Add deviceIndependentSize() to QPixmap and QImage

This function returns the size in device independent
pixels, and should be used when calculating user
interface sizes.


Change-Id: I528123f962595a3da42438ca560289a29aca4917
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 16 insertions, 1 deletions

diff --git a/src/gui/image/qpixmap.cpp b/src/gui/image/qpixmap.cpp
index d8473001aa..2f9c4fd617 100644
--- a/src/gui/image/qpixmap.cpp
+++ b/src/gui/image/qpixmap.cpp
@@ -633,7 +633,7 @@ qreal QPixmap::devicePixelRatio() const
     high-DPI pixmap rather than a large pixmap
     (see \l{Drawing High Resolution Versions of Pixmaps and Images}).
 
-    \sa devicePixelRatio()
+    \sa devicePixelRatio(), devicePixelSize()
 */
 void QPixmap::setDevicePixelRatio(qreal scaleFactor)
 {
@@ -647,6 +647,21 @@ void QPixmap::setDevicePixelRatio(qreal scaleFactor)
     data->setDevicePixelRatio(scaleFactor);
 }
 
+/*!
+    Returns the size of the pixmap in device independent pixels.
+
+    This value should be used when using the pixmap size in user interface
+    size calculations.
+
+    The return value is equivalent to pixmap.size() / pixmap.devicePixelRatio(),
+*/
+QSizeF QPixmap::deviceIndependentSize() const
+{
+    if (!data)
+        return QSizeF(0, 0);
+    return QSizeF(data->width(), data->height()) / data->devicePixelRatio();
+}
+
 #ifndef QT_NO_IMAGE_HEURISTIC_MASK
 /*!
     Creates and returns a heuristic mask for this pixmap.