C/C++ library to blend PNG (including Alpha) with raw ARGB buffer - c++

Question

I have a PNG with an encoded alpha channel that I want to blend with a raw ARGB image in memory that is stored interleaved. The PNG is of a different resolution to the image buffer and needs to be resized accordingly (preferably with interpolation).
Whilst I appreciate it's not particularly difficult to do this by hand (once the PNG image is loaded into an appropriate structure), I was hoping to find a good open source image processing library to do the work for me.
I've looked at a few including:
libGD
libPNG
openCV
ImageMagick
CxImage
Intel Integrated Performance Primitives (IPP)
But none of seem to handle all the requirements of loading PNGs, resizing the PNG image, alpha blending into the image data and handling the ARGB format (as opposed to RGBA).
Performance is a concern so reducing the passes over the image data would be beneficial, especially being able to hold the ARGB data in place rather than having to copy it to a different data structure to perform the blending.
Does anyone know of any libraries that may be able to help or whether I've missed something in one of the above?

Answer 1

You can do this with SDL by using SDL_gfx and SDL_Image.
// load images using SDL_Image
SDL_Surface *image1, image2;
image1=IMG_Load("front.png");
image2=IMG_Load("back.png");
// blit images onto a surface using SDL_gfx
SDL_gfxBlitRGBA ( image1, rect, screen, rect );
SDL_gfxBlitRGBA ( image2, rect, screen, rect );

Answer 2

You need to pair a file-format library (libPNG or ImageMagick) with a image manipulation library. Boost.GIL would be good here. If you can load the ARGB buffer (4 bytes per pixel) into memory, you can create a GIL image with interleaved_view, and reinterpret_casting your buffer pointer to a boost::gil::argb32_ptr_t

Answer 3

With the ImageMagick it is very easy thing to do by using appendImages function.
Like this :
#include <list>
#include <Magick++.h>
using namespace std;
using namespace Magick;
int main(int /*argc*/,char **/*argv*/)
{
list<Image> imageList;
readImages( &imageList, "test_image_anim.gif" );
Image appended;
appendImages( &appended, imageList.begin(), imageList.end() );
appended.write( "appended_image.miff" );
return 0;
}