SwipeDelegate: reposition contentItem, background on width changes

Change-Id: I6af4f1a4517e79f2e34b0bbca401b0eefd0c6ff4
Task-number: QTBUG-54660
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

3 files changed, 61 insertions, 7 deletions

diff --git a/src/quicktemplates2/qquickswipedelegate.cpp b/src/quicktemplates2/qquickswipedelegate.cpp
index aedaf29a..dbf4fc95 100644
--- a/src/quicktemplates2/qquickswipedelegate.cpp
+++ b/src/quicktemplates2/qquickswipedelegate.cpp
@@ -92,6 +92,13 @@ QT_BEGIN_NAMESPACE
     \sa {Customizing SwipeDelegate}, {Delegate Controls}
 */
 
+namespace {
+    enum PositionAnimation {
+        DontAnimatePosition,
+        AnimatePosition
+    };
+}
+
 class QQuickSwipePrivate : public QObjectPrivate
 {
     Q_DECLARE_PUBLIC(QQuickSwipe)
@@ -117,6 +124,7 @@ public:
     QQuickItem *createDelegateItem(QQmlComponent *component);
     QQuickItem *showRelevantItemForPosition(qreal position);
     QQuickItem *createRelevantItemForDistance(qreal distance);
+    void reposition(PositionAnimation animationPolicy);
     void createLeftItem();
     void createBehindItem();
     void createRightItem();
@@ -234,6 +242,27 @@ QQuickItem *QQuickSwipePrivate::createRelevantItemForDistance(qreal distance)
     return nullptr;
 }
 
+void QQuickSwipePrivate::reposition(PositionAnimation animationPolicy)
+{
+    QQuickItem *relevantItem = showRelevantItemForPosition(position);
+    const qreal relevantWidth = relevantItem ? relevantItem->width() : 0.0;
+    const qreal contentItemX = position * relevantWidth + control->leftPadding();
+
+    // "Behavior on x" relies on the property system to know when it should update,
+    // so we can prevent it from animating by setting the x position directly.
+    if (animationPolicy == AnimatePosition) {
+        if (QQuickItem *contentItem = control->contentItem())
+            contentItem->setProperty("x", contentItemX);
+        if (QQuickItem *background = control->background())
+            background->setProperty("x", position * relevantWidth);
+    } else {
+        if (QQuickItem *contentItem = control->contentItem())
+            contentItem->setX(contentItemX);
+        if (QQuickItem *background = control->background())
+            background->setX(position * relevantWidth);
+    }
+}
+
 void QQuickSwipePrivate::createLeftItem()
 {
     if (!leftItem) {
@@ -496,13 +525,7 @@ void QQuickSwipe::setPosition(qreal position)
         return;
 
     d->position = adjustedPosition;
-
-    QQuickItem *relevantItem = d->showRelevantItemForPosition(d->position);
-    const qreal relevantWidth = relevantItem ? relevantItem->width() : 0.0;
-    d->control->contentItem()->setProperty("x", d->position * relevantWidth + d->control->leftPadding());
-    if (QQuickItem *background = d->control->background())
-        background->setProperty("x", d->position * relevantWidth);
-
+    d->reposition(AnimatePosition);
     emit positionChanged();
 }
 
@@ -845,6 +868,17 @@ void QQuickSwipeDelegate::mouseReleaseEvent(QMouseEvent *event)
     d->handleMouseReleaseEvent(this, event);
 }
 
+void QQuickSwipeDelegate::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
+{
+    Q_D(QQuickSwipeDelegate);
+    QQuickControl::geometryChanged(newGeometry, oldGeometry);
+
+    if (!qFuzzyCompare(newGeometry.width(), oldGeometry.width())) {
+        QQuickSwipePrivate *swipePrivate = QQuickSwipePrivate::get(&d->swipe);
+        swipePrivate->reposition(DontAnimatePosition);
+    }
+}
+
 QFont QQuickSwipeDelegate::defaultFont() const
 {
     return QQuickControlPrivate::themeFont(QPlatformTheme::ListViewFont);
diff --git a/src/quicktemplates2/qquickswipedelegate_p.h b/src/quicktemplates2/qquickswipedelegate_p.h
index b2bea3eb..e71455b0 100644
--- a/src/quicktemplates2/qquickswipedelegate_p.h
+++ b/src/quicktemplates2/qquickswipedelegate_p.h
@@ -71,6 +71,8 @@ protected:
     void mouseMoveEvent(QMouseEvent *event) override;
     void mouseReleaseEvent(QMouseEvent *event) override;
 
+    void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry) override;
+
     QFont defaultFont() const override;
 
 #ifndef QT_NO_ACCESSIBILITY
diff --git a/tests/auto/controls/data/tst_swipedelegate.qml b/tests/auto/controls/data/tst_swipedelegate.qml
index f89893c3..42ea3542 100644
--- a/tests/auto/controls/data/tst_swipedelegate.qml
+++ b/tests/auto/controls/data/tst_swipedelegate.qml
@@ -910,4 +910,22 @@ TestCase {
 
         control.destroy();
     }
+
+    // When the width of a SwipeDelegate changes (as it does upon portrait => landscape
+    // rotation, for example), the positions of the contentItem and background items
+    // should be updated accordingly.
+    function test_contentItemPosOnWidthChanged() {
+        var control = swipeDelegateComponent.createObject(testCase);
+        verify(control);
+
+        swipe(control, 0.0, 1.0);
+
+        var oldContentItemX = control.contentItem.x;
+        var oldBackgroundX = control.background.x;
+        control.width += 100;
+        compare(control.contentItem.x, oldContentItemX + 100);
+        compare(control.background.x, oldBackgroundX + 100);
+
+        control.destroy();
+    }
 }