QQuickRangeSlider: add touchDragThreshold property

Add touchDragThreshold property for configuring the threshold to initiate a 'drag',
i.e. touch move, of the handle of the slider. The mouse 'drag' won't be affected
by the property.

This property may be also used to configure the drag events stealing priorities
of nested draggable items in the future.

[ChangeLog][RangeSlider] Added touchDragThreshold property for configuring the threshold
to initiate the touch 'drag' of the handle of the slider. The mouse 'drag' won't be
affected by the property.

Task-number: QTBUG-62784
Change-Id: I5555deb827de9d1dc7be00970fba15001105e419
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 36 insertions, 2 deletions

diff --git a/src/quicktemplates2/qquickrangeslider.cpp b/src/quicktemplates2/qquickrangeslider.cpp
index 36d8ca02..a33bddc5 100644
--- a/src/quicktemplates2/qquickrangeslider.cpp
+++ b/src/quicktemplates2/qquickrangeslider.cpp
@@ -358,6 +358,7 @@ public:
           from(defaultFrom),
           to(defaultTo),
           stepSize(0),
+          touchDragThreshold(-1),
           first(nullptr),
           second(nullptr),
           orientation(Qt::Horizontal),
@@ -381,6 +382,7 @@ public:
     qreal from;
     qreal to;
     qreal stepSize;
+    qreal touchDragThreshold;
     QQuickRangeSliderNode *first;
     QQuickRangeSliderNode *second;
     QPointF pressPoint;
@@ -647,6 +649,38 @@ void QQuickRangeSlider::setTo(qreal to)
 }
 
 /*!
+    \since QtQuick.Controls 2.5 (Qt 5.12)
+    \qmlproperty qreal QtQuick.Controls::RangeSlider::touchDragThreshold
+
+    This property holds the threshold (in logical pixels) at which a touch drag event will be initiated.
+    The mouse drag threshold won't be affected.
+    The default value is \c Qt.styleHints.startDragDistance.
+
+    \sa QStyleHints
+
+*/
+qreal QQuickRangeSlider::touchDragThreshold() const
+{
+    Q_D(const QQuickRangeSlider);
+    return d->touchDragThreshold;
+}
+
+void QQuickRangeSlider::setTouchDragThreshold(qreal touchDragThreshold)
+{
+    Q_D(QQuickRangeSlider);
+    if (d->touchDragThreshold == touchDragThreshold)
+        return;
+
+    d->touchDragThreshold = touchDragThreshold;
+    emit touchDragThresholdChanged();
+}
+
+void QQuickRangeSlider::resetTouchDragThreshold()
+{
+    setTouchDragThreshold(-1);
+}
+
+/*!
     \qmlpropertygroup QtQuick.Controls::RangeSlider::first
     \qmlproperty real QtQuick.Controls::RangeSlider::first.value
     \qmlproperty real QtQuick.Controls::RangeSlider::first.position
@@ -1067,9 +1101,9 @@ void QQuickRangeSlider::touchEvent(QTouchEvent *event)
             case Qt::TouchPointMoved:
                 if (!keepTouchGrab()) {
                     if (d->orientation == Qt::Horizontal)
-                        setKeepTouchGrab(QQuickWindowPrivate::dragOverThreshold(point.pos().x() - point.startPos().x(), Qt::XAxis, &point));
+                        setKeepTouchGrab(QQuickWindowPrivate::dragOverThreshold(point.pos().x() - point.startPos().x(), Qt::XAxis, &point, qRound(d->touchDragThreshold)));
                     else
-                        setKeepTouchGrab(QQuickWindowPrivate::dragOverThreshold(point.pos().y() - point.startPos().y(), Qt::YAxis, &point));
+                        setKeepTouchGrab(QQuickWindowPrivate::dragOverThreshold(point.pos().y() - point.startPos().y(), Qt::YAxis, &point, qRound(d->touchDragThreshold)));
                 }
                 if (keepTouchGrab())
                     d->handleMove(point.pos());