Improve interaction between snapping and sections

* Use velocity to prefer snapping in the active direction.
* Calculate snap based on where the item is, rather than where
  the section is.

Change-Id: I2531501dbe0a58f26f20bc3e719e435185e047a5
Task-number: QTBUG-67051
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

2 files changed, 107 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicklistview/data/sectionSnapping.qml b/tests/auto/quick/qquicklistview/data/sectionSnapping.qml
new file mode 100644
index 0000000000..2583cc0377
--- /dev/null
+++ b/tests/auto/quick/qquicklistview/data/sectionSnapping.qml
@@ -0,0 +1,49 @@
+import QtQuick 2.0
+
+ListView {
+    width: 400
+    height: 400
+    preferredHighlightBegin: 100
+    preferredHighlightEnd: 100
+    highlightRangeMode: ListView.StrictlyEnforceRange
+
+    model: ListModel {
+        ListElement { section: "1" }
+        ListElement { section: "1" }
+        ListElement { section: "1" }
+        ListElement { section: "2" }
+        ListElement { section: "2" }
+        ListElement { section: "2" }
+    }
+
+    delegate: Rectangle {
+        width: parent.width
+        height: 50
+        color: index % 2 ? "lightsteelblue" : "steelblue"
+        Text {
+            anchors.centerIn: parent
+            color: "white"
+            text: model.index
+        }
+    }
+
+    section.property: "section"
+    section.delegate: Rectangle {
+        width: parent.width
+        height: 50
+        color: "green"
+        Text {
+            anchors.centerIn: parent
+            color: "white"
+            text: "section"
+        }
+    }
+
+    highlight: Rectangle {
+        y: 100
+        z: 100
+        width: parent.width
+        height: 50
+        color: "#80FF0000"
+    }
+}
diff --git a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
index 2574eb9c6c..ae02352293 100644
--- a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
+++ b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
@@ -132,6 +132,8 @@ private slots:
     void sectionPropertyChange();
     void sectionDelegateChange();
     void sectionsItemInsertion();
+    void sectionsSnap_data();
+    void sectionsSnap();
     void cacheBuffer();
     void positionViewAtBeginningEnd();
     void positionViewAtIndex();
@@ -2667,6 +2669,62 @@ void tst_QQuickListView::sectionsItemInsertion()
     }
 }
 
+void tst_QQuickListView::sectionsSnap_data()
+{
+    QTest::addColumn<QQuickListView::SnapMode>("snapMode");
+    QTest::addColumn<QPoint>("point");
+    QTest::addColumn<int>("duration");
+
+    QTest::newRow("drag") << QQuickListView::NoSnap << QPoint(100, 45) << 500;
+    QTest::newRow("flick") << QQuickListView::SnapOneItem << QPoint(100, 75) << 50;
+}
+
+void tst_QQuickListView::sectionsSnap()
+{
+    QFETCH(QQuickListView::SnapMode, snapMode);
+    QFETCH(QPoint, point);
+    QFETCH(int, duration);
+
+    QScopedPointer<QQuickView> window(createView());
+    window->setSource(testFileUrl("sectionSnapping.qml"));
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window.data()));
+
+    QQuickListView *listview = qobject_cast<QQuickListView*>(window->rootObject());
+    QTRY_VERIFY(listview != nullptr);
+    listview->setSnapMode(snapMode);
+
+    QTRY_COMPARE(QQuickItemPrivate::get(listview)->polishScheduled, false);
+    QTRY_COMPARE(listview->currentIndex(), 0);
+    QCOMPARE(listview->contentY(), qreal(-50));
+
+    // move down
+    flick(window.data(), QPoint(100, 100), point, duration);
+    QTRY_VERIFY(!listview->isMovingVertically());
+    QCOMPARE(listview->contentY(), qreal(0));
+
+    flick(window.data(), QPoint(100, 100), point, duration);
+    QTRY_VERIFY(!listview->isMovingVertically());
+    QCOMPARE(listview->contentY(), qreal(50));
+
+    flick(window.data(), QPoint(100, 100), point, duration);
+    QTRY_VERIFY(!listview->isMovingVertically());
+    QCOMPARE(listview->contentY(), qreal(150));
+
+    // move back up
+    flick(window.data(), point, QPoint(100, 100), duration);
+    QTRY_VERIFY(!listview->isMovingVertically());
+    QCOMPARE(listview->contentY(), qreal(50));
+
+    flick(window.data(), point, QPoint(100, 100), duration);
+    QTRY_VERIFY(!listview->isMovingVertically());
+    QCOMPARE(listview->contentY(), qreal(0));
+
+    flick(window.data(), point, QPoint(100, 100), duration);
+    QTRY_VERIFY(!listview->isMovingVertically());
+    QCOMPARE(listview->contentY(), qreal(-50));
+}
+
 void tst_QQuickListView::currentIndex_delayedItemCreation()
 {
     QFETCH(bool, setCurrentToZero);