Make ItemViews displayMargin work correctly when set to negative values

We need to call forceLayoutPolish instead of refillOrLayout
so that the visibility is correctly updated. Also update one
line that sets visibility in GridView

Change-Id: I29fa67cdd5196a744fab9507b4104cb83ad4bf5e
Reviewed-by: Martin Jones <martin.jones@jollamobile.com>

2 files changed, 160 insertions, 0 deletions

diff --git a/tests/auto/quick/qquickgridview/data/negativeDisplayMargin.qml b/tests/auto/quick/qquickgridview/data/negativeDisplayMargin.qml
new file mode 100644
index 0000000000..96063e32cf
--- /dev/null
+++ b/tests/auto/quick/qquickgridview/data/negativeDisplayMargin.qml
@@ -0,0 +1,116 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Canonical Limited and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.3
+
+ListView {
+    id: list
+    width: 400
+    height: 600
+    model: ListModel {
+        ListElement { kind: "Bought" }
+        ListElement { kind: "Available To Buy" }
+    }
+
+    delegate: GridView {
+        id: grid
+        objectName: "grid"
+        height: Math.ceil(count / (width / cellWidth)) * cellHeight / 1
+        width: list.width
+        interactive: false
+        property int count: 50
+        cellHeight: 200
+        cellWidth: cellHeight
+        model: count
+        property int createdItems: 0
+        property int destroyedItems: 0
+
+        delegate: Item {
+            objectName: "delegate"
+            width: cellWidth
+            height: cellHeight
+            Rectangle {
+                width: parent.width - 20
+                height: parent.height - 20
+                anchors.centerIn: parent
+                color: Math.random() * 2 > 1 ? "green" : "yellow";
+                Text {
+                    text: index
+                }
+                Component.onCompleted: createdItems++
+                Component.onDestruction: destroyedItems++
+            }
+        }
+
+        displayMarginBeginning: 0
+        displayMarginEnd: -height
+
+        function updatedDelegateCreationRange() {
+            if (list.contentY + list.height <= grid.y) {
+                // Not visible
+                grid.displayMarginBeginning = 0
+                grid.displayMarginEnd = -grid.height
+            } else if (grid.y + grid.height <= list.contentY) {
+                // Not visible
+                grid.displayMarginBeginning = -grid.height
+                grid.displayMarginEnd = 0
+            } else {
+                grid.displayMarginBeginning = -Math.max(list.contentY - grid.y, 0)
+                grid.displayMarginEnd = -Math.max(grid.height - list.height - list.contentY + grid.y, 0)
+            }
+        }
+
+        Component.onCompleted: updatedDelegateCreationRange();
+        onHeightChanged: updatedDelegateCreationRange();
+        Connections {
+            target: list
+            onContentYChanged: updatedDelegateCreationRange();
+            onHeightChanged: updatedDelegateCreationRange();
+        }
+    }
+
+    section.property: "kind"
+    section.delegate: Text {
+        height: 40
+        font.pixelSize: 30
+        text: section
+    }
+}
diff --git a/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp b/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
index 890174e2a8..863fb69b84 100644
--- a/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
+++ b/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
@@ -210,6 +210,7 @@ private slots:
     void moved_topToBottom_RtL_BtT_data();
 
     void displayMargin();
+    void negativeDisplayMargin();
 
 private:
     QList<int> toIntList(const QVariantList &list);
@@ -6393,6 +6394,49 @@ void tst_QQuickGridView::displayMargin()
     delete window;
 }
 
+void tst_QQuickGridView::negativeDisplayMargin()
+{
+    QQuickItem *item;
+    QQuickView *window = createView();
+    window->setSource(testFileUrl("negativeDisplayMargin.qml"));
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window));
+
+    QQuickItem *listview = window->rootObject();
+    QQuickGridView *gridview = findItem<QQuickGridView>(window->rootObject(), "grid");
+    QVERIFY(gridview != 0);
+
+    QTRY_COMPARE(gridview->property("createdItems").toInt(), 11);
+    QCOMPARE(gridview->property("destroyedItem").toInt(), 0);
+
+    QQuickItem *content = gridview->contentItem();
+    QVERIFY(content != 0);
+
+    QVERIFY(item = findItem<QQuickItem>(content, "delegate", 0));
+    QCOMPARE(delegateVisible(item), true);
+
+    QVERIFY(item = findItem<QQuickItem>(content, "delegate", 7));
+    QCOMPARE(delegateVisible(item), true);
+
+    QVERIFY(item = findItem<QQuickItem>(content, "delegate", 8));
+    QCOMPARE(delegateVisible(item), false);
+
+    // Flick until contentY means that delegate8 should be visible
+    listview->setProperty("contentY", 500);
+    QVERIFY(item = findItem<QQuickItem>(content, "delegate", 8));
+    QTRY_COMPARE(delegateVisible(item), true);
+
+    listview->setProperty("contentY", 1000);
+    QTRY_VERIFY(item = findItem<QQuickItem>(content, "delegate", 14));
+    QTRY_COMPARE(delegateVisible(item), true);
+
+    listview->setProperty("contentY", 0);
+    QVERIFY(item = findItem<QQuickItem>(content, "delegate", 4));
+    QTRY_COMPARE(delegateVisible(item), true);
+
+    delete window;
+}
+
 QTEST_MAIN(tst_QQuickGridView)
 
 #include "tst_qquickgridview.moc"