Add Overlay::background that is shown when any modal popup is open

Change-Id: Idc2a5bbb5cf7a08ff21731537a378b1dd8050833
Reviewed-by: Mitch Curtis <mitch.curtis@theqtcompany.com>

3 files changed, 59 insertions, 2 deletions

diff --git a/src/templates/qquickapplicationwindow.cpp b/src/templates/qquickapplicationwindow.cpp
index f21a1a63..db451810 100644
--- a/src/templates/qquickapplicationwindow.cpp
+++ b/src/templates/qquickapplicationwindow.cpp
@@ -337,10 +337,12 @@ QQuickItem *QQuickApplicationWindow::activeFocusControl() const
 }
 
 /*!
+    \qmlpropertygroup Qt.labs.controls::ApplicationWindow::overlay
     \qmlproperty Item Qt.labs.controls::ApplicationWindow::overlay
-    \readonly
+    \qmlproperty Item Qt.labs.controls::ApplicationWindow::overlay.background
 
-    This property holds the window overlay item. Popups are automatically
+    This property holds the window overlay item and its background that implements the
+    background dimming when any modal popups are open. Popups are automatically
     reparented to the overlay.
 
     \sa Popup
diff --git a/src/templates/qquickoverlay.cpp b/src/templates/qquickoverlay.cpp
index 73e0a39d..467c3b52 100644
--- a/src/templates/qquickoverlay.cpp
+++ b/src/templates/qquickoverlay.cpp
@@ -37,6 +37,7 @@
 #include "qquickoverlay_p.h"
 #include "qquickpopup_p.h"
 #include <QtQml/qqmlinfo.h>
+#include <QtQml/qqmlproperty.h>
 #include <QtQuick/private/qquickitem_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -48,11 +49,22 @@ class QQuickOverlayPrivate : public QQuickItemPrivate
 public:
     QQuickOverlayPrivate();
 
+    void resizeBackground();
+
+    QQuickItem *background;
     QHash<QQuickItem *, QQuickPopup *> popups;
     int modalPopups;
 };
 
+void QQuickOverlayPrivate::resizeBackground()
+{
+    Q_Q(QQuickOverlay);
+    background->setWidth(q->width());
+    background->setHeight(q->height());
+}
+
 QQuickOverlayPrivate::QQuickOverlayPrivate() :
+    background(Q_NULLPTR),
     modalPopups(0)
 {
 }
@@ -65,6 +77,31 @@ QQuickOverlay::QQuickOverlay(QQuickItem *parent)
     setVisible(false);
 }
 
+
+QQuickItem *QQuickOverlay::background() const
+{
+    Q_D(const QQuickOverlay);
+    return d->background;
+}
+
+void QQuickOverlay::setBackground(QQuickItem *background)
+{
+    Q_D(QQuickOverlay);
+    if (d->background != background) {
+        delete d->background;
+        d->background = background;
+        if (background) {
+            background->setOpacity(0.0);
+            background->setParentItem(this);
+            if (qFuzzyIsNull(background->z()))
+                background->setZ(-1);
+            if (isComponentComplete())
+                d->resizeBackground();
+        }
+        emit backgroundChanged();
+    }
+}
+
 void QQuickOverlay::itemChange(ItemChange change, const ItemChangeData &data)
 {
     Q_D(QQuickOverlay);
@@ -102,6 +139,18 @@ void QQuickOverlay::itemChange(ItemChange change, const ItemChangeData &data)
             --d->modalPopups;
         d->popups.remove(contentItem);
     }
+
+    // use QQmlProperty instead of QQuickItem::setOpacity() to trigger QML Behaviors
+    if (d->background)
+        QQmlProperty::write(d->background, QStringLiteral("opacity"), d->modalPopups > 0 ? 1.0 : 0.0);
+}
+
+void QQuickOverlay::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
+{
+    Q_D(QQuickOverlay);
+    QQuickItem::geometryChanged(newGeometry, oldGeometry);
+    if (d->background)
+        d->resizeBackground();
 }
 
 void QQuickOverlay::keyPressEvent(QKeyEvent *event)
diff --git a/src/templates/qquickoverlay_p.h b/src/templates/qquickoverlay_p.h
index 3f13e845..8af1372b 100644
--- a/src/templates/qquickoverlay_p.h
+++ b/src/templates/qquickoverlay_p.h
@@ -58,16 +58,22 @@ class QQuickOverlayPrivate;
 class Q_LABSTEMPLATES_EXPORT QQuickOverlay : public QQuickItem
 {
     Q_OBJECT
+    Q_PROPERTY(QQuickItem *background READ background WRITE setBackground NOTIFY backgroundChanged FINAL)
 
 public:
     explicit QQuickOverlay(QQuickItem *parent = Q_NULLPTR);
 
+    QQuickItem *background() const;
+    void setBackground(QQuickItem *background);
+
 Q_SIGNALS:
+    void backgroundChanged();
     void pressed();
     void released();
 
 protected:
     void itemChange(ItemChange change, const ItemChangeData &data) Q_DECL_OVERRIDE;
+    void geometryChanged(const QRectF &oldGeometry, const QRectF &newGeometry) Q_DECL_OVERRIDE;
 
     void keyPressEvent(QKeyEvent *event) Q_DECL_OVERRIDE;
     void keyReleaseEvent(QKeyEvent *event) Q_DECL_OVERRIDE;