Enable making window-screen associations from QML

Qt Quick provides a Screen attached property to query information
about the screen an item's window belongs to. This is a good start,
but has two problems: it lacks some virtual desktop related info
(e.g. the position in the virtual desktop) and it cannot be used in
combination with the Window element in order to achieve a QML
equivalent of QWindow::setScreen().

Therefore add the missing virtualX and virtualY properties and
introduce Qt.application.screens. The latter is an equivalent to
QGuiApplication::screens() and is a JS array the elements of which
can be set as the value of the new Window.targetScreen property.

This means that a call like
window->setScreen(QGuiApplication::screens()[0]) translates to
Window { targetScreen: Qt.application.screens[0]; ... } when using the
Window type from QML. Screen addition or removal can be acted upon via
onScreensChanged.

QQuickScreenAttached has been split into two in order to allow reusing the
QScreen wrapping queries for other purposes as well.

Task-number: QTBUG-56115
Change-Id: I4b2fbd873315b40d0afe878da2fc50966c00e2e0
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 8 insertions, 1 deletions

diff --git a/src/quick/util/qquickapplication_p.h b/src/quick/util/qquickapplication_p.h
index 091cb094ed..70381553b4 100644
--- a/src/quick/util/qquickapplication_p.h
+++ b/src/quick/util/qquickapplication_p.h
@@ -56,10 +56,10 @@
 #include <qqml.h>
 #include <QtQml/private/qqmlglobal_p.h>
 #include <private/qtquickglobal_p.h>
+#include "../items/qquickscreen_p.h"
 
 QT_BEGIN_NAMESPACE
 
-
 class Q_AUTOTEST_EXPORT QQuickApplication : public QQmlApplication
 {
     Q_OBJECT
@@ -68,6 +68,7 @@ class Q_AUTOTEST_EXPORT QQuickApplication : public QQmlApplication
     Q_PROPERTY(bool supportsMultipleWindows READ supportsMultipleWindows CONSTANT)
     Q_PROPERTY(Qt::ApplicationState state READ state NOTIFY stateChanged)
     Q_PROPERTY(QFont font READ font CONSTANT)
+    Q_PROPERTY(QQmlListProperty<QQuickScreenInfo> screens READ screens NOTIFY screensChanged)
 
 public:
     explicit QQuickApplication(QObject *parent = 0);
@@ -77,14 +78,20 @@ public:
     bool supportsMultipleWindows() const;
     Qt::ApplicationState state() const;
     QFont font() const;
+    QQmlListProperty<QQuickScreenInfo> screens();
 
 Q_SIGNALS:
     void activeChanged();
     void layoutDirectionChanged();
     void stateChanged(Qt::ApplicationState state);
+    void screensChanged();
+
+private Q_SLOTS:
+    void updateScreens();
 
 private:
     Q_DISABLE_COPY(QQuickApplication)
+    QVector<QQuickScreenInfo *> m_screens;
 };
 
 QT_END_NAMESPACE