Teach flickable to handle and replay touch as it does mouse

QQuickWindowPrivate::cloneMouseEvent() renamed to clonePointerEvent()
and generalized to be able to clone any of the kinds of QPointerEvent
that we're interested in replaying. Now it is used only in
QQuickFlickablePrivate::captureDelayedPress().

Reverts f278bb7c66bb00c9f81b7a3aceeb94cb9b3a1b66 and
012a4528a515af8d7ec7dbc05a38d8fd0d6d4d1b (don't skip
tst_TouchMouse::buttonOnDelayedPressFlickable). Some test changes
from f128b5dee8a2a03ebc55ed0cd1e749a6599282c3 also get reverted.

QEventPoint should always have valid velocity now, so
Flickable no longer has to calculate it for itself.
Removing that became necessary to fix the movingAndFlicking test.

Adds logging categories qt.quick.flickable.filter and .replay.

Fixes: QTBUG-85607
Task-number: QTBUG-83437
Task-number: QTBUG-78818
Task-number: QTBUG-61144
Task-number: QTBUG-88038
Task-number: QTBUG-88138
Change-Id: I0ed6802dff5e5d1595adddc389642925f1f2c93d
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 31 insertions, 11 deletions

diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index 547c825502..e71ae85c54 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -4198,13 +4198,28 @@ void QQuickItem::dropEvent(QDropEvent *event)
 #endif // quick_draganddrop
 
 /*!
-    Reimplement this method to filter the mouse events that are received by
+    Reimplement this method to filter the pointer events that are received by
     this item's children.
 
-    This method will only be called if filtersChildMouseEvents() is true.
+    This method will only be called if filtersChildMouseEvents() is \c true.
 
-    Return true if the specified \a event should not be passed onto the
-    specified child \a item, and false otherwise.
+    Return \c true if the specified \a event should not be passed on to the
+    specified child \a item, and \c false otherwise.
+
+    \note Despite the name, this function filters all QPointerEvent instances
+    during delivery to all children (typically mouse, touch, and tablet
+    events). When overriding this function in a subclass, we suggest writing
+    generic event-handling code using only the accessors found in
+    QPointerEvent. Alternatively you can switch on \c event->type() and/or
+    \c event->device()->type() to handle different event types in different ways.
+
+    \note Filtering is just one way to share responsibility in case of gestural
+    ambiguity (for example on press, you don't know whether the user will tap
+    or drag). Another way is to call QPointerEvent::addPassiveGrabber() on
+    press, so as to non-exclusively monitor the progress of the QEventPoint.
+    In either case, the item or pointer handler that is monitoring can steal
+    the exclusive grab later on, when it becomes clear that the gesture fits
+    the pattern that it is expecting.
 
     \sa setFiltersChildMouseEvents()
   */
@@ -7331,8 +7346,13 @@ void QQuickItem::setAcceptedMouseButtons(Qt::MouseButtons buttons)
 }
 
 /*!
-    Returns whether mouse and touch events of this item's children should be filtered
-    through this item.
+    Returns whether pointer events intended for this item's children should be
+    filtered through this item.
+
+    If both this item and a child item have acceptTouchEvents() \c true, then
+    when a touch interaction occurs, this item will filter the touch event.
+    But if either this item or the child cannot handle touch events,
+    childMouseEventFilter() will be called with a synthesized mouse event.
 
     \sa setFiltersChildMouseEvents(), childMouseEventFilter()
   */
@@ -7343,11 +7363,11 @@ bool QQuickItem::filtersChildMouseEvents() const
 }
 
 /*!
-    Sets whether mouse and touch events of this item's children should be filtered
-    through this item.
+    Sets whether pointer events intended for this item's children should be
+    filtered through this item.
 
     If \a filter is true, childMouseEventFilter() will be called when
-    a mouse event is triggered for a child item.
+    a pointer event is triggered for a child item.
 
     \sa filtersChildMouseEvents()
   */
@@ -7400,9 +7420,9 @@ void QQuickItem::setAcceptHoverEvents(bool enabled)
 /*!
     Returns whether touch events are accepted by this item.
 
-    The default value is false.
+    The default value is \c false.
 
-    If this is false, then the item will not receive any touch events through
+    If this is \c false, then the item will not receive any touch events through
     the touchEvent() function.
 
     \since 5.10