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Fix bitmap scaling

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Bug introduced in 810f0a42e5.
The uint8 cast were also acting as masks for each of the pixel
components, moving them out of the multiplications made things go wrong.

Use rgb_color instead of messing with bitshifts and masks for better
readbility (the colors are out of order, but the processing is the same
on each color so the end result is valid).
This commit is contained in:
Adrien Destugues
2014-01-14 19:12:45 +01:00
parent 7292163915
commit e326520241
1 changed files with 15 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libs/icon/IconUtils.cpp
+15 -15
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@@ -113,9 +113,9 @@ scale_down(const uint8* srcBits, uint8* dstBits, int32 srcWidth, int32 srcHeight
float tmp;
float d1, d2, d3, d4;
// coefficients
uint32 p1, p2, p3, p4;
rgb_color p1, p2, p3, p4;
// nearby pixels
uint8 red, green, blue, alpha;
rgb_color out;
// color components
for (int32 i = 0; i < dstHeight; i++) {
@@ -143,23 +143,23 @@ scale_down(const uint8* srcBits, uint8* dstBits, int32 srcWidth, int32 srcHeight
d4 = (1 - t) * u;
// nearby pixels
p1 = *((uint32*)srcBits + (l * srcWidth) + c);
p2 = *((uint32*)srcBits + (l * srcWidth) + c + 1);
p3 = *((uint32*)srcBits + ((l + 1)* srcWidth) + c + 1);
p4 = *((uint32*)srcBits + ((l + 1)* srcWidth) + c);
p1 = *((rgb_color*)srcBits + (l * srcWidth) + c);
p2 = *((rgb_color*)srcBits + (l * srcWidth) + c + 1);
p3 = *((rgb_color*)srcBits + ((l + 1)* srcWidth) + c + 1);
p4 = *((rgb_color*)srcBits + ((l + 1)* srcWidth) + c);
// color components
blue = (uint8)(p1 * d1 + p2 * d2 + p3 * d3 + p4 * d4);
green = (uint8)((p1 >> 8) * d1 + (p2 >> 8) * d2
+ (p3 >> 8) * d3 + (p4 >> 8) * d4);
red = (uint8)((p1 >> 16) * d1 + (p2 >> 16) * d2
+ (p3 >> 16) * d3 + (p4 >> 16) * d4);
alpha = (uint8)((p1 >> 24) * d1 + (p2 >> 24) * d2
+ (p3 >> 24) * d3 + (p4 >> 24) * d4);
out.blue = (uint8)(p1.blue * d1 + p2.blue * d2 + p3.blue * d3
+ p4.blue * d4);
out.green = (uint8)(p1.green * d1 + p2.green * d2 + p3.green * d3
+ p4.green * d4);
out.red = (uint8)(p1.red * d1 + p2.red * d2 + p3.red * d3
+ p4.red * d4);
out.alpha = (uint8)(p1.alpha * d1 + p2.alpha * d2 + p3.alpha * d3
+ p4.alpha * d4);
// destination RGBA pixel
*((uint32*)dstBits + (i * dstWidth) + j)
= (alpha << 24) | (red << 16) | (green << 8) | (blue);
*((rgb_color*)dstBits + (i * dstWidth) + j) = out;
}
}
}