WPF drawing performance with large numbers of geometries

  - by MyFaJoArCo

  Hello, I have problems with WPF drawing performance. There are a lot of small EllipseGeometry objects (1024 ellipses, for example), which are added to three separate GeometryGroups with different foreground brushes. After, I render it all on simple Image control. Code: DrawingGroup tmpDrawing = new DrawingGroup(); GeometryGroup onGroup = new GeometryGroup(); GeometryGroup offGroup = new GeometryGroup(); GeometryGroup disabledGroup = new GeometryGroup(); for (int x = 0; x < DisplayWidth; ++x) { for (int y = 0; y < DisplayHeight; ++y) { if (States[x, y] == true) onGroup.Children.Add(new EllipseGeometry(new Rect((double)x * EDGE, (double)y * EDGE, EDGE, EDGE))); else if (States[x, y] == false) offGroup.Children.Add(new EllipseGeometry(new Rect((double)x * EDGE, (double)y * EDGE, EDGE, EDGE))); else disabledGroup.Children.Add(new EllipseGeometry(new Rect((double)x * EDGE, (double)y * EDGE, EDGE, EDGE))); } } tmpDrawing.Children.Add(new GeometryDrawing(OnBrush, null, onGroup)); tmpDrawing.Children.Add(new GeometryDrawing(OffBrush, null, offGroup)); tmpDrawing.Children.Add(new GeometryDrawing(DisabledBrush, null, disabledGroup)); DisplayImage.Source = new DrawingImage(tmpDrawing); It works fine, but takes too much time - 0.5s on Core 2 Quad, 2s on Pentium 4. I need <0.1s everywhere. All Ellipses, how you can see, are equal. Background of control, where is my DisplayImage, is solid (black, for example), so we can use this fact. I tried to use 1024 Ellipse elements instead of Image with EllipseGeometries, and it was working much faster (~0.5s), but not enough. How to speed up it? Regards, Oleg Eremeev P.S. Sorry for my English.

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• C++ interpreter conceptual problem

  - by Jan Wilkins

  I've built an interpreter in C++ for a language created by me. One main problem in the design was that I had two different types in the language: number and string. So I have to pass around a struct like: class myInterpreterValue { myInterpreterType type; int intValue; string strValue; } Objects of this class are passed around million times a second during e.g.: a countdown loop in my language. Profiling pointed out: 85% of the performance is eaten by the allocation function of the string template. This is pretty clear to me: My interpreter has bad design and doesn't use pointers enough. Yet, I don't have an option: I can't use pointers in most cases as I just have to make copies. How to do something against this? Is a class like this a better idea? vector<string> strTable; vector<int> intTable; class myInterpreterValue { myInterpreterType type; int locationInTable; } So the class only knows what type it represents and the position in the table This however again has disadvantages: I'd have to add temporary values to the string/int vector table and then remove them again, this would eat a lot of performance again. Help, how do interpreters of languages like Python or Ruby do that? They somehow need a struct that represents a value in the language like something that can either be int or string.

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• Null reference exceptions in .net

  - by Carlo

  Hello, we're having this big problem with our application. It's a rather large application with several modules, and thousands and thousands lines of code. A lot of parts of the application are designed to exist only with a reference to another object, for example a Person object can never exists without a House object, so if you at any point in the app say: bool check = App.Person.House == null; check should always be false (by design), so, to keep using that example, while creating modules, testing, debugging, App.Person.House is never null, but once we shipped the application to our client, they started getting a bunch of NullReferenceException with the objects that by design, should never have a null reference. They tell us the bug, we try to reproduce it here, but 90% of the times we can't, because here it works fine. The app is being developed with C# and WPF, and by design, it only runs on Windows XP SP 3, and the .net framework v3.5, so we KNOW the user has the same operative system, service pack, and .net framework version as we do here, but they still get this weird NullReferenceExceptions that we can't reproduce. So, I'm just wondering if anyone has seen this before and how you fixed it, we have the app running here at least 8 hours a day in 5 different computers, and we never see those exceptions, this only happens to the client for some reason. ANY thought, any clue, any solution that could get us closer to fixing this problem will be greatly appreciated. Thanks!

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• How should we setup up complex situations for tests?

  - by ShaneC

  I'm currently working on what I would call integration tests. I want to verify that if a WCF service is called it will do what I expect. Let's take a very simple scenario. Assume we have a contract object that we can put on hold or take off hold. Now writing the put on hold test is quite simple. You create a contract instance and execute the code that puts it on code. The question I have comes when we want to test the taking off hold service call. The problem is that putting a contract on hold can be actually quite complicated leading to various objects all be modified. So usually I would use the Builder pattern and do something like this.. var onHoldContract = new ContractBuilder().PutOnHold().Build(); The problem I have with this is now I have to pretty much replicate a large part of my put on hold service. Now when I change what putting something on hold means I have two places I have to modify. The other option that immediately jumps out at me is to just use the put on hold service as part of my test setup but now I'm coupling my test to the success of another piece of code which is something I don't like to do since it can lead to failures in one spot breaking unrelated tests elsewhere (if put on hold failed for example). Any other options I'm missing out here? or opinions on which method is preferable and why?

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• Overriding content_type for Rails Paperclip plugin

  - by Fotios

  I think I have a bit of a chicken and egg problem. I would like to set the content_type of a file uploaded via Paperclip. The problem is that the default content_type is only based on extension, but I'd like to base it on another module. I seem to be able to set the content_type with the before_post_process class Upload < ActiveRecord::Base has_attached_file :upload before_post_process :foo def foo logger.debug "Changing content_type" #This works self.upload.instance_write(:content_type,"foobar") # This fails because the file does not actually exist yet self.upload.instance_write(:content_type,file_type(self.upload.path) end # Returns the filetype based on file command (assume it works) def file_type(path) return `file -ib '#{path}'`.split(/;/)[0] end end But...I cannot base the content type on the file because Paperclip doesn't write the file until after_create. And I cannot seem to set the content_type after it has been saved or with the after_create callback (even back in the controller) So I would like to know if I can somehow get access to the actual file object (assume there are no processors doing anything to the original file) before it is saved, so that I can run the file_type command on that. Or is there a way to modify the content_type after the objects have been created.

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• keyUp event heard?: Overridden NSView method

  - by Old McStopher

  UPDATED: I'm now overriding the NSView keyUp method from a NSView subclass set to first responder like below, but am still not seeing evidence that it is being called. @implementation svsView - (BOOL)acceptsFirstResponder { return YES; } - (void)keyUp:(NSEvent *)event { //--do key up stuff-- NSLog(@"key up'd!"); } @end --ORIGINAL POST-- I'm new to Cocoa and Obj-C and am trying to do a (void)keyUp: from within the implementation of my controller class (which itself is of type NSController). I'm not sure if this is the right place to put it, though. I have a series of like buttons each set to a unique key equivalent (IB button attribute) and each calls my (IBAction)keyInput method which then passes the identity of each key onto another object. This runs just fine, but I also want to track when each key is released. --ORIGINAL [bad] EXAMPLE-- @implementation svsController //init //IBActions - (IBAction)keyInput:(id)sender { //--do key down stuff-- } - (void)keyUp:(NSEvent *)event { //--do key up stuff-- } @end Upon fail, I also tried the keyUp as an IBAction (instead of void), like the user-defined keyInput is, and hooked it up to the appropriate buttons in Interface Builder, but then keyUp was only called when the keys were down and not when released. (Which I kind of figured would happen.) Pardon my noobery, but should I be putting this method in another class or doing something differently? Wherever it is, though, I need it be able to access objects owned by the controller class. Thanks for any insight you may have.

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• ListBox selector odd behavior when there are dupes

  - by byte1918

  I'm working on a bigger project atm, but I made this simple example to show you what happens.. using System.Collections.Generic; using System.Windows; namespace txt { public partial class MainWindow { public MainWindow() { InitializeComponent(); } private void Window_Loaded(object sender, RoutedEventArgs e) { var obsLst = new List<Info> { new Info { name = "asd" }, new Info { name = "asd" }, new Info { name = "asd" }, new Info { name = "asd" } }; var temp = new List<Info>(); for (var i = 1; i <= 3; i++) { temp.Add(obsLst[0]); //I add 3 of the same item from obsLst to temp } lst.DataContext = temp; //lst = ListBox } } public class Info { public string name { get; set; } } } The ListBox ItemsSource is set to {Binding}.. When I start the application I get 3 txt.Info objects displayed and if I click any of them, 2 or even all of them get selected aswell. From my understanding the problem relies in the fact that the listbox selector cannot differentiate between the items and therefor doesn't know which one I selected. Here's a picture of what it looks like.. I only clicked on the second txt.Info item. I found a solution where someone said that I have to specify the DisplayMemberPath, but I can't really do that in the other project because I have a datatemplate for the object. Any ideas on how I could fix this would be great.. Thx in advance.

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• What is the best way to detect white color?

  - by dnul

  I'm trying to detect white objects in a video. The first step is to filter the image so that it leaves only white-color pixels. My first approach was using HSV color space and then checking for high level of VAL channel. Here is the code: //convert image to hsv cvCvtColor( src, hsv, CV_BGR2HSV ); cvCvtPixToPlane( hsv, h_plane, s_plane, v_plane, 0 ); for(int x=0;x<srcSize.width;x++){ for(int y=0;y<srcSize.height;y++){ uchar * hue=&((uchar*) (h_plane->imageData+h_plane->widthStep*y))[x]; uchar * sat=&((uchar*) (s_plane->imageData+s_plane->widthStep*y))[x]; uchar * val=&((uchar*) (v_plane->imageData+v_plane->widthStep*y))[x]; if((*val>170)) *hue=255; else *hue=0; } } leaving the result in the hue channel. Unfortunately, this approach is very sensitive to lighting. I'm sure there is a better way. Any suggestions?

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• How to write Java-like enums in C++ ?

  - by Rahul G

  Coming from Java background, I find C++'s enums very lame. I wanted to know how to write Java-like enums (the ones in which the enum values are objects, and can have attributes and methods) in C++. As an example, translate the following Java code (a part of it, sufficient to demonstrate the technique) to C++ : public enum Planet { MERCURY (3.303e+23, 2.4397e6), VENUS (4.869e+24, 6.0518e6), EARTH (5.976e+24, 6.37814e6), MARS (6.421e+23, 3.3972e6), JUPITER (1.9e+27, 7.1492e7), SATURN (5.688e+26, 6.0268e7), URANUS (8.686e+25, 2.5559e7), NEPTUNE (1.024e+26, 2.4746e7); private final double mass; // in kilograms private final double radius; // in meters Planet(double mass, double radius) { this.mass = mass; this.radius = radius; } private double mass() { return mass; } private double radius() { return radius; } // universal gravitational constant (m3 kg-1 s-2) public static final double G = 6.67300E-11; double surfaceGravity() { return G * mass / (radius * radius); } double surfaceWeight(double otherMass) { return otherMass * surfaceGravity(); } public static void main(String[] args) { if (args.length != 1) { System.err.println("Usage: java Planet <earth_weight>"); System.exit(-1); } double earthWeight = Double.parseDouble(args[0]); double mass = earthWeight/EARTH.surfaceGravity(); for (Planet p : Planet.values()) System.out.printf("Your weight on %s is %f%n", p, p.surfaceWeight(mass)); } } Any hep would be greatly appreciated! Thanks!

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• Group / User based security. Table / SQL question

  - by Brett

  Hi, I'm setting up a group / user based security system. I have 4 tables as follows: user groups group_user_mappings acl where acl is the mapping between an item_id and either a group or a user. The way I've done the acl table, I have 3 columns of note (actually 4th one as an auto-id, but that is irrelevant) col 1 item_id (item to access) col 3 user_id (user that is allowed to access) col 3 group_id (group that is allowed to access) So for example item1, peter, , item2, , group1 item3, jane, , so either the acl will give access to a user or a group. Any one line in the ACL table with either have an item - user mapping, or an item group. If I want to have a query that returns all objects a user has access to, I think I need to have a SQL query with a UNION, because I need 2 separate queries that join like.. item - acl - group - user AND item - acl - user This I guess will work OK. Is this how its normally done? Am I doing this the right way? Seems a little messy. I was thinking I could get around it by creating a single user group for each person, so I only ever deal with groups in my SQL, but this seems a little messy as well..

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• Can a Generic Method handle both Reference and Nullable Value types?

  - by Adam Lassek

  I have a series of Extension methods to help with null-checking on IDataRecord objects, which I'm currently implementing like this: public static int? GetNullableInt32(this IDataRecord dr, int ordinal) { int? nullInt = null; return dr.IsDBNull(ordinal) ? nullInt : dr.GetInt32(ordinal); } public static int? GetNullableInt32(this IDataRecord dr, string fieldname) { int ordinal = dr.GetOrdinal(fieldname); return dr.GetNullableInt32(ordinal); } and so on, for each type I need to deal with. I'd like to reimplement these as a generic method, partly to reduce redundancy and partly to learn how to write generic methods in general. I've written this: public static Nullable<T> GetNullable<T>(this IDataRecord dr, int ordinal) { Nullable<T> nullValue = null; return dr.IsDBNull(ordinal) ? nullValue : (Nullable<T>) dr.GetValue(ordinal); } which works as long as T is a value type, but if T is a reference type it won't. This method would need to return either a Nullable type if T is a value type, and default(T) otherwise. How would I implement this behavior?

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• Ninject: Shared DI/IoC container

  - by joblot

  Hi I want to share the container across various layers in my application. I started creating a static class which initialises the container and register types in the container. public class GeneralDIModule : NinjectModule { public override void Load() { Bind().To().InSingletonScope(); } } public abstract class IoC { private static IKernel _container; public static void Initialize() { _container = new StandardKernel(new GeneralDIModule(), new ViewModelDIModule()); } public static T Get<T>() { return _container.Get<T>(); } } I noticed there is a Resolve method as well. What is the difference between Resolve and Get? In my unit tests I don’t always want every registered type in my container. Is there a way of initializing an empty container and then register types I need. I’ll be mocking types as well in unit test so I’ll have to register them as well. There is an Inject method, but it says lifecycle of instance is not managed? Could someone please set me in right way? How can I register, unregister objects and reset the container. Thanks

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• Adding an unknown number of JComponents to a JPanel

  - by Matthew

  Good day, I am building an Applet (JApplet to be exact) and I sub divided that into two panels. The top panel is called DisplayPanel which is a custom class that extends JPanel. The bottom panel is called InputPanel which also extends JPanel. As mentioned above, I can add those two Panel's to the applet and they display fine. The next thing that I would like to do is have the InputPanel be able to hold a random number of JComponent Objects all listed veritcally. This means that the InputPanel should be able to have JButtons, JLabels, JTextFields etc thrown at it. I then want the InputPanel to display some sort of scrolling capability. The catch is that since these two panels are already inside my applet, I need the InputPanel to stay the same size as it was given when added to the Applet. So for example, if my applet (from the web-browser html code) was given the size 700,700, and then the DisplayPanel was 700 by 350, and the InputPanel was below it with the same dimensions, I want to then be able to add lots of JComponents like buttons, to the InputPanel and the panel would stay 700 x 350 in the same position that it is at, only the panel would have scroll bars if needed. I've played with many different combinations of JScrollPane, but just cannot get it. Thank you.

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• Few Basic Questions in Overriding

  - by Dahlia

  I have few problems with my basic and would be thankful if someone can clear this. What does it mean when I say base *b = new derived; Why would one go for this? We very well separately can create objects for class base and class derived and then call the functions accordingly. I know that this base *b = new derived; is called as Object Slicing but why and when would one go for this? I know why it is not advisable to convert the base class object to derived class object (because base class is not aware of the derived class members and methods). I even read in other StackOverflow threads that if this is gonna be the case then we have to change/re-visit our design. I understand all that, however, I am just curious, Is there any way to do this? class base { public: void f(){cout << "In Base";} }; class derived:public base { public: void f(){cout << "In Derived";} }; int _tmain(int argc, _TCHAR* argv[]) { base b1, b2; derived d1, d2; b2 = d1; d2 = reinterpret_cast<derived*>(b1); //gives error C2440 b1.f(); // Prints In Base d1.f(); // Prints In Derived b2.f(); // Prints In Base d1.base::f(); //Prints In Base d2.f(); getch(); return 0; } In case of my above example, is there any way I could call the base class f() using derived class object? I used d1.base()::f() I just want to know if there any way without using scope resolution operator? Thanks a lot for your time in helping me out!

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• How is a functional programming-based javascript app laid out?

  - by user321521

  I've been working with node.js for awhile on a chat app (I know, very original, but I figured it'd be a good learning project). Underscore.js provides a lot of functional programming concepts which look interesting, so I'd like to understand how a functional program in javascript would be setup. From my understanding of functional programming (which may be wrong), the whole idea is to avoid side effects, which are basically having a function which updates another variable outside of the function so something like var external; function foo() { external = 'bar'; } foo(); would be creating a side effect, correct? So as a general rule, you want to avoid disturbing variables in the global scope. Ok, so how does that work when you're dealing with objects and what not? For example, a lot of times, I'll have a constructor and an init method that initializes the object, like so: var Foo = function(initVars) { this.init(initVars); } Foo.prototype.init = function(initVars) { this.bar1 = initVars['bar1']; this.bar2 = initVars['bar2']; //.... } var myFoo = new Foo({'bar1': '1', 'bar2': '2'}); So my init method is intentionally causing side effects, but what would be a functional way to handle the same sort of situation? Also, if anyone could point me to either a python or javascript source code of a program that tries to be as functional as possible, that would also be much appreciated. I feel like I'm close to "getting it", but I'm just not quite there. Mainly I'm interested in how functional programming works with traditional OOP classes concept (or does away with it for something different if that's the case).

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• Matplotlib autodatelocator custom date formatting?

  - by jawonlee

  I'm using Matplotlib to dynamically generate .png charts from a database. The user may set as the x-axis any given range of datetimes, and I need to account for all of it. While Matplotlib has the dates.AutoDateLocator(), I want the datetime format printed on the chart to be context-specific - e.g. if the user is charting from 3 p.m. to 5 p.m., the year/month/day information doesn't need to be displayed. Right now, I'm manually creating Locator and Formatter objects thusly: def get_ticks(start, end): from datetime import timedelta as td delta = end - start if delta <= td(minutes=10): loc = mdates.MinuteLocator() fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(minutes=30): loc = mdates.MinuteLocator(byminute=range(0,60,5)) fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(hours=1): loc = mdates.MinuteLocator(byminute=range(0,60,15)) fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(hours=6): loc = mdates.HourLocator() fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(days=1): loc = mdates.HourLocator(byhour=range(0,24,3)) fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(days=3): loc = mdates.HourLocator(byhour=range(0,24,6)) fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(weeks=2): loc = mdates.DayLocator() fmt = mdates.DateFormatter('%b %d') elif delta <= td(weeks=12): loc = mdates.WeekdayLocator() fmt = mdates.DateFormatter('%b %d') elif delta <= td(weeks=52): loc = mdates.MonthLocator() fmt = mdates.DateFormatter('%b') else: loc = mdates.MonthLocator(interval=3) fmt = mdates.DateFormatter('%b %Y') return loc,fmt Is there a better way of doing this?

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• subquery in join with doctrine dql

  - by Martijn de Munnik

  I want to use DQL to create a query which looks like this in SQL: select e.* from e inner join ( select uuid, max(locale) as locale from e where locale = 'nl_NL' or locale = 'nl' group by uuid ) as e_ on e.uuid = e_.uuid and e.locale = e_.locale I tried to use QueryBuilder to generate the query and subquery. I think they do the right thing by them selves but I can't combine them in the join statement. Does anybody now if this is possible with DQL? I can't use native SQL because I want to return real objects and I don't know for which object this query is run (I only know the base class which have the uuid and locale property). $subQueryBuilder = $this->_em->createQueryBuilder(); $subQueryBuilder ->addSelect('e.uuid, max(e.locale) as locale') ->from($this->_entityName, 'e') ->where($subQueryBuilder->expr()->in('e.locale', $localeCriteria)) ->groupBy('e.uuid'); $queryBuilder = $this->_em->createQueryBuilder(); $queryBuilder ->addSelect('e') ->from($this->_entityName, 'e') ->join('('.$subQueryBuilder.') as', 'e_')->join ->where('e.uuid = e_.uuid') ->andWhere('e.locale = e_.locale');

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• Loading an XML configuration file BEFORE the flex application loads

  - by Shahar

  Hi, We are using an XML file as an external configuration file for several parameters in our application (including default values for UI components and properties values of some service layer objects). The idea is to be able to load the XML configuration file before the flex application initializes any of its components. This is crucial because XML loading is processed a-synchronously in flex, which can potentially cause race-conditions in the application. For example: the configuration file holds the endpoint URL of a web service used to obtain data from the server. The URL resides in the XML because we want to allow our users to alter the endpoint URL according to their environment. Now because the endpoint URL is retrieved only after the XML has been completely loaded, some of the application's components might be invoking operations on this web service before it is initialized with the correct endpoint. The trivial solution would have been to suspend the initialization of the application until the complete event is dispatched by the loader. But it appears that this solution is far from being trivial. I haven't found a single solution that allows me to load the XML before any other object in the application. Can anyone advice or comment on this matter? Regards, Shahar

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• navigate all items in a wpf tree view

  - by Brian Leahy

  I want to be able to traverse the visual ui tree looking for an element with an ID bound to the visual element's Tag property. I'm wondering how i do this. Controls don't have children to traverse. I started using LogicalTreeHelper.GetChildren, which seems to work as intended, up until i hit a TreeView control... then LogicalTreeHelper.GetChildren doesnt return any children. Note: the purpose is to find the visual UI element that corresponds to the data item. That is, given an ID of the item, Go find the UI element displaying it. Edit: I am apparently am not explaining this well enough. I am binding some data objects to a TreeView control and then wanting to select a specific item programaticly given that business object's ID. I dont see why it's so hard to travers the visual tree and find the element i want, as the data object's ID is in the Tag property of the appropriate visual element. I'm using Mole and I am able to find the UI element with the appropriate ID in it's Tag. I just cannot find the visual element in code. LogicalTreeHelper does not traverse any items in the tree. Neither does ItemContainerGenerator.ContainerFromItem retrieve anything for items in the tree view.

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• Weak hashmap with weak references to the values?

  - by Razor Storm

  I am building an android app where each entity has a bitmap that represents its sprite. However, each entity can be be duplicated (there might be 3 copies of entity asdf for example). One approach is to load all the sprites upfront, and then put the correct sprite in the constructors of the entities. However, I want to decode the bitmaps lazily, so that the constructors of the entities will decode the bitmaps. The only problem with this is that duplicated entities will load the same bitmap twice, using 2x the memory (Or n times if the entity is created n times). To fix this, I built a SingularBitmapFactory that will store a decoded Bitmap into a hash, and if the same bitmap is asked for again, will simply return the previously hashed one instead of building a new one. Problem with this, though, is that the factory holds a copy of all bitmaps, and so won't ever get garbage collected. What's the best way to switch the hashmap to one with weakly referenced values? In otherwords, I want a structure where the values won't be GC'd if any other object holds a reference to it, but as long as no other objects refers it, then it can be GC'd.

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• Is it possible to restrict instantiation of an object to only one other (parent) object in VB.NET?

  - by Casey

  VB 2008 .NET 3.5 Suppose we have two classes, Order and OrderItem, that represent some type of online ordering system. OrderItem represents a single line item in an Order. One Order can contain multiple OrderItems, in the form of a List(of OrderItem). Public Class Order Public Property MyOrderItems() as List(of OrderItem) End Property End Class It makes sense that an OrderItem should not exist without an Order. In other words, an OrderItem class should not be able to be instantiated on its own, it should be dependent on an Order class to contain it and instantiate it. However, the OrderItem should be public in scope so that it's properties are accessible to other objects. So, the requirements for OrderItem are: Can not be instantiated as a stand alone object; requires Order to exist. Must be public so that any other object can access it's properties/methods through the Order object. e.g. Order.OrderItem(0).ProductID. OrderItem should be able to be passed to other subs/functions that will operate on it. How can I achieve these goals? Is there a better approach?

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• Return type from DAL class (Sql ce, Linq to Sql)

  - by bretddog

  Hi, Using VS2008 and Sql CE 3.5, and preferably Linq to Sql. I'm learning database, and unsure about DAL methods return types and how/where to map the data over to my business objects: I don't want direct UI binding. A business object class UserData, and a class UserDataList (Inherits List(Of UserData)), is represented in the database by the table "Users". I use SQL Compact and run SqlMetal which creates dbml/designer.vb file. This gives me a class with a TableAttribute: <Table()> _ Partial Public Class Users I'm unsure how to use this class. Should my business object know about this class, such that the DAL can return the type Users, or List(Of Users) ? So for example the "UserDataService Class" is a part of the DAL, and would have for example the functions GetAll and GetById. Will this be correct : ? Public Class UserDataService Public Function GetAll() As List(Of Users) Dim ctx As New MyDB(connection) Dim q As List(Of Users) = From n In ctx.Users Select n Return q End Function Public Function GetById(ByVal id As Integer) As Users Dim ctx As New MyDB(connection) Dim q As Users = (From n In ctx.Users Where n.UserID = id Select n).Single Return q End Function And then, would I perhaps have a method, say in the UserDataList class, like: Public Class UserDataList Inherits List(Of UserData) Public Sub LoadFromDatabase() Me.clear() Dim database as New UserDataService dim users as List(Of Users) users = database.GetAll() For each u in users dim newUser as new UserData newUser.Id = u.Id newUser.Name = u.Name Me.Add(newUser) Next End Sub End Class Is this a sensible approach? Would appreciate any suggestions/alternatives, as this is my first attempt on a database DAL. cheers!

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• Difference in BackgroundWorker thread access in VS2010 / .NET 4.0?

  - by Jonners

  Here's an interesting one - in VS2005 / VS2008 running against .NET 2.0 / .NET 3.0 / .NET 3.5, a BackgroundWorker thread may not directly update controls on a WinForms form that initiated that thread - you'll get a System.InvalidOperationException out of the BackgroundWorker stating "Cross-thread operation not valid: Control 'thecontrol' accessed from a thread other than the thread it was created on". I remember hitting this back in 2004 or so when I first started writing .NET WinForms apps with background threads. There are several ways around the problem - this is not a question asking for that answer. I've been told recently that this kind of operation is now allowed when written in VS2010 / .NET 4.0. This seems unlikely to me, since this kind of object access restriction has always been a fairly fundamental part of thread-safe programming. Allowing a BackgroundWorker thread direct access to objects owned not by itself but by its parent UI form seems contrary to that principle. A trawl through the .NET 4.0 docs hasn't revealed any obvious changes that could account for this behaviour. I don't have VS2010 / .NET 4.0 to test this out - does anyone who has access to that toolset know for sure whether the model has changed to allow that kind of thread interaction? I'd like to either take advantage of it in future, or deploy the cluestick. ;)

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• How do I declare "Member Fields" in Java?

  - by Bub

  This question probably reveals my total lack of knowledge in Java. But let me first show you what I thought was the correct way to declare a "member field": public class NoteEdit extends Activity { private Object mTitleText; private Object mBodyText; I'm following a google's notepad tutorial for android (here) and they simply said: "Note that mTitleText and mBodyText are member fields (you need to declare them at the top of the class definition)." I thought I got it and then realized that this little snippet of code wasn't working. if (title != null) { mTitleText.setText(title); } if (body != null) { mBodyText.setText(body); } So either I didn't set the "member fields" correctly which I thought all that was needed was to declare them private Objects at the top of the NoteEdit class or I'm missing something else. Thanks in advance for any help.UPDATE I was asked to show where these fields were being intialized here is another code snippet hope that it's helpful... @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.note_edit); Long mRowId; mTitleText = (EditText) findViewById(R.id.title); mBodyText = (EditText) findViewById(R.id.body);

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