BLADERUNNER: Fixed alpha channel issues

Alpha channel is inverted in the game assets and that lead to issues in
OpenGL renderer. E.g. screenshot of savegames were partly black or
showing artifacts

closes #10983

1 files changed, 8 insertions, 4 deletions

diff --git a/engines/bladerunner/bladerunner.cpp b/engines/bladerunner/bladerunner.cpp
index e3e54299fb..9621612ac6 100644
--- a/engines/bladerunner/bladerunner.cpp
+++ b/engines/bladerunner/bladerunner.cpp
@@ -2163,14 +2163,18 @@ void BladeRunnerEngine::blitToScreen(const Graphics::Surface &src) const {
 
 Graphics::Surface BladeRunnerEngine::generateThumbnail() const {
 	Graphics::Surface thumbnail;
-	thumbnail.create(640 / 8, 480 / 8, _surfaceFront.format);
+	thumbnail.create(640 / 8, 480 / 8, gameDataPixelFormat());
 
 	for (int y = 0; y < thumbnail.h; ++y) {
 		for (int x = 0; x < thumbnail.w; ++x) {
-			uint16       *dstPixel = (uint16 *)thumbnail.getBasePtr(x, y);
-			const uint16 *srcPixel = (const uint16 *)_surfaceFront.getBasePtr(x * 8, y * 8);
+			uint8 r, g, b;
 
-			*dstPixel = *srcPixel;
+			uint16  srcPixel = *(uint16 *)_surfaceFront.getBasePtr(x * 8, y * 8);
+			uint16 *dstPixel = (uint16 *)thumbnail.getBasePtr(x, y);
+
+			// Throw away alpha channel as it is not needed
+			_surfaceFront.format.colorToRGB(srcPixel, r, g, b);
+			*dstPixel = thumbnail.format.RGBToColor(r, g, b);
 		}
 	}