Enable non-integer device pixel ratio

Work around QPaintDevice::metric's int return type
by adding a new metric that returns a scaled devicePixelRatio.
Choose a scale factor that gives us more than enough
range.

The QPaintDevice::devicePixelRatio() convenience accessor
is public API and can unfortunately not be changed
to return a qreal. Add devicePixelRatioF() which
returns the (unscaled) devicePixelRatio.

Change all call sites of QPaintDevice::devicePixelRatio()
to use QPainDevice::devicePixelRatioF().

Task-number: QTBUG-46615
Change-Id: I97ec4000fe379b7ff5e1624a871ae2512790aad9
Reviewed-by: Paul Olav Tvete <paul.tvete@theqtcompany.com>
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/plugins/platforms/direct2d/qwindowsdirect2dpaintdevice.cpp b/src/plugins/platforms/direct2d/qwindowsdirect2dpaintdevice.cpp
index fee9ad88fa..40709fc3d0 100644
--- a/src/plugins/platforms/direct2d/qwindowsdirect2dpaintdevice.cpp
+++ b/src/plugins/platforms/direct2d/qwindowsdirect2dpaintdevice.cpp
@@ -113,6 +113,9 @@ int QWindowsDirect2DPaintDevice::metric(QPaintDevice::PaintDeviceMetric metric)
     case QPaintDevice::PdmDevicePixelRatio:
         return 1;
         break;
+    case QPaintDevice::PdmDevicePixelRatioScaled:
+        return 1 * devicePixelRatioFScale();
+        break;
     case QPaintDevice::PdmWidthMM:
     case QPaintDevice::PdmHeightMM:
         return -1;