Doc: Override DragHandler.accepted* and margin

DragHandler docs have been showing TapHandler code snippets, because
both DragHandler and TapHandler inherit properties from
PointerDeviceHandler, which is abstract and uses TapHandler code
snippets in some of its property documentation.

Override documentation for acceptedDevices, acceptedModifiers,
acceptedPointerTypes and margin by adding to the DragHandler class, and
add testable snippets for a couple of them. draggableGridView is adapted
from examples/quick/draganddrop/views/gridview.qml.

Fixes: QTBUG-119866
Change-Id: I9f98d831ec1691c84da6a38a7625f9aba086cebf
Reviewed-by: Santhosh Kumar <santhosh.kumar.selvaraj@qt.io>
(cherry picked from commit 7ddbb8f972fadc9073d1a8fd651dc08783b92a3a)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 8890effa5f9bd702ff9abd781947ff3eb5a3510f)
(cherry picked from commit 05106ec5794f453d1d5fd7e9b24507c59f3c7bdc)
(cherry picked from commit 39c3655d2d770e6d1daf252efcf5a89e2a98bbac)
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

3 files changed, 329 insertions, 0 deletions

diff --git a/src/quick/doc/snippets/pointerHandlers/dragHandlerMargin.qml b/src/quick/doc/snippets/pointerHandlers/dragHandlerMargin.qml
new file mode 100644
index 0000000000..20a3a802cf
--- /dev/null
+++ b/src/quick/doc/snippets/pointerHandlers/dragHandlerMargin.qml
@@ -0,0 +1,74 @@
+/****************************************************************************
+**
+** Copyright (C) 2024 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
+
+//! [entire]
+Item {
+    width: 320
+    height: 240
+    //![draggable]
+    Rectangle {
+        width: 24
+        height: 24
+        border.color: "steelblue"
+        Text {
+            text: "it's\ntiny"
+            font.pixelSize: 7
+            rotation: -45
+            anchors.centerIn: parent
+        }
+
+        DragHandler {
+            margin: 12
+        }
+    }
+    //![draggable]
+}
+//! [entire]
diff --git a/src/quick/doc/snippets/pointerHandlers/draggableGridView.qml b/src/quick/doc/snippets/pointerHandlers/draggableGridView.qml
new file mode 100644
index 0000000000..0b19274e0d
--- /dev/null
+++ b/src/quick/doc/snippets/pointerHandlers/draggableGridView.qml
@@ -0,0 +1,168 @@
+/****************************************************************************
+**
+** Copyright (C) 2024 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."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+pragma ComponentBehavior: Bound
+import QtQml
+import QtQuick
+import QtQml.Models
+
+//! [entire]
+GridView {
+    id: root
+    width: 320
+    height: 480
+    cellWidth: 80
+    cellHeight: 80
+    interactive: false
+
+    displaced: Transition {
+        NumberAnimation {
+            properties: "x,y"
+            easing.type: Easing.OutQuad
+        }
+    }
+
+    model: DelegateModel {
+        id: visualModel
+        model: 24
+        property var dropTarget: undefined
+        property bool copy: false
+        delegate: DropArea {
+            id: delegateRoot
+
+            width: 80
+            height: 80
+
+            onEntered: drag => {
+                if (visualModel.copy) {
+                    if (drag.source !== icon)
+                        visualModel.dropTarget = icon
+                } else {
+                    visualModel.items.move(drag.source.DelegateModel.itemsIndex, icon.DelegateModel.itemsIndex)
+                }
+            }
+
+            Rectangle {
+                id: icon
+                objectName: DelegateModel.itemsIndex
+
+                property string text
+                Component.onCompleted: {
+                    color = Qt.rgba(0.2 + (48 - DelegateModel.itemsIndex) * Math.random() / 48,
+                                    0.3 + DelegateModel.itemsIndex * Math.random() / 48,
+                                    0.4 * Math.random(),
+                                    1.0)
+                    text = DelegateModel.itemsIndex
+                }
+                border.color: visualModel.dropTarget === this ? "black" : "transparent"
+                border.width: 2
+                radius: 3
+                width: 72
+                height: 72
+                anchors {
+                    horizontalCenter: parent.horizontalCenter
+                    verticalCenter: parent.verticalCenter
+                }
+
+                states: [
+                    State {
+                        when: dragHandler.active || controlDragHandler.active
+                        ParentChange {
+                            target: icon
+                            parent: root
+                        }
+
+                        AnchorChanges {
+                            target: icon
+                            anchors {
+                                horizontalCenter: undefined
+                                verticalCenter: undefined
+                            }
+                        }
+                    }
+                ]
+
+                Text {
+                    anchors.centerIn: parent
+                    color: "white"
+                    font.pointSize: 14
+                    text: controlDragHandler.active ? "+" : icon.text
+                }
+
+                //! [draghandlers]
+                DragHandler {
+                    id: dragHandler
+                    acceptedModifiers: Qt.NoModifier
+                    onActiveChanged: if (!active) visualModel.dropTarget = undefined
+                }
+
+                DragHandler {
+                    id: controlDragHandler
+                    acceptedModifiers: Qt.ControlModifier
+                    onActiveChanged: {
+                        visualModel.copy = active
+                        if (!active) {
+                            visualModel.dropTarget.text = icon.text
+                            visualModel.dropTarget.color = icon.color
+                            visualModel.dropTarget = undefined
+                        }
+                    }
+                }
+                //! [draghandlers]
+
+                Drag.active: dragHandler.active || controlDragHandler.active
+                Drag.source: icon
+                Drag.hotSpot.x: 36
+                Drag.hotSpot.y: 36
+            }
+        }
+    }
+}
+//! [entire]
diff --git a/src/quick/handlers/qquickdraghandler.cpp b/src/quick/handlers/qquickdraghandler.cpp
index 5faded0925..0c99130cb8 100644
--- a/src/quick/handlers/qquickdraghandler.cpp
+++ b/src/quick/handlers/qquickdraghandler.cpp
@@ -394,6 +394,93 @@ void QQuickDragHandler::setActiveTranslation(const QVector2D &trans)
     \c {0, 0} again.
 */
 
+/*!
+    \qmlproperty flags QtQuick::DragHandler::acceptedButtons
+
+    The mouse buttons that can activate this DragHandler.
+
+    By default, this property is set to
+    \l {QtQuick::MouseEvent::button} {Qt.LeftButton}.
+    It can be set to an OR combination of mouse buttons, and will ignore events
+    from other buttons.
+
+    For example, if a component (such as TextEdit) already handles
+    left-button drags in its own way, it can be augmented with a
+    DragHandler that does something different when dragged via the
+    right button:
+
+    \snippet pointerHandlers/dragHandlerAcceptedButtons.qml 0
+*/
+
+/*!
+    \qmlproperty flags DragHandler::acceptedDevices
+
+    The types of pointing devices that can activate this DragHandler.
+
+    By default, this property is set to
+    \l{QInputDevice::DeviceType}{PointerDevice.AllDevices}.
+    If you set it to an OR combination of device types, it will ignore events
+    from non-matching devices.
+
+    \note Not all platforms are yet able to distinguish mouse and touchpad; and
+    on those that do, you often want to make mouse and touchpad behavior the same.
+*/
+
+/*!
+    \qmlproperty flags DragHandler::acceptedModifiers
+
+    If this property is set, it will require the given keyboard modifiers to
+    be pressed in order to react to pointer events, and otherwise ignore them.
+
+    For example, two DragHandlers can perform two different drag-and-drop
+    operations, depending on whether the \c Control modifier is pressed:
+
+    \snippet pointerHandlers/draggableGridView.qml entire
+
+    If this property is set to \c Qt.KeyboardModifierMask (the default value),
+    then the DragHandler ignores the modifier keys.
+
+    If you set \c acceptedModifiers to an OR combination of modifier keys,
+    it means \e all of those modifiers must be pressed to activate the handler.
+
+    The available modifiers are as follows:
+
+    \value NoModifier       No modifier key is allowed.
+    \value ShiftModifier    A Shift key on the keyboard must be pressed.
+    \value ControlModifier  A Ctrl key on the keyboard must be pressed.
+    \value AltModifier      An Alt key on the keyboard must be pressed.
+    \value MetaModifier     A Meta key on the keyboard must be pressed.
+    \value KeypadModifier   A keypad button must be pressed.
+    \value GroupSwitchModifier X11 only (unless activated on Windows by a command line argument).
+                            A Mode_switch key on the keyboard must be pressed.
+    \value KeyboardModifierMask The handler does not care which modifiers are pressed.
+
+    \sa Qt::KeyboardModifier
+*/
+
+/*!
+    \qmlproperty flags DragHandler::acceptedPointerTypes
+
+    The types of pointing instruments (finger, stylus, eraser, etc.)
+    that can activate this DragHandler.
+
+    By default, this property is set to
+    \l {QPointingDevice::PointerType} {PointerDevice.AllPointerTypes}.
+    If you set it to an OR combination of device types, it will ignore events
+    from non-matching \l {PointerDevice}{devices}.
+*/
+
+/*!
+    \qmlproperty real DragHandler::margin
+
+    The margin beyond the bounds of the \l {PointerHandler::parent}{parent}
+    item within which an \l eventPoint can activate this handler. For example,
+    you can make it easier to drag small items by allowing the user to drag
+    from a position nearby:
+
+    \snippet pointerHandlers/dragHandlerMargin.qml draggable
+*/
+
 QT_END_NAMESPACE
 
 #include "moc_qquickdraghandler_p.cpp"