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, 2 insertions, 2 deletions

diff --git a/src/widgets/styles/qmacstyle_mac.mm b/src/widgets/styles/qmacstyle_mac.mm
index f4686f2810..aa1a783577 100644
--- a/src/widgets/styles/qmacstyle_mac.mm
+++ b/src/widgets/styles/qmacstyle_mac.mm
@@ -1972,7 +1972,7 @@ void QMacStylePrivate::drawColorlessButton(const HIRect &macRect, HIThemeButtonD
         }
     }
 
-    int devicePixelRatio = p->device()->devicePixelRatio();
+    int devicePixelRatio = p->device()->devicePixelRatioF();
     int width = devicePixelRatio * (int(macRect.size.width) + extraWidth);
     int height = devicePixelRatio * (int(macRect.size.height) + extraHeight);
 
@@ -7199,7 +7199,7 @@ CGContextRef qt_mac_cg_context(const QPaintDevice *pdev)
         }
 
         CGContextTranslateCTM(ret, 0, pm->height());
-        int devicePixelRatio = pdev->devicePixelRatio();
+        qreal devicePixelRatio = pdev->devicePixelRatioF();
         CGContextScaleCTM(ret, devicePixelRatio, devicePixelRatio);
         CGContextScaleCTM(ret, 1, -1);
         return ret;