Make Overlay.modal and modeless Components

This way we can simply instantiate a visual overlay for each modal or
dimming popup without having tricky problems with overlay's stacking
order. It makes also sense to not instantiate the overlays for hidden
popups.

Coincidentally, this change also fixes a problem that the overlay
turned out to be _always_ visible since a hidden overlay background
was always instantiated no matter if there were open popups, or
popups at all.

Change-Id: Ieb64a72c827d0a005418027428378ebe04f41117
Task-number: QTBUG-53519
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 68 insertions, 85 deletions

diff --git a/src/quicktemplates2/qquickoverlay.cpp b/src/quicktemplates2/qquickoverlay.cpp
index 0fb9f3ca..67eb3ceb 100644
--- a/src/quicktemplates2/qquickoverlay.cpp
+++ b/src/quicktemplates2/qquickoverlay.cpp
@@ -39,6 +39,7 @@
 #include "qquickdrawer_p.h"
 #include <QtQml/qqmlinfo.h>
 #include <QtQml/qqmlproperty.h>
+#include <QtQml/qqmlcomponent.h>
 #include <QtQuick/private/qquickitem_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -52,12 +53,14 @@ public:
 
     void popupAboutToShow();
     void popupAboutToHide();
-    void drawerPositionChange();
-    void resizeOverlay(QQuickItem *overlay);
-    void restackOverlay();
+    void popupClosed();
 
-    QQuickItem *modal;
-    QQuickItem *modeless;
+    void createOverlay(QQuickPopup *popup);
+    void destroyOverlay(QQuickPopup *popup);
+    void resizeOverlay(QQuickPopup *popup);
+
+    QQmlComponent *modal;
+    QQmlComponent *modeless;
     QVector<QQuickDrawer *> drawers;
     QVector<QQuickPopup *> popups;
     QPointer<QQuickPopup> mouseGrabberPopup;
@@ -71,14 +74,12 @@ void QQuickOverlayPrivate::popupAboutToShow()
     if (!popup || !popup->dim())
         return;
 
+    createOverlay(popup);
+
     // use QQmlProperty instead of QQuickItem::setOpacity() to trigger QML Behaviors
-    if (popup->isModal()) {
-        if (modal)
-            QQmlProperty::write(modal, QStringLiteral("opacity"), 1.0);
-    } else {
-        if (modeless)
-            QQmlProperty::write(modeless, QStringLiteral("opacity"), 1.0);
-    }
+    QQuickPopupPrivate *p = QQuickPopupPrivate::get(popup);
+    if (p->dimmer)
+        QQmlProperty::write(p->dimmer, QStringLiteral("opacity"), 1.0);
 }
 
 void QQuickOverlayPrivate::popupAboutToHide()
@@ -89,71 +90,67 @@ void QQuickOverlayPrivate::popupAboutToHide()
         return;
 
     // use QQmlProperty instead of QQuickItem::setOpacity() to trigger QML Behaviors
-    if (popup->isModal()) {
-        if (modal && modalPopups <= 1)
-            QQmlProperty::write(modal, QStringLiteral("opacity"), 0.0);
-    } else {
-        if (modeless)
-            QQmlProperty::write(modeless, QStringLiteral("opacity"), 0.0);
-    }
+    QQuickPopupPrivate *p = QQuickPopupPrivate::get(popup);
+    if (p->dimmer)
+        QQmlProperty::write(p->dimmer, QStringLiteral("opacity"), 0.0);
 }
 
-void QQuickOverlayPrivate::drawerPositionChange()
+void QQuickOverlayPrivate::popupClosed()
 {
     Q_Q(QQuickOverlay);
-    QQuickDrawer *drawer = qobject_cast<QQuickDrawer *>(q->sender());
-    if (!drawer || !drawer->dim())
+    QQuickPopup *popup = qobject_cast<QQuickPopup *>(q->sender());
+    if (!popup || !popup->dim())
         return;
 
-    // call QQuickItem::setOpacity() directly to avoid triggering QML Behaviors
-    // which would make the fading feel laggy compared to the drawer movement
-    if (drawer->isModal()) {
-        if (modal)
-            modal->setOpacity(drawer->position());
-    } else {
-        if (modeless)
-            modeless->setOpacity(drawer->position());
+    destroyOverlay(popup);
+}
+
+static QQuickItem *createDimmer(QQmlComponent *component, QQuickPopup *popup, QQuickItem *parent)
+{
+    if (!component)
+        return nullptr;
+
+    QQmlContext *creationContext = component->creationContext();
+    if (!creationContext)
+        creationContext = qmlContext(parent);
+    QQmlContext *context = new QQmlContext(creationContext);
+    context->setContextObject(popup);
+    QQuickItem *item = qobject_cast<QQuickItem*>(component->beginCreate(context));
+    if (item) {
+        item->setOpacity(0.0);
+        item->setParentItem(parent);
+        item->stackBefore(popup->popupItem());
+        item->setZ(popup->z());
+        component->completeCreate();
     }
+    return item;
 }
 
-void QQuickOverlayPrivate::resizeOverlay(QQuickItem *overlay)
+void QQuickOverlayPrivate::createOverlay(QQuickPopup *popup)
 {
     Q_Q(QQuickOverlay);
-    overlay->setWidth(q->width());
-    overlay->setHeight(q->height());
+    QQuickPopupPrivate *p = QQuickPopupPrivate::get(popup);
+    if (!p->dimmer)
+        p->dimmer = createDimmer(popup->isModal() ? modal : modeless, popup, q);
+    resizeOverlay(popup);
 }
 
-void QQuickOverlayPrivate::restackOverlay()
+void QQuickOverlayPrivate::destroyOverlay(QQuickPopup *popup)
 {
-    if (!modal && !modeless)
-        return;
-
-    // find the bottom-most modal and top-most modeless dimming popups
-    QQuickPopup *modalPopup = nullptr;
-    QQuickPopup *modelessPopup = nullptr;
-    for (auto it = popups.crbegin(), end = popups.crend(); it != end; ++it) {
-        QQuickPopup *popup = (*it);
-        if (!popup->dim())
-            continue;
-
-        if (popup->isModal()) {
-            if (!modalPopup || modalPopup->z() >= popup->z())
-                modalPopup = popup;
-        } else {
-            if (!modelessPopup)
-                modelessPopup = popup;
-        }
+    QQuickPopupPrivate *p = QQuickPopupPrivate::get(popup);
+    if (p->dimmer) {
+        p->dimmer->deleteLater();
+        p->dimmer = nullptr;
     }
+}
 
-    if (modal) {
-        modal->setZ(modalPopup ? modalPopup->z() : 0.0);
-        if (modalPopup)
-            modal->stackBefore(modalPopup->popupItem());
-    }
-    if (modeless) {
-        modeless->setZ(modelessPopup ? modelessPopup->z() : 0.0);
-        if (modelessPopup)
-            modeless->stackBefore(modelessPopup->popupItem());
+void QQuickOverlayPrivate::resizeOverlay(QQuickPopup *popup)
+{
+    Q_Q(QQuickOverlay);
+    QQuickPopupPrivate *p = QQuickPopupPrivate::get(popup);
+    if (p->dimmer) {
+        p->dimmer->setWidth(q->width());
+        p->dimmer->setHeight(q->height());
     }
 }
 
@@ -172,13 +169,13 @@ QQuickOverlay::QQuickOverlay(QQuickItem *parent)
     setVisible(false);
 }
 
-QQuickItem *QQuickOverlay::modal() const
+QQmlComponent *QQuickOverlay::modal() const
 {
     Q_D(const QQuickOverlay);
     return d->modal;
 }
 
-void QQuickOverlay::setModal(QQuickItem *modal)
+void QQuickOverlay::setModal(QQmlComponent *modal)
 {
     Q_D(QQuickOverlay);
     if (d->modal == modal)
@@ -186,22 +183,16 @@ void QQuickOverlay::setModal(QQuickItem *modal)
 
     delete d->modal;
     d->modal = modal;
-    if (modal) {
-        modal->setOpacity(0.0);
-        modal->setParentItem(this);
-        if (isComponentComplete())
-            d->resizeOverlay(modal);
-    }
     emit modalChanged();
 }
 
-QQuickItem *QQuickOverlay::modeless() const
+QQmlComponent *QQuickOverlay::modeless() const
 {
     Q_D(const QQuickOverlay);
     return d->modeless;
 }
 
-void QQuickOverlay::setModeless(QQuickItem *modeless)
+void QQuickOverlay::setModeless(QQmlComponent *modeless)
 {
     Q_D(QQuickOverlay);
     if (d->modeless == modeless)
@@ -209,12 +200,6 @@ void QQuickOverlay::setModeless(QQuickItem *modeless)
 
     delete d->modeless;
     d->modeless = modeless;
-    if (modeless) {
-        modeless->setOpacity(0.0);
-        modeless->setParentItem(this);
-        if (isComponentComplete())
-            d->resizeOverlay(modeless);
-    }
     emit modelessChanged();
 }
 
@@ -233,33 +218,33 @@ void QQuickOverlay::itemChange(ItemChange change, const ItemChangeData &data)
 
     if (change == ItemChildAddedChange) {
         d->popups.append(popup);
-        d->restackOverlay();
 
         QQuickDrawer *drawer = qobject_cast<QQuickDrawer *>(popup);
         if (drawer) {
-            QObjectPrivate::connect(drawer, &QQuickDrawer::positionChanged, d, &QQuickOverlayPrivate::drawerPositionChange);
             d->drawers.append(drawer);
+            d->createOverlay(drawer);
         } else {
             if (popup->isModal())
                 ++d->modalPopups;
 
             QObjectPrivate::connect(popup, &QQuickPopup::aboutToShow, d, &QQuickOverlayPrivate::popupAboutToShow);
             QObjectPrivate::connect(popup, &QQuickPopup::aboutToHide, d, &QQuickOverlayPrivate::popupAboutToHide);
+            QObjectPrivate::connect(popup, &QQuickPopup::closed, d, &QQuickOverlayPrivate::popupClosed);
         }
     } else if (change == ItemChildRemovedChange) {
         d->popups.removeOne(popup);
-        d->restackOverlay();
 
         QQuickDrawer *drawer = qobject_cast<QQuickDrawer *>(popup);
         if (drawer) {
-            QObjectPrivate::disconnect(drawer, &QQuickDrawer::positionChanged, d, &QQuickOverlayPrivate::drawerPositionChange);
             d->drawers.removeOne(drawer);
+            d->destroyOverlay(drawer);
         } else {
             if (popup->isModal())
                 --d->modalPopups;
 
             QObjectPrivate::disconnect(popup, &QQuickPopup::aboutToShow, d, &QQuickOverlayPrivate::popupAboutToShow);
             QObjectPrivate::disconnect(popup, &QQuickPopup::aboutToHide, d, &QQuickOverlayPrivate::popupAboutToHide);
+            QObjectPrivate::disconnect(popup, &QQuickPopup::closed, d, &QQuickOverlayPrivate::popupClosed);
         }
     }
 }
@@ -268,10 +253,8 @@ void QQuickOverlay::geometryChanged(const QRectF &newGeometry, const QRectF &old
 {
     Q_D(QQuickOverlay);
     QQuickItem::geometryChanged(newGeometry, oldGeometry);
-    if (d->modal)
-        d->resizeOverlay(d->modal);
-    if (d->modeless)
-        d->resizeOverlay(d->modeless);
+    for (QQuickPopup *popup : d->popups)
+        d->resizeOverlay(popup);
 }
 
 bool QQuickOverlay::event(QEvent *event)