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Diffstat (limited to 'src/gui/kernel/qdrag.cpp')
-rw-r--r-- | src/gui/kernel/qdrag.cpp | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/src/gui/kernel/qdrag.cpp b/src/gui/kernel/qdrag.cpp new file mode 100644 index 0000000..e980d1c --- /dev/null +++ b/src/gui/kernel/qdrag.cpp @@ -0,0 +1,357 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Qt Software Information (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 either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** 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 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at qt-sales@nokia.com. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include <qwidget.h> +#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 QWidget + 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(QWidget *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. +*/ +QWidget *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. +*/ +QWidget *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 while during the 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(QWidget *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 |