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authorLars Knoll <lars.knoll@nokia.com>2011-05-18 12:56:51 +0200
committerLars Knoll <lars.knoll@nokia.com>2011-05-20 12:21:02 +0200
commit82bba7e4efc369f75f09eb96846d733cd99ba95b (patch)
tree210f73a2df63e626f471452ed3fce5578ed17ae1 /src/gui/kernel/qdrag.cpp
parent1f572c694b6801e9f706ce2c67cc3b1b50f32a5e (diff)
move drag handling back to Gui
Move the DnD related classes back into QtGui. Parts of the implementation is currently commented out and needs to be moved to QWidgetWindow. SC incompatible change: APIs taking QWidget * now take QObject *
Diffstat (limited to 'src/gui/kernel/qdrag.cpp')
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diff --git a/src/gui/kernel/qdrag.cpp b/src/gui/kernel/qdrag.cpp
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+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <qdrag.h>
+#include <qpixmap.h>
+#include <qpoint.h>
+#include "qdnd_p.h"
+
+#ifndef QT_NO_DRAGANDDROP
+
+QT_BEGIN_NAMESPACE
+
+/*!
+ \class QDrag
+ \brief The QDrag class provides support for MIME-based drag and drop data
+ transfer.
+
+ Drag and drop is an intuitive way for users to copy or move data around in an
+ application, and is used in many desktop environments as a mechanism for copying
+ data between applications. Drag and drop support in Qt is centered around the
+ QDrag class that handles most of the details of a drag and drop operation.
+
+ The data to be transferred by the drag and drop operation is contained in a
+ QMimeData object. This is specified with the setMimeData() function in the
+ following way:
+
+ \snippet doc/src/snippets/dragging/mainwindow.cpp 1
+
+ Note that setMimeData() assigns ownership of the QMimeData object to the
+ QDrag object. The QDrag must be constructed on the heap with a parent QObject
+ to ensure that Qt can clean up after the drag and drop operation has been
+ completed.
+
+ A pixmap can be used to represent the data while the drag is in
+ progress, and will move with the cursor to the drop target. This
+ pixmap typically shows an icon that represents the MIME type of
+ the data being transferred, but any pixmap can be set with
+ setPixmap(). The cursor's hot spot can be given a position
+ relative to the top-left corner of the pixmap with the
+ setHotSpot() function. The following code positions the pixmap so
+ that the cursor's hot spot points to the center of its bottom
+ edge:
+
+ \snippet doc/src/snippets/separations/finalwidget.cpp 2
+
+ \note On X11, the pixmap may not be able to keep up with the mouse
+ movements if the hot spot causes the pixmap to be displayed
+ directly under the cursor.
+
+ The source and target widgets can be found with source() and target().
+ These functions are often used to determine whether drag and drop operations
+ started and finished at the same widget, so that special behavior can be
+ implemented.
+
+ QDrag only deals with the drag and drop operation itself. It is up to the
+ developer to decide when a drag operation begins, and how a QDrag object should
+ be constructed and used. For a given widget, it is often necessary to
+ reimplement \l{QWidget::mousePressEvent()}{mousePressEvent()} to determine
+ whether the user has pressed a mouse button, and reimplement
+ \l{QWidget::mouseMoveEvent()}{mouseMoveEvent()} to check whether a QDrag is
+ required.
+
+ \sa {Drag and Drop}, QClipboard, QMimeData, QWindowsMime, QMacPasteboardMime,
+ {Draggable Icons Example}, {Draggable Text Example}, {Drop Site Example},
+ {Fridge Magnets Example}
+*/
+
+/*!
+ Constructs a new drag object for the widget specified by \a dragSource.
+*/
+QDrag::QDrag(QObject *dragSource)
+ : QObject(*new QDragPrivate, dragSource)
+{
+ Q_D(QDrag);
+ d->source = dragSource;
+ d->target = 0;
+ d->data = 0;
+ d->hotspot = QPoint(-10, -10);
+ d->possible_actions = Qt::CopyAction;
+ d->executed_action = Qt::IgnoreAction;
+ d->defaultDropAction = Qt::IgnoreAction;
+}
+
+/*!
+ Destroys the drag object.
+*/
+QDrag::~QDrag()
+{
+ Q_D(QDrag);
+ delete d->data;
+ QDragManager *manager = QDragManager::self();
+ if (manager && manager->object == this)
+ manager->cancel(false);
+}
+
+/*!
+ Sets the data to be sent to the given MIME \a data. Ownership of the data is
+ transferred to the QDrag object.
+*/
+void QDrag::setMimeData(QMimeData *data)
+{
+ Q_D(QDrag);
+ if (d->data == data)
+ return;
+ if (d->data != 0)
+ delete d->data;
+ d->data = data;
+}
+
+/*!
+ Returns the MIME data that is encapsulated by the drag object.
+*/
+QMimeData *QDrag::mimeData() const
+{
+ Q_D(const QDrag);
+ return d->data;
+}
+
+/*!
+ Sets \a pixmap as the pixmap used to represent the data in a drag
+ and drop operation. You can only set a pixmap before the drag is
+ started.
+*/
+void QDrag::setPixmap(const QPixmap &pixmap)
+{
+ Q_D(QDrag);
+ d->pixmap = pixmap;
+}
+
+/*!
+ Returns the pixmap used to represent the data in a drag and drop operation.
+*/
+QPixmap QDrag::pixmap() const
+{
+ Q_D(const QDrag);
+ return d->pixmap;
+}
+
+/*!
+ Sets the position of the hot spot relative to the top-left corner of the
+ pixmap used to the point specified by \a hotspot.
+
+ \bold{Note:} on X11, the pixmap may not be able to keep up with the mouse
+ movements if the hot spot causes the pixmap to be displayed
+ directly under the cursor.
+*/
+void QDrag::setHotSpot(const QPoint& hotspot)
+{
+ Q_D(QDrag);
+ d->hotspot = hotspot;
+}
+
+/*!
+ Returns the position of the hot spot relative to the top-left corner of the
+ cursor.
+*/
+QPoint QDrag::hotSpot() const
+{
+ Q_D(const QDrag);
+ return d->hotspot;
+}
+
+/*!
+ Returns the source of the drag object. This is the widget where the drag
+ and drop operation originated.
+*/
+QObject *QDrag::source() const
+{
+ Q_D(const QDrag);
+ return d->source;
+}
+
+/*!
+ Returns the target of the drag and drop operation. This is the widget where
+ the drag object was dropped.
+*/
+QObject *QDrag::target() const
+{
+ Q_D(const QDrag);
+ return d->target;
+}
+
+/*!
+ \since 4.3
+
+ Starts the drag and drop operation and returns a value indicating the requested
+ drop action when it is completed. The drop actions that the user can choose
+ from are specified in \a supportedActions. The default proposed action will be selected
+ among the allowed actions in the following order: Move, Copy and Link.
+
+ \bold{Note:} On Linux and Mac OS X, the drag and drop operation
+ can take some time, but this function does not block the event
+ loop. Other events are still delivered to the application while
+ the operation is performed. On Windows, the Qt event loop is
+ blocked while during the operation.
+*/
+
+Qt::DropAction QDrag::exec(Qt::DropActions supportedActions)
+{
+ return exec(supportedActions, Qt::IgnoreAction);
+}
+
+/*!
+ \since 4.3
+
+ Starts the drag and drop operation and returns a value indicating the requested
+ drop action when it is completed. The drop actions that the user can choose
+ from are specified in \a supportedActions.
+
+ The \a defaultDropAction determines which action will be proposed when the user performs a
+ drag without using modifier keys.
+
+ \bold{Note:} On Linux and Mac OS X, the drag and drop operation
+ can take some time, but this function does not block the event
+ loop. Other events are still delivered to the application while
+ the operation is performed. On Windows, the Qt event loop is
+ blocked during the operation. However, QDrag::exec() on
+ Windows causes processEvents() to be called frequently to keep the GUI responsive.
+ If any loops or operations are called while a drag operation is active, it will block the drag operation.
+*/
+
+Qt::DropAction QDrag::exec(Qt::DropActions supportedActions, Qt::DropAction defaultDropAction)
+{
+ Q_D(QDrag);
+ if (!d->data) {
+ qWarning("QDrag: No mimedata set before starting the drag");
+ return d->executed_action;
+ }
+ QDragManager *manager = QDragManager::self();
+ d->defaultDropAction = Qt::IgnoreAction;
+ d->possible_actions = supportedActions;
+
+ if (manager) {
+ if (defaultDropAction == Qt::IgnoreAction) {
+ if (supportedActions & Qt::MoveAction) {
+ d->defaultDropAction = Qt::MoveAction;
+ } else if (supportedActions & Qt::CopyAction) {
+ d->defaultDropAction = Qt::CopyAction;
+ } else if (supportedActions & Qt::LinkAction) {
+ d->defaultDropAction = Qt::LinkAction;
+ }
+ } else {
+ d->defaultDropAction = defaultDropAction;
+ }
+ d->executed_action = manager->drag(this);
+ }
+
+ return d->executed_action;
+}
+
+/*!
+ \obsolete
+
+ \bold{Note:} It is recommended to use exec() instead of this function.
+
+ Starts the drag and drop operation and returns a value indicating the requested
+ drop action when it is completed. The drop actions that the user can choose
+ from are specified in \a request. Qt::CopyAction is always allowed.
+
+ \bold{Note:} Although the drag and drop operation can take some time, this function
+ does not block the event loop. Other events are still delivered to the application
+ while the operation is performed.
+
+ \sa exec()
+*/
+Qt::DropAction QDrag::start(Qt::DropActions request)
+{
+ Q_D(QDrag);
+ if (!d->data) {
+ qWarning("QDrag: No mimedata set before starting the drag");
+ return d->executed_action;
+ }
+ QDragManager *manager = QDragManager::self();
+ d->defaultDropAction = Qt::IgnoreAction;
+ d->possible_actions = request | Qt::CopyAction;
+ if (manager)
+ d->executed_action = manager->drag(this);
+ return d->executed_action;
+}
+
+/*!
+ Sets the drag \a cursor for the \a action. This allows you
+ to override the default native cursors. To revert to using the
+ native cursor for \a action pass in a null QPixmap as \a cursor.
+
+ The \a action can only be CopyAction, MoveAction or LinkAction.
+ All other values of DropAction are ignored.
+*/
+void QDrag::setDragCursor(const QPixmap &cursor, Qt::DropAction action)
+{
+ Q_D(QDrag);
+ if (action != Qt::CopyAction && action != Qt::MoveAction && action != Qt::LinkAction)
+ return;
+ if (cursor.isNull())
+ d->customCursors.remove(action);
+ else
+ d->customCursors[action] = cursor;
+}
+
+/*!
+ \fn void QDrag::actionChanged(Qt::DropAction action)
+
+ This signal is emitted when the \a action associated with the
+ drag changes.
+
+ \sa targetChanged()
+*/
+
+/*!
+ \fn void QDrag::targetChanged(QObject *newTarget)
+
+ This signal is emitted when the target of the drag and drop
+ operation changes, with \a newTarget the new target.
+
+ \sa target(), actionChanged()
+*/
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_DRAGANDDROP