QClipboard Class

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# QClipboard Class Reference

The QClipboard class provides access to the window system clipboard. More...

`#include <qclipboard.h>`

Inherits QObject.

List of all member functions.

## Public Members

- enum Mode { Clipboard, Selection }
- void clear ( Mode mode )
- void clear ()
- bool supportsSelection () const
- bool ownsSelection () const
- bool ownsClipboard () const
- void setSelectionMode ( bool enable ) (obsolete)
- bool selectionModeEnabled () const (obsolete)
- QString text ( Mode mode ) const
- QString text ( QCString & subtype, Mode mode ) const
- void setText ( const QString & text, Mode mode )
- QMimeSource * data ( Mode mode ) const
- void setData ( QMimeSource * src, Mode mode )
- QImage image ( Mode mode ) const
- QPixmap pixmap ( Mode mode ) const
- void setImage ( const QImage & image, Mode mode )
- void setPixmap ( const QPixmap & pixmap, Mode mode )
- QString text () const
- QString text ( QCString & subtype ) const
- void setText ( const QString & text )
- QMimeSource * data () const
- void setData ( QMimeSource * src )
- QImage image () const
- QPixmap pixmap () const
- void setImage ( const QImage & image )
- void setPixmap ( const QPixmap & pixmap )

## Signals

- void selectionChanged ()
- void dataChanged ()

## Detailed Description

The QClipboard class provides access to the window system clipboard.

The clipboard offers a simple mechanism to copy and paste data between applications.

QClipboard supports the same data types that QDragObject does, and uses similar mechanisms. For advanced clipboard usage read the drag-and-drop documentation.

There is a single QClipboard object in an application, and you can access it using QApplication::clipboard().

Example:

        QClipboard *cb = QApplication::clipboard();

        // Copy text from the clipboard (paste)
        QString text = cb->text(QClipboard::Clipboard);
        if ( !text.isNull() )
            qDebug( "The clipboard contains: " + text );

        // Copy text into the clipboard
        cb->setText( "This text can be pasted by other programs",
                     QClipboard::Clipboard );

QClipboard features some convenience functions to access common data types: setText() allows the exchange of Unicode text and setPixmap() and setImage() allows the exchange of QPixmaps and QImages between applications. The setData() function is the ultimate in flexibility: it allows you to add any QMimeSource into the clipboard. There are corresponding getters for each of these, e.g. text(), image() and pixmap().

You can clear the clipboard by calling clear().

### Platform Specific Information

#### X11

- The X11 Window System has the concept of a separate selection and clipboard. When text is selected, it is immediately available as the global mouse selection. The global mouse selection may later be copied to the clipboard. By convention, the middle mouse button is used to paste the global mouse selection.

- X11 also has the concept of ownership; if you change the selection within a window, X11 will only notify the owner and the previous owner of the change, i.e. it will not notify all applications that the selection or clipboard data changed.

- Lastly, the X11 clipboard is event driven, i.e. the clipboard will not function properly if the event loop is not running. Similarly, it is recommended that the contents of the clipboard are stored or retrieved in direct response to user-input events, e.g. mouse button or key presses and releases. You should not store or retrieve the clipboard contents in response to timer or non-user-input events.

#### Windows

- Microsoft Windows does not support the global mouse selection; it only supports the global clipboard, e.g. Windows only adds text to the clipboard when an explicit copy or cut is made.

- Windows does not have the concept of ownership; the clipboard is a fully global resource so all applications are notified of changes.

See the multiclip example in the Qt Designer examples directory for an example of a multiplatform clipboard application that also demonstrates selection handling.

See also Environment Classes and Input/Output and Networking.

## Member Type Documentation

### QClipboard::Mode

This enum type is used to control which part of the system clipboard is used by QClipboard::data(), QClipboard::setData() and related functions.

- `QClipboard::Clipboard` - indicates that data should be stored and retrieved from the global clipboard.
- `QClipboard::Selection` - indicates that data should be stored and retrieved from the global mouse selection.

Note: Support for Selection is provided only on systems with a global mouse selection (e.g. X11).

See also QClipboard::supportsSelection().

## Member Function Documentation

### void QClipboard::clear ( Mode mode )

Clear the clipboard contents.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, this function clears the the global clipboard contents. If mode is QClipboard::Selection, this function clears the global mouse selection contents.

See also QClipboard::Mode and supportsSelection().

### void QClipboard::clear ()

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This function uses the QClipboard::clear() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

### QMimeSource * QClipboard::data ( Mode mode ) const

Returns a reference to a QMimeSource representation of the current clipboard data.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, the data is retrieved from the global clipboard. If mode is QClipboard::Selection, the data is retrieved from the global mouse selection.

See also setData().

### QMimeSource * QClipboard::data () const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This function uses the QClipboard::data() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

### void QClipboard::dataChanged ()`[signal]`

This signal is emitted when the clipboard data is changed.

### QImage QClipboard::image ( Mode mode ) const

Returns the clipboard image, or returns a null image if the clipboard does not contain an image or if it contains an image in an unsupported image format.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, the image is retrieved from the global clipboard. If mode is QClipboard::Selection, the image is retrieved from the global mouse selection.

See also setImage(), pixmap(), data(), and QImage::isNull().

### QImage QClipboard::image () const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This function uses the QClipboard::image() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

### bool QClipboard::ownsClipboard () const

Returns TRUE if this clipboard object owns the clipboard data; otherwise returns FALSE.

### bool QClipboard::ownsSelection () const

Returns TRUE if this clipboard object owns the mouse selection data; otherwise returns FALSE.

### QPixmap QClipboard::pixmap ( Mode mode ) const

Returns the clipboard pixmap, or null if the clipboard does not contain a pixmap. Note that this can lose information. For example, if the image is 24-bit and the display is 8-bit, the result is converted to 8 bits, and if the image has an alpha channel, the result just has a mask.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, the pixmap is retrieved from the global clipboard. If mode is QClipboard::Selection, the pixmap is retrieved from the global mouse selection.

See also setPixmap(), image(), data(), and QPixmap::convertFromImage().

### QPixmap QClipboard::pixmap () const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This function uses the QClipboard::pixmap() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

### void QClipboard::selectionChanged ()`[signal]`

This signal is emitted when the selection is changed. This only applies to windowing systems that support selections, e.g. X11. Windows doesn't support selections.

### bool QClipboard::selectionModeEnabled () const

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Use the QClipboard::data(), QClipboard::setData() and related functions which take a QClipboard::Mode argument.

Returns the selection mode.

See also setSelectionMode() and supportsSelection().

### void QClipboard::setData ( QMimeSource * src, Mode mode )

Sets the clipboard data to src. Ownership of the data is transferred to the clipboard. If you want to remove the data either call clear() or call setData() again with new data.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, the data is retrieved from the global clipboard. If mode is QClipboard::Selection, the data is retrieved from the global mouse selection.

The QDragObject subclasses are reasonable objects to put into the clipboard (but do not try to call QDragObject::drag() on the same object). Any QDragObject placed in the clipboard should have a parent of 0. Do not put QDragMoveEvent or QDropEvent subclasses in the clipboard, as they do not belong to the event handler which receives them.

The setText(), setImage() and setPixmap() functions are simpler wrappers for setting text, image and pixmap data respectively.

See also data().

### void QClipboard::setData ( QMimeSource * src )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This function uses the QClipboard::setData() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

### void QClipboard::setImage ( const QImage & image, Mode mode )

Copies image into the clipboard.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, the image is stored in the global clipboard. If mode is QClipboard::Selection, the data is stored in the global mouse selection.

This is shorthand for:

            setData( new QImageDrag(image), mode )

See also image(), setPixmap(), and setData().

### void QClipboard::setImage ( const QImage & image )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This function uses the QClipboard::setImage() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

### void QClipboard::setPixmap ( const QPixmap & pixmap, Mode mode )

Copies pixmap into the clipboard. Note that this is slower than setImage() because it needs to convert the QPixmap to a QImage first.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, the pixmap is stored in the global clipboard. If mode is QClipboard::Selection, the pixmap is stored in the global mouse selection.

See also pixmap(), setImage(), and setData().

### void QClipboard::setPixmap ( const QPixmap & pixmap )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This function uses the QClipboard::setPixmap() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

### void QClipboard::setSelectionMode ( bool enable )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Use the QClipboard::data(), QClipboard::setData() and related functions which take a QClipboard::Mode argument.

Sets the clipboard selection mode. If enable is TRUE, then subsequent calls to QClipboard::setData() and other functions which put data into the clipboard will put the data into the mouse selection, otherwise the data will be put into the clipboard.

See also supportsSelection() and selectionModeEnabled().

### void QClipboard::setText ( const QString & text, Mode mode )

Copies text into the clipboard as plain text.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, the text is stored in the global clipboard. If mode is QClipboard::Selection, the text is stored in the global mouse selection.

See also text() and setData().

Example: regexptester/regexptester.cpp.

### void QClipboard::setText ( const QString & text )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This function uses the QClipboard::setText() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

### bool QClipboard::supportsSelection () const

Returns TRUE if the clipboard supports mouse selection; otherwise returns FALSE.

Example: regexptester/regexptester.cpp.

### QString QClipboard::text ( Mode mode ) const

Returns the clipboard text as plain text, or a null string if the clipboard does not contain any text.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, the text is retrieved from the global clipboard. If mode is QClipboard::Selection, the text is retrieved from the global mouse selection.

See also setText(), data(), and QString::operator!().

### QString QClipboard::text ( QCString & subtype, Mode mode ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns the clipboard text in subtype subtype, or a null string if the clipboard does not contain any text. If subtype is null, any subtype is acceptable, and subtype is set to the chosen subtype.

The mode argument is used to control which part of the system clipboard is used. If mode is QClipboard::Clipboard, the text is retrieved from the global clipboard. If mode is QClipboard::Selection, the text is retrieved from the global mouse selection.

Common values for subtype are "plain" and "html".

See also setText(), data(), and QString::operator!().

### QString QClipboard::text () const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This function uses the QClipboard::text() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

### QString QClipboard::text ( QCString & subtype ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns the clipboard text in subtype subtype, or a null string if the clipboard does not contain any text. This function uses the QClipboard::text() function which takes a QClipboard::Mode argument. The value of the mode argument is determined by the return value of selectionModeEnabled(). If selectionModeEnabled() returns TRUE, the mode argument is QClipboard::Selection, otherwise the mode argument is QClipboard::Clipboard.

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