SDL makes a great companion library to cairo. With SDL, you can create portable multimedia applications very easily. Install the latest SDL development packages for your distribution, or download the latest SDL development kit from http://www.libsdl.org.
Drawing with cairo to an SDL Surface is quite simple, as all you need
to do is create a
cairo_surface_t from the SDL_Surface using
cairo_image_surface_create_for_data(). This works as expected as
long as SDL and cairo agree on the pixel format. For example:
SDL_Surface *sdlsurf = SDL_CreateRGBSurface ( flags, width, height, 32, 0x00FF0000, /* Rmask */ 0x0000FF00, /* Gmask */ 0x000000FF, /* Bmask */ 0); /* Amask */ /* ... make sure sdlsurf is locked or doesn't need locking ... */ cairo_surface_t *cairosurf = cairo_image_surface_create_for_data ( sdlsurf->pixels, CAIRO_FORMAT_RGB24, sdlsurf->w, sdlsurf->h, sdlsurf->pitch); /* ... normal cairo calls ... */
All the usual SDL locking rules apply, so the
pixels member of your
SDL_Surface needs to be valid and stay put for the lifetime of the
SDL's 32 bit pixel formats with per pixel alpha are not supported
directly by cairo because cairo and SDL disagree on the interpretation
of pixel values with alpha: SDL uses unpremultiplied pixels but cairo
uses premultiplied pixels. However, using
cairosdl drawing to
SDL_Surfaces is almost as straightforward as to any other cairo
surface; chiefly the difference is that one needs to flush the surface
before the results appear in the
SDL_Surface. You can also use cairo
to composite a cairo surface with transparency to an
without, and thus sidestep the problem entirely.
Examples of using SDL with cairo are available in the demos branch of cairosdl.