Basic high-dpi "retina" support for Qt 5.

Bring Qt 5 on par with Qt 4, prepare for more comprehensive
support later on.

Introduce device independent pixels (dips), device pixels,
and devicePixelRatio. Add high-dpi support to QPainter,
QGLWidget, the cocoa platform plugin, mac and fusion styles.

Dips are similar to CSS pixels, Apple points and
Android density-independent pixels. Device pixels
are pixels in the backing store/physical pixels on screen.
devicePixelRatio is the ratio between them, which is
1.0 on standard displays and 2.0 on "retina" displays.

New API:
QImage::devicePixelRatio() and setDevicePixelRatio()
QPixmap::devicePixelRatio() and setDevicePixelRatio()
QWindow::devicePixelRatio()
QScreen::devicePixelRatio()
QGuiApplicaiton::devicePixelRatio()

Change-Id: If98c3ca9bfdf0e1bdbcf7574cd5b912c9ff63856
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

8 files changed, 127 insertions, 70 deletions

diff --git a/src/widgets/itemviews/qitemdelegate.cpp b/src/widgets/itemviews/qitemdelegate.cpp
index e7ca2d0c6c..7631403933 100644
--- a/src/widgets/itemviews/qitemdelegate.cpp
+++ b/src/widgets/itemviews/qitemdelegate.cpp
@@ -1060,10 +1060,12 @@ QRect QItemDelegate::rect(const QStyleOptionViewItem &option,
         switch (value.type()) {
         case QVariant::Invalid:
             break;
-        case QVariant::Pixmap:
-            return QRect(QPoint(0, 0), qvariant_cast<QPixmap>(value).size());
-        case QVariant::Image:
-            return QRect(QPoint(0, 0), qvariant_cast<QImage>(value).size());
+        case QVariant::Pixmap: {
+            const QPixmap &pixmap = qvariant_cast<QPixmap>(value);
+            return QRect(QPoint(0, 0), pixmap.size() / pixmap.devicePixelRatio() ); }
+        case QVariant::Image: {
+            const QImage &image = qvariant_cast<QImage>(value);
+            return QRect(QPoint(0, 0), image.size() /  image.devicePixelRatio() ); }
         case QVariant::Icon: {
             QIcon::Mode mode = d->iconMode(option.state);
             QIcon::State state = d->iconState(option.state);
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index e167e646c0..ace25fa78b 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -1794,6 +1794,23 @@ QRegion QWidgetPrivate::clipRegion() const
     return r;
 }
 
+void QWidgetPrivate::setSystemClip(QPaintDevice *paintDevice, const QRegion &region)
+{
+// Transform the system clip region from device-independent pixels to device pixels
+// Qt 5.0.0: This is a Mac-only code path for now, can be made cross-platform once
+// it has been tested.
+    QPaintEngine *paintEngine = paintDevice->paintEngine();
+#ifdef Q_OS_MAC
+    const qreal devicePixelRatio = (paintDevice->physicalDpiX() == 0 || paintDevice->logicalDpiX() == 0) ?
+                                    1.0 : (paintDevice->physicalDpiX() / paintDevice->logicalDpiX());
+    QTransform scaleTransform;
+    scaleTransform.scale(devicePixelRatio, devicePixelRatio);
+    paintEngine->d_func()->systemClip = scaleTransform.map(region);
+#else
+    paintEngine->d_func()->systemClip = region;
+#endif
+}
+
 #ifndef QT_NO_GRAPHICSEFFECT
 void QWidgetPrivate::invalidateGraphicsEffectsRecursively()
 {
@@ -4998,13 +5015,12 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
             QWidgetPaintContext context(pdev, rgn, offset, flags, sharedPainter, backingStore);
             sourced->context = &context;
             if (!sharedPainter) {
-                QPaintEngine *paintEngine = pdev->paintEngine();
-                paintEngine->d_func()->systemClip = rgn.translated(offset);
+                setSystemClip(pdev, rgn.translated(offset));
                 QPainter p(pdev);
                 p.translate(offset);
                 context.painter = &p;
                 graphicsEffect->draw(&p);
-                paintEngine->d_func()->systemClip = QRegion();
+                setSystemClip(pdev, QRegion());
             } else {
                 context.painter = sharedPainter;
                 if (sharedPainter->worldTransform() != sourced->lastEffectTransform) {
@@ -5061,7 +5077,7 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
 
 #endif
                 if (sharedPainter)
-                    paintEngine->d_func()->systemClip = toBePainted;
+                    setSystemClip(pdev, toBePainted);
                 else
                     paintEngine->d_func()->systemRect = q->data->crect;
 
@@ -5073,7 +5089,7 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
                 }
 
                 if (!sharedPainter)
-                    paintEngine->d_func()->systemClip = toBePainted.translated(offset);
+                    setSystemClip(pdev, toBePainted.translated(offset));
 
                 if (!onScreen && !asRoot && !isOpaque && q->testAttribute(Qt::WA_TintedBackground)) {
                     QPainter p(q);
@@ -5108,7 +5124,8 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
                     paintEngine->d_func()->systemRect = QRect();
                 else
                     paintEngine->d_func()->currentClipDevice = 0;
-                paintEngine->d_func()->systemClip = QRegion();
+
+                setSystemClip(pdev, QRegion());
             }
             q->setAttribute(Qt::WA_WState_InPaintEvent, false);
             if (q->paintingActive())
diff --git a/src/widgets/kernel/qwidget_p.h b/src/widgets/kernel/qwidget_p.h
index 8aba276966..1d183e41f1 100644
--- a/src/widgets/kernel/qwidget_p.h
+++ b/src/widgets/kernel/qwidget_p.h
@@ -402,6 +402,7 @@ public:
 
     QRect clipRect() const;
     QRegion clipRegion() const;
+    void setSystemClip(QPaintDevice *paintDevice, const QRegion &region);
     void subtractOpaqueChildren(QRegion &rgn, const QRect &clipRect) const;
     void subtractOpaqueSiblings(QRegion &source, bool *hasDirtySiblingsAbove = 0,
                                 bool alsoNonOpaque = false) const;
diff --git a/src/widgets/styles/qfusionstyle.cpp b/src/widgets/styles/qfusionstyle.cpp
index ebcdc10d59..623cdb55b9 100644
--- a/src/widgets/styles/qfusionstyle.cpp
+++ b/src/widgets/styles/qfusionstyle.cpp
@@ -303,7 +303,7 @@ static void qt_fusion_draw_mdibutton(QPainter *painter, const QStyleOptionTitleB
     gradient.setColorAt(1, mdiButtonGradientStopColor);
     QColor mdiButtonBorderColor(active ? option->palette.highlight().color().darker(180): dark.darker(110));
 
-    painter->setPen(QPen(mdiButtonBorderColor, 1));
+    painter->setPen(QPen(mdiButtonBorderColor));
     const QLine lines[4] = {
         QLine(tmp.left() + 2, tmp.top(), tmp.right() - 2, tmp.top()),
         QLine(tmp.left() + 2, tmp.bottom(), tmp.right() - 2, tmp.bottom()),
@@ -457,7 +457,7 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
         if (const QStyleOptionTabBarBase *tbb
                 = qstyleoption_cast<const QStyleOptionTabBarBase *>(option)) {
             painter->save();
-            painter->setPen(QPen(outline.lighter(110), 0));
+            painter->setPen(QPen(outline.lighter(110)));
             switch (tbb->shape) {
             case QTabBar::RoundedNorth: {
                 QRegion region(tbb->rect);
@@ -603,7 +603,7 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
         }
     }
         break;
-    case PE_Frame:
+    case PE_Frame: {
         if (widget && widget->inherits("QComboBoxPrivateContainer")){
             QStyleOption copy = *option;
             copy.state |= State_Raised;
@@ -611,14 +611,16 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
             break;
         }
         painter->save();
-        painter->setPen(outline.lighter(108));
+        QPen thePen(outline.lighter(108));
+        thePen.setCosmetic(false);
+        painter->setPen(thePen);
         painter->drawRect(option->rect.adjusted(0, 0, -1, -1));
-        painter->restore();
+        painter->restore(); }
         break;
     case PE_FrameMenu:
         painter->save();
     {
-        painter->setPen(QPen(outline, 1));
+        painter->setPen(QPen(outline));
         painter->drawRect(option->rect.adjusted(0, 0, -1, -1));
         QColor frameLight = option->palette.background().color().lighter(160);
         QColor frameShadow = option->palette.background().color().darker(110);
@@ -644,9 +646,9 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
         QRect rect= option->rect;
         painter->setPen(softshadow);
         painter->drawRect(option->rect.adjusted(0, 0, -1, -1));
-        painter->setPen(QPen(option->palette.light(), 0));
+        painter->setPen(QPen(option->palette.light(), 1));
         painter->drawLine(QPoint(rect.left() + 1, rect.top() + 1), QPoint(rect.left() + 1, rect.bottom() - 1));
-        painter->setPen(QPen(option->palette.background().color().darker(120), 0));
+        painter->setPen(QPen(option->palette.background().color().darker(120)));
         painter->drawLine(QPoint(rect.left() + 1, rect.bottom() - 1), QPoint(rect.right() - 2, rect.bottom() - 1));
         painter->drawLine(QPoint(rect.right() - 1, rect.top() + 1), QPoint(rect.right() - 1, rect.bottom() - 1));
 
@@ -680,12 +682,12 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
         painter->save();
     {
         QRect rect= option->rect;
-        painter->setPen(QPen(outline.darker(150), 0));
+        painter->setPen(QPen(outline.darker(150)));
         painter->drawRect(option->rect.adjusted(0, 0, -1, -1));
-        painter->setPen(QPen(option->palette.light(), 0));
+        painter->setPen(QPen(option->palette.light(), 1));
         painter->drawLine(QPoint(rect.left() + 1, rect.top() + 1),
                           QPoint(rect.left() + 1, rect.bottom() - 1));
-        painter->setPen(QPen(option->palette.background().color().darker(120), 0));
+        painter->setPen(QPen(option->palette.background().color().darker(120)));
         painter->drawLine(QPoint(rect.left() + 1, rect.bottom() - 1),
                           QPoint(rect.right() - 2, rect.bottom() - 1));
         painter->drawLine(QPoint(rect.right() - 1, rect.top() + 1),
@@ -705,7 +707,7 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
         painter->translate(0.5, 0.5);
 
         // Draw Outline
-        painter->setPen( QPen(hasFocus ? highlightedOutline : outline, 0));
+        painter->setPen( QPen(hasFocus ? highlightedOutline : outline));
         painter->setBrush(option->palette.base());
         painter->drawRoundedRect(r.adjusted(0, 0, -1, -1), 2, 2);
 
@@ -740,10 +742,10 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
             gradient.setColorAt(1, (state & State_Sunken) ? pressedColor : option->palette.base().color());
 
             painter->setBrush((state & State_Sunken) ? QBrush(pressedColor) : gradient);
-            painter->setPen(QPen(outline.lighter(110), 1));
+            painter->setPen(QPen(outline.lighter(110)));
 
             if (option->state & State_HasFocus && option->state & State_KeyboardFocusChange)
-                painter->setPen(QPen(highlightedOutline, 1));
+                painter->setPen(QPen(highlightedOutline));
             painter->drawRect(rect);
 
             QColor checkMarkColor = option->palette.text().color().darker(120);
@@ -785,9 +787,9 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
         painter->setRenderHint(QPainter::Antialiasing, true);
         QPainterPath circle;
         circle.addEllipse(rect.center() + QPoint(1.0, 1.0), 6.5, 6.5);
-        painter->setPen(QPen(option->palette.background().color().darker(150), 1));
+        painter->setPen(QPen(option->palette.background().color().darker(150)));
         if (option->state & State_HasFocus && option->state & State_KeyboardFocusChange)
-            painter->setPen(QPen(highlightedOutline, 1));
+            painter->setPen(QPen(highlightedOutline));
         painter->drawPath(circle);
 
         if (state & (State_On )) {
@@ -862,7 +864,7 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
         if (isFlat && !isDown) {
             if (isDefault) {
                 r = option->rect.adjusted(0, 1, 0, -1);
-                painter->setPen(QPen(Qt::black, 0));
+                painter->setPen(QPen(Qt::black));
                 const QLine lines[4] = {
                     QLine(QPoint(r.left() + 2, r.top()),
                     QPoint(r.right() - 2, r.top())),
@@ -910,7 +912,7 @@ void QFusionStyle::drawPrimitive(PrimitiveElement elem,
         p->setBrush(Qt::NoBrush);
 
         // Outline
-        p->setPen(!isEnabled ? QPen(darkOutline.lighter(115)) : QPen(darkOutline, 1));
+        p->setPen(!isEnabled ? QPen(darkOutline.lighter(115)) : QPen(darkOutline));
         p->drawRoundedRect(r, 2.0, 2.0);
 
         p->setPen(d->innerContrastLine());
@@ -1300,7 +1302,7 @@ void QFusionStyle::drawControl(ControlElement element, const QStyleOption *optio
         painter->drawLine(rect.topLeft() - QPoint(0, 1), rect.topRight() - QPoint(0, 1));
 
         painter->setBrush(option->palette.base());
-        painter->setPen(QPen(outline, 0));
+        painter->setPen(QPen(outline));
         painter->drawRoundedRect(rect.adjusted(0, 0, -1, -1), 2, 2);
 
         // Inner shadow
@@ -1359,14 +1361,14 @@ void QFusionStyle::drawControl(ControlElement element, const QStyleOption *optio
                     progressBar.setRect(rect.left(), rect.top(), width - 1, rect.height() - 1);
                     if (!complete) {
                         painter->drawLine(progressBar.topRight() + QPoint(2, 1), progressBar.bottomRight() + QPoint(2, 0));
-                        painter->setPen(QPen(highlight.darker(140), 0));
+                        painter->setPen(QPen(highlight.darker(140)));
                         painter->drawLine(progressBar.topRight() + QPoint(1, 1), progressBar.bottomRight() + QPoint(1, 0));
                     }
                 } else {
                     progressBar.setRect(rect.right() - width - 1, rect.top(), width + 2, rect.height() - 1);
                     if (!complete) {
                         painter->drawLine(progressBar.topLeft() + QPoint(-2, 1), progressBar.bottomLeft() + QPoint(-2, 0));
-                        painter->setPen(QPen(highlight.darker(140), 0));
+                        painter->setPen(QPen(highlight.darker(140)));
                         painter->drawLine(progressBar.topLeft() + QPoint(-1, 1), progressBar.bottomLeft() + QPoint(-1, 0));
                     }
                 }
@@ -1376,7 +1378,7 @@ void QFusionStyle::drawControl(ControlElement element, const QStyleOption *optio
 
             if (indeterminate || bar->progress > bar->minimum) {
 
-                painter->setPen(QPen(outline, 0));
+                painter->setPen(QPen(outline));
 
                 QColor highlightedGradientStartColor = highlight.lighter(120);
                 QColor highlightedGradientStopColor  = highlight;
@@ -1471,7 +1473,7 @@ void QFusionStyle::drawControl(ControlElement element, const QStyleOption *optio
             QRect r = option->rect;
             if (act) {
                 painter->setBrush(option->palette.highlight().color());
-                painter->setPen(QPen(highlightOutline, 0));
+                painter->setPen(QPen(highlightOutline));
                 painter->drawRect(r.adjusted(0, 0, -1, -1));
 
                 //                painter->drawRoundedRect(r.adjusted(1, 1, -1, -1), 2, 2);
@@ -1518,7 +1520,7 @@ void QFusionStyle::drawControl(ControlElement element, const QStyleOption *optio
             if (selected) {
                 QRect r = option->rect;
                 painter->fillRect(r, highlight);
-                painter->setPen(QPen(highlightOutline, 0));
+                painter->setPen(QPen(highlightOutline));
                 const QLine lines[4] = {
                     QLine(QPoint(r.left() + 1, r.bottom()), QPoint(r.right() - 1, r.bottom())),
                     QLine(QPoint(r.left() + 1, r.top()), QPoint(r.right() - 1, r.top())),
@@ -2141,15 +2143,18 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
                     QPixmap upArrow = colorizedImage(QLatin1String(":/qt-project.org/styles/commonstyle/images/fusion_arrow.png"),
                                                      (spinBox->stepEnabled & QAbstractSpinBox::StepUpEnabled) ? arrowColor : disabledColor);
 
-                    cachePainter.drawPixmap(QRect(upRect.center().x() - upArrow.width() / 4 + 1,
-                                                  upRect.center().y() - upArrow.height() / 4 + 1,
-                                                  upArrow.width()/2, upArrow.height()/2), upArrow);
+                    QRectF upArrowRect = QRectF(upRect.center().x() - upArrow.width() / 4.0 + 1.0,
+                                                upRect.center().y() - upArrow.height() / 4.0 + 1.0,
+                                                upArrow.width() / 2.0, upArrow.height() / 2.0);
+
+                    cachePainter.drawPixmap(upArrowRect, upArrow, QRectF(QPointF(0.0, 0.0), upArrow.size()));
 
                     QPixmap downArrow = colorizedImage(QLatin1String(":/qt-project.org/styles/commonstyle/images/fusion_arrow.png"),
                                                        (spinBox->stepEnabled & QAbstractSpinBox::StepDownEnabled) ? arrowColor : disabledColor, 180);
-                    cachePainter.drawPixmap(QRect(downRect.center().x() - downArrow.width() / 4 + 1,
-                                                  downRect.center().y() - downArrow.height() / 4 + 1,
-                                                  downArrow.width()/2, downArrow.height()/2), downArrow);
+                    QRectF downArrowRect = QRectF(downRect.center().x() - downArrow.width() / 4.0 + 1.0,
+                                                  downRect.center().y() - downArrow.height() / 4.0 + 1.0,
+                                                  downArrow.width() / 2.0, downArrow.height() / 2.0);
+                    cachePainter.drawPixmap(downArrowRect, downArrow, QRectF(QPointF(0.0, 0.0), downArrow.size()));
                 }
 
                 cachePainter.end();
@@ -2486,7 +2491,7 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
             // Paint slider
             if (scrollBar->subControls & SC_ScrollBarSlider) {
                 QRect pixmapRect = scrollBarSlider;
-                painter->setPen(QPen(alphaOutline, 0));
+                painter->setPen(QPen(alphaOutline));
                 if (option->state & State_Sunken && scrollBar->activeSubControls & SC_ScrollBarSlider)
                     painter->setBrush(midColor2);
                 else if (option->state & State_MouseOver && scrollBar->activeSubControls & SC_ScrollBarSlider)
@@ -2521,7 +2526,7 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
 
                 painter->setPen(Qt::NoPen);
                 painter->drawRect(scrollBarSubLine.adjusted(horizontal ? 0 : 1, horizontal ? 1 : 0, 0, 0));
-                painter->setPen(QPen(alphaOutline, 1));
+                painter->setPen(QPen(alphaOutline));
                 if (option->state & State_Horizontal) {
                     if (option->direction == Qt::RightToLeft) {
                         pixmapRect.setLeft(scrollBarSubLine.left());
@@ -2545,9 +2550,10 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
                     rotation = option->direction == Qt::LeftToRight ? -90 : 90;
                 QRect upRect = scrollBarSubLine.translated(horizontal ? -2 : -1, 0);
                 QPixmap arrowPixmap = colorizedImage(QLatin1String(":/qt-project.org/styles/commonstyle/images/fusion_arrow.png"), arrowColor, rotation);
-                painter->drawPixmap(QRect(upRect.center().x() - arrowPixmap.width() / 4  + 2,
-                                          upRect.center().y() - arrowPixmap.height() / 4 + 1,
-                                          arrowPixmap.width()/2, arrowPixmap.height()/2), arrowPixmap);
+                painter->drawPixmap(QRectF(upRect.center().x() - arrowPixmap.width() / 4.0  + 2.0,
+                                          upRect.center().y() - arrowPixmap.height() / 4.0 + 1.0,
+                                          arrowPixmap.width() / 2.0, arrowPixmap.height() / 2.0),
+                                          arrowPixmap, QRectF(QPoint(0.0, 0.0), arrowPixmap.size()));
             }
 
             // The AddLine (down/right) button
@@ -2584,9 +2590,10 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
                     rotation = option->direction == Qt::LeftToRight ? 90 : -90;
                 QRect downRect = scrollBarAddLine.translated(-1, 1);
                 QPixmap arrowPixmap = colorizedImage(QLatin1String(":/qt-project.org/styles/commonstyle/images/fusion_arrow.png"), arrowColor, rotation);
-                painter->drawPixmap(QRect(downRect.center().x() - arrowPixmap.width() / 4 + 2,
-                                          downRect.center().y() - arrowPixmap.height() / 4,
-                                          arrowPixmap.width()/2, arrowPixmap.height()/2), arrowPixmap);
+                painter->drawPixmap(QRectF(downRect.center().x() - arrowPixmap.width() / 4.0 + 2.0,
+                                           downRect.center().y() - arrowPixmap.height() / 4.0,
+                                           arrowPixmap.width() / 2.0, arrowPixmap.height() / 2.0),
+                                           arrowPixmap, QRectF(QPoint(0.0, 0.0), arrowPixmap.size()));
             }
 
         }
@@ -2640,7 +2647,7 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
                                                   downArrowRect.left() - 6: downArrowRect.right() + 6);
                     proxy()->drawPrimitive(PE_PanelButtonCommand, &buttonOption, &cachePainter, widget);
                     cachePainter.restore();
-                    cachePainter.setPen( QPen(hasFocus ? option->palette.highlight() : outline.lighter(110), 0));
+                    cachePainter.setPen( QPen(hasFocus ? option->palette.highlight() : outline.lighter(110), 1));
 
                     if (!sunken) {
                         int borderSize = 1;
@@ -2677,9 +2684,10 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
                     QColor arrowColor = option->palette.buttonText().color();
                     arrowColor.setAlpha(220);
                     QPixmap downArrow = colorizedImage(QLatin1String(":/qt-project.org/styles/commonstyle/images/fusion_arrow.png"), arrowColor, 180);
-                    cachePainter.drawPixmap(QRect(downArrowRect.center().x() - downArrow.width() / 4 + 1,
-                                                  downArrowRect.center().y() - downArrow.height() / 4 + 1,
-                                                  downArrow.width()/2, downArrow.height()/2), downArrow);
+                    cachePainter.drawPixmap(QRectF(downArrowRect.center().x() - downArrow.width() / 4.0 + 1.0,
+                                                   downArrowRect.center().y() - downArrow.height() / 4.0 + 1.0,
+                                                   downArrow.width() / 2.0, downArrow.height() / 2.0),
+                                                   downArrow, QRectF(QPointF(0.0, 0.0), downArrow.size()));
                 }
                 cachePainter.end();
                 QPixmapCache::insert(pixmapName, cache);
@@ -2730,7 +2738,7 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
                         gradient.setStart(pixmapRect.left(), pixmapRect.center().y());
                         gradient.setFinalStop(pixmapRect.right(), pixmapRect.center().y());
                     }
-                    groovePainter.setPen(QPen(outline, 0));
+                    groovePainter.setPen(QPen(outline));
                     gradient.setColorAt(0, grooveColor.darker(110));
                     gradient.setColorAt(1, grooveColor.lighter(110));//palette.button().color().darker(115));
                     groovePainter.setBrush(gradient);
@@ -2764,7 +2772,7 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
 
                     groovePainter.setRenderHint(QPainter::Antialiasing, true);
                     groovePainter.translate(0.5, 0.5);
-                    groovePainter.setPen(QPen(outline, 0));
+                    groovePainter.setPen(QPen(outline));
                     gradient.setColorAt(0, activeHighlight);
                     gradient.setColorAt(1, activeHighlight.lighter(130));
                     groovePainter.setBrush(gradient);
@@ -2813,9 +2821,9 @@ void QFusionStyle::drawComplexControl(ComplexControl control, const QStyleOption
                     handlePainter.setBrush(QColor(0, 0, 0, 40));
                     handlePainter.drawRect(r.adjusted(-1, 2, 1, -2));
 
-                    handlePainter.setPen(QPen(d->outline(option->palette), 1));
+                    handlePainter.setPen(QPen(d->outline(option->palette)));
                     if (option->state & State_HasFocus && option->state & State_KeyboardFocusChange)
-                        handlePainter.setPen(QPen(d->highlightedOutline(option->palette), 1));
+                        handlePainter.setPen(QPen(d->highlightedOutline(option->palette)));
 
                     handlePainter.setBrush(gradient);
                     handlePainter.drawRoundedRect(r, 2, 2);
diff --git a/src/widgets/styles/qmacstyle_mac.mm b/src/widgets/styles/qmacstyle_mac.mm
index 759b3678d7..89ea4d553a 100644
--- a/src/widgets/styles/qmacstyle_mac.mm
+++ b/src/widgets/styles/qmacstyle_mac.mm
@@ -462,7 +462,7 @@ class QMacCGContext
 {
     CGContextRef context;
 public:
-    QMacCGContext(QPainter *p); //qpaintengine_mac.cpp
+    QMacCGContext(QPainter *p);
     inline QMacCGContext() { context = 0; }
     inline QMacCGContext(const QPaintDevice *pdev) {
         extern CGContextRef qt_mac_cg_context(const QPaintDevice *);
@@ -6476,6 +6476,18 @@ void qt_mac_clip_cg(CGContextRef hd, const QRegion &rgn, CGAffineTransform *orig
     }
 }
 
+// move to QRegion?
+void qt_mac_scale_region(QRegion *region, qreal scaleFactor)
+{
+    QVector<QRect> scaledRects;
+    scaledRects.reserve(region->rects().count());
+
+    foreach (const QRect &rect, region->rects()) {
+        scaledRects.append(QRect(rect.topLeft(), rect.size() * scaleFactor));
+    }
+    region->setRects(&scaledRects[0], scaledRects.count());
+}
+
 QMacCGContext::QMacCGContext(QPainter *p)
 {
     QPaintEngine *pe = p->paintEngine();
@@ -6502,20 +6514,28 @@ QMacCGContext::QMacCGContext(QPainter *p)
         CGContextScaleCTM(context, 1, -1);
 
         if (devType == QInternal::Widget) {
-            QRegion clip = p->paintEngine()->systemClip();
-            QTransform native = p->deviceTransform();
+            // Set the clip rect which is an intersection of the system clip
+            // and the painter clip. To make matters more interesting these
+            // are in device pixels and device-independent pixels, respectively.
+            const qreal devicePixelRatio =  image->devicePixelRatio();
+
+            QRegion clip = p->paintEngine()->systemClip(); // get system clip in device pixels
+            QTransform native = p->deviceTransform();      // get device transform. dx/dy is in device pixels
 
             if (p->hasClipping()) {
-                QRegion r = p->clipRegion();
+                QRegion r = p->clipRegion();               // get painter clip, which is in device-independent pixels
+                qt_mac_scale_region(&r, devicePixelRatio); // scale painter clip to device pixels
                 r.translate(native.dx(), native.dy());
                 if (clip.isEmpty())
                     clip = r;
                 else
                     clip &= r;
             }
-            qt_mac_clip_cg(context, clip, 0);
+            qt_mac_clip_cg(context, clip, 0); // clip in device pixels
 
-            CGContextTranslateCTM(context, native.dx(), native.dy());
+            // Scale the context so that painting happens in device-independet pixels.
+            CGContextScaleCTM(context, devicePixelRatio, devicePixelRatio);
+            CGContextTranslateCTM(context, native.dx() / devicePixelRatio, native.dy() / devicePixelRatio);
         }
     } else {
         qDebug() << "QMacCGContext:: Unsupported painter devtype type" << devType;
diff --git a/src/widgets/styles/qstyle.cpp b/src/widgets/styles/qstyle.cpp
index 76d6efadee..ab66cdae9f 100644
--- a/src/widgets/styles/qstyle.cpp
+++ b/src/widgets/styles/qstyle.cpp
@@ -618,10 +618,11 @@ void QStyle::drawItemText(QPainter *painter, const QRect &rect, int alignment, c
 void QStyle::drawItemPixmap(QPainter *painter, const QRect &rect, int alignment,
                             const QPixmap &pixmap) const
 {
-    QRect aligned = alignedRect(QApplication::layoutDirection(), QFlag(alignment), pixmap.size(), rect);
+    int scale = pixmap.devicePixelRatio();
+    QRect aligned = alignedRect(QApplication::layoutDirection(), QFlag(alignment), pixmap.size() / scale, rect);
     QRect inter = aligned.intersected(rect);
 
-    painter->drawPixmap(inter.x(), inter.y(), pixmap, inter.x() - aligned.x(), inter.y() - aligned.y(), inter.width(), inter.height());
+    painter->drawPixmap(inter.x(), inter.y(), pixmap, inter.x() - aligned.x(), inter.y() - aligned.y(), inter.width() * scale, inter.height() *scale);
 }
 
 /*!
diff --git a/src/widgets/styles/qstyle_p.h b/src/widgets/styles/qstyle_p.h
index 85e8e54b16..78dfc6fed9 100644
--- a/src/widgets/styles/qstyle_p.h
+++ b/src/widgets/styles/qstyle_p.h
@@ -43,6 +43,7 @@
 #define QSTYLE_P_H
 
 #include "private/qobject_p.h"
+#include <QtGui/qguiapplication.h>
 #include <QtWidgets/qstyle.h>
 
 QT_BEGIN_NAMESPACE
@@ -74,12 +75,18 @@ public:
 
 inline QImage styleCacheImage(const QSize &size)
 {
-    return QImage(size, QImage::Format_ARGB32_Premultiplied);
+    const qreal pixelRatio = qApp->devicePixelRatio();
+    QImage cacheImage = QImage(size * pixelRatio, QImage::Format_ARGB32_Premultiplied);
+    cacheImage.setDevicePixelRatio(pixelRatio);
+    return cacheImage;
 }
 
 inline QPixmap styleCachePixmap(const QSize &size)
 {
-    return QPixmap(size);
+    const qreal pixelRatio = qApp->devicePixelRatio();
+    QPixmap cachePixmap = QPixmap(size * pixelRatio);
+    cachePixmap.setDevicePixelRatio(pixelRatio);
+    return cachePixmap;
 }
 
 #define BEGIN_STYLE_PIXMAPCACHE(a) \
diff --git a/src/widgets/widgets/qlabel.cpp b/src/widgets/widgets/qlabel.cpp
index a133b9c310..3b3d15f6d0 100644
--- a/src/widgets/widgets/qlabel.cpp
+++ b/src/widgets/widgets/qlabel.cpp
@@ -562,17 +562,18 @@ QSize QLabelPrivate::sizeForWidth(int w) const
     int vextra = hextra;
     QFontMetrics fm = q->fontMetrics();
 
-    if (pixmap && !pixmap->isNull())
+    if (pixmap && !pixmap->isNull()) {
         br = pixmap->rect();
+        br.setSize(br.size() / pixmap->devicePixelRatio());
 #ifndef QT_NO_PICTURE
-    else if (picture && !picture->isNull())
+    } else if (picture && !picture->isNull()) {
         br = picture->boundingRect();
 #endif
 #ifndef QT_NO_MOVIE
-    else if (movie && !movie->currentPixmap().isNull())
+    } else if (movie && !movie->currentPixmap().isNull()) {
         br = movie->currentPixmap().rect();
 #endif
-    else if (isTextLabel) {
+    } else if (isTextLabel) {
         int align = QStyle::visualAlignment(textDirection(), QFlag(this->align));
         // Add indentation
         int m = indent;