From e3265202413cd402548ba28003e430e08f8acea6 Mon Sep 17 00:00:00 2001
From: Adrien Destugues <pulkomandy@pulkomandy.tk>
Date: Tue, 14 Jan 2014 18:46:45 +0100
Subject: [PATCH] Fix bitmap scaling

Bug introduced in 810f0a42e50b32d17c478f0bdf73b1b34d315ad0.
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).
---
 src/libs/icon/IconUtils.cpp | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/src/libs/icon/IconUtils.cpp b/src/libs/icon/IconUtils.cpp
index bbefa873f4..229fe6bd02 100644
--- a/src/libs/icon/IconUtils.cpp
+++ b/src/libs/icon/IconUtils.cpp
@@ -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;
 		}
 	}
 }