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Copy blend mode to recreated surface

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This fixes a "root cause" bug (that's existed since 2.2 and below) where
recreated surfaces wouldn't preserve the blend mode of their original
surface.

The surface-level (pun genuinely unintended) bug that this root bug
fixes is the one where there's no background to the room name during the
map menu animation in Flip Mode.

This is because the room name background relies on graphics.backBuffer
being filled with complete black. This is achieved by a call to
ClearSurface() - however, ClearSurface() actually fills it with
transparent black (this is not a regression; in 2.2 and previous, this
was an "inlined" FillRect(backBuffer, 0x00000000)). This would be okay,
and indeed the room name background renders fine in unflipped mode - but
it suddenly breaks in Flip Mode.

Why? Because backBuffer gets fed through FlipSurfaceVerticle(), and
FlipSurfaceVerticle() creates a temporary surface with the same
dimensions and color masks as backBuffer - it, however, does NOT create
it with the same blend mode, and kind of sort of just forgets that the
original was SDL_BLENDMODE_NONE; the new surface is SDL_BLENDMODE_BLEND.
Thus, transparency applies on the new surface, and instead of the room
name being drawn against black, it gets drawn against transparency.
This commit is contained in:
Misa 2021-03-05 20:17:56 -08:00
parent aca33e5587
commit d19a6cc437
1 changed files with 4 additions and 0 deletions
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4
desktop_version/src/GraphicsUtil.cpp
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@ -17,6 +17,7 @@ static SDL_Surface* RecreateSurfaceWithDimensions(
const int height
) {
SDL_Surface* retval;
SDL_BlendMode blend_mode;
if (surface == NULL)
{
@ -39,6 +40,9 @@ static SDL_Surface* RecreateSurfaceWithDimensions(
return NULL;
}
SDL_GetSurfaceBlendMode(surface, &blend_mode);
SDL_SetSurfaceBlendMode(retval, blend_mode);
return retval;
}