Mac/Retina: Fix target selector icon painting.

Task-number: QTCREATORBUG-10917
Change-Id: If151da45a83ce5b7ddf3166c16f8c63783f53f6a
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/projectexplorer/miniprojecttargetselector.cpp

@@ -59,21 +59,42 @@
 #include <QAction>
 #include <QItemDelegate>
 
+#if QT_VERSION >= 0x050100
+#include <QGuiApplication>
+#endif
+
 static QIcon createCenteredIcon(const QIcon &icon, const QIcon &overlay)
 {
     QPixmap targetPixmap;
-    targetPixmap = QPixmap(Core::Constants::TARGET_ICON_SIZE, Core::Constants::TARGET_ICON_SIZE);
+    qreal appDevicePixelRatio = 1.0;
+#if QT_VERSION >= 0x050100
+    appDevicePixelRatio = qApp->devicePixelRatio();
+#endif
+    int deviceSpaceIconSize = Core::Constants::TARGET_ICON_SIZE * appDevicePixelRatio;
+    targetPixmap = QPixmap(deviceSpaceIconSize, deviceSpaceIconSize);
+#if QT_VERSION >= 0x050100
+    targetPixmap.setDevicePixelRatio(appDevicePixelRatio);
+#endif
     targetPixmap.fill(Qt::transparent);
-    QPainter painter(&targetPixmap);
-
-    QPixmap pixmap = icon.pixmap(Core::Constants::TARGET_ICON_SIZE);
-    painter.drawPixmap((Core::Constants::TARGET_ICON_SIZE - pixmap.width())/2,
-                       (Core::Constants::TARGET_ICON_SIZE - pixmap.height())/2, pixmap);
+    QPainter painter(&targetPixmap); // painter in user space
+
+    QPixmap pixmap = icon.pixmap(Core::Constants::TARGET_ICON_SIZE); // already takes app devicePixelRatio into account
+    qreal pixmapDevicePixelRatio = 1.0;
+#if QT_VERSION >= 0x050100
+    pixmapDevicePixelRatio = pixmap.devicePixelRatio();
+#endif
+    painter.drawPixmap((Core::Constants::TARGET_ICON_SIZE - pixmap.width() / pixmapDevicePixelRatio) / 2,
+                       (Core::Constants::TARGET_ICON_SIZE - pixmap.height() / pixmapDevicePixelRatio) / 2, pixmap);
     if (!overlay.isNull()) {
-        pixmap = overlay.pixmap(Core::Constants::TARGET_ICON_SIZE);
-        painter.drawPixmap((Core::Constants::TARGET_ICON_SIZE - pixmap.width())/2,
-                           (Core::Constants::TARGET_ICON_SIZE - pixmap.height())/2, pixmap);
+        pixmap = overlay.pixmap(Core::Constants::TARGET_ICON_SIZE); // already takes app devicePixelRatio into account
+        pixmapDevicePixelRatio = 1.0;
+#if QT_VERSION >= 0x050100
+        pixmapDevicePixelRatio = pixmap.devicePixelRatio();
+#endif
+        painter.drawPixmap((Core::Constants::TARGET_ICON_SIZE - pixmap.width() / pixmapDevicePixelRatio) / 2,
+                           (Core::Constants::TARGET_ICON_SIZE - pixmap.height() / pixmapDevicePixelRatio) / 2, pixmap);
     }
+
     return QIcon(targetPixmap);
 }