Doc: add example snippets for containmentMask

This shows how to use non-rectangular shapes for hit tests,
as well as how to define the contains function in QML.

Task-number: QTBUG-89380
Pick-to: 5.15 6.1 6.2
Change-Id: I93c686d840b292816a788c05a0a76fafa338d5f8
Reviewed-by: Venugopal Shivashankar <Venugopal.Shivashankar@qt.io>
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

5 files changed, 171 insertions, 4 deletions

diff --git a/src/quick/doc/images/containmentMask-circle.gif b/src/quick/doc/images/containmentMask-circle.gif
new file mode 100644
index 0000000000..80abce625f
--- /dev/null
+++ b/src/quick/doc/images/containmentMask-circle.gif
diff --git a/src/quick/doc/images/containmentMask-shape.gif b/src/quick/doc/images/containmentMask-shape.gif
new file mode 100644
index 0000000000..e7989352eb
--- /dev/null
+++ b/src/quick/doc/images/containmentMask-shape.gif
diff --git a/src/quick/doc/snippets/qml/item/containmentMask-circle-js.qml b/src/quick/doc/snippets/qml/item/containmentMask-circle-js.qml
new file mode 100644
index 0000000000..2d97bcdafa
--- /dev/null
+++ b/src/quick/doc/snippets/qml/item/containmentMask-circle-js.qml
@@ -0,0 +1,71 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQml 2.12
+import QtQuick 2.12
+
+//![0]
+Rectangle {
+    id: circle
+    width: 100; height: width
+    radius: width / 2
+    color: tapHandler.pressed ? "tomato" : hoverHandler.hovered ? "darkgray" : "lightgray"
+
+    TapHandler { id: tapHandler }
+    HoverHandler { id: hoverHandler }
+
+    containmentMask: QtObject {
+        property alias radius: circle.radius
+        function contains(point: point) : bool {
+            return (Math.pow(point.x - radius, 2) + Math.pow(point.y - radius, 2)) < Math.pow(radius, 2)
+        }
+    }
+}
+//![0]
diff --git a/src/quick/doc/snippets/qml/item/containmentMask-shape.qml b/src/quick/doc/snippets/qml/item/containmentMask-shape.qml
new file mode 100644
index 0000000000..a3da217e73
--- /dev/null
+++ b/src/quick/doc/snippets/qml/item/containmentMask-shape.qml
@@ -0,0 +1,80 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.12
+import QtQuick.Shapes 1.12
+
+//![0]
+Rectangle {
+    width: 90; height: 100
+    color: hoverHandler.hovered ? "wheat" : "lightgray"
+    containmentMask: shape
+
+    HoverHandler { id: hoverHandler }
+
+    Shape {
+        id: shape
+        containsMode: Shape.FillContains
+
+        ShapePath {
+            fillColor: "lightsteelblue"
+            startX: 10; startY: 20
+            PathArc {
+                x: 10; y: 80
+                radiusX: 40; radiusY: 40
+                useLargeArc: true
+            }
+            PathLine {
+                x: 10; y: 20
+            }
+        }
+    }
+}
+//![0]
diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index 253ed09821..cdaf4773f1 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -8118,10 +8118,26 @@ bool QQuickItem::contains(const QPointF &point) const
     \e{item}'s contains method would then return \c true only if
     \e{anotherItem}'s contains() implementation returns \c true.
 
-    A \l Shape can be used in this way, to make an item react to
-    \l {QPointerEvent}{pointer events} only within a non-rectangular region,
-    as illustrated in the \l {Qt Quick Examples - Shapes}{Shapes example}
-    (see \c tapableTriangle.qml).
+    A \l Shape can be used as a mask, to make an item react to
+    \l {QPointerEvent}{pointer events} only within a non-rectangular region:
+
+    \table
+    \row
+    \li \image containmentMask-shape.gif
+    \li \snippet qml/item/containmentMask-shape.qml 0
+    \endtable
+
+    It is also possible to define the contains method in QML. For example,
+    to create a circular item that only responds to events within its
+    actual bounds:
+
+    \table
+    \row
+    \li \image containmentMask-circle.gif
+    \li \snippet qml/item/containmentMask-circle-js.qml 0
+    \endtable
+
+    \sa {Qt Quick Examples - Shapes}
 */
 /*!
     \property QQuickItem::containmentMask