File qt-4.8.0-Description-rewrite-INV_PREMUL-to-fix-a-glass-jaw-on.patch of Package qt

From b70fabfc9c480d5c9d7831b48d61fbaec80aef4f Mon Sep 17 00:00:00 2001
From: Robin Burchell <robin.burchell@collabora.com>
Date: Sun, 13 Nov 2011 12:31:18 +0100
Subject: [PATCH] Description: rewrite INV_PREMUL to fix a glass jaw on Atom

Author: Arjan van de Ven <arjan@linux.intel.com>
---
 src/gui/image/qimage.cpp |   18 +++++++++++++++++-
 1 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index f527bcf..9b46a51 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -2574,6 +2574,22 @@ static bool convert_RGB_to_RGB16_inplace(QImageData *data, Qt::ImageConversionFl
     }
 }
 
+
+static inline QRgb inv_premul(QRgb p)
+{
+    unsigned char alpha, red, green, blue;
+    
+    alpha = qAlpha(p);
+    if (alpha == 0)
+        return 0;
+    if (alpha == 255)
+        return p;
+    red = 255 * qRed(p) / alpha;
+    green = 255 * qGreen(p) / alpha;
+    blue = 255 * qBlue(p) / alpha;
+    return (alpha << 24) | (red << 16) | (green << 8) | blue;
+}
+
 static void convert_ARGB_PM_to_ARGB(QImageData *dest, const QImageData *src, Qt::ImageConversionFlags)
 {
     Q_ASSERT(src->format == QImage::Format_ARGB32_Premultiplied);
@@ -2589,7 +2605,7 @@ static void convert_ARGB_PM_to_ARGB(QImageData *dest, const QImageData *src, Qt:
     for (int i = 0; i < src->height; ++i) {
         const QRgb *end = src_data + src->width;
         while (src_data < end) {
-            *dest_data = INV_PREMUL(*src_data);
+            *dest_data = inv_premul(*src_data);
             ++src_data;
             ++dest_data;
         }
-- 
1.7.7.4