Fix potential use of incorrect bounds in delegate tracking.

Using GridView.SnapToRow and GridView.ApplyRange with a top margin
could lead to the view jumping (rather than smoothly transitioning)
when changing the currentIndex.

Change-Id: I6936b378220f59e8d416f7531cf8b6906c723cb2
Task-number: QTBUG-45640
Reviewed-by: Martin Jones <martin.jones@qinetic.com.au>

2 files changed, 45 insertions, 0 deletions

diff --git a/tests/auto/quick/qquickgridview/data/qtbug45640.qml b/tests/auto/quick/qquickgridview/data/qtbug45640.qml
new file mode 100644
index 0000000000..6973773432
--- /dev/null
+++ b/tests/auto/quick/qquickgridview/data/qtbug45640.qml
@@ -0,0 +1,24 @@
+import QtQuick 2.0
+
+GridView {
+    id: gridView
+    width: 400; height: 400
+    cellHeight: 100
+    cellWidth: 100
+    model: 32
+
+    topMargin: 50
+    snapMode: GridView.SnapToRow
+    preferredHighlightBegin: 50
+    preferredHighlightEnd: 50
+    highlightRangeMode: GridView.ApplyRange
+
+    delegate: Rectangle {
+        width: 100
+        height: 100
+        color: index % 2 == 0 ? "#FFFF00" : "#0000FF"
+    }
+
+    highlight: Rectangle { color: "red"; z: 2 }
+    highlightMoveDuration: 1000
+}
diff --git a/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp b/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
index d53ee00b45..b8ad1948ed 100644
--- a/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
+++ b/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
@@ -209,6 +209,8 @@ private slots:
     void contentHeightWithDelayRemove_data();
     void contentHeightWithDelayRemove();
 
+    void QTBUG_45640();
+
 private:
     QList<int> toIntList(const QVariantList &list);
     void matchIndexLists(const QVariantList &indexLists, const QList<int> &expectedIndexes);
@@ -6542,6 +6544,25 @@ void tst_QQuickGridView::contentHeightWithDelayRemove()
     delete window;
 }
 
+void tst_QQuickGridView::QTBUG_45640()
+{
+    QQuickView *window = createView();
+    window->setSource(testFileUrl("qtbug45640.qml"));
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window));
+
+    QQuickGridView *gridview = qobject_cast<QQuickGridView*>(window->rootObject());
+    QVERIFY(gridview != 0);
+
+    QCOMPARE(gridview->contentY(), qreal(-50.0));
+
+    gridview->moveCurrentIndexDown();
+
+    QTRY_VERIFY(gridview->contentY() > qreal(-50.0) && gridview->contentY() < qreal(0.0));
+
+    delete window;
+}
+
 QTEST_MAIN(tst_QQuickGridView)
 
 #include "tst_qquickgridview.moc"