Added QPA window system interface handler for logical DPI changes.

Logical DPI is independent from geometry and physical DPI.

Change-Id: Ice487f61e1bda9e6791e2adf6998ebf61cdbaef2
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: Jørgen Lind <jorgen.lind@nokia.com>

src/gui/kernel/qguiapplication.cpp

@@ -586,6 +586,10 @@ void QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePriv
         QGuiApplicationPrivate::reportAvailableGeometryChange(
                 static_cast<QWindowSystemInterfacePrivate::ScreenAvailableGeometryEvent *>(e));
         break;
+    case QWindowSystemInterfacePrivate::ScreenLogicalDotsPerInch:
+        QGuiApplicationPrivate::reportLogicalDotsPerInchChange(
+                static_cast<QWindowSystemInterfacePrivate::ScreenLogicalDotsPerInchEvent *>(e));
+        break;
     case QWindowSystemInterfacePrivate::Map:
         QGuiApplicationPrivate::processMapEvent(static_cast<QWindowSystemInterfacePrivate::MapEvent *>(e));
         break;
@@ -998,9 +1002,6 @@ void QGuiApplicationPrivate::reportGeometryChange(QWindowSystemInterfacePrivate:
     emit s->physicalDotsPerInchXChanged(s->physicalDotsPerInchX());
     emit s->physicalDotsPerInchYChanged(s->physicalDotsPerInchY());
     emit s->physicalDotsPerInchChanged(s->physicalDotsPerInch());
-    emit s->logicalDotsPerInchXChanged(s->logicalDotsPerInchX());
-    emit s->logicalDotsPerInchYChanged(s->logicalDotsPerInchY());
-    emit s->logicalDotsPerInchChanged(s->logicalDotsPerInch());
     emit s->availableSizeChanged(s->availableSize());
     emit s->availableGeometryChanged(s->availableGeometry());
 }
@@ -1021,6 +1022,22 @@ void QGuiApplicationPrivate::reportAvailableGeometryChange(
     emit s->availableGeometryChanged(s->availableGeometry());
 }
 
+void QGuiApplicationPrivate::reportLogicalDotsPerInchChange(QWindowSystemInterfacePrivate::ScreenLogicalDotsPerInchEvent *e)
+{
+    // This operation only makes sense after the QGuiApplication constructor runs
+    if (QCoreApplication::startingUp())
+        return;
+
+    if (!e->screen)
+        return;
+
+    QScreen *s = e->screen.data();
+
+    emit s->logicalDotsPerInchXChanged(s->logicalDotsPerInchX());
+    emit s->logicalDotsPerInchYChanged(s->logicalDotsPerInchY());
+    emit s->logicalDotsPerInchChanged(s->logicalDotsPerInch());
+}
+
 void QGuiApplicationPrivate::processMapEvent(QWindowSystemInterfacePrivate::MapEvent *e)
 {
     if (!e->mapped)

src/gui/kernel/qguiapplication_p.h

@@ -125,6 +125,7 @@ public:
     static void reportScreenOrientationChange(QWindowSystemInterfacePrivate::ScreenOrientationEvent *e);
     static void reportGeometryChange(QWindowSystemInterfacePrivate::ScreenGeometryEvent *e);
     static void reportAvailableGeometryChange(QWindowSystemInterfacePrivate::ScreenAvailableGeometryEvent *e);
+    static void reportLogicalDotsPerInchChange(QWindowSystemInterfacePrivate::ScreenLogicalDotsPerInchEvent *e);
 
     static void processMapEvent(QWindowSystemInterfacePrivate::MapEvent *e);
     static void processUnmapEvent(QWindowSystemInterfacePrivate::UnmapEvent *e);

src/gui/kernel/qwindowsysteminterface_qpa.cpp

@@ -278,6 +278,13 @@ void QWindowSystemInterface::handleScreenAvailableGeometryChange(QScreen *screen
     QWindowSystemInterfacePrivate::queueWindowSystemEvent(e);
 }
 
+void QWindowSystemInterface::handleScreenLogicalDotsPerInchChange(QScreen *screen)
+{
+    QWindowSystemInterfacePrivate::ScreenLogicalDotsPerInchEvent *e =
+            new QWindowSystemInterfacePrivate::ScreenLogicalDotsPerInchEvent(screen);
+    QWindowSystemInterfacePrivate::queueWindowSystemEvent(e);
+}
+
 void QWindowSystemInterface::handleMapEvent(QWindow *tlw)
 {
     QWindowSystemInterfacePrivate::MapEvent *e = new QWindowSystemInterfacePrivate::MapEvent(tlw);

src/gui/kernel/qwindowsysteminterface_qpa.h

@@ -117,6 +117,7 @@ public:
     static void handleScreenOrientationChange(QScreen *screen);
     static void handleScreenGeometryChange(QScreen *screen);
     static void handleScreenAvailableGeometryChange(QScreen *screen);
+    static void handleScreenLogicalDotsPerInchChange(QScreen *screen);
 
     // For event dispatcher implementations
     static bool sendWindowSystemEvents(QAbstractEventDispatcher *eventDispatcher, QEventLoop::ProcessEventsFlags flags);

src/gui/kernel/qwindowsysteminterface_qpa_p.h

@@ -63,6 +63,7 @@ public:
         ScreenOrientation,
         ScreenGeometry,
         ScreenAvailableGeometry,
+        ScreenLogicalDotsPerInch,
         Map,
         Unmap,
         Expose
@@ -215,6 +216,13 @@ public:
         QWeakPointer<QScreen> screen;
     };
 
+    class ScreenLogicalDotsPerInchEvent : public WindowSystemEvent {
+    public:
+        ScreenLogicalDotsPerInchEvent(QScreen *s)
+            : WindowSystemEvent(ScreenLogicalDotsPerInch), screen(s) { }
+        QWeakPointer<QScreen> screen;
+    };
+
     class MapEvent : public WindowSystemEvent {
     public:
         MapEvent(QWindow *mapped)