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# QAbstractTextDocumentLayout Class Reference
[QtGui module]

The QAbstractTextDocumentLayout class is an abstract base class used to implement custom layouts for QTextDocuments. More...

     #include <QAbstractTextDocumentLayout>

Inherits QObject.

Inherited by QPlainTextDocumentLayout.

Note: All the functions in this class are reentrant.

- List of all members, including inherited members

### Public Types

- class PaintContext
- class Selection

### Public Functions

- QAbstractTextDocumentLayout ( QTextDocument * document )
- QString anchorAt ( const QPointF & position ) const
- virtual QRectF blockBoundingRect ( const QTextBlock & block ) const = 0
- QTextDocument * document () const
- virtual QSizeF documentSize () const = 0
- virtual void draw ( QPainter * painter, const PaintContext & context ) = 0
- virtual QRectF frameBoundingRect ( QTextFrame * frame ) const = 0
- QTextObjectInterface * handlerForObject ( int objectType ) const
- virtual int hitTest ( const QPointF & point, Qt::HitTestAccuracy accuracy ) const = 0
- virtual int pageCount () const = 0
- QPaintDevice * paintDevice () const
- void registerHandler ( int formatType, QObject * component )
- void setPaintDevice ( QPaintDevice * device )

- 29 public functions inherited from QObject

### Signals

- void documentSizeChanged ( const QSizeF & newSize )
- void pageCountChanged ( int newPages )
- void update ( const QRectF & rect = QRectF( 0., 0., 1000000000., 1000000000. ) )
- void updateBlock ( const QTextBlock & block )

- 1 signal inherited from QObject

### Protected Functions

- virtual void documentChanged ( int position, int charsRemoved, int charsAdded ) = 0
- virtual void drawInlineObject ( QPainter * painter, const QRectF & rect, QTextInlineObject object, int posInDocument, const QTextFormat & format )
- QTextCharFormat format ( int position )
- virtual void positionInlineObject ( QTextInlineObject item, int posInDocument, const QTextFormat & format )
- virtual void resizeInlineObject ( QTextInlineObject item, int posInDocument, const QTextFormat & format )

- 7 protected functions inherited from QObject

### Additional Inherited Members

- 1 property inherited from QObject
- 1 public slot inherited from QObject
- 5 static public members inherited from QObject

## Detailed Description

The QAbstractTextDocumentLayout class is an abstract base class used to implement custom layouts for QTextDocuments.

The standard layout provided by Qt can handle simple word processing including inline layouts, lists and tables.

Some applications (e.g. a word processor or a DTP application) might need more features than the ones provided by Qt's layout engine, in which case you can subclass QAbstractTextDocumentLayout to provide your own custom layout behavior for your text documents.

## Member Function Documentation

### QAbstractTextDocumentLayout::QAbstractTextDocumentLayout ( QTextDocument * document )

Creates a new text document layout for the given document.

### QString QAbstractTextDocumentLayout::anchorAt ( const QPointF & position ) const

Returns the reference of the anchor at the given position, or an empty string if no anchor exists at that point.

### QRectF QAbstractTextDocumentLayout::blockBoundingRect ( const QTextBlock & block ) const `[pure virtual]`

Returns the bounding rectangle of block.

### QTextDocument * QAbstractTextDocumentLayout::document () const

Returns the text document that this layout is operating on.

### void QAbstractTextDocumentLayout::documentChanged ( int position, int charsRemoved, int charsAdded ) `[pure virtual protected]`

This function is called whenever the contents of the document change. A change occurs when text is inserted, removed, or a combination of the two types of operation. The change is specified by position, charsRemoved, and charsAdded corresponding to the starting character position of the change, the number of character removed from the document, and the number of characters added.

For example, when inserting the text "Hello" into an empty document, charsRemoved would be 0 and charsAdded would be 5 (the length of the string).

Replacing text is the combination of removal and insertion. For example, if the text "Hello" gets replaced by "Hi", charsRemoved would be 5 and charsAdded would be 2.

### QSizeF QAbstractTextDocumentLayout::documentSize () const `[pure virtual]`

Returns the total size of the document. This is useful to display widgets since they can use the information to update their scroll bars correctly.

See also documentSizeChanged() and QTextDocument::pageSize.

### void QAbstractTextDocumentLayout::documentSizeChanged ( const QSizeF & newSize ) `[signal]`

This signal is emitted when the size of the document changes. The new size is specified by newSize.

This information is useful to widgets that display text documents since it enables them to update their scroll bars correctly.

See also documentSize().

### void QAbstractTextDocumentLayout::draw ( QPainter * painter, const PaintContext & context ) `[pure virtual]`

Draws the layout on the given painter with the given context.

### void QAbstractTextDocumentLayout::drawInlineObject ( QPainter * painter, const QRectF & rect, QTextInlineObject object, int posInDocument, const QTextFormat & format ) `[virtual protected]`

Called to draw the inline object object on the given painter within the rectangle specified by rect using the text format specified by format. posInDocument specifies the position of the object within the document.

See also draw().

### QTextCharFormat QAbstractTextDocumentLayout::format ( int position ) `[protected]`

Returns the character format that is applicable at the given position.

### QRectF QAbstractTextDocumentLayout::frameBoundingRect ( QTextFrame * frame ) const `[pure virtual]`

Returns the bounding rectacle of frame. Returns the bounding rectangle of frame.

### QTextObjectInterface * QAbstractTextDocumentLayout::handlerForObject ( int objectType ) const

Returns a handler for objects of the given objectType.

### int QAbstractTextDocumentLayout::hitTest ( const QPointF & point, Qt::HitTestAccuracy accuracy ) const `[pure virtual]`

Returns the cursor postion for the given point with the accuracy specified. Returns -1 to indicate failure if no valid cursor position was found.

### int QAbstractTextDocumentLayout::pageCount () const `[pure virtual]`

Returns the number of pages required by the layout.

See also pageCountChanged().

### void QAbstractTextDocumentLayout::pageCountChanged ( int newPages ) `[signal]`

This signal is emitted when the number of pages in the layout changes; newPages is the updated page count.

Changes to the page count are due to the changes to the layout or the document content itself.

See also pageCount().

### QPaintDevice * QAbstractTextDocumentLayout::paintDevice () const

Returns the paint device used to render the document's layout.

See also setPaintDevice().

### void QAbstractTextDocumentLayout::positionInlineObject ( QTextInlineObject item, int posInDocument, const QTextFormat & format ) `[virtual protected]`

Lays out the inline object item using the given text format. The base class implementation does nothing. posInDocument specifies the position of the object within the document.

See also drawInlineObject().

### void QAbstractTextDocumentLayout::registerHandler ( int formatType, QObject * component )

Registers the given component as a handler for items of the given formatType.

### void QAbstractTextDocumentLayout::resizeInlineObject ( QTextInlineObject item, int posInDocument, const QTextFormat & format ) `[virtual protected]`

Sets the size of the inline object item in accordance with the text format. posInDocument specifies the position of the object within the document.

### void QAbstractTextDocumentLayout::setPaintDevice ( QPaintDevice * device )

Sets the paint device used for rendering the document's layout to the given device.

See also paintDevice().

### void QAbstractTextDocumentLayout::update ( const QRectF & rect = QRectF( 0., 0., 1000000000., 1000000000. ) ) `[signal]`

This signal is emitted when the rectangle rect has been updated.

### void QAbstractTextDocumentLayout::updateBlock ( const QTextBlock & block ) `[signal]`

This signal is emitted when the specified block has been updated.

This function was introduced in Qt 4.4.