Add and use QQPopupPrivate::handleReleaseWithoutGrab for menus

QQuickDeliveryAgent doesn't allow an item to see a pointer release event
unless the item has already grabbed; that's usually done on press.
But during the drag-press-release gesture, we don't know which menu item
the user will choose until the release. QQuickMenu isn't doing all the
event handling on its own, and thus isn't the grabber: QQuickMenuItem
inherits QQuickAbstractButton, and if that "button" didn't get grabbed,
it's not going to react to the release. So we need a workaround.

Given that the popup window did not see the mouse/touch/tablet press
but just some moves and a release, there will not be a grabber within
the popup window. In that case, on release, call virtual
QQuickPopupPrivate::handleReleaseWithoutGrab(), which is overridden in
QQuickMenuPrivate to programmatically "click" the currently-hovered menu
item. Then propagation continues, to allow the component that opened
the menu to also see the release, and exit from its "pressed" state.

Task-number: QTBUG-68080
Change-Id: I3280ffe722560726003522bb33e5152302cb8cbc
Reviewed-by: Mitch Curtis <[email protected]>
Reviewed-by: Richard Moe Gustavsen <[email protected]>

5 files changed, 47 insertions, 0 deletions

diff --git a/src/quicktemplates/qquickmenu.cpp b/src/quicktemplates/qquickmenu.cpp
index 7f06c9682f..6cf039a710 100644
--- a/src/quicktemplates/qquickmenu.cpp
+++ b/src/quicktemplates/qquickmenu.cpp
@@ -35,6 +35,7 @@
 #include <QtQuick/private/qquickitem_p.h>
 #include <QtQuick/private/qquickitemchangelistener_p.h>
 #include <QtQuick/private/qquickevents_p_p.h>
+#include <QtQuick/private/qquicklistview_p.h>
 #include <QtQuick/private/qquickrendercontrol_p.h>
 #include <QtQuick/private/qquickwindow_p.h>
 
@@ -942,6 +943,33 @@ bool QQuickMenuPrivate::blockInput(QQuickItem *item, const QPointF &point) const
     return (cascade && parentMenu && contains(point)) || QQuickPopupPrivate::blockInput(item, point);
 }
 
+/*! \internal
+    QQuickPopupWindow::event() calls this to handle the release event of a
+    menu drag-press-release gesture, because the \a eventPoint does not have
+    a grabber within the popup window. This override finds and activates the
+    appropriate menu item, as if it had been pressed and released.
+    Returns true on success, to indicate that handling \a eventPoint is done.
+ */
+bool QQuickMenuPrivate::handleReleaseWithoutGrab(const QEventPoint &eventPoint)
+{
+    QQuickMenuItem *menuItem = nullptr;
+    // Usually, hover events have occurred, and currentIndex is set.
+    // If not, use eventPoint.position() for picking.
+    if (currentIndex < 0) {
+        auto *list = qobject_cast<QQuickListView *>(contentItem);
+        if (!list)
+            return false;
+        menuItem = qobject_cast<QQuickMenuItem *>(list->itemAt(eventPoint.position().x(), eventPoint.position().y()));
+    } else {
+        menuItem = qobject_cast<QQuickMenuItem *>(itemAt(currentIndex));
+    }
+    if (Q_LIKELY(menuItem)) {
+        menuItem->animateClick();
+        return true;
+    }
+    return false;
+}
+
 void QQuickMenuPrivate::onItemHovered()
 {
     Q_Q(QQuickMenu);
diff --git a/src/quicktemplates/qquickmenu_p_p.h b/src/quicktemplates/qquickmenu_p_p.h
index 368623e873..e3003b7d55 100644
--- a/src/quicktemplates/qquickmenu_p_p.h
+++ b/src/quicktemplates/qquickmenu_p_p.h
@@ -93,6 +93,7 @@ public:
     bool prepareEnterTransition() override;
     bool prepareExitTransition() override;
     bool blockInput(QQuickItem *item, const QPointF &point) const override;
+    bool handleReleaseWithoutGrab(const QEventPoint &eventPoint) override;
 
     void onItemHovered();
     void onItemTriggered();
diff --git a/src/quicktemplates/qquickpopup_p_p.h b/src/quicktemplates/qquickpopup_p_p.h
index 556f3b6154..1c6d5283f5 100644
--- a/src/quicktemplates/qquickpopup_p_p.h
+++ b/src/quicktemplates/qquickpopup_p_p.h
@@ -85,6 +85,7 @@ public:
     virtual bool handlePress(QQuickItem* item, const QPointF &point, ulong timestamp);
     virtual bool handleMove(QQuickItem* item, const QPointF &point, ulong timestamp);
     virtual bool handleRelease(QQuickItem* item, const QPointF &point, ulong timestamp);
+    virtual bool handleReleaseWithoutGrab(const QEventPoint &) { return false; }
     virtual void handleUngrab();
 
     bool handleMouseEvent(QQuickItem *item, QMouseEvent *event);
diff --git a/src/quicktemplates/qquickpopupwindow.cpp b/src/quicktemplates/qquickpopupwindow.cpp
index c61be40f94..03d7472bf1 100644
--- a/src/quicktemplates/qquickpopupwindow.cpp
+++ b/src/quicktemplates/qquickpopupwindow.cpp
@@ -99,6 +99,22 @@ void QQuickPopupWindow::resizeEvent(QResizeEvent *e)
     d->m_popupItem->setHeight(e->size().height());
 }
 
+bool QQuickPopupWindow::event(QEvent *e)
+{
+    Q_D(QQuickPopupWindow);
+    if (e->isPointerEvent()) {
+        auto *pe = static_cast<QPointerEvent *>(e);
+        const auto &eventPoint = pe->points().first();
+        const auto *grabber = qmlobject_cast<QQuickItem *>(pe->exclusiveGrabber(eventPoint));
+        if (pe->isEndEvent() && (!grabber || grabber->window() != this))
+            QQuickPopupPrivate::get(d->m_popup)->handleReleaseWithoutGrab(eventPoint);
+        // handleReleaseWithoutGrab() returns true if the popup handled eventPoint.
+        // Nevertheless, the component that opened the menu needs to see the release too,
+        // to avoid getting stuck in "pressed" state; so we don't return early.
+    }
+    return QQuickWindowQmlImpl::event(e);
+}
+
 void QQuickPopupWindow::windowChanged(QWindow *window)
 {
     if (window) {
diff --git a/src/quicktemplates/qquickpopupwindow_p_p.h b/src/quicktemplates/qquickpopupwindow_p_p.h
index d4d4adda61..0b9842c059 100644
--- a/src/quicktemplates/qquickpopupwindow_p_p.h
+++ b/src/quicktemplates/qquickpopupwindow_p_p.h
@@ -37,6 +37,7 @@ protected:
     void hideEvent(QHideEvent *e) override;
     void moveEvent(QMoveEvent *e) override;
     void resizeEvent(QResizeEvent *e) override;
+    bool event(QEvent *e) override;
 
 private:
     void windowChanged(QWindow *window);