Introduce Flickable.OvershootBounds behavior

Related to QTBUG-38515. It is not always desired to allow dragging over
bounds even if flicking overshoots. This makes it possible to implement
collision effects for flicks, while a drag over bounds would still do
nothing.

[ChangeLog][QtQuick][Flickable] Introduced Flickable.OvershootBounds
behavior that allows content overshooting the boundary when flicked,
but does not allow dragging content beyond the boundary of Flickable.

[ChangeLog][QtQuick][Important Behavior Changes]
Flickable.DragAndOvershootBounds value changed from 2 to 3. This will
only affect you if you've worked around enum type checking and have
the integer value explicitly in your code.

Change-Id: I63c3540ab293a9c7c801d81220f74909d3fa1e17
Reviewed-by: Martin Jones <martin.jones@qinetic.com.au>

4 files changed, 17 insertions, 8 deletions

diff --git a/src/quick/items/qquickflickable.cpp b/src/quick/items/qquickflickable.cpp
index f851ef1bac..6273499e54 100644
--- a/src/quick/items/qquickflickable.cpp
+++ b/src/quick/items/qquickflickable.cpp
@@ -319,7 +319,7 @@ bool QQuickFlickablePrivate::flick(AxisData &data, qreal minExtent, qreal maxExt
         maxDistance = qAbs(maxExtent - data.move.value());
         data.flickTarget = maxExtent;
     }
-    if (maxDistance > 0 || boundsBehavior == QQuickFlickable::DragAndOvershootBounds) {
+    if (maxDistance > 0 || boundsBehavior & QQuickFlickable::OvershootBounds) {
         qreal v = velocity;
         if (maxVelocity != -1 && maxVelocity < qAbs(v)) {
             if (v < 0)
@@ -339,7 +339,7 @@ bool QQuickFlickablePrivate::flick(AxisData &data, qreal minExtent, qreal maxExt
         accel = v2 / (2.0f * qAbs(dist));
 
         resetTimeline(data);
-        if (boundsBehavior == QQuickFlickable::DragAndOvershootBounds)
+        if (boundsBehavior & QQuickFlickable::OvershootBounds)
             timeline.accel(data.move, v, accel);
         else
             timeline.accel(data.move, v, accel, maxDistance);
@@ -1011,7 +1011,7 @@ void QQuickFlickablePrivate::handleMouseMoveEvent(QMouseEvent *event)
             // the estimate to be altered
             const qreal minY = vData.dragMinBound + vData.startMargin;
             const qreal maxY = vData.dragMaxBound - vData.endMargin;
-            if (boundsBehavior == QQuickFlickable::StopAtBounds) {
+            if (!(boundsBehavior & QQuickFlickable::DragOverBounds)) {
                 if (fuzzyLessThanOrEqualTo(newY, maxY)) {
                     newY = maxY;
                     rejectY = vData.pressPos == maxY && vData.move.value() == maxY && dy < 0;
@@ -1045,7 +1045,7 @@ void QQuickFlickablePrivate::handleMouseMoveEvent(QMouseEvent *event)
             qreal newX = dx + hData.pressPos - hData.dragStartOffset;
             const qreal minX = hData.dragMinBound + hData.startMargin;
             const qreal maxX = hData.dragMaxBound - hData.endMargin;
-            if (boundsBehavior == QQuickFlickable::StopAtBounds) {
+            if (!(boundsBehavior & QQuickFlickable::DragOverBounds)) {
                 if (fuzzyLessThanOrEqualTo(newX, maxX)) {
                     newX = maxX;
                     rejectX = hData.pressPos == maxX && hData.move.value() == maxX && dx < 0;
@@ -1627,6 +1627,8 @@ QQmlListProperty<QQuickItem> QQuickFlickable::flickableChildren()
     of the flickable, and flicks will not overshoot.
     \li Flickable.DragOverBounds - the contents can be dragged beyond the boundary
     of the Flickable, but flicks will not overshoot.
+    \li Flickable.OvershootBounds - the contents can overshoot the boundary when flicked,
+    but the content cannot be dragged beyond the boundary of the flickable. (since \c{QtQuick 2.5})
     \li Flickable.DragAndOvershootBounds (default) - the contents can be dragged
     beyond the boundary of the Flickable, and can overshoot the
     boundary when flicked.
diff --git a/src/quick/items/qquickflickable_p.h b/src/quick/items/qquickflickable_p.h
index c996d18b01..6b58584751 100644
--- a/src/quick/items/qquickflickable_p.h
+++ b/src/quick/items/qquickflickable_p.h
@@ -94,7 +94,7 @@ class Q_QUICK_PRIVATE_EXPORT QQuickFlickable : public QQuickItem
     Q_CLASSINFO("DefaultProperty", "flickableData")
 
     Q_ENUMS(FlickableDirection)
-    Q_ENUMS(BoundsBehavior)
+    Q_FLAGS(BoundsBehavior)
 
 public:
     QQuickFlickable(QQuickItem *parent=0);
@@ -103,7 +103,14 @@ public:
     QQmlListProperty<QObject> flickableData();
     QQmlListProperty<QQuickItem> flickableChildren();
 
-    enum BoundsBehavior { StopAtBounds, DragOverBounds, DragAndOvershootBounds };
+    enum BoundsBehaviorFlag {
+        StopAtBounds = 0x0,
+        DragOverBounds = 0x1,
+        OvershootBounds = 0x2,
+        DragAndOvershootBounds = DragOverBounds | OvershootBounds
+    };
+    Q_DECLARE_FLAGS(BoundsBehavior, BoundsBehaviorFlag)
+
     BoundsBehavior boundsBehavior() const;
     void setBoundsBehavior(BoundsBehavior);
 
diff --git a/src/quick/items/qquickgridview.cpp b/src/quick/items/qquickgridview.cpp
index e3af926e22..e19d635b00 100644
--- a/src/quick/items/qquickgridview.cpp
+++ b/src/quick/items/qquickgridview.cpp
@@ -1036,7 +1036,7 @@ bool QQuickGridViewPrivate::flick(AxisData &data, qreal minExtent, qreal maxExte
         if (snapMode == QQuickGridView::NoSnap && highlightRange != QQuickGridView::StrictlyEnforceRange)
             data.flickTarget = maxExtent;
     }
-    bool overShoot = boundsBehavior == QQuickFlickable::DragAndOvershootBounds;
+    bool overShoot = boundsBehavior & QQuickFlickable::OvershootBounds;
     if (maxDistance > 0 || overShoot) {
         // This mode requires the grid to stop exactly on a row boundary.
         qreal v = velocity;
diff --git a/src/quick/items/qquicklistview.cpp b/src/quick/items/qquicklistview.cpp
index 8afd5793fc..ba8203124b 100644
--- a/src/quick/items/qquicklistview.cpp
+++ b/src/quick/items/qquicklistview.cpp
@@ -1572,7 +1572,7 @@ bool QQuickListViewPrivate::flick(AxisData &data, qreal minExtent, qreal maxExte
         if (snapMode == QQuickListView::NoSnap && highlightRange != QQuickListView::StrictlyEnforceRange)
             data.flickTarget = maxExtent;
     }
-    bool overShoot = boundsBehavior == QQuickFlickable::DragAndOvershootBounds;
+    bool overShoot = boundsBehavior & QQuickFlickable::OvershootBounds;
     if (maxDistance > 0 || overShoot) {
         // These modes require the list to stop exactly on an item boundary.
         // The initial flick will estimate the boundary to stop on.