From 8b62673d9f0cf8aea126b3cd2f52686f013d7fe1 Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@qt.io>
Date: Tue, 18 Apr 2017 15:02:08 +0200
Subject: [PATCH] QGraphicsDropShadowEffect: Fix for high DPI scaling

Preserve the device pixel ratio.

Task-number: QTBUG-60026
Change-Id: Ie818c582fe2c7b11ceb347b39cfbf7ea49361021
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
---
 src/widgets/effects/qpixmapfilter.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/widgets/effects/qpixmapfilter.cpp b/src/widgets/effects/qpixmapfilter.cpp
index 2a069d7529..bb949fcebf 100644
--- a/src/widgets/effects/qpixmapfilter.cpp
+++ b/src/widgets/effects/qpixmapfilter.cpp
@@ -1316,6 +1316,7 @@ void QPixmapDropShadowFilter::draw(QPainter *p,
         return;
 
     QImage tmp(px.size(), QImage::Format_ARGB32_Premultiplied);
+    tmp.setDevicePixelRatio(px.devicePixelRatioF());
     tmp.fill(0);
     QPainter tmpPainter(&tmp);
     tmpPainter.setCompositionMode(QPainter::CompositionMode_Source);
@@ -1324,6 +1325,7 @@ void QPixmapDropShadowFilter::draw(QPainter *p,
 
     // blur the alpha channel
     QImage blurred(tmp.size(), QImage::Format_ARGB32_Premultiplied);
+    blurred.setDevicePixelRatio(px.devicePixelRatioF());
     blurred.fill(0);
     QPainter blurPainter(&blurred);
     qt_blurImage(&blurPainter, tmp, d->radius, false, true);