Make QWindow update its screen when moved to a different one

Also implements the Cocoa backend for that.

Change-Id: I32977e12a04e1cf48b12333442482746c69ce133
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

7 files changed, 56 insertions, 15 deletions

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 3c79e62e75..2a1d7e3bcc 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -1285,6 +1285,9 @@ void QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePriv
     case QWindowSystemInterfacePrivate::WindowStateChanged:
         QGuiApplicationPrivate::processWindowStateChangedEvent(static_cast<QWindowSystemInterfacePrivate::WindowStateChangedEvent *>(e));
         break;
+    case QWindowSystemInterfacePrivate::WindowScreenChanged:
+        QGuiApplicationPrivate::processWindowScreenChangedEvent(static_cast<QWindowSystemInterfacePrivate::WindowScreenChangedEvent *>(e));
+        break;
     case QWindowSystemInterfacePrivate::ApplicationStateChanged:
             QGuiApplicationPrivate::processApplicationStateChangedEvent(static_cast<QWindowSystemInterfacePrivate::ApplicationStateChangedEvent *>(e));
         break;
@@ -1655,6 +1658,16 @@ void QGuiApplicationPrivate::processWindowStateChangedEvent(QWindowSystemInterfa
     }
 }
 
+void QGuiApplicationPrivate::processWindowScreenChangedEvent(QWindowSystemInterfacePrivate::WindowScreenChangedEvent *wse)
+{
+    if (QWindow *window  = wse->window.data()) {
+        if (QScreen *screen = wse->screen.data())
+            window->d_func()->setScreen(screen, false /* recreate */);
+        else // Fall back to default behavior, and try to find some appropriate screen
+            window->setScreen(0);
+    }
+}
+
 void QGuiApplicationPrivate::processApplicationStateChangedEvent(QWindowSystemInterfacePrivate::ApplicationStateChangedEvent *e)
 {
     if (e->newState == applicationState)
diff --git a/src/gui/kernel/qguiapplication_p.h b/src/gui/kernel/qguiapplication_p.h
index 376890ef47..cd8dfff103 100644
--- a/src/gui/kernel/qguiapplication_p.h
+++ b/src/gui/kernel/qguiapplication_p.h
@@ -126,6 +126,7 @@ public:
 
     static void processActivatedEvent(QWindowSystemInterfacePrivate::ActivatedWindowEvent *e);
     static void processWindowStateChangedEvent(QWindowSystemInterfacePrivate::WindowStateChangedEvent *e);
+    static void processWindowScreenChangedEvent(QWindowSystemInterfacePrivate::WindowScreenChangedEvent *e);
 
     static void processApplicationStateChangedEvent(QWindowSystemInterfacePrivate::ApplicationStateChangedEvent *e);
 
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 918c2e0b97..68ba1901c1 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -345,6 +345,25 @@ void QWindowPrivate::updateVisibility()
         emit q->visibilityChanged(visibility);
 }
 
+void QWindowPrivate::setScreen(QScreen *newScreen, bool recreate)
+{
+    Q_Q(QWindow);
+    if (newScreen != q->screen()) {
+        const bool shouldRecreate = recreate && platformWindow != 0;
+        if (shouldRecreate)
+            q->destroy();
+        if (screen)
+            q->disconnect(screen, SIGNAL(destroyed(QObject*)), q, SLOT(screenDestroyed(QObject*)));
+        screen = newScreen;
+        if (newScreen) {
+            q->connect(screen, SIGNAL(destroyed(QObject*)), q, SLOT(screenDestroyed(QObject*)));
+            if (shouldRecreate)
+                q->create();
+        }
+        emit q->screenChanged(newScreen);
+    }
+}
+
 /*!
     Sets the \a surfaceType of the window.
 
@@ -1568,20 +1587,7 @@ void QWindow::setScreen(QScreen *newScreen)
     Q_D(QWindow);
     if (!newScreen)
         newScreen = QGuiApplication::primaryScreen();
-    if (newScreen != screen()) {
-        const bool wasCreated = d->platformWindow != 0;
-        if (wasCreated)
-            destroy();
-        if (d->screen)
-            disconnect(d->screen, SIGNAL(destroyed(QObject*)), this, SLOT(screenDestroyed(QObject*)));
-        d->screen = newScreen;
-        if (newScreen) {
-            connect(d->screen, SIGNAL(destroyed(QObject*)), this, SLOT(screenDestroyed(QObject*)));
-            if (wasCreated)
-                create();
-        }
-        emit screenChanged(newScreen);
-    }
+    d->setScreen(newScreen, true /* recreate */);
 }
 
 void QWindow::screenDestroyed(QObject *object)
diff --git a/src/gui/kernel/qwindow_p.h b/src/gui/kernel/qwindow_p.h
index ea2cb722ab..f43c1ea8ec 100644
--- a/src/gui/kernel/qwindow_p.h
+++ b/src/gui/kernel/qwindow_p.h
@@ -127,6 +127,8 @@ public:
     void updateVisibility();
     void _q_clearAlert();
 
+    void setScreen(QScreen *newScreen, bool recreate);
+
     QWindow::SurfaceType surfaceType;
     Qt::WindowFlags windowFlags;
     QWindow *parentWindow;
diff --git a/src/gui/kernel/qwindowsysteminterface.cpp b/src/gui/kernel/qwindowsysteminterface.cpp
index 7dc1e7f7e5..6fc63fe96c 100644
--- a/src/gui/kernel/qwindowsysteminterface.cpp
+++ b/src/gui/kernel/qwindowsysteminterface.cpp
@@ -126,6 +126,13 @@ void QWindowSystemInterface::handleWindowStateChanged(QWindow *tlw, Qt::WindowSt
     QWindowSystemInterfacePrivate::handleWindowSystemEvent(e);
 }
 
+void QWindowSystemInterface::handleWindowScreenChanged(QWindow *tlw, QScreen *screen)
+{
+    QWindowSystemInterfacePrivate::WindowScreenChangedEvent *e =
+        new QWindowSystemInterfacePrivate::WindowScreenChangedEvent(tlw, screen);
+    QWindowSystemInterfacePrivate::handleWindowSystemEvent(e);
+}
+
 void QWindowSystemInterface::handleApplicationStateChanged(Qt::ApplicationState newState)
 {
     Q_ASSERT(QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::ApplicationState));
diff --git a/src/gui/kernel/qwindowsysteminterface.h b/src/gui/kernel/qwindowsysteminterface.h
index 521c2a4941..b0327701bb 100644
--- a/src/gui/kernel/qwindowsysteminterface.h
+++ b/src/gui/kernel/qwindowsysteminterface.h
@@ -138,6 +138,7 @@ public:
     static void handleWindowActivated(QWindow *w, Qt::FocusReason r = Qt::OtherFocusReason);
 
     static void handleWindowStateChanged(QWindow *w, Qt::WindowState newState);
+    static void handleWindowScreenChanged(QWindow *w, QScreen *newScreen);
 
     static void handleApplicationStateChanged(Qt::ApplicationState newState);
 
diff --git a/src/gui/kernel/qwindowsysteminterface_p.h b/src/gui/kernel/qwindowsysteminterface_p.h
index a6ea15c5f2..c4968f8ca6 100644
--- a/src/gui/kernel/qwindowsysteminterface_p.h
+++ b/src/gui/kernel/qwindowsysteminterface_p.h
@@ -91,7 +91,8 @@ public:
         PlatformPanel = UserInputEvent | 0x17,
         ContextMenu = UserInputEvent | 0x18,
         ApplicationStateChanged = 0x19,
-        FlushEvents = 0x20
+        FlushEvents = 0x20,
+        WindowScreenChanged = 0x21
     };
 
     class WindowSystemEvent {
@@ -158,6 +159,16 @@ public:
         Qt::WindowState newState;
     };
 
+    class WindowScreenChangedEvent : public WindowSystemEvent {
+    public:
+        WindowScreenChangedEvent(QWindow *w, QScreen *s)
+            : WindowSystemEvent(WindowScreenChanged), window(w), screen(s)
+        { }
+
+        QPointer<QWindow> window;
+        QPointer<QScreen> screen;
+    };
+
     class ApplicationStateChangedEvent : public WindowSystemEvent {
     public:
         ApplicationStateChangedEvent(Qt::ApplicationState newState)