QAbstractItemView: don't block dragging after double click

After d6551fe12520 it was no longer possible to start a drag with a
double click (where the first click selects an item, and the second
press+move starts the drag). Resetting the pressedItem variable to block
the emission of the clicked() signal had this unwanted side effect.

Instead, use an explicit boolean to store that the next release event
will be the result of a double click, so that the clicked() signal is not
emitted again (preventing the double-emission was the purpose of change
d6551fe12520).

Task-number: QTBUG-77771
Fixes: QTBUG-94087
Change-Id: I082c5169d89eb980dcd7985ef3d302b6ff060fb9
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>
Reviewed-by: Olivier BARTHELEMY <perso.olivier.barthelemy@gmail.com>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
(cherry picked from commit 17c1ebf8bfd254ff75cc55e335d1c1fb01da547f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 7 insertions, 3 deletions

diff --git a/src/widgets/itemviews/qabstractitemview.cpp b/src/widgets/itemviews/qabstractitemview.cpp
index bd89f43ca1..8a6c197b5d 100644
--- a/src/widgets/itemviews/qabstractitemview.cpp
+++ b/src/widgets/itemviews/qabstractitemview.cpp
@@ -89,6 +89,7 @@ QAbstractItemViewPrivate::QAbstractItemViewPrivate()
         pressedModifiers(Qt::NoModifier),
         pressedPosition(QPoint(-1, -1)),
         pressedAlreadySelected(false),
+        releaseFromDoubleClick(false),
         viewportEnteredNeeded(false),
         state(QAbstractItemView::NoState),
         stateBeforeAnimation(QAbstractItemView::NoState),
@@ -1913,6 +1914,8 @@ void QAbstractItemView::mouseMoveEvent(QMouseEvent *event)
 void QAbstractItemView::mouseReleaseEvent(QMouseEvent *event)
 {
     Q_D(QAbstractItemView);
+    const bool releaseFromDoubleClick = d->releaseFromDoubleClick;
+    d->releaseFromDoubleClick = false;
 
     QPoint pos = event->position().toPoint();
     QPersistentModelIndex index = indexAt(pos);
@@ -1925,7 +1928,7 @@ void QAbstractItemView::mouseReleaseEvent(QMouseEvent *event)
         return;
     }
 
-    bool click = (index == d->pressedIndex && index.isValid());
+    bool click = (index == d->pressedIndex && index.isValid() && !releaseFromDoubleClick);
     bool selectedClicked = click && (event->button() == Qt::LeftButton) && d->pressedAlreadySelected;
     EditTrigger trigger = (selectedClicked ? SelectedClicked : NoEditTriggers);
     const bool edited = click ? edit(index, trigger, event) : false;
@@ -1980,7 +1983,7 @@ void QAbstractItemView::mouseDoubleClickEvent(QMouseEvent *event)
     if ((event->button() == Qt::LeftButton) && !edit(persistent, DoubleClicked, event)
         && !style()->styleHint(QStyle::SH_ItemView_ActivateItemOnSingleClick, nullptr, this))
         emit activated(persistent);
-    d->pressedIndex = QModelIndex();
+    d->releaseFromDoubleClick = true;
 }
 
 #if QT_CONFIG(draganddrop)
diff --git a/src/widgets/itemviews/qabstractitemview_p.h b/src/widgets/itemviews/qabstractitemview_p.h
index 83012a650d..521d341b8f 100644
--- a/src/widgets/itemviews/qabstractitemview_p.h
+++ b/src/widgets/itemviews/qabstractitemview_p.h
@@ -371,6 +371,7 @@ public:
     Qt::KeyboardModifiers pressedModifiers;
     QPoint pressedPosition;
     bool pressedAlreadySelected;
+    bool releaseFromDoubleClick;
 
     //forces the next mouseMoveEvent to send the viewportEntered signal
     //if the mouse is over the viewport and not over an item
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index 49585d8b26..8d7057deff 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -1992,7 +1992,7 @@ void QTreeView::mouseDoubleClickEvent(QMouseEvent *event)
         if (!style()->styleHint(QStyle::SH_ItemView_ActivateItemOnSingleClick, nullptr, this))
             emit activated(persistent);
 
-        d->pressedIndex = QModelIndex();
+        d->releaseFromDoubleClick = true;
         d->executePostedLayout(); // we need to make sure viewItems is updated
         if (d->itemsExpandable
             && d->expandsOnDoubleClick