Qt 4.0: QTextDocument Class Reference

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# QTextDocument Class Reference
[QtGui module]

The QTextDocument class holds formatted text that can be viewed and edited using a QTextEdit. More...

    #include <QTextDocument>

Inherits QObject.

- List of all members, including inherited members

### Public Types

- enum FindFlag { FindBackward, FindCaseSensitively, FindWholeWords }
- flags FindFlags
- enum MetaInformation { DocumentTitle }
- enum ResourceType { HtmlResource, ImageResource, UserResource }

### Properties

- defaultFont : QFont
- modified : bool
- pageSize : QSizeF
- undoRedoEnabled : bool

- 1 property inherited from QObject

### Public Functions

- QTextDocument ( QObject * parent = 0 )
- QTextDocument ( const QString & text, QObject * parent = 0 )
- ~QTextDocument ()
- void addResource ( int type, const QUrl & name, const QVariant & resource )
- QVector<QTextFormat> allFormats () const
- QTextBlock begin () const
- virtual void clear ()
- QTextDocument * clone ( QObject * parent = 0 ) const
- QFont defaultFont () const
- QAbstractTextDocumentLayout * documentLayout () const
- QTextBlock end () const
- QTextCursor find ( const QString & expr, const QTextCursor & cursor, FindFlags options = 0 ) const
- QTextCursor find ( const QString & expr, int position = 0, FindFlags options = 0 ) const
- QTextBlock findBlock ( int pos ) const
- bool isEmpty () const
- bool isModified () const
- bool isRedoAvailable () const
- bool isUndoAvailable () const
- bool isUndoRedoEnabled () const
- void markContentsDirty ( int position, int length )
- QString metaInformation ( MetaInformation info ) const
- QTextObject * object ( int objectIndex ) const
- QTextObject * objectForFormat ( const QTextFormat & f ) const
- int pageCount () const
- QSizeF pageSize () const
- void print ( QPrinter * printer ) const
- QVariant resource ( int type, const QUrl & name ) const
- QTextFrame * rootFrame () const
- void setDefaultFont ( const QFont & font )
- void setDocumentLayout ( QAbstractTextDocumentLayout * layout )
- void setHtml ( const QString & html )
- void setMetaInformation ( MetaInformation info, const QString & string )
- void setPageSize ( const QSizeF & size )
- void setPlainText ( const QString & text )
- void setUndoRedoEnabled ( bool enable )
- QString toHtml ( const QByteArray & encoding = QByteArray() ) const
- QString toPlainText () const

- 28 public functions inherited from QObject

### Public Slots

- void redo ()
- void setModified ( bool m = true )
- void undo ()

- 1 public slot inherited from QObject

### Signals

- void contentsChange ( int position, int charsRemoved, int charsAdded )
- void contentsChanged ()
- void cursorPositionChanged ( const QTextCursor & cursor )
- void modificationChanged ( bool changed )
- void redoAvailable ( bool available )
- void undoAvailable ( bool available )

- 1 signal inherited from QObject

### Protected Functions

- virtual QTextObject * createObject ( const QTextFormat & format )
- virtual QVariant loadResource ( int type, const QUrl & name )

- 7 protected functions inherited from QObject

### Additional Inherited Members

- 4 static public members inherited from QObject

## Detailed Description

The QTextDocument class holds formatted text that can be viewed and edited using a QTextEdit.

QTextDocument is a container for structured rich text documents, providing support for styled text and various types of document elements, such as lists, tables, frames, and images. They can be created for use in a QTextEdit, or used independently.

Each document element is described by an associated format object. Each format object is treated as a unique object by QTextDocuments, and can be passed to objectForFormat() to obtain the document element that it is applied to.

A QTextDocument can be edited programmatically using a QTextCursor, and its contents can be examined by traversing the document structure. The entire document structure is stored as a hierarchy of document elements beneath the root frame, found with the rootFrame() function. Alternatively, if you just want to iterate over the textual contents of the document you can use begin(), end(), and findBlock() to retrieve text blocks that you can examine and iterate over.

The layout of a document is determined by the documentLayout(); you can create your own QAbstractTextDocumentLayout subclass and set it using setDocumentLayout() if you want to use your own layout logic. The document's title can be obtained by calling the documentTitle() function.

The toPlainText() and toHtml() convenience functions allow you to retrieve the contents of the document as plain text and HTML. The document's text can be searched using the find() functions.

Undo/redo of operations performed on the document can be controlled using the setUndoRedoEnabled() function. The undo/redo system can be controlled by an editor widget through the undo() and redo() slots; the document also provides contentsChanged(), undoAvailable(), and redoAvailable() signals that inform connected editor widgets about the state of the undo/redo system.

See also QTextCursor, QTextEdit, and Rich Text Processing.

## Member Type Documentation

### enum QTextDocument::FindFlag
flags QTextDocument::FindFlags

This enum describes the options available to QTextDocument's find function. The options can be OR-red together from the following list:

Constant | Value | Description
--- | --- | ---
`QTextDocument::FindBackward` | `0x00001` |
`QTextDocument::FindCaseSensitively` | `0x00002` | By default find works case insensitive. Specifying this option changes the behaviour to a case sensitive find operation.
`QTextDocument::FindWholeWords` | `0x00004` | Makes find match only complete words.

The FindFlags type is a typedef for QFlags<FindFlag>. It stores an OR combination of FindFlag values.

### enum QTextDocument::MetaInformation

This enum describes the different types of meta information that can be added to a document.

Constant | Value | Description
--- | --- | ---
`QTextDocument::DocumentTitle` | `0` | The title of the document.

See also metaInformation() and setMetaInformation().

### enum QTextDocument::ResourceType

This enum describes the types of resources that can be loaded by QTextDocument's loadResource() function.

Constant | Value | Description
--- | --- | ---
`QTextDocument::HtmlResource` | `1` | The resource contains HTML.
`QTextDocument::ImageResource` | `2` | The resource contains image data.
`QTextDocument::UserResource` | `100` | The first available value for user defined resource types.

See also loadResource().

## Property Documentation

### defaultFont : QFont

This property holds the default font used to display the document's text.

Access functions:

- QFont defaultFont () const
- void setDefaultFont ( const QFont & font )

### modified : bool

This property holds whether the document has been modified by the user.

Access functions:

- bool isModified () const
- void setModified ( bool m = true )

See also modificationChanged().

### pageSize : QSizeF

This property holds the page size that should be used for layouting the document.

Access functions:

- QSizeF pageSize () const
- void setPageSize ( const QSizeF & size )

See also modificationChanged().

### undoRedoEnabled : bool

This property holds whether undo/redo are enabled for this document.

This defaults to true. If disabled, the undo stack is cleared and no items will be added to it.

Access functions:

- bool isUndoRedoEnabled () const
- void setUndoRedoEnabled ( bool enable )

## Member Function Documentation

### QTextDocument::QTextDocument ( QObject * parent = 0 )

Constructs an empty QTextDocument with the given parent.

### QTextDocument::QTextDocument ( const QString & text, QObject * parent = 0 )

Constructs a QTextDocument containing the plain (unformatted) text specified, and with the given parent.

### QTextDocument::~QTextDocument ()

Destroys the document.

### void QTextDocument::addResource ( int type, const QUrl & name, const QVariant & resource )

Adds the resource resource to the resource cache, using type and name as identifiers.

### QVector<QTextFormat> QTextDocument::allFormats () const

Returns a vector of text formats for all the formats used in the document.

### QTextBlock QTextDocument::begin () const

Returns the document's first text block.

### void QTextDocument::clear () `[virtual]`

Clears the document.

### QTextDocument * QTextDocument::clone ( QObject * parent = 0 ) const

Creates a new QTextDocument that is a copy of this text document. parent is the parent of the returned text document.

### void QTextDocument::contentsChange ( int position, int charsRemoved, int charsAdded ) `[signal]`

This signal is emitted whenever the document's content changes; for example, when text is inserted or deleted, or when formatting is applied.

Information is provided about the position of the character in the document where the change occurred, the number of characters removed (charsRemoved), and the number of characters added (charsAdded).

The signal is emitted before the document's layout manager is notified about the change. This hook allows you to implement syntax highlighting for the document.

See also QAbstractTextDocumentLayout::documentChanged() and contentsChanged().

### void QTextDocument::contentsChanged () `[signal]`

This signal is emitted whenever the document's content changes; for example, when text is inserted or deleted, or when formatting is applied.

See also contentsChange().

### QTextObject * QTextDocument::createObject ( const QTextFormat & format ) `[virtual protected]`

Creates and returns a new document object (a QTextObject), based on the given format.

QTextObjects will always get created through this method, so you must reimplement it if you use custom text objects inside your document.

### void QTextDocument::cursorPositionChanged ( const QTextCursor & cursor ) `[signal]`

This signal is emitted whenever the position of a cursor changed due to an editing operation. The cursor that changed is passed in cursor.

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

Returns the document layout for this document.

See also setDocumentLayout().

### QTextBlock QTextDocument::end () const

Returns the document's last text block.

### QTextCursor QTextDocument::find ( const QString & expr, const QTextCursor & cursor, FindFlags options = 0 ) const

Finds the next occurrence of the string, expr, in the document. The search starts at the position of the given cursor, and proceeds forwards through the document unless specified otherwise in the search options. The options control the type of search performed.

Returns a cursor with the match selected if expr was found; otherwise returns a null cursor.

If the given cursor has a selection, the search begins after the selection; otherwise it begins at the cursor's position.

By default the search is case-sensitive, and can match text anywhere in the document.

### QTextCursor QTextDocument::find ( const QString & expr, int position = 0, FindFlags options = 0 ) const

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

Finds the next occurrence of the string, expr, in the document. The search starts at the given position, and proceeds forwards through the document unless specified otherwise in the search options. The options control the type of search performed.

Returns a cursor with the match selected if expr was found; otherwise returns a null cursor.

If the position is 0 (the default) the search begins from the beginning of the document; otherwise it begins at the specified position.

### QTextBlock QTextDocument::findBlock ( int pos ) const

Returns the text block that contains the pos-th character.

### bool QTextDocument::isEmpty () const

Returns true if the document is empty; otherwise returns false.

### bool QTextDocument::isRedoAvailable () const

Returns true is redo is available; otherwise returns false.

### bool QTextDocument::isUndoAvailable () const

Returns true is undo is available; otherwise returns false.

### QVariant QTextDocument::loadResource ( int type, const QUrl & name ) `[virtual protected]`

Loads data of the specified type from the resource with the given name.

This function is called by the rich text engine to request data that isn't directly stored by QTextDocument, but still associated with it. For example, images are referenced indirectly by the name attribute of a QTextImageFormat object.

When called by Qt, type is one of the values of QTextDocument::ResourceType.

If the QTextDocument is a child object of a QTextEdit, QTextBrowser, or a QTextDocument itself then the default implementation tries to retrieve the data from the parent.

### void QTextDocument::markContentsDirty ( int position, int length )

Marks the contents specified by the given position and length as "dirty", informing the document that it needs to be layed out again.

### QString QTextDocument::metaInformation ( MetaInformation info ) const

Returns meta information about the document of the type specified by info.

See also setMetaInformation().

### void QTextDocument::modificationChanged ( bool changed ) `[signal]`

This signal is emitted whenever the content of the document changes in a way that affects the modification state. If changed is true if the document has been modified; otherwise it is false.

For example calling setModified(false) on a document and then inserting text causes the signal to get emitted. If you undo that operation, causing the document to return to its original unmodified state, the signal will get emitted again.

### QTextObject * QTextDocument::object ( int objectIndex ) const

Returns the text object associated with the given objectIndex.

### QTextObject * QTextDocument::objectForFormat ( const QTextFormat & f ) const

Returns the text object associated with the format f.

### int QTextDocument::pageCount () const

returns the number of pages in this document.

### void QTextDocument::print ( QPrinter * printer ) const

Prints the document to the given printer. The QPrinter must be set up before being used with this function.

This is only a convenience method to print the whole document to the printer.

### void QTextDocument::redo () `[slot]`

Redoes the last editing operation on the document if redo is available.

### void QTextDocument::redoAvailable ( bool available ) `[signal]`

This signal is emitted whenever redo operations become available (available is true) or unavailable (available is false).

### QVariant QTextDocument::resource ( int type, const QUrl & name ) const

Returns data of the specified type from the resource with the given name.

This function is called by the rich text engine to request data that isn't directly stored by QTextDocument, but still associated with it. For example, images are referenced indirectly by the name attribute of a QTextImageFormat object.

Resources are cached internally in the document. If a resource can not be found in the cache, loadResource is called to try to load the resource. loadResource should then use addResource to add the resource to the cache.

### QTextFrame * QTextDocument::rootFrame () const

Returns the document's root frame.

### void QTextDocument::setDocumentLayout ( QAbstractTextDocumentLayout * layout )

Sets the document to use the given layout. The previous layout is deleted.

See also documentLayout().

### void QTextDocument::setHtml ( const QString & html )

Replaces the entire contents of the document with the given HTML-formatted text in the html string.

The HTML formatting is respected as much as possible; for example, "<b>bold</b> text" will produce text where the first word has a font weight that gives it a bold appearance: "bold text".

See also setPlainText().

### void QTextDocument::setMetaInformation ( MetaInformation info, const QString & string )

Sets the document's meta information of the type specified by info to the given string.

See also metaInformation().

### void QTextDocument::setPlainText ( const QString & text )

Replaces the entire contents of the document with the given plain text.

See also setHtml().

### QString QTextDocument::toHtml ( const QByteArray & encoding = QByteArray() ) const

Returns a string containing an HTML representation of the document.

The encoding parameter specifies the value for the charset attribute in the html header. For example if 'utf-8' is specified then the beginning of the generated html will look like this:

        <html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body>...

If no encoding is specified then no such meta information is generated.

If you later on convert the returned html string into a byte array for transmission over a network or when saving to disk you should specify the encoding you're going to use for the conversion to a byte array here.

### QString QTextDocument::toPlainText () const

Returns the plain text contained in the document. If you want formatting information use a QTextCursor instead.

See also toHtml().

### void QTextDocument::undo () `[slot]`

Undoes the last editing operation on the document if undo is available.

### void QTextDocument::undoAvailable ( bool available ) `[signal]`

This signal is emitted whenever undo operations become available (available is true) or unavailable (available is false).