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>

1 files changed, 1 insertions, 0 deletions

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;