From d16c565ca6a55788435c52ad45647eda67854d80 Mon Sep 17 00:00:00 2001 From: Frederik Gladhorn Date: Tue, 18 Sep 2012 20:32:53 +0200 Subject: Move opengl/wid/net example docs to proper folders. Change-Id: I846439a9cf7ad965ed27a00f98dbc4ff97abe73b Reviewed-by: Jerome Pasion Reviewed-by: Martin Smith --- examples/widgets/doc/src/draggableicons.qdoc | 90 ++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 examples/widgets/doc/src/draggableicons.qdoc (limited to 'examples/widgets/doc/src/draggableicons.qdoc') diff --git a/examples/widgets/doc/src/draggableicons.qdoc b/examples/widgets/doc/src/draggableicons.qdoc new file mode 100644 index 0000000000..627aa673e0 --- /dev/null +++ b/examples/widgets/doc/src/draggableicons.qdoc @@ -0,0 +1,90 @@ +/**************************************************************************** +** +** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). +** Contact: http://www.qt-project.org/ +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:FDL$ +** GNU Free Documentation License +** Alternatively, this file may be used under the terms of the GNU Free +** Documentation License version 1.3 as published by the Free Software +** Foundation and appearing in the file included in the packaging of +** this file. +** +** Other Usage +** Alternatively, this file may be used in accordance with the terms +** and conditions contained in a signed written agreement between you +** and Nokia. +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \example draganddrop/draggableicons + \title Draggable Icons Example + + The Draggable Icons example shows how to drag and drop image data between widgets + in the same application, and between different applications. + + \image draggableicons-example.png + + In many situations where drag and drop is used, the user starts dragging from + a particular widget and drops the payload onto another widget. In this example, + we subclass QLabel to create labels that we use as drag sources, and place them + inside \l{QWidget}s that serve as both containers and drop sites. + + In addition, when a drag and drop operation occurs, we want to send more than + just an image. We also want to send information about where the user clicked in + the image so that the user can place it precisely on the drop target. This level + of detail means that we must create a custom MIME type for our data. + + \section1 DragWidget Class Definition + + The icon widgets that we use to display icons are subclassed from QLabel: + + \snippet draganddrop/draggableicons/dragwidget.h 0 + + Since the QLabel class provides most of what we require for the icon, we + only need to reimplement the \l QWidget::mousePressEvent() to provide + drag and drop facilities. + + \section1 DragWidget Class Implementation + + The \c DragWidget constructor sets an attribute on the widget that ensures + that it will be deleted when it is closed: + + \snippet draganddrop/draggableicons/dragwidget.cpp 0 + + To enable dragging from the icon, we need to act on a mouse press event. + We do this by reimplementing \l QWidget::mousePressEvent() and setting up + a QDrag object. + + \snippet draganddrop/draggableicons/dragwidget.cpp 1 + + Since we will be sending pixmap data for the icon and information about the + user's click in the icon widget, we construct a QByteArray and package up the + details using a QDataStream. + + For interoperability, drag and drop operations describe the data they contain + using MIME types. In Qt, we describe this data using a QMimeData object: + + \snippet draganddrop/draggableicons/dragwidget.cpp 2 + + We choose an unofficial MIME type for this purpose, and supply the QByteArray + to the MIME data object. + + The drag and drop operation itself is handled by a QDrag object: + + \snippet draganddrop/draggableicons/dragwidget.cpp 3 + + Here, we pass the data to the drag object, set a pixmap that will be shown + alongside the cursor during the operation, and define the position of a hot + spot that places the position of this pixmap under the cursor. + +*/ -- cgit v1.2.3