From bb594453f9cb96bf8f2975d4a8aa5379cfc46e23 Mon Sep 17 00:00:00 2001
From: J-P Nurmi <jpnurmi@qt.io>
Date: Sat, 25 Jun 2016 12:16:25 +0200
Subject: Flickable: add horizontal/verticalOvershoot properties

[ChangeLog][QtQuick][Flickable] Added horizontalOvershoot and
verticalOvershoot properties that can be used for implementing
boundary actions and effects.

Task-number: QTBUG-38515
Change-Id: I06379348a67d03507b56788d6fc7020bbb2d375f
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>
---
 src/quick/items/qquickflickable.cpp | 80 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 78 insertions(+), 2 deletions(-)

(limited to 'src/quick/items/qquickflickable.cpp')

diff --git a/src/quick/items/qquickflickable.cpp b/src/quick/items/qquickflickable.cpp
index 00a1306627..4ab604b30f 100644
--- a/src/quick/items/qquickflickable.cpp
+++ b/src/quick/items/qquickflickable.cpp
@@ -1570,12 +1570,52 @@ void QQuickFlickablePrivate::replayDelayedPress()
 //XXX pixelAligned ignores the global position of the Flickable, i.e. assumes Flickable itself is pixel aligned.
 void QQuickFlickablePrivate::setViewportX(qreal x)
 {
-    contentItem->setX(pixelAligned ? -Round(-x) : x);
+    Q_Q(QQuickFlickable);
+    if (pixelAligned)
+        x = -Round(-x);
+
+    contentItem->setX(x);
+    if (contentItem->x() != x)
+        return; // reentered
+
+    const qreal maxX = q->maxXExtent();
+    const qreal minX = q->minXExtent();
+
+    qreal overshoot = 0.0;
+    if (x <= maxX)
+        overshoot = maxX - x;
+    else if (x >= minX)
+        overshoot = minX - x;
+
+    if (overshoot != hData.overshoot) {
+        hData.overshoot = overshoot;
+        emit q->horizontalOvershootChanged();
+    }
 }
 
 void QQuickFlickablePrivate::setViewportY(qreal y)
 {
-    contentItem->setY(pixelAligned ? -Round(-y) : y);
+    Q_Q(QQuickFlickable);
+    if (pixelAligned)
+        y = -Round(-y);
+
+    contentItem->setY(y);
+    if (contentItem->y() != y)
+        return; // reentered
+
+    const qreal maxY = q->maxYExtent();
+    const qreal minY = q->minYExtent();
+
+    qreal overshoot = 0.0;
+    if (y <= maxY)
+        overshoot = maxY - y;
+    else if (y >= minY)
+        overshoot = minY - y;
+
+    if (overshoot != vData.overshoot) {
+        vData.overshoot = overshoot;
+        emit q->verticalOvershootChanged();
+    }
 }
 
 void QQuickFlickable::timerEvent(QTimerEvent *event)
@@ -1841,6 +1881,8 @@ QQmlListProperty<QQuickItem> QQuickFlickable::flickableChildren()
     beyond the boundary of the Flickable, and can overshoot the
     boundary when flicked.
     \endlist
+
+    \sa horizontalOvershoot, verticalOvershoot
 */
 QQuickFlickable::BoundsBehavior QQuickFlickable::boundsBehavior() const
 {
@@ -2638,4 +2680,38 @@ void QQuickFlickablePrivate::updateVelocity()
     emit q->verticalVelocityChanged();
 }
 
+/*!
+    \qmlproperty real QtQuick::Flickable::horizontalOvershoot
+    \since 5.9
+
+    This property holds the horizontal overshoot, that is, the horizontal distance by
+    which the contents has been dragged or flicked past the bounds of the flickable.
+    The value is negative when the content is dragged or flicked beyond the beginning,
+    and positive when beyond the end; \c 0.0 otherwise.
+
+    \sa verticalOvershoot, boundsBehavior
+*/
+qreal QQuickFlickable::horizontalOvershoot() const
+{
+    Q_D(const QQuickFlickable);
+    return d->hData.overshoot;
+}
+
+/*!
+    \qmlproperty real QtQuick::Flickable::verticalOvershoot
+    \since 5.9
+
+    This property holds the vertical overshoot, that is, the vertical distance by
+    which the contents has been dragged or flicked past the bounds of the flickable.
+    The value is negative when the content is dragged or flicked beyond the beginning,
+    and positive when beyond the end; \c 0.0 otherwise.
+
+    \sa horizontalOvershoot, boundsBehavior
+*/
+qreal QQuickFlickable::verticalOvershoot() const
+{
+    Q_D(const QQuickFlickable);
+    return d->vData.overshoot;
+}
+
 QT_END_NAMESPACE
-- 
cgit v1.2.3