From 95712c5e5438e4eb5cd205ab4659febf3192137a Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@qt.io>
Date: Wed, 10 Feb 2021 16:26:25 +0100
Subject: Fix QImage::fill with semi-transparent QColor

A few formats were not treating the input QColor correctly. Fixed and
added more exhaustive test.

Pick-to: 6.1 6.0 5.15
Change-Id: I872aeeb45e518f9a34b4ac35642264821f9927f2
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
---
 src/gui/image/qimage.cpp                   | 21 ++++++++---------
 tests/auto/gui/image/qimage/tst_qimage.cpp | 38 ++++++++++++++++++++++++------
 2 files changed, 41 insertions(+), 18 deletions(-)

diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index c3054bccfe..11eabcc9af 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -1781,6 +1781,8 @@ void QImage::fill(const QColor &color)
     if (!d)
         return;
 
+    QRgba64 opaque = color.rgba64();
+    opaque.setAlpha(65535);
     switch (d->format) {
     case QImage::Format_RGB32:
     case QImage::Format_ARGB32:
@@ -1799,12 +1801,10 @@ void QImage::fill(const QColor &color)
         fill(ARGB2RGBA(qPremultiply(color.rgba())));
         break;
     case QImage::Format_BGR30:
-    case QImage::Format_A2BGR30_Premultiplied:
-        fill(qConvertRgb64ToRgb30<PixelOrderBGR>(color.rgba64()));
+        fill(qConvertRgb64ToRgb30<PixelOrderBGR>(opaque));
         break;
     case QImage::Format_RGB30:
-    case QImage::Format_A2RGB30_Premultiplied:
-        fill(qConvertRgb64ToRgb30<PixelOrderRGB>(color.rgba64()));
+        fill(qConvertRgb64ToRgb30<PixelOrderRGB>(opaque));
         break;
     case QImage::Format_RGB16:
         fill((uint) qConvertRgb32To16(color.rgba()));
@@ -1827,19 +1827,18 @@ void QImage::fill(const QColor &color)
         else
             fill((uint) 0);
         break;
-    case QImage::Format_RGBX64: {
-        QRgba64 c = color.rgba64();
-        c.setAlpha(65535);
-        qt_rectfill<quint64>(reinterpret_cast<quint64*>(d->data), c,
+    case QImage::Format_RGBX64:
+        qt_rectfill<quint64>(reinterpret_cast<quint64*>(d->data), opaque,
                              0, 0, d->width, d->height, d->bytes_per_line);
         break;
-
-    }
     case QImage::Format_RGBA64:
-    case QImage::Format_RGBA64_Premultiplied:
         qt_rectfill<quint64>(reinterpret_cast<quint64*>(d->data), color.rgba64(),
                              0, 0, d->width, d->height, d->bytes_per_line);
         break;
+    case QImage::Format_RGBA64_Premultiplied:
+        qt_rectfill<quint64>(reinterpret_cast<quint64 *>(d->data), color.rgba64().premultiplied(),
+                             0, 0, d->width, d->height, d->bytes_per_line);
+        break;
     default: {
         QPainter p(this);
         p.setCompositionMode(QPainter::CompositionMode_Source);
diff --git a/tests/auto/gui/image/qimage/tst_qimage.cpp b/tests/auto/gui/image/qimage/tst_qimage.cpp
index 2c9f3a3746..6e7fce0b75 100644
--- a/tests/auto/gui/image/qimage/tst_qimage.cpp
+++ b/tests/auto/gui/image/qimage/tst_qimage.cpp
@@ -148,6 +148,7 @@ private slots:
     void fillColor_data();
     void fillColor();
 
+    void fillColorWithAlpha_data();
     void fillColorWithAlpha();
 
     void fillRGB888();
@@ -2348,15 +2349,38 @@ void tst_QImage::fillColor()
     }
 }
 
-void tst_QImage::fillColorWithAlpha()
+void tst_QImage::fillColorWithAlpha_data()
 {
-    QImage argb32(1, 1, QImage::Format_ARGB32);
-    argb32.fill(QColor(255, 0, 0, 127));
-    QCOMPARE(argb32.pixel(0, 0), qRgba(255, 0, 0, 127));
+    QTest::addColumn<QImage::Format>("format");
 
-    QImage argb32pm(1, 1, QImage::Format_ARGB32_Premultiplied);
-    argb32pm.fill(QColor(255, 0, 0, 127));
-    QCOMPARE(argb32pm.pixel(0, 0), 0x7f7f0000u);
+    for (int c = QImage::Format_RGB32; c < QImage::NImageFormats; ++c) {
+        if (c == QImage::Format_Grayscale8)
+            continue;
+        if (c == QImage::Format_Grayscale16)
+            continue;
+        if (c == QImage::Format_Alpha8)
+            continue;
+        QTest::newRow(qPrintable(formatToString(QImage::Format(c)))) << QImage::Format(c);
+    }
+}
+
+void tst_QImage::fillColorWithAlpha()
+{
+    QFETCH(QImage::Format, format);
+    QImage image(1, 1, format);
+    image.fill(QColor(255, 170, 85, 170));
+    QRgb referenceColor = qRgba(255, 170, 85, 170);
+
+    if (!image.hasAlphaChannel())
+        referenceColor = 0xff000000 | referenceColor;
+    else if (image.pixelFormat().premultiplied() == QPixelFormat::Premultiplied)
+        referenceColor = qPremultiply(referenceColor);
+
+    QRgb color = image.pixel(0, 0);
+    QCOMPARE(qRed(color) & 0xf0, qRed(referenceColor) & 0xf0);
+    QCOMPARE(qGreen(color) & 0xf0, qGreen(referenceColor) & 0xf0);
+    QCOMPARE(qBlue(color) & 0xf0, qBlue(referenceColor) & 0xf0);
+    QCOMPARE(qAlpha(color) & 0xf0, qAlpha(referenceColor) & 0xf0);
 }
 
 void tst_QImage::fillRGB888()
-- 
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