Add helpers: RageDisplay::CreateSurfaceFromPixfmt, RageDisplay::FindPixelFormat.

UpdateTexture can now take any image format; it doesn't have to match the
original format, or even be a standard pixel format.  This is because we
can often do the conversion much more efficiently within UpdateTexture
than we can in the caller.  With D3D, we can convert any source format
as we copy, preventing an extra blit. OpenGL can do it on the fly if
it happens to be a known texture format.

We can figure out the pixel format from the image itself, so there's
no need to pass pixfmt to UpdateTexture.

Add BGR8, for movies with OpenGL.

stepmania/src/RageDisplay.cpp

@@ -17,6 +17,7 @@
 #include "RageMath.h"
 #include "RageUtil.h"
 #include "GameConstantsAndTypes.h"
+#include "SDL_utils.h"
 
 //
 // Statistics stuff
@@ -566,3 +567,35 @@ RageMatrix RageDisplay::GetPerspectiveMatrix(float fovy, float aspect, float zNe
 
    return GetFrustrumMatrix(xmin, xmax, ymin, ymax, zNear, zFar);
 }
+
+SDL_Surface *RageDisplay::CreateSurfaceFromPixfmt( PixelFormat pixfmt,
+						void *pixels, int width, int height, int pitch )
+{
+	const PixelFormatDesc *tpf = GetPixelFormatDesc(pixfmt);
+
+	SDL_Surface *surf = SDL_CreateRGBSurfaceFrom(
+		pixels, width, height, tpf->bpp, pitch,
+		tpf->masks[0], tpf->masks[1], tpf->masks[2], tpf->masks[3]);
+
+	return surf;
+}
+
+PixelFormat RageDisplay::FindPixelFormat( 
+	int bpp, int Rmask, int Gmask, int Bmask, int Amask )
+{
+	PixelFormatDesc tmp = { bpp, Rmask, Gmask, Bmask, Amask };
+
+	int pixfmt;
+	for(pixfmt = 0; pixfmt < NUM_PIX_FORMATS; ++pixfmt)
+	{
+		const PixelFormatDesc *pf = GetPixelFormatDesc(PixelFormat(pixfmt));
+		if(!SupportsTextureFormat( PixelFormat(pixfmt) ))
+			continue;
+
+		if(memcmp(pf, &tmp, sizeof(tmp)))
+			continue;
+		return PixelFormat(pixfmt);
+	}
+
+	return NUM_PIX_FORMATS;
+}