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.
Related
I need to use a program made in C for a C# project , and for this I need to generate a DLL in Visual Studio 2013, anyone have any tutorial or know how to do it?
I want make a DLL for a structs and read/write functions in C, cheers guys.
You have to use p/invokes. I think this is very often discussed here. Take a look at: Access a method from a DLL from C# program
DLL is probably overkill for what you are doing. You can just write a C procedure and P/Invoke it using CDecl. The problem is that you need to know a whole lot for this. If you are simply trying to iterate over an array fast for a performance critical section, you are better off using structs in C#, slapping unsafe on your method, and then using pointers and addresses to do what you want to do. Code that looks a whole lot like C/C++ is perfectly legal in C#.
See a reference here: MSDN : Unsafe Pointers
Also fished out a somewhat dated reference showing how to P/Invoke the visual c Runtime printf function as an example. Keep in mind that things get really hard when you need to give a pointer to a function and when you need to read offsets etc. to pass around structs. You'll need to pin anything you pass into the method to stop it from being moved by the garbage collector, which will also have performance implications.
MSDN: CDecl P/Invoke example
How I can translate small C++/CLI project to c#
One roundabout, manual way would be to compile your C++/CLI project and open the output assembly in Reflector. Disassemble each class, have it convert the disassembled IL to C#, and save that code off.
As for an automatic way to do it, I can't think of any off the top of my head.
Those things being said, are you sure you really want to convert your project to C#? If your C++/CLI project uses any unmanaged code, you'll have a difficult time coming up with a purely managed equivalent. If the project is more or less composed of pure CLR code, and it was written in C++/CLI for the sake of being written in C++/CLI, I can understand wanting to convert it to C#. But if there was a reason for writing it in C++/CLI, you may want to keep it that way.
IMHO, line by line is the best way. I've ported several C++ style projects to a managed language and I've tried various approaches; translators, line by line, scripting, etc ... Over time I've found the most effective way is to do it line by line even though it seems like the slowest way at first.
Too much is lost in a translator. No translator is perfect and you end up spending a lot of time fixing up the translated code. Also, translated code as a rule is ugly and tends to be less readable than hand crafted code. So the result is a fixed up, not very pretty code base.
A couple of tips I have on line by line
Start by defining all of the leaf types
For every type that has a non-trivial (freeing memory) destructor, implement IDisposable
Turn on the FxCop rule that checks for lack of Dispose calls to catch all of the places use used stack based RAII and missed it
Pay very close attention to the uses of byref in C++.
I haven't tried it, but I just googled it and found this: http://code2code.net/
According t it, you shouldn't fully rely on the code it produces:
You accept that this page does only half the work.
Futher work on your part is required. In most cases, the translated code will not even compile.
Also, read this: Translate C++/CLI to C#
I need to import some ANSI C code into a project I'm working on. For reasons I prefer not to go into, I want to refactor the code to C# rather than trying to wrap the original code. It will take me perhaps a couple of days to do the work by hand, but before I start, is there an automated tool that can get me most of the way there? I'm a cheapskate and the work I'm doing is pro bono, so free tools only please.
If manual refactoring is "only" going to take a few days, that would get my vote. Depending on what the C code is doing and how it is written (pointers, custom libraries, etc.) an automated converter may just make a mess. And untangling that mess could be a larger task than just converting by hand.
Setting up, cleaning up, refactoring, and just plain making converted code (if there is even a converter available) would probably be something in the magnitude of weeks or months, so you'll be better served just to go ahead with the manual rewrite.
There is an experimental CLI Back-End and Front-End for GCC. It is already capable of compiling a subset of C programs into CIL, the byte-code that the CLR runs.
(The webpage makes it seem like the code was only developed over a few months and then ignored since then, but it's out of date; ST Microelectronics is continuing maintenance and development.)
You don't specify why you want a C to C# translator, but if you just want to get C and C# to play together without P/Invoke or COM, it might be good enough.
It may make sense to start by getting the existing code to compile as managed C++ aka C++/CLI. Assuming that went smoothly enough, then you have a working, testable foundation on which to build. Move key features to their own classes, and as needed, rewrite as C# along the way.
I've recently been wrestling with an algorithm which was badly implemented (i.e. the developer was pulled off onto another project and failed to adequately document what he'd done) in C#.
I've found an alternative (from numerical recipes) which works but is written in C++. So I'm thinking probably the safest way to get something working would be to wrap the C++ up in a DLL.
Bearing in mind that I'm still a bit green when it comes to C# and have never tried making a DLL from scratch, does this sound like a reasonable approach (and if so, has anyone tried this / got any advice)? Or should I go the whole hog and try and port the C++ routine into C#?
Edit - I'm not looking for anyone to make the decision for me, but if anyone has any exprience of either route I'd be interested to hear their opinions and any nasty pitfalls that should be avoided. For example, how nasty is passing in lists of data from C# to a C++ STL vector?
I tried linking to c-dll's from c# code with quite good results, even though I had some problems sending data between the environments. Otherwise the procedure is quite straight forward. The more data you send back and forth (both amount and frequency) the slower your program will run, but you have probably already figured this out on your own.
The main drawback was maintaining the c#-c glue code (interface code) each time something changed or someone found a bug.
Here is a bit of code to get you started:
using System.Runtime.InteropServices;
class myDllCaller {
//call to function in the dll returning an int
[DllImport("MyFavorite.dll")]
private static extern int dllFunction(//list of parameters to function);
public static void Main() {
int rerult = dllFunction();
}
}
If the C# version Mitch references isn't of a suitable licence for your purposes, You could use a managed C++ wrapper, that could reuse, and wrap the C code you have, but still be visible to your managed applications as a native .Net assembly. I've used this approach in the past for using the C API of a library that didn't have its own native .Net API, and found it relatively painless marshalling data between the two.
It depends what your goals are.
If it's to have a working application I'd weigh-up the costs and benefits of both approaches and go with the most cost effective.
If it's to improve your C# then by all means rewrite the C.
...Or you could download the already implemented code in C# from here.
I'm exploring various options for mapping common C# code constructs to C++ CUDA code for running on a GPU. The structure of the system is as follows (arrows represent method calls):
C# program -> C# GPU lib -> C++ CUDA implementation lib
A method in the GPU library could look something like this:
public static void Map<T>(this ICollection<T> c, Func<T,T> f)
{
//Call 'f' on each element of 'c'
}
This is an extension method to ICollection<> types which runs a function on each element. However, what I would like it to do is to call the C++ library and make it run the methods on the GPU. This would require the function to be, somehow, translated into C++ code. Is this possible?
To elaborate, if the user of my library executes a method (in C#) with some arbitrary code in it, I would like to translate this code into the C++ equivelant such that I can run it on CUDA. I have the feeling that there are no easy way to do this but I would like to know if there are any way to do it or to achieve some of the same effect.
One thing I was wondering about is capturing the function to translate in an Expression and use this to map it to a C++ equivelant. Anyone has any experience with this?
There's CUDA.Net if you want some reference how C# can be run on GPU.
To be honest, I'm not sure I fully understand what you are getting at. However, you may be interested in this project which converts .Net applications / libraries into straight C++ w/o any .Net framework required. http://www.codeplex.com/crossnet
I would recommend the following process to accelerate some of your computation using CUDA from a C# program:
First, create an unmanaged C++ library that you P/Invoke for the functions you want to accelerate. This will restrict you more or less to the data types you can easily work with in CUDA.
Integrate your unmanaged library with your C# application. If you're doing things correctly, you should already notice some kind of speed up. If not, you should probably give up.
Replace the C++ functions inside your library (without changing its interface) to perform the computations on the GPU with CUDA kernels.
Interesting question. I'm not very expert at C#, but I think an ICollection is a container of objects. If each element of c was, say, a pixel, you'd have to do a lot of marshalling to convert that into a buffer of bytes or floats that CUDA could use. I suspect that would slow everything down enough to negate the advantage of doing anything on the gpu.
What you could do would be to write an own IQueryable LINQ provider, as is done for LINQ to SQL to translate LINQ queries to SQL.
However, one problem that I see with this approach is the fact that LINQ queries are usually evaluated lazily. In order to benefit from pipelining, this is probably not a viable solution.
It might also be worth investigating how to implement Google’s MapReduce API for C# and CUDA and then use an approach similar to PyCuda to ship the logic to the GPU. In that context, it might also be useful to take a look at the already existing MapReduce implementation in CUDA.
That's a very interesting question and I have no idea how to do this.
However, the Brahma library seems to do something very similar. You can define functions using LINQ which are then compiled to GLSL shaders to run efficiently on a GPU. Have a look at their code and in particular the Game of Life sample.