Qt 4.3: QClipboard Class Reference

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# QClipboard Class Reference
[QtGui module]

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

     #include <QClipboard>

Inherits QObject.

- List of all members, including inherited members
- Qt 3 support members

### Public Types

- enum Mode { Clipboard, Selection, FindBuffer }

### Public Functions

- void clear ( Mode mode = Clipboard )
- QImage image ( Mode mode = Clipboard ) const
- const QMimeData * mimeData ( Mode mode = Clipboard ) const
- bool ownsClipboard () const
- bool ownsFindBuffer () const
- bool ownsSelection () const
- QPixmap pixmap ( Mode mode = Clipboard ) const
- void setImage ( const QImage & image, Mode mode = Clipboard )
- void setMimeData ( QMimeData * src, Mode mode = Clipboard )
- void setPixmap ( const QPixmap & pixmap, Mode mode = Clipboard )
- void setText ( const QString & text, Mode mode = Clipboard )
- bool supportsFindBuffer () const
- bool supportsSelection () const
- QString text ( Mode mode = Clipboard ) const
- QString text ( QString & subtype, Mode mode = Clipboard ) const

- 29 public functions inherited from QObject

### Signals

- void changed ( QClipboard::Mode mode )
- void dataChanged ()
- void findBufferChanged ()
- void selectionChanged ()

- 1 signal inherited from QObject

### Additional Inherited Members

- 1 property inherited from QObject
- 1 public slot inherited from QObject
- 5 static public members inherited from QObject
- 7 protected functions inherited from QObject

## 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 QDrag does, and uses similar mechanisms. For advanced clipboard usage read Drag and Drop.

There is a single QClipboard object in an application, accessible as QApplication::clipboard().

Example:

     QClipboard *clipboard = QApplication::clipboard();
     QString originalText = clipboard->text();
     ...
     clipboard->setText(newText);

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 setMimeData() function is the ultimate in flexibility: it allows you to add any QMimeData 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().

### Notes for X11 Users

- 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.

### Notes for Mac OS X Users

Mac OS X supports a separate find buffer that holds the current search string in Find operations. This find clipboard can be accessed by specifying the FindBuffer mode.

### Notes for Windows and Mac OS X Users

- Windows and Mac OS X do not support the global mouse selection; they only supports the global clipboard, i.e. they only add text to the clipboard when an explicit copy or cut is made.
- Windows and Mac OS X does not have the concept of ownership; the clipboard is a fully global resource so all applications are notified of changes.

See also QApplication.

## Member Type Documentation

### enum QClipboard::Mode

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

Constant | Value | Description
--- | --- | ---
`QClipboard::Clipboard` | `0` | indicates that data should be stored and retrieved from the global clipboard.
`QClipboard::Selection` | `1` | indicates that data should be stored and retrieved from the global mouse selection. Support for `Selection` is provided only on systems with a global mouse selection (e.g. X11).
`QClipboard::FindBuffer` | `2` | indicates that data should be stored and retrieved from the Find buffer. This mode is used for holding search strings on Mac OS X.

See also QClipboard::supportsSelection().

## Member Function Documentation

### void QClipboard::changed ( QClipboard::Mode mode ) `[signal]`

This signal is emitted when the data for the given clipboard mode is changed.

This function was introduced in Qt 4.2.

See also dataChanged(), selectionChanged(), and findBufferChanged().

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

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. If mode is QClipboard::FindBuffer, this function clears the search string buffer.

See also QClipboard::Mode and supportsSelection().

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

This signal is emitted when the clipboard data is changed.

On Mac OS X and with Qt version 4.3 or higher, clipboard changes made by other applications will only be detected when the application is activated.

See also findBufferChanged(), selectionChanged(), and changed().

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

This signal is emitted when the find buffer is changed. This only applies to Mac OS X.

With Qt version 4.3 or higher, clipboard changes made by other applications will only be detected when the application is activated.

This function was introduced in Qt 4.2.

See also dataChanged(), selectionChanged(), and changed().

### QImage QClipboard::image ( Mode mode = Clipboard ) 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(), mimeData(), and QImage::isNull().

### const QMimeData * QClipboard::mimeData ( Mode mode = Clipboard ) const

Returns a reference to a QMimeData 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. If mode is QClipboard::FindBuffer, the data is retrieved from the search string buffer.

The text(), image(), and pixmap() functions are simpler wrappers for retrieving text, image, and pixmap data.

See also setMimeData().

### bool QClipboard::ownsClipboard () const

Returns true if this clipboard object owns the clipboard data; otherwise returns false.

### bool QClipboard::ownsFindBuffer () const

Returns true if this clipboard object owns the find buffer data; otherwise returns false.

This function was introduced in Qt 4.2.

### bool QClipboard::ownsSelection () const

Returns true if this clipboard object owns the mouse selection data; otherwise returns false.

### QPixmap QClipboard::pixmap ( Mode mode = Clipboard ) 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(), mimeData(), and QPixmap::convertFromImage().

### 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 and Mac OS X don't support selections.

See also dataChanged(), findBufferChanged(), and changed().

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

Copies the 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:

     QMimeData *data = new QMimeData;
     data->setImageData(image);
     clipboard->setMimeData(data, mode);

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

### void QClipboard::setMimeData ( QMimeData * src, Mode mode = Clipboard )

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 setMimeData() 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 stored in the global clipboard. If mode is QClipboard::Selection, the data is stored in the global mouse selection. If mode is QClipboard::FindBuffer, the data is stored in the search string buffer.

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

See also mimeData().

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

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 setMimeData().

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

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. If mode is QClipboard::FindBuffer, the text is stored in the search string buffer.

See also text() and setMimeData().

### bool QClipboard::supportsFindBuffer () const

Returns true if the clipboard supports a separate search buffer; otherwise returns false.

### bool QClipboard::supportsSelection () const

Returns true if the clipboard supports mouse selection; otherwise returns false.

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

Returns the clipboard text as plain text, or an empty 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. If mode is QClipboard::FindBuffer, the text is retrieved from the search string buffer.

See also setText() and mimeData().

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

This is an overloaded member function, provided for convenience.

Returns the clipboard text in subtype subtype, or an empty 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".

Note that calling this function repeatedly, for instance from a key event handler, may be slow. In such cases, you should use the `dataChanged()` signal instead.

See also setText() and mimeData().