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  • WPF Coordinates of intersection from two Line objects

    - by Becky Franklin
    I have two Line objects in C# WPF, and I'm trying to construct a method to work out the coordinates at which the lines intersect (if at all). After giving myself a headache reminding myself of high school maths to do this, I can't work out how to map it into programming format - anyone know how to do this? Thanks very much, Becky

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  • running a parallel port controlling program through php.

    - by prateek
    I have a program that is interacting with hardware via parallel port programming. i had compiled it and using its object file to interact with the hardware (a simple led). when i execute it directly on the shell it serves the purpose of glowing the LED but when i execute it using shell_exec() in php the command is executed but unable to interact with the hardware. i am totally confused.. .

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  • What is Covariance and Contravariance

    - by xyz
    Please explain me in simple terms (if possible simple example) the covariance and contravariance in c# .net . I know many are available(even in stackoverflow) but my problem is in which scenario I should use that is not explained in the articles that I am refering to. e.g. Covariance and Contravariance in Delegates (C# Programming Guide) Thanks

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  • Tarballing without git metadata

    - by zaf
    My source tree contains several directories which are using git source control and I need to tarball the whole tree excluding any references to the git metadata or custom log files. I thought I'd have a go using a combo of find/egrep/xargs/tar but somehow the tar file contains the .git directories and the *.log files. This is what I have: find -type f . | egrep -v '\.git|\.log' | xargs tar rvf ~/app.tar Can someone explain my misunderstanding here? Why is tar processing the files that find and egrep are filtering? I'm open to other techniques as well.

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  • Hibernate CRUD à la Ruby on Rails' Scaffolding

    - by schonarth
    Guys, Do you know of any tool that would do like Ruby on Rails' Scaffolding (create simple CRUD pages for any particular class to allow quickly populating a database with dummy data), only which used Java classes with Hibernate for database access, and JSP/JSF for the pages? It is a drag when you are programming one part of an application, but need data that can only be added with another part that is not ready yet, or very cumbersomely by directly inserting it into the DB.

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  • What does the operator "<<" mean in C#?

    - by Kurru
    I was doing some basic audio programming in C# using the NAudio package and I came across the following expression and I have no idea what it means, as i've never seen the << operator being used before. So what does << mean? Please give a quick explaination of this expression. short sample = (short)((buffer[index + 1] << 8) | buffer[index + 0]);

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  • How to share information across controllers?

    - by Steffen
    Hi everybody, I recently started programming my first Cocoa app. I have ran into a problem i hope you can help me with. I have a MainController who controls the user browsing his computer and sets some textfield = the chosen folder. I need to retrieve that chosen folder in my AnalyzeController in order to do some work. How do i pass the textfield objectValue from the MainController to the AnalyzeController? Thanks

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  • what great software engineers know or aspiring ones should know?

    - by trojanwarrior3000
    I do not mean any particular language or methodology. But basics( one have abstracted from ones experience and interaction with smarter people in this field) one should have including concepts, practical issues, tips/techniques/tricks one should be aware of.For example the lessons or ideas may relate to programming,testing,design,project schedules, that are really useful in daily life of software engineer/developer etc ? This may be a good question because it looks not to specific, however experience of many is better than reading from books.I find discussions much helpful than books.Hope every one will have some lessons/ideas to contribute.please substantiate with atleast one example.

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  • Approaches for memcached sessions

    - by Industrial
    Hi everybody, I was thinking about using memcached to store sessions instead of mySQL, which seemed like a good idea, at first. When it comes to the failover part of utilizing memcached servers, It's a bit worrying that my sessions will stop working if the memcached would go offline. It will certainly affect my users. There's a few techniques that we already utilize to reduce failover, including having a pool of servers available to compensate in the event of downtime, utilizing sharding/consistent hashing across the server pool and so on. We would also do some sort of graceful degradation that tells the users that something have gone wrong and they are welcome to login again, in the event of them being kicked out due to memcached server failover. So how does people generally deal with these issues when storing sessions on memcached servers?

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  • Will these optimizations to my Ruby implementation of diff improve performance in a Rails app?

    - by grg-n-sox
    <tl;dr> In source version control diff patch generation, would it be worth it to use the optimizations listed at the very bottom of this writing (see <optimizations>) in my Ruby implementation of diff for making diff patches? </tl;dr> <introduction> I am programming something I have never done before and there might already be tools out there to do the exact thing I am programming but at this point I am having too much fun to care so I am still going to do it from scratch, even if there is a tool for this. So anyways, I am working on a Ruby on Rails app and need a certain feature. Basically I want each entry in a table of mine, let's say for example a table of video games, to have a stored chunk of text that represents a review or something of the sort for that table entry. However, I want this text to be both editable by any registered user and also keep track of different submissions in a version control system. The simplest solution I could think of is just implement a solution that keeps track of the text body and the diff patch history of different versions of the text body as objects in Ruby and then serialize it, preferably in human readable form (so I'll most likely use YAML for this) for editing if needed due to corruption by a software bug or a mistake is made by an admin doing some version editing. So at first I just tried to dive in head first into this feature to find that the problem of generating a diff patch is more difficult that I thought to do efficiently. So I did some research and came across some ideas. Some I have implemented already and some I have not. However, it all pretty much revolves around the longest common subsequence problem, as you would already know if you have already done anything with diff or diff-like features, and optimization the function that solves it. Currently I have it so it truncates the compared versions of the text body from the beginning and end until non-matching lines are found. Then it solves the problem using a comparison matrix, but instead of incrementing the value stored in a cell when it finds a matching line like in most longest common subsequence algorithms I have seen examples of, I increment when I have a non-matching line so as to calculate edit distance instead of longest common subsequence. Although as far as I can tell between the two approaches, they are essentially two sides of the same coin so either could be used to derive an answer. It then back-traces through the comparison matrix and notes when there was an incrementation and in which adjacent cell (West, Northwest, or North) to determine that line's diff entry and assumes all other lines to be unchanged. Normally I would leave it at that, but since this is going into a Rails environment and not just some stand-alone Ruby script, I started getting worried about needing to optimize at least enough so if a spammer that somehow knew how I implemented the version control system and knew my worst case scenario entry still wouldn't be able to hit the server that bad. After some searching and reading of research papers and articles through the internet, I've come across several that seem decent but all seem to have pros and cons and I am having a hard time deciding how well in this situation that the pros and cons balance out. So are the ones listed here worth it? I have listed them with known pros and cons. </introduction> <optimizations> Chop the compared sequences into multiple chucks of subsequences by splitting where lines are unchanged, and then truncating each section of unchanged lines at the beginning and end of each section. Then solve the edit distance of each subsequence. Pro: Changes the time increase as the changed area gets bigger from a quadratic increase to something more similar to a linear increase. Con: Figuring out where to split already seems like you have to solve edit distance except now you don't care how it is changed. Would be fine if this was solvable by a process closer to solving hamming distance but a single insertion would throw this off. Use a cryptographic hash function to both convert all sequence elements into integers and ensure uniqueness. Then solve the edit distance comparing the hash integers instead of the sequence elements themselves. Pro: The operation of comparing two integers is faster than the operation of comparing two strings, so a slight performance gain is received after every comparison, which can be a lot overall. Con: Using a cryptographic hash function takes time to convert all the sequence elements and may end up costing more time to do the conversion that you gain back from the integer comparisons. You could use the built in hash function for a string but that will not guarantee uniqueness. Use lazy evaluation to only calculate the three center-most diagonals of the comparison matrix and then only calculate additional diagonals as needed. And then also use this approach to possibly remove the need on some comparisons to compare all three adjacent cells as desribed here. Pro: Can turn an algorithm that always takes O(n * m) time and make it so only worst case scenario is that time, best case becomes practically linear, and average case is somewhere between the two. Con: It is an algorithm I've only seen implemented in functional programming languages and I am having a difficult time comprehending how to convert this into Ruby based on how it is described at the site linked to above. Make a C module and do the hard work at the native level in C and just make a Ruby wrapper for it so Ruby can make all the calls to it that it needs. Pro: I have to imagine that evaluating something like this in could be a LOT faster. Con: I have no idea how Rails handles apps with ruby code that has C extensions and it hurts the portability of the app. This is an optimization for after the solving of edit distance, but idea is to store additional combined diffs with the ones produced by each version to make a delta-tree data structure with the most recently made diff as the root node of the tree so getting to any version takes worst case time of O(log n) instead of O(n). Pro: Would make going back to an old version a lot faster. Con: It would mean every new commit, the delta-tree would get a new root node that will cost time to reorganize the delta-tree for an operation that will be carried out a lot more often than going back a version, not to mention the unlikelihood it will be an old version. </optimizations> So are these things worth the effort?

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  • How to use derived class shared variables in shared methods of base class

    - by KoolKabin
    Hi guys, I am trying to add shared members in derived classes and use that values in base classes... I have base class DBLayer public shared function GetDetail(byval UIN as integer) dim StrSql = string.format("select * from {0} where uin = {1}", tablename, uin) .... end function end class my derived class class User inherits dblayer public shared tabledname as string = "users" end class class item inherits dblayer public shared tabledname as string = "item" end class class category inherits dblayer public shared tabledname as string = "category" end class currently there is error using the tablename variable of derived class in base class but i want to use it... coz i dun know other techniques... if other solutions are better then u can post it or u can say how can i make it work? confused...

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  • Comparison of music data

    - by Christian P.
    Hey I am looking for theory, algorithms and similar for how to compare music. More specifically, I am looking into how to dupecheck music tracks that have different bitrates or perhaps slightly different variations (radio vs album version), but otherwise sound the same. Use cases for this include services such as Grooveshark, Youtube, etc. where they get a lot of duplicate tracks. I am also interested in text comparisons (Britney Spers vs Britney Spears, how far they deviate, etc.) although this is secondary and I already have some sources to go on in this area. I am mostly interested in codec-agnostic comparison techniques and algoritms (assuming a "raw" stream), but codec-specific resources are appreciated. I am aware of projects such as musicbrainz.org, but have not investigated it further, and would be interested if such projects could be of help in this endeavor.

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  • R in a netbook - system requirements for using R

    - by Brani
    I know it's not a programming question but I'm in a hurry to choose a netbook like this and I haven't been able to find the minimum system requirements for an R installation (e.g. minimum RAM). I am interested in a small netbook so as to be able to use it in class. Has anybody used R in a netbook that would recommend for that use?

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  • How do I blur (ios7 style) a section of an image in a UITableViewCell?

    - by George McKibbin
    I've got a UIImageView that takes up the whole cell and shows an image. I'd like to blur the bottom third of the view in the iOS7 style (we're targeting iOS7). There will be a label over the blurred part. The issue seems to be that I can't "screenshot" the UIImageView right as I am setting up the cell in tableView:cellForRowAtIndexPath: as it hasn't loaded yet. Although i've even tried setting up a timer for a 0.1 second delay and that also doesn't work. I've tried the stuff on http://damir.me/posts/ios7-blurring-techniques I've tried https://github.com/justinmfischer/7blur I'd like to use the new screenshotting API drawViewHierarchyInRect:afterScreenUpdates: I'd also like to use apple's sample code UIImage+ImageEffects The only thing that has worked so far has been to just put a UIToolbar in but the performance is really slow. I don't need dynamic updates. I've managed to get the following effect a few times but it has just tinted the view and hasn't actually blurred anything so I'm a bit confused.

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  • Android question. Is there a link to a simple example of changing the screen brightness for an activ

    - by John
    There are apparently at least three different techniques for changing screen brightness in the Android OS. Two of them no longer work post-cupcake and the third accepted technique evidently has a bug. I would like to increase screen brightness at the start of a one-view activity then turn the brightness back to the user setting at the end of the activity. No buttons, no second view or second activity. Just a maxed brightness at start and a return to original brightness setting at the end of the activity. The examples of the current technique using WindowManager.LayoutParams that I have located range from 2 lines of code WindowManager.LayoutParams lp = getWindow().getAttributes(); lp.screenBrightness = 100 / 100.0f; getWindow().setAttributes(lp); to several pages of source code and numerous activities. Is there a simple example of maxing the screen brightness at start that someone can provide a link to? Thank you for reading my question.

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  • enCapsa -what is it and what is used for?

    - by agnieszka
    It may not be a pure programming question but I'm looking for information about enCapsa. Do you know what it is, have you ever used it? I'm reading some papers about it but I can't really see how it works and what it can be used for in an IT company (and this is what i am supposed to find out).

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  • why develop in windows/desktop application?

    - by Alexander
    Just wondering what your comments are regarding the current trend as everything is moving to the web or even the cloud. The significance of an OS or desktop application is getting less attention than web application. So to those folks out there who still develop windows applications, such as WPF. Why still do it? Why not move to web programming? Silverlight instead for example...

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  • Regex: How do I match some regex logic 1 or more times?

    - by tom
    I already have some regex logic which says to look for a div tag with class=something. However, this might occur more than once (one after another). You can't simply add square brackets around that complex regex logic already (e.g. [:some complicated regex logic already existing:]* -- so how do you do it in regex? I want to avoid having to use the programming language logic to append that regex logic after itself if I can... Thanks

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