SelectionRectangle: ensure we remove or update selection handles if selection changes

If you make a selection with SelectionRectangle and then resize a
row, the selection handles will not move to the resized position.
Likewise, if you do a selection, but then clear the selection
by interacting with the ItemSelectionModel directly, the
selection handles will not be updated to reflect the changes.

To fix this bug, this patch will add a callback from TableView to
SelectionRectangle that can be used to notify when changes are
done outside of SelectionRectangle. This especially allows us to:

- Remove the selection handles if the active selection is cleared
  or changed programatically (or anyway not by SelectionRectangle).
- Keep the selection handles, and update their position, when rows
  or columns are merely resized.

This change also allows us to clean up qquickselectionrectangle.cpp
a bit, and remove e.g a now superfluous tap handler listener.

Task-number: QTBUG-121143
Pick-to: 6.7 6.6 6.5
Change-Id: Id170520d49bc92c0bb9d16deaba741cab6f5c553
Reviewed-by: Santhosh Kumar <santhosh.kumar.selvaraj@qt.io>

3 files changed, 41 insertions, 8 deletions

diff --git a/src/quick/items/qquickselectable_p.h b/src/quick/items/qquickselectable_p.h
index 16e1379e23..475660ab2d 100644
--- a/src/quick/items/qquickselectable_p.h
+++ b/src/quick/items/qquickselectable_p.h
@@ -23,6 +23,11 @@ QT_BEGIN_NAMESPACE
 class Q_QUICK_EXPORT QQuickSelectable
 {
 public:
+    enum class CallBackFlag {
+        CancelSelection,
+        SelectionRectangleChanged
+    };
+
     virtual QQuickItem *selectionPointerHandlerTarget() const = 0;
 
     virtual bool startSelection(const QPointF &pos) = 0;
@@ -33,6 +38,8 @@ public:
 
     virtual QRectF selectionRectangle() const = 0;
     virtual QSizeF scrollTowardsSelectionPoint(const QPointF &pos, const QSizeF &step) = 0;
+
+    virtual void setCallback(std::function<void(CallBackFlag)> func) = 0;
 };
 
 QT_END_NAMESPACE
diff --git a/src/quick/items/qquicktableview.cpp b/src/quick/items/qquicktableview.cpp
index 13b6de40fc..4d971525d4 100644
--- a/src/quick/items/qquicktableview.cpp
+++ b/src/quick/items/qquicktableview.cpp
@@ -1743,6 +1743,7 @@ void QQuickTableViewPrivate::setSelectionStartPos(const QPointF &pos)
         return;
 
     // Update selection model
+    QScopedValueRollback callbackGuard(inSelectionModelUpdate, true);
     updateSelection(prevSelection, selection());
 }
 
@@ -1791,6 +1792,7 @@ void QQuickTableViewPrivate::setSelectionEndPos(const QPointF &pos)
         return;
 
     // Update selection model
+    QScopedValueRollback callbackGuard(inSelectionModelUpdate, true);
     updateSelection(prevSelection, selection());
 }
 
@@ -1859,14 +1861,22 @@ void QQuickTableViewPrivate::updateSelection(const QRect &oldSelection, const QR
     selectionModel->select(select, QItemSelectionModel::Select);
 }
 
-void QQuickTableViewPrivate::clearSelection()
+void QQuickTableViewPrivate::cancelSelectionTracking()
 {
+    // Cancel any ongoing key/mouse aided selection tracking
     selectionStartCell = QPoint(-1, -1);
     selectionEndCell = QPoint(-1, -1);
     existingSelection.clear();
+    if (selectableCallbackFunction)
+        selectableCallbackFunction(QQuickSelectable::CallBackFlag::CancelSelection);
+}
 
-    if (selectionModel)
-        selectionModel->clearSelection();
+void QQuickTableViewPrivate::clearSelection()
+{
+    if (!selectionModel)
+        return;
+    QScopedValueRollback callbackGuard(inSelectionModelUpdate, true);
+    selectionModel->clearSelection();
 }
 
 void QQuickTableViewPrivate::normalizeSelection()
@@ -2004,6 +2014,11 @@ QSizeF QQuickTableViewPrivate::scrollTowardsSelectionPoint(const QPointF &pos, c
     return dist;
 }
 
+void QQuickTableViewPrivate::setCallback(std::function<void (CallBackFlag)> func)
+{
+    selectableCallbackFunction = func;
+}
+
 QQuickTableViewAttached *QQuickTableViewPrivate::getAttachedObject(const QObject *object) const
 {
     QObject *attachedObject = qmlAttachedPropertiesObject<QQuickTableView>(object);
@@ -4099,10 +4114,11 @@ bool QQuickTableViewPrivate::currentInSelectionModel(const QPoint &cell) const
 
 void QQuickTableViewPrivate::selectionChangedInSelectionModel(const QItemSelection &selected, const QItemSelection &deselected)
 {
-    if (!selectionModel->hasSelection()) {
-        // Ensure that we cancel any ongoing key/mouse-based selections
-        // if selectionModel.clearSelection() is called.
-        clearSelection();
+    if (!inSelectionModelUpdate) {
+        // The selection model was manipulated outside of TableView
+        // and SelectionRectangle. In that case we cancel any ongoing
+        // selection tracking.
+        cancelSelectionTracking();
     }
 
     const auto &selectedIndexes = selected.indexes();
@@ -4934,8 +4950,10 @@ void QQuickTableViewPrivate::handleTap(const QQuickHandlerPoint &point)
     // the current selection and move the current index instead.
     if (pointerNavigationEnabled) {
         q->closeEditor();
-        if (selectionBehavior != QQuickTableView::SelectionDisabled)
+        if (selectionBehavior != QQuickTableView::SelectionDisabled) {
             clearSelection();
+            cancelSelectionTracking();
+        }
         setCurrentIndexFromTap(point.position());
     }
 }
@@ -5074,6 +5092,8 @@ bool QQuickTableViewPrivate::setCurrentIndexFromKeyEvent(QKeyEvent *e)
             if (loadedItems.contains(serializedStartIndex)) {
                 const QRectF startGeometry = loadedItems.value(serializedStartIndex)->geometry();
                 setSelectionStartPos(startGeometry.center());
+                if (selectableCallbackFunction)
+                    selectableCallbackFunction(QQuickSelectable::CallBackFlag::SelectionRectangleChanged);
             }
         }
     };
@@ -5086,6 +5106,8 @@ bool QQuickTableViewPrivate::setCurrentIndexFromKeyEvent(QKeyEvent *e)
             if (loadedItems.contains(serializedEndIndex)) {
                 const QRectF endGeometry = loadedItems.value(serializedEndIndex)->geometry();
                 setSelectionEndPos(endGeometry.center());
+                if (selectableCallbackFunction)
+                    selectableCallbackFunction(QQuickSelectable::CallBackFlag::SelectionRectangleChanged);
             }
         }
         selectionModel->setCurrentIndex(q->modelIndex(cell), QItemSelectionModel::NoUpdate);
diff --git a/src/quick/items/qquicktableview_p_p.h b/src/quick/items/qquicktableview_p_p.h
index 0bfc2a9c0a..1f0c8549a5 100644
--- a/src/quick/items/qquicktableview_p_p.h
+++ b/src/quick/items/qquicktableview_p_p.h
@@ -360,6 +360,8 @@ public:
     QPointer<QItemSelectionModel> selectionModel;
     QQuickTableView::SelectionBehavior selectionBehavior = QQuickTableView::SelectCells;
     QQuickTableView::SelectionMode selectionMode = QQuickTableView::ExtendedSelection;
+    std::function<void(CallBackFlag)> selectableCallbackFunction;
+    bool inSelectionModelUpdate = false;
 
     int assignedPositionViewAtRowAfterRebuild = 0;
     int assignedPositionViewAtColumnAfterRebuild = 0;
@@ -587,6 +589,8 @@ public:
     void normalizeSelection() override;
     QRectF selectionRectangle() const override;
     QSizeF scrollTowardsSelectionPoint(const QPointF &pos, const QSizeF &step) override;
+    void setCallback(std::function<void(CallBackFlag)> func) override;
+    void cancelSelectionTracking();
 
     QPoint clampedCellAtPos(const QPointF &pos) const;
     virtual void updateSelection(const QRect &oldSelection, const QRect &newSelection);