Flickering image (with *double buffering*)
Ok, this is my code. It is supposed to black out surfaceSecondary, then blit the image from surfaceBitmap onto surfaceSecondary, then display the result on the screen:
blackBltFx is a DDBLTFX that is memsetted to 0 (then its dwSize is reset to sizeof(DDBLTFX)), and rect is a RECT filled in with the image's dimensions.
surfaceSecondary->Blt(NULL, NULL, NULL, DDBLT_WAIT | DDBLT_COLORFILL, &blackBltFx);
surfaceSecondary->Blt(&rect, surfaceBitmap, NULL, DDBLT_WAIT, NULL);
surfacePrimary->Blt(&rect, surfaceSecondary, NULL, DDBLT_WAIT, NULL);
while(surfacePrimary->Flip(NULL, DDFLIP_WAIT) != DD_OK);
The problem isn't that it flickers from black to image to black to image, but that only part of the image gets drawn, except for occasional glimpses. Putting a Sleep(1) after the two surfaceSecondary blits gets the whole image to display except occasional partial-blits, and a Sleep(2) gets the thing to blit very nicely. Why is it that I need the Sleep()'s to make it blit properly?
n/m, think I figured it out... the surfacePrimary blt() is the culprit. BUT, just a question, but what is the point of using Flip() instead of Blt() when surfaceSecondary is an attached surface?