[c/c++] JPG to BMP conversion

[code_ninja]

Do any of you have a (working) .jpg to .bmp converter?

I'm working on a setbackground type script app that loads random backgrounds from my pc.

I already got it to load BMP's. But It won't load JPEG's.

I would prefer it if you provided the source code.

[code_ninja]

bump

[azcodemonkey]

grrr it was bmp to jpeg

I take it you're trying to do this on Windows?

Edited July 29, 2009 by azcodemonkey

[azcodemonkey]

Just in case you're doing it on Windows, here's an example of converting a jpeg to bmp:

#include <windows.h>
#include <gdiplus.h>

#define WINDOWS_LEAN_AND_MEAN
using namespace Gdiplus;

int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
	UINT  num = 0;		  // number of image encoders
	UINT  size = 0;		 // size of the image encoder array in bytes

	ImageCodecInfo* pImageCodecInfo = NULL;

	GetImageEncodersSize(&num, &size);
	if(size == 0)
		return -1;  // Failure

	pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
	if(pImageCodecInfo == NULL)
		return -1;  // Failure

	GetImageEncoders(num, size, pImageCodecInfo);

	for(UINT j = 0; j < num; ++j)
	{
		if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
		{
			*pClsid = pImageCodecInfo[j].Clsid;
			free(pImageCodecInfo);
			return j;  // Success
		}
	}
	free(pImageCodecInfo);
	return -1;
}

int main(void){

	GdiplusStartupInput startupInput;
	ULONG_PTR token;
	GdiplusStartup(&token, &startupInput, NULL);
	Image testImg(L"c:\\test.jpg", false);
	CLSID clsid;
	int ret = -1;

	if(-1 != GetEncoderClsid(L"image/bmp", &clsid)){
		ret = testImg.Save(L"c:\\test.bmp", &clsid);
	}

	GdiplusShutdown(token);
	return ret;
}

[code_ninja]

Oh, yeah. I need it to be cross-platform.

Looking for a function like:

int JpegToBmp(char* jfile, char* bfile){

//code here
//jpeg output to bfile


return bfile;

}

int main(){
JpegToBmp("C:\\1.jpg","C:\\1.bmp");

}

Thanks

Edited July 30, 2009 by dramonai

[code.kliu.org]

BMP is a Windows (and OS/2) format. The HBITMAP handle is very much a Windows-specific thing. Why do you want this to be cross-platform? And you do realize that, even for .bmp files, there are many different types of bitmaps, right? So... um, are you really sure you need/want this to be cross-platform?

[code_ninja]

I would prefer not to use the Gdiplus namespace.

[code.kliu.org]

I would prefer not to use the Gdiplus namespace.

That's a really bad reason to reject this approach. First, you don't have to use that namespace. Or, you can squirrel all this away in a separate source file. Etc.

The alternative is to roll your own implementation (or copy some existing implementation), which is wasteful if you can avoid it by using a system library like GdiPlus or WIC (Vista or later).

[code_ninja]

Gdiplus doesn't even work on my machine.

I don't have the header files and libraries with my compiler(mingw32-gcc).

I've tried CxImage,ipl98,DevIL, and a bunch of other Image Processing Libraries and none of them worked

(probably because they were coded with MS VC++ 6, and I'm using mingw)

BTW I want to convert a 24-bit JPG to a 24-bit bitmap

(another thing)

I already tried using a command-line image converter via system() but it didn't work.

[Mike]

DevIL should work fine what you want to do and afaik it's cross-platform, what specific issues did you come across?

[code.kliu.org]

So it's not cross-platform you're after, it's cross-compiler...

If you're developing on Windows, you are going to need the Windows SDK no matter what compiler you use. And as a bonus, the SDK also contains a free copy of MSFT's own compiler that you can use (though mingw-gcc should work for GDI+).

GDI+ actually uses a regular, flat C API (which is definitely cross-compiler-safe), that is then wrapped in a bunch of C++ classes via the headers (which you get through the SDK) so that C++ users can pretend that GDI+ is C++. As a last resort, you can always just bypass the middleman and use GDI+ as any old set of flat C APIs.

[code_ninja]

So it's not cross-platform you're after, it's cross-compiler...

Well, actually it is cross-platform because unix/macosx have gcc.

Downloading SDK... EDIT:(OMG this will take a while...)

Edited July 30, 2009 by dramonai

[Karl L.]

Funny, I was about to suggest CxImage, after my pleasant experience with it in a recent project. It compiles fine for me on both MinGW 3.4.5 (stable) and MinGW 4.4.0 (testing) (with the latest Win32API, of course.) I had to make some slight modifications, though, to get it to compile with libJPEG and libPNG. It should work like a charm for what you need.

[code.kliu.org]

Well, actually it is cross-platform because unix/macosx have gcc.

If you intend to have your program run on *nix without Wine, then it's cross-platform, and you probably shouldn't use GDI+ (you still can, if you find an alternative method for your *nix builds) (note that BMP files are used much outside of Windows). If you intend your program to run only on Windows, then it's cross-compiler (even if the compiler can compile for other platforms).

[code_ninja]

Funny, I was about to suggest CxImage, after my pleasant experience with it in a recent project. It compiles fine for me on both MinGW 3.4.5 (stable) and MinGW 4.4.0 (testing) (with the latest Win32API, of course.) I had to make some slight modifications, though, to get it to compile with libJPEG and libPNG. It should work like a charm for what you need.

Do you think you could send me a CxImage Makefile? Or tell me how to compile it.

Before I couldn't get it to compile.

If you intend to have your program run on *nix without Wine, then it's cross-platform, and you probably shouldn't use GDI+ (you still can, if you find an alternative method for your *nix builds) (note that BMP files are used much outside of Windows). If you intend your program to run only on Windows, then it's cross-compiler (even if the compiler can compile for other platforms).

Well, I'm developing this for both Ubuntu and Windows, maybe even Mac so...

[azcodemonkey]

If you're serious about cross-platform, use QT.

[code_ninja]

If you're serious about cross-platform, use QT.

Me no like qt. The framework is way too freakin large. To run my program, the downloader would have to download 100MB+ of DLL's.

Plus, right now I'm just working on the console with file handling, and the like.

[code_ninja]

I still can't get anything to work.

Help? Anyone?

Load JPEG from file, save as bitmap.

not working :angry:

argh...

[code_ninja]

Giving up... :(

Don't really need to convert.

I'll just convert the jpeg's manually then add the path's to the bmp's to my ini file.

Thanks to everyone who helped.

[Patrick333]

Just in case you're doing it on Windows, here's an example of converting a jpeg to bmp:

Useless code.

You can do it with 1 api call on Windows (Shell)...

[azcodemonkey]

Useless code.

You can do it with 1 api call on Windows (Shell)...

So... Instead of you being an arrogant **** head, why not post the code and enlighten us? Jeezus, now I remember why I stopped posting here. I mostly code for the web these days, so forgive my ignorance of the shell that I haven't even looked at in years, O Mighty One!