From e346c751eccf023b668c6b653f9f72382f830250 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20K=C3=BCgler?= <sebas@kde.org>
Date: Thu, 23 Jan 2014 04:05:45 +0100
Subject: [PATCH] Allow to reset devicePixelRatio

Setting devicePixelRatio to 0 re-reads it and resets it to its default
value.
---
 src/declarativeimports/core/units.cpp | 21 ++++++++++++---------
 src/declarativeimports/core/units.h   | 17 ++++++++++++++++-
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/src/declarativeimports/core/units.cpp b/src/declarativeimports/core/units.cpp
index bc5ec0df5..d02835fa1 100644
--- a/src/declarativeimports/core/units.cpp
+++ b/src/declarativeimports/core/units.cpp
@@ -32,13 +32,10 @@
 
 Units::Units (QObject *parent)
     : QObject(parent),
-      m_gridUnit(-1)
+      m_gridUnit(-1),
+      m_devicePixelRatio(-1)
 {
-    //Usual "default" is 96 dpi
-    //that magic ratio follows the definition of "device independent pixel" by Microsoft
-    m_dpi = QApplication::desktop()->physicalDpiX();
-    m_devicePixelRatio = (qreal)m_dpi / (qreal)96;
-
+    setDevicePixelRatio(0);
     updateSpacing();
 
     m_iconSizes = new QQmlPropertyMap(this);
@@ -80,15 +77,21 @@ QQmlPropertyMap *Units::iconSizes() const
 
 qreal Units::devicePixelRatio() const
 {
-
     return m_devicePixelRatio;
 }
 
 void Units::setDevicePixelRatio(const qreal scale)
 {
     if (m_devicePixelRatio != scale) {
-        m_devicePixelRatio = scale;
-        qDebug() << "Setting dpi scale to " << scale;
+        if (scale <= 0) {
+            //Usual "default" is 96 dpi
+            //that magic ratio follows the definition of "device independent pixel" by Microsoft
+            m_dpi = QApplication::desktop()->physicalDpiX();
+            m_devicePixelRatio = (qreal)m_dpi / (qreal)96;
+        } else {
+            m_devicePixelRatio = scale;
+        }
+            qDebug() << "Setting dpi scale to " << scale;
         emit devicePixelRatioChanged();
     }
 }
diff --git a/src/declarativeimports/core/units.h b/src/declarativeimports/core/units.h
index dde38d843..7f6da5cc7 100644
--- a/src/declarativeimports/core/units.h
+++ b/src/declarativeimports/core/units.h
@@ -64,6 +64,9 @@ class Units : public QObject
     Q_PROPERTY(int smallSpacing READ smallSpacing NOTIFY spacingChanged)
     Q_PROPERTY(int largeSpacing READ largeSpacing NOTIFY spacingChanged)
 
+    /**
+     * The ratio between physical and device-independent pixels.
+     */
     Q_PROPERTY(qreal devicePixelRatio READ devicePixelRatio WRITE setDevicePixelRatio NOTIFY devicePixelRatioChanged)
 
 public:
@@ -74,7 +77,19 @@ public:
 
     qreal gridUnit() const;
 
-    void setDevicePixelRatio(const qreal scale);
+
+    /**
+     * Overrides the devicePixelRatio
+     *
+     * Set the device pixel ratio to a custom value.
+     *
+     * @arg ratio, 0 resets to detected value
+     */
+    void setDevicePixelRatio(const qreal ratio);
+
+    /**
+     * @return The ratio between physical and device-independent pixels.
+     */
     qreal devicePixelRatio() const;
 
     QQmlPropertyMap *iconSizes() const;