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 <[email protected]>
Reviewed-by: Lars Knoll <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/opengl/qglpaintdevice.cpp b/src/opengl/qglpaintdevice.cpp
index 89cf01d8ec5..b5df45bcc81 100644
--- a/src/opengl/qglpaintdevice.cpp
+++ b/src/opengl/qglpaintdevice.cpp
@@ -62,6 +62,8 @@ int QGLPaintDevice::metric(QPaintDevice::PaintDeviceMetric metric) const
     }
     case PdmDevicePixelRatio:
         return 1;
+    case PdmDevicePixelRatioScaled:
+        return 1 * QPaintDevice::devicePixelRatioFScale();
     default:
         qWarning("QGLPaintDevice::metric() - metric %d not known", metric);
         return 0;