Add a DragHandler::translation property

This allows the application developer to get the translation of the
dragged pointer, and apply it in a custom way.
This should usually be combined with setting target to null.

This will for instance be needed when we want to drag QtLocations map,
where a map is dragged by specifying the geo location of the center of the
map.
The map2.qml example demonstrates this.

Change-Id: I652d9fc92fa9b6dfd3796c7147832f25af0cc5bc
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 10 insertions, 0 deletions

diff --git a/src/quick/handlers/qquickdraghandler.cpp b/src/quick/handlers/qquickdraghandler.cpp
index dc3116e300..945d60119d 100644
--- a/src/quick/handlers/qquickdraghandler.cpp
+++ b/src/quick/handlers/qquickdraghandler.cpp
@@ -88,6 +88,7 @@ void QQuickDragHandler::handleEventPoint(QQuickEventPoint *point)
         if (!m_yAxis.enabled())
             delta.setY(0);
         if (active()) {
+            setTranslation(delta);
             if (target() && target()->parentItem()) {
                 QPointF pos = target()->parentItem()->mapFromScene(m_startPos + delta);
                 enforceAxisConstraints(&pos);
@@ -122,6 +123,15 @@ void QQuickDragHandler::enforceAxisConstraints(QPointF *localPos)
         localPos->setY(qBound(m_yAxis.minimum(), localPos->y(), m_yAxis.maximum()));
 }
 
+void QQuickDragHandler::setTranslation(const QPointF &trans)
+{
+    if (trans == m_translation) // fuzzy compare?
+        return;
+    m_translation = trans;
+    emit translationChanged();
+}
+
+
 QQuickDragAxis::QQuickDragAxis()
   : m_minimum(-DBL_MAX)
   , m_maximum(DBL_MAX)