From abe3217bac18fe8a99cbb2f494a5e4cf6c6d70ce Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Date: Fri, 29 Jan 2016 14:03:41 +0100
Subject: Reimplement QShapedPixmapWindow using QRasterWindow.
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The current implementation makes the window too big when
a QPixmap with a DPR != 1 is set. Circumvent the problem
by using a QRasterWindow.

Task-number: QTBUG-46068
Task-number: QTBUG-50938
Change-Id: I0fca91f571937250c740f1400bd60286330fb595
Reviewed-by: Błażej Szczygieł <spaz16@wp.pl>
Reviewed-by: Alexander Volkov <a.volkov@rusbitech.ru>
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>
---
 src/gui/kernel/qshapedpixmapdndwindow.cpp | 72 +++++++++++++------------------
 src/gui/kernel/qshapedpixmapdndwindow_p.h | 10 ++---
 2 files changed, 33 insertions(+), 49 deletions(-)

diff --git a/src/gui/kernel/qshapedpixmapdndwindow.cpp b/src/gui/kernel/qshapedpixmapdndwindow.cpp
index d77b6dc262..850987ac1d 100644
--- a/src/gui/kernel/qshapedpixmapdndwindow.cpp
+++ b/src/gui/kernel/qshapedpixmapdndwindow.cpp
@@ -42,52 +42,31 @@
 QT_BEGIN_NAMESPACE
 
 QShapedPixmapWindow::QShapedPixmapWindow(QScreen *screen)
-    : QWindow(screen),
-      m_backingStore(0),
-      m_useCompositing(true)
+    : m_useCompositing(true)
 {
+    setScreen(screen);
     QSurfaceFormat format;
     format.setAlphaBufferSize(8);
     setFormat(format);
-    setSurfaceType(RasterSurface);
-    setFlags(Qt::ToolTip | Qt::FramelessWindowHint |
-                   Qt::X11BypassWindowManagerHint | Qt::WindowTransparentForInput | Qt::WindowDoesNotAcceptFocus);
-    create();
-    m_backingStore = new QBackingStore(this);
+    setFlags(Qt::ToolTip | Qt::FramelessWindowHint | Qt::X11BypassWindowManagerHint
+             | Qt::WindowTransparentForInput | Qt::WindowDoesNotAcceptFocus);
 }
 
 QShapedPixmapWindow::~QShapedPixmapWindow()
 {
-    delete m_backingStore;
-    m_backingStore = 0;
-}
-
-void QShapedPixmapWindow::render()
-{
-    QRect rect(QPoint(), geometry().size());
-
-    m_backingStore->beginPaint(rect);
-
-    QPaintDevice *device = m_backingStore->paintDevice();
-
-    {
-        QPainter p(device);
-        if (m_useCompositing)
-            p.setCompositionMode(QPainter::CompositionMode_Source);
-        else
-            p.fillRect(rect, QGuiApplication::palette().base());
-        p.drawPixmap(0, 0, m_pixmap);
-    }
-
-    m_backingStore->endPaint();
-    m_backingStore->flush(rect);
 }
 
 void QShapedPixmapWindow::setPixmap(const QPixmap &pixmap)
 {
     m_pixmap = pixmap;
-    if (!m_useCompositing)
-        setMask(m_pixmap.mask());
+    if (!m_useCompositing) {
+        const QBitmap mask = m_pixmap.mask();
+        if (!mask.isNull()) {
+            if (!handle())
+                create();
+            setMask(mask);
+        }
+    }
 }
 
 void QShapedPixmapWindow::setHotspot(const QPoint &hotspot)
@@ -95,19 +74,28 @@ void QShapedPixmapWindow::setHotspot(const QPoint &hotspot)
     m_hotSpot = hotspot;
 }
 
-void QShapedPixmapWindow::updateGeometry(const QPoint &pos)
+void QShapedPixmapWindow::paintEvent(QPaintEvent *)
 {
-    if (m_pixmap.isNull())
-        m_backingStore->resize(QSize(1,1));
-    else if (m_backingStore->size() != m_pixmap.size())
-        m_backingStore->resize(m_pixmap.size());
-
-    setGeometry(QRect(pos - m_hotSpot, m_backingStore->size()));
+    if (!m_pixmap.isNull()) {
+        const QRect rect(QPoint(0, 0), size());
+        QPainter painter(this);
+        if (m_useCompositing)
+            painter.setCompositionMode(QPainter::CompositionMode_Source);
+        else
+            painter.fillRect(rect, QGuiApplication::palette().base());
+        painter.drawPixmap(rect, m_pixmap);
+    }
 }
 
-void QShapedPixmapWindow::exposeEvent(QExposeEvent *)
+void QShapedPixmapWindow::updateGeometry(const QPoint &pos)
 {
-    render();
+    QSize size(1, 1);
+    if (!m_pixmap.isNull()) {
+        size = qFuzzyCompare(m_pixmap.devicePixelRatio(), 1.0)
+            ? m_pixmap.size()
+            : (QSizeF(m_pixmap.size()) / m_pixmap.devicePixelRatio()).toSize();
+    }
+    setGeometry(QRect(pos - m_hotSpot, size));
 }
 
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qshapedpixmapdndwindow_p.h b/src/gui/kernel/qshapedpixmapdndwindow_p.h
index 3d7974fa82..f2d678c1b4 100644
--- a/src/gui/kernel/qshapedpixmapdndwindow_p.h
+++ b/src/gui/kernel/qshapedpixmapdndwindow_p.h
@@ -45,21 +45,18 @@
 // We mean it.
 //
 
-#include <QtGui/QWindow>
+#include <QtGui/QRasterWindow>
 #include <QtGui/QPixmap>
-#include <QtGui/QBackingStore>
 
 QT_BEGIN_NAMESPACE
 
-class QShapedPixmapWindow : public QWindow
+class QShapedPixmapWindow : public QRasterWindow
 {
     Q_OBJECT
 public:
     explicit QShapedPixmapWindow(QScreen *screen = 0);
     ~QShapedPixmapWindow();
 
-    void render();
-
     void setUseCompositing(bool on) { m_useCompositing = on; }
     void setPixmap(const QPixmap &pixmap);
     void setHotspot(const QPoint &hotspot);
@@ -67,10 +64,9 @@ public:
     void updateGeometry(const QPoint &pos);
 
 protected:
-    void exposeEvent(QExposeEvent *) Q_DECL_OVERRIDE;
+    void paintEvent(QPaintEvent *) Q_DECL_OVERRIDE;
 
 private:
-    QBackingStore *m_backingStore;
     QPixmap m_pixmap;
     QPoint m_hotSpot;
     bool m_useCompositing;
-- 
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