Determine QQuickItem::childAt() correctly

[ChangeLog][QtQuick][QQuickItem] Fix to wrong calculation of child at a
given point. Previously coordinates of width+1 and height+1 were counted
as a child. That caused a child Rect of (0, 0, 100, 100) to be reported
as a child at (100, 100), which is wrong (correct max coordinate is (99, 99).)

Task-number: QTBUG-41833
Change-Id: I6124a275a5dc1a38eab448235102d563e2a8b0ca
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

3 files changed, 114 insertions, 2 deletions

diff --git a/tests/auto/quick/qquickitem/data/childAtRectangle.qml b/tests/auto/quick/qquickitem/data/childAtRectangle.qml
new file mode 100644
index 0000000000..d459c2b3f1
--- /dev/null
+++ b/tests/auto/quick/qquickitem/data/childAtRectangle.qml
@@ -0,0 +1,70 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** 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 The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/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 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.0
+
+Item {
+    width: 20
+    height: 20
+
+    Rectangle {
+        id: rect1
+
+        color: "red"
+        x: 0
+        y: 0
+        width: 16
+        height: 16
+    }
+
+    Rectangle {
+        id: rect2
+
+        color: "red"
+        x: 18
+        y: 0
+        width: 1
+        height: 1
+    }
+
+    Rectangle {
+        id: rect3
+
+        x: 19
+        y: 19
+        width: 0
+        height: 0
+    }
+
+}
+
diff --git a/tests/auto/quick/qquickitem/tst_qquickitem.cpp b/tests/auto/quick/qquickitem/tst_qquickitem.cpp
index 143f8f2b1c..4b2c86697e 100644
--- a/tests/auto/quick/qquickitem/tst_qquickitem.cpp
+++ b/tests/auto/quick/qquickitem/tst_qquickitem.cpp
@@ -167,6 +167,8 @@ private slots:
     void contains_data();
     void contains();
 
+    void childAt();
+
 private:
 
     enum PaintOrderOp {
@@ -1966,6 +1968,46 @@ void tst_qquickitem::contains()
     QCOMPARE(result.toBool(), contains);
 }
 
+void tst_qquickitem::childAt()
+{
+    QQuickView view;
+    view.setSource(testFileUrl("childAtRectangle.qml"));
+    QQuickItem *root = qobject_cast<QQuickItem*>(view.rootObject());
+
+    int found = 0;
+    for (int i = 0; i < 16; i++)
+    {
+        if (root->childAt(i, 0))
+            found++;
+    }
+    QCOMPARE(found, 16);
+
+    found = 0;
+    for (int i = 0; i < 16; i++)
+    {
+        if (root->childAt(0, i))
+            found++;
+    }
+    QCOMPARE(found, 16);
+
+    found = 0;
+    for (int i = 0; i < 2; i++)
+    {
+        if (root->childAt(18 + i, 0))
+            found++;
+    }
+    QCOMPARE(found, 1);
+
+    found = 0;
+    for (int i = 0; i < 16; i++)
+    {
+        if (root->childAt(18, i))
+            found++;
+    }
+    QCOMPARE(found, 1);
+
+    QVERIFY(!root->childAt(19,19));
+}
 
 QTEST_MAIN(tst_qquickitem)
 
diff --git a/tests/auto/quick/qquickitem2/tst_qquickitem.cpp b/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
index b4131a2df8..62ff09e698 100644
--- a/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
+++ b/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
@@ -2995,12 +2995,12 @@ void tst_QQuickItem::childAt()
     child3.setParentItem(&parent);
 
     QCOMPARE(parent.childAt(0, 0), &child1);
-    QCOMPARE(parent.childAt(0, 100), &child1);
+    QCOMPARE(parent.childAt(0, 99), &child1);
     QCOMPARE(parent.childAt(25, 25), &child1);
     QCOMPARE(parent.childAt(25, 75), &child1);
     QCOMPARE(parent.childAt(75, 25), &child1);
     QCOMPARE(parent.childAt(75, 75), &child2);
-    QCOMPARE(parent.childAt(150, 150), &child2);
+    QCOMPARE(parent.childAt(149, 149), &child2);
     QCOMPARE(parent.childAt(25, 200), &child3);
     QCOMPARE(parent.childAt(0, 150), static_cast<QQuickItem *>(0));
     QCOMPARE(parent.childAt(300, 300), static_cast<QQuickItem *>(0));