Convert any IImage to A8R8G8B8

[eye776]

If anyone ever needed to draw inside a texture, but couldn't because of Color format differences, heres' a short snippet on how to convert any IImage that Irrlicht can load to 32-bit ARGB.

Code: Select all

IImage* getARGBImage(stringc filename)
{
IImage* srcImage = System::Driver->createImageFromFile(filename);
IImage* bmpImage = NULL;

	if(srcImage->getColorFormat() != ECF_A8R8G8B8) {
		printf("Image color format doesn't match, converting!\n");
		dimension2du dim = srcImage->getDimension();
		void* load_pixels = malloc((dim.Width * dim.Height) << 2);
		switch(srcImage->getColorFormat())
		{
		case ECF_A1R5G5B5:
			convert_A1R5G5B5toA8R8G8B8(srcImage->lock(), (dim.Width * dim.Height), load_pixels);
			break;
		case ECF_R5G6B5:
			convert_R5G6B5toA8R8G8B8(srcImage->lock(), (dim.Width * dim.Height), load_pixels);
			break;
		case ECF_R8G8B8:
		        convert_R8G8B8toA8R8G8B8(srcImage->lock(), (dim.Width * dim.Height), load_pixels);
			break;
		}
		bmpImage = System::Driver->createImageFromData(ECF_A8R8G8B8, dim, load_pixels, false, true);
		free(load_pixels);
		srcImage->drop();
                return bmpImage;
       } else {
                return srcImage;
       }
}

You then use:

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IImage* newImage = getARGBImage(filename);
ITexture* newTexture = IVideoDriver::addTexture(filename, newImage);

You can now use (u32*)newTexture->lock(); and draw inside it as you please using SColor::color.

PS: convert_A1R5G5B5toA8R8G8B8, convert_A1R5G5B5toA8R8G8B8, convert_R8G8B8toA8R8G8B8 are found in CColorConverter.cpp (in the irrlicht sources).

[hybrid]

Check latest SVN trunk for a properly exported conversion function. This will redue the code to basically a few lines and works even on non-linux systems.

[eye776]

Okay. What's the function called like?

PS: Is this it?

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IVideoDriver::convertColor(const void* sP, ECOLOR_FORMAT sF, s32 sN, void* dP, ECOLOR_FORMAT dF)

PS2: The code I wrote was tested on win32 with VC9 express

[hybrid]

Yes, that's the function. However, I cannot see how you can access the functions which are buried inside the dll. There's no public interface for them, so they are largely inaccessible.

[slavik262]

Could you expose that function? It would be incredibly useful to a lot of people.

[hybrid]

As you can see from the code snippet above, it will be exposed in Irrlicht 1.8. The convertColor function subsumes all the specialised convertColorAtoColorB functions via the color format parameters. So you basically only need one such function, which will be part of the video driver interface.

[slavik262]

Awesome. Can't wait to see it!

[eye776]

So the code would become (in irrlicht 1.:

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IImage* getARGBImage(stringc filename) 
{ 
IImage* srcImage = IVideoDriver::createImageFromFile(filename); 
IImage* bmpImage = NULL; 

   if(srcImage->getColorFormat() != ECF_A8R8G8B8) { 
      printf("Image color format doesn't match, converting!\n"); 
      bmpImage = System::Driver->createImage(ECF_A8R8G8B8, srcImage->getDimension()); 
      IVideoDriver::convertColor(srcImage->lock(), srcImage->getColorFormat(), (srcImage->getDimension().Width * srcImage->getDimension().Height), bmpImage->lock(), ECF_A8R8G8B8);
      srcImage->unlock();
      srcImage->drop();
      bmpImage->unlock();
      return bmpImage; 
  } else {
       return srcImage; 
  }

}

EDIT: Edited according to what hybrid stated below.

[hybrid]

You can avoid the additional alloc/free and data copy by creating an empty image with the proper dimension and color format, lock it, and use that pointer as parameter for convert destination.