Make draganddrop example less confusing

Use required properties, rather than context, use direct binding rather
than Binding elements, clarify that we're using the drag passed as
parameter, not the drag property of DropArea, move Icon to a different
file so that we get a distinct type for it. Give the icon a defined
color while it is being dragged.

Change-Id: I0e8b77abaedb9fc52660dfd4ddef1a4161f1323a
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

3 files changed, 109 insertions, 44 deletions

diff --git a/examples/quick/draganddrop/draganddrop.qrc b/examples/quick/draganddrop/draganddrop.qrc
index 6d064f7722..df9fec51d2 100644
--- a/examples/quick/draganddrop/draganddrop.qrc
+++ b/examples/quick/draganddrop/draganddrop.qrc
@@ -5,5 +5,6 @@
         <file>tiles/DropTile.qml</file>
         <file>tiles/tiles.qml</file>
         <file>views/gridview.qml</file>
+        <file>views/Icon.qml</file>
     </qresource>
 </RCC>
diff --git a/examples/quick/draganddrop/views/Icon.qml b/examples/quick/draganddrop/views/Icon.qml
new file mode 100644
index 0000000000..261d6d146a
--- /dev/null
+++ b/examples/quick/draganddrop/views/Icon.qml
@@ -0,0 +1,96 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples 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 2.14
+
+Rectangle {
+    id: icon
+    required property Item dragParent
+
+    property int visualIndex: 0
+    width: 72
+    height: 72
+    anchors {
+        horizontalCenter: parent.horizontalCenter
+        verticalCenter: parent.verticalCenter
+    }
+    radius: 3
+
+    Text {
+        anchors.centerIn: parent
+        color: "white"
+        text: parent.visualIndex
+    }
+
+    DragHandler {
+        id: dragHandler
+    }
+
+    Drag.active: dragHandler.active
+    Drag.source: icon
+    Drag.hotSpot.x: 36
+    Drag.hotSpot.y: 36
+
+    states: [
+        State {
+            when: dragHandler.active
+            ParentChange {
+                target: icon
+                parent: icon.dragParent
+            }
+
+            AnchorChanges {
+                target: icon
+                anchors.horizontalCenter: undefined
+                anchors.verticalCenter: undefined
+            }
+        }
+    ]
+}
diff --git a/examples/quick/draganddrop/views/gridview.qml b/examples/quick/draganddrop/views/gridview.qml
index 6c5bcef729..05bd48e7fa 100644
--- a/examples/quick/draganddrop/views/gridview.qml
+++ b/examples/quick/draganddrop/views/gridview.qml
@@ -48,8 +48,9 @@
 **
 ****************************************************************************/
 
-import QtQuick 2.12
-import QtQml.Models 2.1
+import QtQml 2.14
+import QtQuick 2.14
+import QtQml.Models 2.14
 
 GridView {
     id: root
@@ -94,54 +95,21 @@ GridView {
 //! [1]
         delegate: DropArea {
             id: delegateRoot
+            required property color color;
 
             width: 80; height: 80
 
-            onEntered: visualModel.items.move(drag.source.visualIndex, icon.visualIndex)
+            onEntered: function(drag) {
+                visualModel.items.move((drag.source as Icon).visualIndex, icon.visualIndex)
+            }
+
             property int visualIndex: DelegateModel.itemsIndex
-            Binding { target: icon; property: "visualIndex"; value: visualIndex }
 
-            Rectangle {
+            Icon {
                 id: icon
-                property int visualIndex: 0
-                width: 72; height: 72
-                anchors {
-                    horizontalCenter: parent.horizontalCenter;
-                    verticalCenter: parent.verticalCenter
-                }
-                radius: 3
-                color: model.color
-
-                Text {
-                    anchors.centerIn: parent
-                    color: "white"
-                    text: parent.visualIndex
-                }
-
-                DragHandler {
-                    id: dragHandler
-                }
-
-                Drag.active: dragHandler.active
-                Drag.source: icon
-                Drag.hotSpot.x: 36
-                Drag.hotSpot.y: 36
-
-                states: [
-                    State {
-                        when: icon.Drag.active
-                        ParentChange {
-                            target: icon
-                            parent: root
-                        }
-
-                        AnchorChanges {
-                            target: icon
-                            anchors.horizontalCenter: undefined
-                            anchors.verticalCenter: undefined
-                        }
-                    }
-                ]
+                dragParent: root
+                visualIndex: delegateRoot.visualIndex
+                color: delegateRoot.color
             }
         }
 //! [1]