Fix drawer visibility and overlay event handling

Drawers were visible all the time, lurking at the window edges to be
able to catch presses and drag themselves visible when appropriate.

This change moves the handling of window edge presses from QQuickDrawer
to QQuickOverlay, making it possible to show and hide drawers like any
other popups. Instead of having all drawers visible all the time, we
just keep QQuickOverlay visible when there are any registered drawers,
even hidden ones.

Furthermore, this change makes modal popup/drawer background dimming
items accept mouse press events just like they accept hover events to
ensure that a modal overlay does not leak input events through. When
the background dimming of a modal drawer has been dragged over the
drag-threshold, the drawer simply steals/grabs mouse to start dragging
of the drawer.

Task-number: QTBUG-54794
Task-number: QTBUG-54800
Task-number: QTBUG-55022
Task-number: QTBUG-55703
Task-number: QTBUG-55713
Change-Id: I65fb38fcf1466d4e41192c4321d80fb90b49da9a
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 81 insertions, 63 deletions

diff --git a/src/quicktemplates2/qquickoverlay.cpp b/src/quicktemplates2/qquickoverlay.cpp
index d34fd7fc..19677cb7 100644
--- a/src/quicktemplates2/qquickoverlay.cpp
+++ b/src/quicktemplates2/qquickoverlay.cpp
@@ -37,11 +37,12 @@
 #include "qquickoverlay_p.h"
 #include "qquickoverlay_p_p.h"
 #include "qquickpopup_p_p.h"
-#include "qquickdrawer_p.h"
+#include "qquickdrawer_p_p.h"
 #include "qquickapplicationwindow_p.h"
 #include <QtQml/qqmlinfo.h>
 #include <QtQml/qqmlproperty.h>
 #include <QtQml/qqmlcomponent.h>
+#include <algorithm>
 
 QT_BEGIN_NAMESPACE
 
@@ -93,7 +94,8 @@ static QQuickItem *createDimmer(QQmlComponent *component, QQuickPopup *popup, QQ
         item->setParentItem(parent);
         item->stackBefore(popup->popupItem());
         item->setZ(popup->z());
-        if (popup->isModal() && !qobject_cast<QQuickDrawer *>(popup)) {
+        if (popup->isModal()) {
+            item->setAcceptedMouseButtons(Qt::AllButtons);
             // TODO: switch to QStyleHints::useHoverEffects in Qt 5.8
             item->setAcceptHoverEvents(true);
             // item->setAcceptHoverEvents(QGuiApplication::styleHints()->useHoverEffects());
@@ -162,6 +164,15 @@ QVector<QQuickPopup *> QQuickOverlayPrivate::stackingOrderPopups() const
     return popups;
 }
 
+QVector<QQuickDrawer *> QQuickOverlayPrivate::stackingOrderDrawers() const
+{
+    QVector<QQuickDrawer *> sorted(allDrawers);
+    std::sort(sorted.begin(), sorted.end(), [](const QQuickDrawer *one, const QQuickDrawer *another) {
+        return one->z() > another->z();
+    });
+    return sorted;
+}
+
 void QQuickOverlayPrivate::itemGeometryChanged(QQuickItem *, const QRectF &newGeometry, const QRectF &)
 {
     Q_Q(QQuickOverlay);
@@ -170,22 +181,26 @@ void QQuickOverlayPrivate::itemGeometryChanged(QQuickItem *, const QRectF &newGe
 
 QQuickOverlayPrivate::QQuickOverlayPrivate() :
     modal(nullptr),
-    modeless(nullptr),
-    modalPopups(0)
+    modeless(nullptr)
 {
 }
 
 void QQuickOverlayPrivate::addPopup(QQuickPopup *popup)
 {
+    Q_Q(QQuickOverlay);
     allPopups += popup;
-    if (QQuickDrawer *drawer = qobject_cast<QQuickDrawer *>(popup))
+    if (QQuickDrawer *drawer = qobject_cast<QQuickDrawer *>(popup)) {
         allDrawers += drawer;
+        q->setVisible(!allDrawers.isEmpty() || !q->childItems().isEmpty());
+    }
 }
 
 void QQuickOverlayPrivate::removePopup(QQuickPopup *popup)
 {
+    Q_Q(QQuickOverlay);
     allPopups.removeOne(popup);
-    allDrawers.removeOne(static_cast<QQuickDrawer *>(popup));
+    if (allDrawers.removeOne(static_cast<QQuickDrawer *>(popup)))
+        q->setVisible(!allDrawers.isEmpty() || !q->childItems().isEmpty());
 }
 
 QQuickOverlay::QQuickOverlay(QQuickItem *parent)
@@ -275,7 +290,7 @@ void QQuickOverlay::itemChange(ItemChange change, const ItemChangeData &data)
     QQuickPopup *popup = nullptr;
     if (change == ItemChildAddedChange || change == ItemChildRemovedChange) {
         popup = qobject_cast<QQuickPopup *>(data.item->parent());
-        setVisible(!childItems().isEmpty());
+        setVisible(!d->allDrawers.isEmpty() || !childItems().isEmpty());
     }
     if (!popup)
         return;
@@ -286,8 +301,6 @@ void QQuickOverlay::itemChange(ItemChange change, const ItemChangeData &data)
         QObjectPrivate::connect(popup, &QQuickPopup::dimChanged, d, &QQuickOverlayPrivate::toggleOverlay);
         QObjectPrivate::connect(popup, &QQuickPopup::modalChanged, d, &QQuickOverlayPrivate::toggleOverlay);
         if (!qobject_cast<QQuickDrawer *>(popup)) {
-            if (popup->isModal())
-                ++d->modalPopups;
             QObjectPrivate::connect(popup, &QQuickPopup::aboutToShow, d, &QQuickOverlayPrivate::popupAboutToShow);
             QObjectPrivate::connect(popup, &QQuickPopup::aboutToHide, d, &QQuickOverlayPrivate::popupAboutToHide);
         }
@@ -296,8 +309,6 @@ void QQuickOverlay::itemChange(ItemChange change, const ItemChangeData &data)
         QObjectPrivate::disconnect(popup, &QQuickPopup::dimChanged, d, &QQuickOverlayPrivate::toggleOverlay);
         QObjectPrivate::disconnect(popup, &QQuickPopup::modalChanged, d, &QQuickOverlayPrivate::toggleOverlay);
         if (!qobject_cast<QQuickDrawer *>(popup)) {
-            if (popup->isModal())
-                --d->modalPopups;
             QObjectPrivate::disconnect(popup, &QQuickPopup::aboutToShow, d, &QQuickOverlayPrivate::popupAboutToShow);
             QObjectPrivate::disconnect(popup, &QQuickPopup::aboutToHide, d, &QQuickOverlayPrivate::popupAboutToHide);
         }
@@ -312,75 +323,82 @@ void QQuickOverlay::geometryChanged(const QRectF &newGeometry, const QRectF &old
         d->resizeOverlay(popup);
 }
 
-bool QQuickOverlay::event(QEvent *event)
+void QQuickOverlay::mousePressEvent(QMouseEvent *event)
 {
     Q_D(QQuickOverlay);
-    switch (event->type()) {
-    case QEvent::MouseButtonPress: {
-        emit pressed();
+    emit pressed();
+
+    if (!d->allDrawers.isEmpty()) {
+        // the overlay background was pressed, so there are no modal popups open.
+        // test if the press point lands on any drawer's drag margin
+
+        const QVector<QQuickDrawer *> drawers = d->stackingOrderDrawers();
+        for (QQuickDrawer *drawer : drawers) {
+            QQuickDrawerPrivate *p = QQuickDrawerPrivate::get(drawer);
+            if (p->startDrag(window(), event)) {
+                d->mouseGrabberPopup = drawer;
+                return;
+            }
+        }
+    }
+
+    if (!d->mouseGrabberPopup) {
         const auto popups = d->stackingOrderPopups();
         for (QQuickPopup *popup : popups) {
             if (popup->overlayEvent(this, event)) {
                 d->mouseGrabberPopup = popup;
-                return true;
+                return;
             }
         }
-        break;
     }
-    case QEvent::MouseMove:
-        if (d->mouseGrabberPopup) {
-            if (d->mouseGrabberPopup->overlayEvent(this, event))
-                return true;
-        } else {
-            const auto popups = d->stackingOrderPopups();
-            for (QQuickPopup *popup : popups) {
-                if (popup->overlayEvent(this, event))
-                    return true;
-            }
-        }
-        break;
-    case QEvent::MouseButtonRelease:
-        emit released();
-        if (d->mouseGrabberPopup) {
-            QQuickPopup *grabber = d->mouseGrabberPopup;
-            d->mouseGrabberPopup = nullptr;
-            if (grabber->overlayEvent(this, event))
-                return true;
-        } else {
-            const auto popups = d->stackingOrderPopups();
-            for (QQuickPopup *popup : popups) {
-                if (popup->overlayEvent(this, event))
-                    return true;
-            }
+
+    event->ignore();
+}
+
+void QQuickOverlay::mouseMoveEvent(QMouseEvent *event)
+{
+    Q_D(QQuickOverlay);
+    if (d->mouseGrabberPopup)
+        d->mouseGrabberPopup->overlayEvent(this, event);
+}
+
+void QQuickOverlay::mouseReleaseEvent(QMouseEvent *event)
+{
+    Q_D(QQuickOverlay);
+    emit released();
+
+    if (d->mouseGrabberPopup) {
+        d->mouseGrabberPopup->overlayEvent(this, event);
+        d->mouseGrabberPopup = nullptr;
+    } else {
+        const auto popups = d->stackingOrderPopups();
+        for (QQuickPopup *popup : popups) {
+            if (popup->overlayEvent(this, event))
+                break;
         }
-        break;
-    default:
-        break;
     }
-
-    return QQuickItem::event(event);
 }
 
 bool QQuickOverlay::childMouseEventFilter(QQuickItem *item, QEvent *event)
 {
     Q_D(QQuickOverlay);
-    if (d->modalPopups == 0)
-        return false;
-    // TODO Filter touch events
-    if (event->type() != QEvent::MouseButtonPress)
-        return false;
-    while (item->parentItem() != this)
-        item = item->parentItem();
-
-    const auto popups = d->stackingOrderPopups();
-    for (QQuickPopup *popup : popups) {
-        if (popup->popupItem() == item)
-            break;
-
-        if (popup->overlayEvent(item, event))
-            return true;
+    for (QQuickPopup *popup : qAsConst(d->allPopups)) {
+        QQuickItem *dimmer = QQuickPopupPrivate::get(popup)->dimmer;
+        if (item == dimmer) {
+            switch (event->type()) {
+            case QEvent::MouseButtonPress:
+                emit pressed();
+                return popup->overlayEvent(item, event);
+            case QEvent::MouseMove:
+                return popup->overlayEvent(item, event);
+            case QEvent::MouseButtonRelease:
+                emit released();
+                return popup->overlayEvent(item, event);
+            default:
+                break;
+            }
+        }
     }
-
     return false;
 }