Make DragHandler a MultiPointHandler

That is, minimumPointCount can now be set to a value > 1 to require
multiple fingers to do the dragging, or to track the displacement
of multiple fingers to adjust some value (such as the tilt of a map).

Task-number: QTBUG-68106
Change-Id: Ib35823e36deb81c8b277d3070fcc758c7c019564
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index f921e3962b..22425a96a6 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -2511,6 +2511,12 @@ bool QQuickWindowPrivate::deliverPressOrReleaseEvent(QQuickPointerEvent *event,
     int pointCount = event->pointCount();
     QVector<QQuickItem *> targetItems;
     bool isTouchEvent = (event->asPointerTouchEvent() != nullptr);
+    if (isTouchEvent && event->isPressEvent()) {
+        // When a second point is pressed, we're starting over with delivery, so
+        // don't let prior conception of which one is acting as a mouse interfere
+        touchMouseId = -1;
+        touchMouseDevice = nullptr;
+    }
     for (int i = 0; i < pointCount; ++i) {
         auto point = event->point(i);
         point->setAccepted(false); // because otherwise touchEventForItem will ignore it
@@ -2977,6 +2983,12 @@ bool QQuickWindowPrivate::dragOverThreshold(qreal d, Qt::Axis axis, QMouseEvent
     return overThreshold;
 }
 
+bool QQuickWindowPrivate::dragOverThreshold(QVector2D delta)
+{
+    int threshold = qApp->styleHints()->startDragDistance();
+    return qAbs(delta.x()) > threshold || qAbs(delta.y()) > threshold;
+}
+
 /*!
     \qmlproperty list<Object> Window::data
     \default