Narin wrote:So is it not possible to "draw into" an RGBA surface the same way you can draw into GapiSurface?
Well. GapiRGBASurface does not have the drawing toolkit of CGapiSurface, such as line drawing and font rendering. But you can draw into a CGapiRGBASurface yourself using GetBuffer() to write pixels manually.
Narin wrote:I was hoping to "build up" RGBA surfaces by blitting images with alpha channels and drawing lines and such, then keep them around for fast blitting later.
You can do this! Use one CGapiSurface as "color" texture, and one CGapiSurface as "alpha" texture. You can then draw as you want to these CGapiSurfaces, either modifying alpha, color channel, or both. Then call the CGapiSurface::AlphaBlt that takes two CGapiSurface pointers as source (one CGapiSurface for color and one CGapiSurface for alpha).