Expose drag threshold in MouseArea

In several cases such as for creating a Slider, it is useful to  have a
0 pixel threshold in order to initiate a drag operation. We have
previously hardcoded this to a platform dependent (usually 10 pixel)
value for MouseArea.

Note that we have no way of indicating the version/revision number
in a grouped property for documentation at the moment.

In addition we deliberately had to remove the REVISION from the
property because it is blocked by QTBUG-33179. However, since
this is not a user-creatable type it should not cause any
issues in practice.

This patch adds MouseArea.drag.threshold in order to improve on this.

Change-Id: Ia4871e64fab39e30c4494f00be99ad38cdd630df
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/quick/items/qquickdrag_p.h b/src/quick/items/qquickdrag_p.h
index 098fcc61b9..22829350fe 100644
--- a/src/quick/items/qquickdrag_p.h
+++ b/src/quick/items/qquickdrag_p.h
@@ -157,6 +157,9 @@ class Q_AUTOTEST_EXPORT QQuickDrag : public QObject
     Q_PROPERTY(qreal maximumY READ ymax WRITE setYmax NOTIFY maximumYChanged)
     Q_PROPERTY(bool active READ active NOTIFY activeChanged)
     Q_PROPERTY(bool filterChildren READ filterChildren WRITE setFilterChildren NOTIFY filterChildrenChanged)
+    // Note, threshold was added in QtQuick 2.2 but REVISION is not supported (or needed) for grouped
+    // properties See QTBUG-33179
+    Q_PROPERTY(qreal threshold READ threshold WRITE setThreshold NOTIFY thresholdChanged RESET resetThreshold)
     //### consider drag and drop
 
 public:
@@ -182,6 +185,10 @@ public:
     qreal ymax() const;
     void setYmax(qreal);
 
+    qreal threshold() const;
+    void setThreshold(qreal);
+    void resetThreshold();
+
     bool active() const;
     void setActive(bool);
 
@@ -199,6 +206,7 @@ Q_SIGNALS:
     void maximumYChanged();
     void activeChanged();
     void filterChildrenChanged();
+    void thresholdChanged();
 
 private:
     QQuickItem *_target;
@@ -209,6 +217,7 @@ private:
     qreal _ymax;
     bool _active : 1;
     bool _filterChildren: 1;
+    qreal _threshold;
     Q_DISABLE_COPY(QQuickDrag)
 };