Check if there's opengl - c#

I'm trying to check if there's opengl in pc with c#, but didn't found any simple solution for now. I'm looking the simplest and the best way to do that, something like:
if ( exists_OpenGL ) MessageBox.Show( "yeah, go do your stuff..." );
So please, can anyone help me with a code, witch would be fast, and simply enough ?

On most operating systems you'll find the API library. This however tells you nothing about the actual OpenGL capabilities. The only way to check for what's available is to create a minimal OpenGL context and query it's properties (version, renderer, available extensions).

You could try creating a context with a C# OpenGL library such as OpenTK. This might also give you the version number if it succeeds.
I'm pretty sure most OSs come with some form of OpenGL, so just checking if it exists might not work without knowing the capability too (look how much trouble chrome went to attempting this with webgl, using a list of compatible graphics cards). An alternative, which doesn't seem that stable, might be directly loading the native DLL, and maybe even querying it.

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How can I access the address book in Xamarin.forms (for android and iOS)?

I'm a noob who have struggling with this for hours. Tried a lot of stuff (including trying to use AppCompact and ContactsPlugin (maybe those would work, but I just wasn't able to achieve it)) and nothing.
If you have a simple solution, it would be ideal.
Well, the answer turned out to be disappointing: at this moment, there's no simple way and it's better to just work natively on each version (in any case, there seems to be a way to add native code to your Xamarin project, but it's useless if you already write the most important things separately)

Running CPython functions from C#

I'm working on a project where I need to be able to run a python function that depends on SciPy/NumPy. Due to this being an add-on to a project already in progress, using IronPython would not be an option.
Additional info:
Python.NET seemed to be a good fit, but I was unable to get the return value from RunString() (it would only return NULL).
Passing arguments and catching the return value (a tuple) is necessary.
The function is in a statistical package that was created by a support group for the team, so modification of that would also not be possible.
I'm at quite a loss for what to do. Any hints in the right direction are appreciated. Thanks for any help you can give!
I understand that this may be quite vague, but I cannot give explicit details to the project. If any clarification is needed please let me know and I'll do my best!
I guess you could write a DLL that uses the CPython API to expose the function, then call it in C#?
It's possible to embed the Python interpreter; although I've never done this personally, I guess it would be useful: http://docs.python.org/extending/embedding.html
Does it need to be portable beyond Windows? If not, perhaps you can embed the CPython interpreter with C++/CLI, wrap that in a nice .Net-ish interface and use the resulting code from C#. Never tried that, so I don't know if it's going to work.
Regardless if you go through this route or the 'write a native DLL' route, it will probably be easier to to embed python using Boost.Python, though I'm not sure if your wrapper code enough is going to be large enough to make all of this (compiling the Boost behemoth, learning Boost.Python, making sure it works with C++/CLR, increasing your target file size) worth it.
IronPython using DLR might be the way to go. Mind you it won't be the fastest way, but it seems like something worth pursuing if you're going to do this a lot. Another useful link
The ironclad project was started to allow using CPython extensions from IronPython, especially SciPy/NumPy it seems. I don't know how usable it is (and how actively it is still being developed)

Play sounds with managed code

I've been trying to create a sound library as a learning project. I get the reading and parsing, I just don't understand how to actually make sound come out of the speaker. I've looked around for quite some time now, but I could never find something that explains this. It seems to be trivial. Am I missing something here? How do I do this in C#?
I would try NBass. It's free and open source, you can peek how they do it in detail.
You can also use the Microsoft Media Player SDK, if you prefer, or the media layer from WPF, which is probably merely the same I guess.
If you want to output things directly then the managed DirectX can help you out, have a look at DirectX.AudioVideoPlayback.
Could you use System.Media.SoundPlayer?
http://msdn.microsoft.com/en-us/library/system.media.soundplayer.aspx

c# compile source code from database

I would like to build an application framework that is mainly interpreted.
Say that the source code would be stored in the database that could be edited by the users and always the latest version would be executed.
Can anyone give me some ideas how does one implement sth like this !
cheers,
gabor
In .Net, you can use reflection and CodeDOM to compile code on the fly. But neither approach is really very simple or practical. Mono has some ability to interpret c# on the fly as well, but I haven't looked closely at it yet.
Another alternative is to go with an interpreted .Net language like Boo or IronPython as the language for your database code.
Either way, make sure you think long and hard about the security of your platform. Allowing users to execute arbitrary code is always an exercise fraught with peril. It's often too tempting to look for a simple eval() method, and even if one exists, that is not good enough for this kind of scenario.
Try Mono ( http://www.monoproject.org ). It supports many scripting languages including JavaScript.
If you don't want to use any scripting you can use CodeDOM or Reflection (see Reflection.Emit).
Here are really useful links on the topic :
Dynamically executing code in .Net (Here you can find a tool which can be very helpul)
Late Binding and On-the-Fly Code
Generation Using Reflection in C#
Dynamic Source Code Generation and
Compilation
Usually the Program uses a scripting language for the scriptable parts, i.e. Lua or Javascript.
To answer your technical question: You don't want to write your own language and interpreter. That's too much work for you to do. So pick some other language, say Python or Lua, and look for the documentation that lets your C program hand it blocks of code to execute. Of course, the script needs to be able to do something, so you'll need to find how to expose your program's objects to the script. Also, what will happen if a client is running the program when you update its source code in the database? Should the client restart? Are you going to store the entire program as a single row in this database, or did you want to store individual functions? That affects how you structure your updates.
To address other issues with your question: Why do you want to do this? Making "interpreted language" part of your design spec for a system is not often a good sign. Is the real requirement something like this: "I update the program often and I want users to always have the latest copy?" If so, there are other, better ways to go about this (just give us your actual scenario and requirements).

Use C++ class from C#

Alright so I have this C++ image capturing class. I was wondering if I could get some help..I know basic C++ (I have done one intro to c and one intro to c++ class) and I have NO idea how to do this:
I need to use this class (ie create a new c++ project in my solution) and use c# to reference it and use it to save a screenshot of the screen.
When I try to add a new project I dont know which one to choose (win32, mfc, atl, clr, abc, xyz, and so on) .
The image capturing class is here:
http://pastebin.com/m72414ab
I don't know if I need to create .h files or just a .cpp file would do.. like honestly I have no clue where to start lol. I am looking for a solution, but i want to learn in the process so I dont have to ask next time (not to mention that I like c++ so I am gonna continue coding with it)
You cannot easily use C++ classes from C# without knowing some somewhat specialized information about C++/CLI - either rewrite your C++ class in C and use P/Invoke, or find a fully C# solution.
But I'd like to use this c++ class for speed and memory.
I question this, unless you are capturing images thousands of times a second, there's no way choosing C++ would be of any benefit, and it makes your program much more complicated. Stick with C# until you know you need the slight performance boost.
.NET version 2.0 and above include a CopyFromScreen method on the Graphics object. You can create an image, obtain a drawing surface (Graphics) for that, and then copy from the screen into the image.
A quick bit of Googling produced a simple tutorial which demonstrates this using Visual Basic .NET, although it's trivial to port to C#.
This solution results in the same GDI+ calls that your C++ version uses, with the benefit of not having to link in external C++ code (which, as mentioned above, is not straightforward).
It is definitely possible to use C++ constructs from C#, but it does require some dirty tricks. If I remember correctly, last time I tried to do this I used a Managed C++ layer between C++ and C#, and I think this is the most common way to do it. This method worked well, but indeed was unnecessarily complicated.

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