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-rw-r--r--src/resources/image.cpp73
1 files changed, 53 insertions, 20 deletions
diff --git a/src/resources/image.cpp b/src/resources/image.cpp
index b217db683..4229cb8af 100644
--- a/src/resources/image.cpp
+++ b/src/resources/image.cpp
@@ -320,30 +320,63 @@ void Image::setAlpha(const float alpha)
if (SDL_MUSTLOCK(mSDLSurface))
SDL_LockSurface(mSDLSurface);
- // Precompute as much as possible
- const int maxHeight = std::min((mBounds.y + mBounds.h),
- mSDLSurface->h);
- const int maxWidth = std::min((mBounds.x + mBounds.w),
- mSDLSurface->w);
- const int i1 = mBounds.y * mSDLSurface->w + mBounds.x;
- const int i2 = (maxHeight - 1) * mSDLSurface->w + maxWidth - 1;
-
+ const int bx = mBounds.x;
+ const int by = mBounds.y;
+ const int bw = mBounds.w;
+ const int bh = mBounds.h;
+ const int bxw = bx + bw;
+ const int sw = mSDLSurface->w;
+ const int maxHeight = std::min(by + bh, mSDLSurface->h);
+ const int maxWidth = std::min(bxw, sw);
+ const int i1 = by * sw + bx;
const SDL_PixelFormat * const fmt = mSDLSurface->format;
+ const uint32_t amask = fmt->Amask;
+ const uint32_t invMask = ~fmt->Amask;
+ const uint8_t aloss = fmt->Aloss;
+ const uint8_t ashift = fmt->Ashift;
- for (int i = i1; i <= i2; i++)
+ if (!bx && bxw == sw)
+ {
+ const int i2 = (maxHeight - 1) * sw + maxWidth - 1;
+ for (int i = i1; i <= i2; i++)
+ {
+ const uint8_t sourceAlpha = mAlphaChannel[i];
+ if (sourceAlpha > 0)
+ {
+ const uint8_t a = static_cast<uint8_t>(
+ static_cast<float>(sourceAlpha) * mAlpha);
+
+ uint32_t c = (static_cast<uint32_t*>(
+ mSDLSurface->pixels))[i];
+ c &= invMask;
+ c |= ((a >> aloss) << ashift & amask);
+ (static_cast<uint32_t*>(mSDLSurface->pixels))[i] = c;
+ }
+ }
+ }
+ else
{
- // Only change the pixel if it was visible at load time...
- const uint8_t sourceAlpha = mAlphaChannel[i];
- if (sourceAlpha > 0)
+ for (int y = by; y < maxHeight; y ++)
{
- const uint8_t a = static_cast<uint8_t>(
- static_cast<float>(sourceAlpha) * mAlpha);
-
- uint32_t c = (static_cast<uint32_t*>(
- mSDLSurface->pixels))[i];
- c &= ~fmt->Amask;
- c |= ((a >> fmt->Aloss) << fmt->Ashift & fmt->Amask);
- (static_cast<uint32_t*>(mSDLSurface->pixels))[i] = c;
+ const int i1 = y * sw;
+ const int x1 = i1 + bx;
+ const int x2 = i1 + maxWidth;
+ for (int i = x1; i < x2; i ++)
+ {
+ const uint8_t sourceAlpha = mAlphaChannel[i];
+ if (sourceAlpha > 0)
+ {
+ const uint8_t a = static_cast<uint8_t>(
+ static_cast<float>(sourceAlpha) * mAlpha);
+
+ uint32_t c = (static_cast<uint32_t*>(
+ mSDLSurface->pixels))[i];
+ c &= invMask;
+ c |= ((a >> aloss) << ashift & amask);
+ (static_cast<uint32_t*>(
+ mSDLSurface->pixels))[i] = c;
+ }
+ }
}
}