Add imageSource property to attached Drag property

This property holds a URL which is loaded into a QPixmap via
QQuickPixmap, and subsequently set on the QDrag object.

This is especially important for drag and drop to external applications,
where of course a QQuickItem cannot be dragged; however, combined with
QQuickItem::grabToImage(), this change allows setting a QQuickItem's
contents as the drag pixmap.

[ChangeLog][QtQuick][Drag] Added imageSource property to attached Drag
object: this allows drag sources to specify the pixmap to be drawn next
to the mouse cursor when starting a drag and drop operation.

Task-number: QTBUG-37366
Change-Id: Ibcf1d888c525e50976a116ec743ce6fca4c31525
Reviewed-by: Michael Brasser <michael.brasser@live.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/src/quick/doc/snippets/qml/externaldrag.qml b/src/quick/doc/snippets/qml/externaldrag.qml
new file mode 100644
index 0000000000..096a7702b4
--- /dev/null
+++ b/src/quick/doc/snippets/qml/externaldrag.qml
@@ -0,0 +1,76 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+//![0]
+import QtQuick 2.8
+
+Item {
+    width: 200; height: 200
+
+    Rectangle {
+        anchors.centerIn: parent
+        width: text.implicitWidth + 20; height: text.implicitHeight + 10
+        color: "green"
+        radius: 5
+
+        Drag.active: dragArea.drag.active
+        Drag.dragType: Drag.Automatic
+        Drag.supportedActions: Qt.CopyAction
+        Drag.mimeData: {
+            "text/plain": "Copied text"
+        }
+
+        Text {
+            id: text
+            anchors.centerIn: parent
+            text: "Drag me"
+        }
+
+        MouseArea {
+            id: dragArea
+            anchors.fill: parent
+
+            drag.target: parent
+            onPressed: parent.grabToImage(function(result) {
+                parent.Drag.imageSource = result.url
+            })
+        }
+    }
+}
+//![0]