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, 2 insertions, 2 deletions

diff --git a/src/gui/painting/qpaintengineex.cpp b/src/gui/painting/qpaintengineex.cpp
index 113cbd8a8e..2c41ab9ff2 100644
--- a/src/gui/painting/qpaintengineex.cpp
+++ b/src/gui/painting/qpaintengineex.cpp
@@ -939,12 +939,12 @@ void QPaintEngineEx::drawPolygon(const QPoint *points, int pointCount, PolygonDr
 
 void QPaintEngineEx::drawPixmap(const QPointF &pos, const QPixmap &pm)
 {
-    drawPixmap(QRectF(pos, pm.size()), pm, pm.rect());
+    drawPixmap(QRectF(pos, pm.size() / pm.devicePixelRatio()), pm, pm.rect());
 }
 
 void QPaintEngineEx::drawImage(const QPointF &pos, const QImage &image)
 {
-    drawImage(QRectF(pos, image.size()), image, image.rect());
+    drawImage(QRectF(pos, image.size() / image.devicePixelRatio()), image, image.rect());
 }
 
 void QPaintEngineEx::drawTiledPixmap(const QRectF &r, const QPixmap &pixmap, const QPointF &s)