Add displayMarginBeginning/End to ListView and GridView.

This allows displaying content outside the visible area of
the view.

[ChangeLog][QtQuick] Add displayMarginBeginning/End to
ListView and GridView.

Change-Id: Idf9b5a0cd34a781c9603a9ad98ea189754972ba1
Reviewed-by: Alan Alpert (Personal) <416365416c@gmail.com>

2 files changed, 124 insertions, 0 deletions

diff --git a/tests/auto/quick/qquickgridview/data/displayMargin.qml b/tests/auto/quick/qquickgridview/data/displayMargin.qml
new file mode 100644
index 0000000000..1086b8defd
--- /dev/null
+++ b/tests/auto/quick/qquickgridview/data/displayMargin.qml
@@ -0,0 +1,85 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Jolla Ltd.
+** 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
+
+Item {
+    width: 400; height: 400
+
+    GridView {
+        id: view
+        anchors.top: header.bottom
+        anchors.bottom: footer.top
+        width: parent.width
+
+        cellWidth: 50
+        cellHeight: 25
+
+        cacheBuffer: 0
+        displayMarginBeginning: 60
+        displayMarginEnd: 60
+
+        model: 200
+        delegate: Rectangle {
+            objectName: "delegate"
+            width: 50
+            height: 25
+            color: index % 2 ? "steelblue" : "lightsteelblue"
+            Text {
+                anchors.centerIn: parent
+                text: index
+            }
+        }
+    }
+
+    Rectangle {
+        id: header
+        width: parent.width; height: 60
+        color: "#80FF0000"
+    }
+
+    Rectangle {
+        id: footer
+        anchors.bottom: parent.bottom
+        width: parent.width; height: 60
+        color: "#80FF0000"
+    }
+}
diff --git a/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp b/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
index f1adb7858f..2ee98c6c61 100644
--- a/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
+++ b/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
@@ -207,6 +207,8 @@ private slots:
     void moved_topToBottom_RtL_BtT();
     void moved_topToBottom_RtL_BtT_data();
 
+    void displayMargin();
+
 private:
     QList<int> toIntList(const QVariantList &list);
     void matchIndexLists(const QVariantList &indexLists, const QList<int> &expectedIndexes);
@@ -6307,6 +6309,43 @@ void tst_QQuickGridView::matchItemLists(const QVariantList &itemLists, const QLi
     }
 }
 
+void tst_QQuickGridView::displayMargin()
+{
+    QQuickView *window = createView();
+    window->setSource(testFileUrl("displayMargin.qml"));
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window));
+
+    QQuickGridView *gridview = window->rootObject()->findChild<QQuickGridView*>();
+    QVERIFY(gridview != 0);
+
+    QQuickItem *content = gridview->contentItem();
+    QVERIFY(content != 0);
+
+    QQuickItem *item0;
+    QQuickItem *item97;
+
+    QVERIFY(item0 = findItem<QQuickItem>(content, "delegate", 0));
+    QCOMPARE(delegateVisible(item0), true);
+
+    // the 97th item should be within the end margin
+    QVERIFY(item97 = findItem<QQuickItem>(content, "delegate", 96));
+    QCOMPARE(delegateVisible(item97), true);
+
+    // GridView staggers item creation, so the 118th item should be outside the end margin.
+    QVERIFY(findItem<QQuickItem>(content, "delegate", 117) == 0);
+
+    // the first delegate should still be within the begin margin
+    gridview->positionViewAtIndex(20, QQuickGridView::Beginning);
+    QCOMPARE(delegateVisible(item0), true);
+
+    // the first delegate should now be outside the begin margin
+    gridview->positionViewAtIndex(36, QQuickGridView::Beginning);
+    QCOMPARE(delegateVisible(item0), false);
+
+    delete window;
+}
+
 QTEST_MAIN(tst_QQuickGridView)
 
 #include "tst_qquickgridview.moc"