From ae9d18ce9ecb16110256e113dbd372aa88dcf89f Mon Sep 17 00:00:00 2001
From: Peter Cai <peter@typeblog.net>
Date: Sat, 11 Aug 2018 17:44:32 +0800
Subject: [PATCH] blur: fix HiDPI awareness (#305)

When copying from a QPixmap, the rectangle area should be scaled according to `devicePixelRatio`.

This fixes #300.
---
 src/tools/blur/blurtool.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/tools/blur/blurtool.cpp b/src/tools/blur/blurtool.cpp
index 9d119ce8..e845d471 100644
--- a/src/tools/blur/blurtool.cpp
+++ b/src/tools/blur/blurtool.cpp
@@ -52,13 +52,15 @@ void BlurTool::process(QPainter &painter, const QPixmap &pixmap, bool recordUndo
     }
     QPoint &p0 = m_points.first;
     QPoint &p1 = m_points.second;
+    auto pixelRatio = pixmap.devicePixelRatio();
 
     QRect selection = QRect(p0, p1).normalized();
+    QRect selectionScaled = QRect(p0 * pixelRatio, p1 * pixelRatio).normalized();
 
     QGraphicsBlurEffect *blur = new QGraphicsBlurEffect;
     blur->setBlurRadius(10);
     QGraphicsPixmapItem *item = new QGraphicsPixmapItem (
-                pixmap.copy(selection));
+                pixmap.copy(selectionScaled));
     item->setGraphicsEffect(blur);
 
     QGraphicsScene scene;