From 9a63863d6f0c614c041c3d4b375bf88d93148ef7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Samuel=20R=C3=B8dal?= <samuel.rodal@nokia.com>
Date: Mon, 6 Dec 2010 14:06:56 +0100
Subject: Make sure to do a deep copy of a QImage when it's being painted on.

Not doing so can produce some hard-to-track-down bugs in the app.

Task-number: QTBUG-15749
Reviewed-by: Gunnar Sletta
---
 src/gui/image/qimage.cpp           | 25 +++++++++++++++++--------
 src/gui/image/qpixmap_raster.cpp   |  8 ++++++++
 tests/auto/qimage/tst_qimage.cpp   | 16 ++++++++++++++++
 tests/auto/qpixmap/tst_qpixmap.cpp | 17 +++++++++++++++++
 4 files changed, 58 insertions(+), 8 deletions(-)

diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index 1157b93..6ba3858 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -1121,9 +1121,14 @@ QImage::QImage(const char * const xpm[])
 QImage::QImage(const QImage &image)
     : QPaintDevice()
 {
-    d = image.d;
-    if (d)
-        d->ref.ref();
+    if (image.paintingActive()) {
+        d = 0;
+        operator=(image.copy());
+    } else {
+        d = image.d;
+        if (d)
+            d->ref.ref();
+    }
 }
 
 #ifdef QT3_SUPPORT
@@ -1320,11 +1325,15 @@ QImage::~QImage()
 
 QImage &QImage::operator=(const QImage &image)
 {
-    if (image.d)
-        image.d->ref.ref();
-    if (d && !d->ref.deref())
-        delete d;
-    d = image.d;
+    if (image.paintingActive()) {
+        operator=(image.copy());
+    } else {
+        if (image.d)
+            image.d->ref.ref();
+        if (d && !d->ref.deref())
+            delete d;
+        d = image.d;
+    }
     return *this;
 }
 
diff --git a/src/gui/image/qpixmap_raster.cpp b/src/gui/image/qpixmap_raster.cpp
index 53f3559..f080687 100644
--- a/src/gui/image/qpixmap_raster.cpp
+++ b/src/gui/image/qpixmap_raster.cpp
@@ -44,6 +44,7 @@
 #include "qpixmap_raster_p.h"
 #include "qnativeimage_p.h"
 #include "qimage_p.h"
+#include "qpaintengine.h"
 
 #include "qbitmap.h"
 #include "qimage.h"
@@ -302,6 +303,13 @@ bool QRasterPixmapData::hasAlphaChannel() const
 
 QImage QRasterPixmapData::toImage() const
 {
+    if (image.paintEngine()
+        && image.paintEngine()->isActive()
+        && image.paintEngine()->paintDevice() == &image)
+    {
+        return image.copy();
+    }
+
     return image;
 }
 
diff --git a/tests/auto/qimage/tst_qimage.cpp b/tests/auto/qimage/tst_qimage.cpp
index b446941..b2c59fc 100644
--- a/tests/auto/qimage/tst_qimage.cpp
+++ b/tests/auto/qimage/tst_qimage.cpp
@@ -142,6 +142,8 @@ private slots:
 
     void rgbSwapped_data();
     void rgbSwapped();
+
+    void deepCopyWhenPaintingActive();
 };
 
 tst_QImage::tst_QImage()
@@ -1886,5 +1888,19 @@ void tst_QImage::rgbSwapped()
     QCOMPARE(memcmp(image.constBits(), imageSwappedTwice.constBits(), image.numBytes()), 0);
 }
 
+void tst_QImage::deepCopyWhenPaintingActive()
+{
+    QImage image(64, 64, QImage::Format_ARGB32_Premultiplied);
+    image.fill(0);
+
+    QPainter painter(&image);
+    QImage copy = image;
+
+    painter.setBrush(Qt::black);
+    painter.drawEllipse(image.rect());
+
+    QVERIFY(copy != image);
+}
+
 QTEST_MAIN(tst_QImage)
 #include "tst_qimage.moc"
diff --git a/tests/auto/qpixmap/tst_qpixmap.cpp b/tests/auto/qpixmap/tst_qpixmap.cpp
index 51e6cf5..d5267b5 100644
--- a/tests/auto/qpixmap/tst_qpixmap.cpp
+++ b/tests/auto/qpixmap/tst_qpixmap.cpp
@@ -185,6 +185,8 @@ private slots:
     void preserveDepth();
     void splash_crash();
 
+    void toImageDeepCopy();
+
     void loadAsBitmapOrPixmap();
 };
 
@@ -1751,6 +1753,21 @@ void tst_QPixmap::loadAsBitmapOrPixmap()
     QVERIFY(bitmap.isQBitmap());
 }
 
+void tst_QPixmap::toImageDeepCopy()
+{
+    QPixmap pixmap(64, 64);
+    pixmap.fill(Qt::white);
+
+    QPainter painter(&pixmap);
+    QImage first = pixmap.toImage();
+
+    painter.setBrush(Qt::black);
+    painter.drawEllipse(pixmap.rect());
+
+    QImage second = pixmap.toImage();
+
+    QVERIFY(first != second);
+}
 
 
 QTEST_MAIN(tst_QPixmap)
-- 
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