From 85cdc8ebc1a85c6206443a1ba5511f1e6d072e51 Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@qt.io>
Date: Tue, 1 Sep 2020 14:55:51 +0200
Subject: [PATCH] Vista style: Fix pixelized elements after focus/activation

Use a float device pixel ratio in the style animations and default
to the application's device pixel ratio.

Pick-to: 5.15
Task-number: QTBUG-86344
Change-Id: I093bfefc0f544eb488da0993a183f92c9c77a286
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>
---
 src/plugins/styles/windowsvista/qwindowsvistastyle.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp b/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
index 016fd3a6cc..86db78429c 100644
--- a/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
+++ b/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
@@ -104,7 +104,8 @@ bool canAnimate(const QStyleOption *option) {
 
 static inline QImage createAnimationBuffer(const QStyleOption *option, const QWidget *widget)
 {
-    const int devicePixelRatio = widget ? widget->devicePixelRatio() : 1;
+    const qreal devicePixelRatio = widget
+        ? widget->devicePixelRatioF() : qApp->devicePixelRatio();
     QImage result(option->rect.size() * devicePixelRatio, QImage::Format_ARGB32_Premultiplied);
     result.setDevicePixelRatio(devicePixelRatio);
     result.fill(0);