From c32cd44d34910cfd42e32537578e4a573138a282 Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@qt.io>
Date: Thu, 11 Feb 2021 11:23:05 +0100
Subject: Fix alpha handling of QImage::setPixel

It was treated differently depending on format, made it consistently
behave the same for all formats (following the behavior of the primary
formats).

Pick-to: 6.1 6.0 5.15
Change-Id: Ie24e19957d076fdf3ebd333074e26ede187489eb
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
---
 src/gui/painting/qpixellayout.cpp | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

(limited to 'src/gui/painting')

diff --git a/src/gui/painting/qpixellayout.cpp b/src/gui/painting/qpixellayout.cpp
index 8dd62b0c00..ca6bca344f 100644
--- a/src/gui/painting/qpixellayout.cpp
+++ b/src/gui/painting/qpixellayout.cpp
@@ -1333,7 +1333,7 @@ static void QT_FASTCALL storeRGB64FromRGB32(uchar *dest, const uint *src, int in
 {
     QRgba64 *d = reinterpret_cast<QRgba64 *>(dest) + index;
     for (int i = 0; i < count; ++i)
-        d[i] = QRgba64::fromArgb32(src[i]);
+        d[i] = QRgba64::fromArgb32(src[i] | 0xff000000);
 }
 
 static const uint *QT_FASTCALL fetchRGBA64ToARGB32PM(uint *buffer, const uchar *src, int index, int count,
@@ -1345,12 +1345,24 @@ static const uint *QT_FASTCALL fetchRGBA64ToARGB32PM(uint *buffer, const uchar *
     return buffer;
 }
 
+template<bool Mask>
 static void QT_FASTCALL storeRGBA64FromARGB32PM(uchar *dest, const uint *src, int index, int count,
                                                 const QList<QRgb> *, QDitherInfo *)
 {
     QRgba64 *d = reinterpret_cast<QRgba64 *>(dest) + index;
-    for (int i = 0; i < count; ++i)
+    for (int i = 0; i < count; ++i) {
         d[i] = QRgba64::fromArgb32(src[i]).unpremultiplied();
+        if (Mask)
+            d[i].setAlpha(65535);
+    }
+}
+
+static void QT_FASTCALL storeRGBA64FromARGB32(uchar *dest, const uint *src, int index, int count,
+                                              const QList<QRgb> *, QDitherInfo *)
+{
+    QRgba64 *d = reinterpret_cast<QRgba64 *>(dest) + index;
+    for (int i = 0; i < count; ++i)
+        d[i] = QRgba64::fromArgb32(src[i]);
 }
 
 // Note:
@@ -1437,15 +1449,15 @@ QPixelLayout qPixelLayouts[QImage::NImageFormats] = {
     { false, false, QPixelLayout::BPP64, rbSwap_4x16,
       convertPassThrough, nullptr,
       fetchRGB64ToRGB32, fetchPassThrough64,
-      storeRGB64FromRGB32, storeRGB64FromRGB32 }, // Format_RGBX64
+      storeRGBA64FromARGB32PM<true>, storeRGB64FromRGB32 }, // Format_RGBX64
     { true, false, QPixelLayout::BPP64, rbSwap_4x16,
       convertARGB32ToARGB32PM, nullptr,
       fetchRGBA64ToARGB32PM, fetchRGBA64ToRGBA64PM,
-      storeRGBA64FromARGB32PM, storeRGB64FromRGB32 }, // Format_RGBA64
+      storeRGBA64FromARGB32PM<false>, storeRGB64FromRGB32 }, // Format_RGBA64
     { true, true, QPixelLayout::BPP64, rbSwap_4x16,
       convertPassThrough, nullptr,
       fetchRGB64ToRGB32, fetchPassThrough64,
-      storeRGB64FromRGB32, storeRGB64FromRGB32 }, // Format_RGBA64_Premultiplied
+      storeRGBA64FromARGB32, storeRGB64FromRGB32 }, // Format_RGBA64_Premultiplied
     { false, false, QPixelLayout::BPP16, nullptr,
       convertGrayscale16ToRGB32, convertGrayscale16ToRGBA64,
       fetchGrayscale16ToRGB32, fetchGrayscale16ToRGBA64,
-- 
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