QTextDocument Class Reference
[QtGui module]

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-ed together from the following list:

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.

See also metaInformation() and setMetaInformation().

enum QTextDocument::ResourceType

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

See also loadResource().

Property Documentation

blockCount : const int

Returns the number of text blocks in the document.

The value of this property is undefined in documents with tables or frames.

By default, if defined, this property contains a value of 1.

This property was introduced in Qt 4.2.

Access functions:

• int blockCount () const

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 )

defaultStyleSheet : QString

The default style sheet is applied to all newly HTML formatted text that is inserted into the document, for example using setHtml() or QTextCursor::insertHtml().

The style sheet needs to be compliant to CSS 2.1 syntax.

Note: Changing the default style sheet does not have any effect to the existing content of the document.

This property was introduced in Qt 4.2.

Access functions:

• QString defaultStyleSheet () const
• void setDefaultStyleSheet ( const QString & sheet )

See also Supported HTML Subset.

defaultTextOption : QTextOption

This property holds the default text option will be set on all QTextLayouts in the document.

When QTextBlocks are created, the defaultTextOption is set on their QTextLayout. This allows setting global properties for the document such as the default word wrap mode.

Access functions:

• QTextOption defaultTextOption () const
• void setDefaultTextOption ( const QTextOption & option )

indentWidth : qreal

Returns the width used for text list and text block indenting.

The indent properties of QTextListFormat and QTextBlockFormat specify multiples of this value. The default indent width is 40.

This property was introduced in Qt 4.4.

Access functions:

• qreal indentWidth () const
• void setIndentWidth ( qreal width )

maximumBlockCount : int

This property specifies the limit for blocks in the document.

Specifies the maximum number of blocks the document may have. If there are more blocks in the document that specified with this property blocks are removed from the beginning of the document.

A negative or zero value specifies that the document may contain an unlimited amount of blocks.

The default value is 0.

Note that setting this property will apply the limit immediately to the document contents.

Setting this property also disables the undo redo history.

This property is undefined in documents with tables or frames.

This property was introduced in Qt 4.2.

Access functions:

• int maximumBlockCount () const
• void setMaximumBlockCount ( int maximum )

modified : bool

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

By default, this property is false.

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 laying out the document.

By default, for a newly-created, empty document, this property contains an undefined size.

Access functions:

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

See also modificationChanged().

size : const QSizeF

Returns the actual size of the document. This is equivalent to documentLayout()->documentSize();

The size of the document can be changed either by setting a text width or setting an entire page size.

Note that the width is always >= pageSize().width().

By default, for a newly-created, empty document, this property contains a configuration-dependent size.

This property was introduced in Qt 4.2.

Access functions:

• QSizeF size () const

See also setTextWidth(), setPageSize(), and idealWidth().

textWidth : qreal

The text width specifies the preferred width for text in the document. If the text (or content in general) is wider than the specified with it is broken into multiple lines and grows vertically. If the text cannot be broken into multiple lines to fit into the specified text width it will be larger and the size() and the idealWidth() property will reflect that.

If the text width is set to -1 then the text will not be broken into multiple lines unless it is enforced through an explicit line break or a new paragraph.

The default value is -1.

Setting the text width will also set the page height to -1, causing the document to grow or shrink vertically in a continuous way. If you want the document layout to break the text into multiple pages then you have to set the pageSize property instead.

This property was introduced in Qt 4.2.

Access functions:

• qreal textWidth () const
• void setTextWidth ( qreal width )

See also size(), idealWidth(), and pageSize().

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 )

useDesignMetrics : bool

This property holds whether the document uses design metrics of fonts to improve the accuracy of text layout.

If this property is set to true, the layout will use design metrics. Otherwise, the metrics of the paint device as set on QAbstractTextDocumentLayout::setPaintDevice() will be used.

By default, this property is false.

This property was introduced in Qt 4.1.

Access functions:

• bool useDesignMetrics () const
• void setUseDesignMetrics ( bool b )

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. type should be a value from QTextDocument::ResourceType.

For example, you can add an image as a resource in order to reference it from within the document:

     document->addResource(QTextDocument::ImageResource,
         QUrl("mydata://image.png"), QVariant(image));

The image can be inserted into the document using the QTextCursor API:

     QTextImageFormat imageFormat;
     imageFormat.setName("mydata://image.png");
     cursor.insertImage(imageFormat);

Alternatively, you can insert images using the HTML img tag:

     editor->append("<img src=\"mydata://image.png\" />");

void QTextDocument::adjustSize ()

Adjusts the document to a reasonable size.

This function was introduced in Qt 4.2.

See also idealWidth(), textWidth, and size.

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.

See also firstBlock().

void QTextDocument::blockCountChanged ( int newBlockCount )   [signal]

This signal is emitted when the total number of text blocks in the document changes. The value passed in newBlockCount is the new total.

This function was introduced in Qt 4.3.

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. If you need a signal when the cursor is moved with the arrow keys you can use the cursorPositionChanged() signal in QTextEdit.

QAbstractTextDocumentLayout * QTextDocument::documentLayout () const

Returns the document layout for this document.

See also setDocumentLayout().

void QTextDocument::documentLayoutChanged ()   [signal]

This signal is emitted when a new document layout is set.

This function was introduced in Qt 4.4.

See also setDocumentLayout().

void QTextDocument::drawContents ( QPainter * p, const QRectF & rect = QRectF() )

Draws the content of the document with painter p, clipped to rect. If rect is a null rectangle (default) then the document is painted unclipped.

This function was introduced in Qt 4.2.

QTextBlock QTextDocument::end () const

This function returns a block to test for the end of the document while iterating over it.

     for (QTextBlock it = doc->begin(); it != doc->end(); it = it.next())
         cout << it.text().toStdString() << endl;

The block returned is invalid and represents the block after the last block in the document. You can use lastBlock() to retrieve the last valid block of the document.

See also lastBlock().

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

Finds the next occurrence of the string, subString, 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 subString 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 QRegExp & expr, const QTextCursor & cursor, FindFlags options = 0 ) const

This is an overloaded member function, provided for convenience.

Finds the next occurrence, matching the regular expression, 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. The FindCaseSensitively option is ignored for this overload, use QRegExp::caseSensitivity instead.

Returns a cursor with the match selected if a match 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 & subString, int position = 0, FindFlags options = 0 ) const

This is an overloaded member function, provided for convenience.

Finds the next occurrence of the string, subString, 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 subString 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.

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

This is an overloaded member function, provided for convenience.

Finds the next occurrence, matching the regular expression, 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. The FindCaseSensitively option is ignored for this overload, use QRegExp::caseSensitivity instead.

Returns a cursor with the match selected if a match 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.

QTextBlock QTextDocument::findBlockByNumber ( int blockNumber ) const

Returns the text block with the specified blockNumber.

This function was introduced in Qt 4.4.

See also QTextBlock::blockNumber().

QTextBlock QTextDocument::firstBlock () const

Returns the document's first text block.

This function was introduced in Qt 4.4.

qreal QTextDocument::idealWidth () const

Returns the ideal width of the text document. The ideal width is the actually used width of the document without optional alignments taken into account. It is always <= size().width().

This function was introduced in Qt 4.2.

See also adjustSize() and textWidth.

bool QTextDocument::isEmpty () const

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

bool QTextDocument::isRedoAvailable () const

Returns true if redo is available; otherwise returns false.

bool QTextDocument::isUndoAvailable () const

Returns true if undo is available; otherwise returns false.

QTextBlock QTextDocument::lastBlock () const

Returns the document's last (valid) text block.

This function was introduced in Qt 4.4.

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 laid 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, 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.

If the document is already paginated through a specified height in the pageSize() property it is printed as-is.

If the document is not paginated, like for example a document used in a QTextEdit, then a temporary copy of the document is created and the copy is broken into multiple pages according to the size of the QPrinter's paperRect(). By default a 2 cm margin is set around the document contents. In addition the current page number is printed at the bottom of each page.

Note that QPrinter::Selection is not supported as print range with this function since the selection is a property of QTextCursor. If you have a QTextEdit associated with your QTextDocument then you can use QTextEdit's print() function because QTextEdit has access to the user's selection.

See also QTextEdit::print().

void QTextDocument::redo ( QTextCursor * cursor )

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

The provided cursor is positioned at the end of the location where the edition operation was redone.

This function was introduced in Qt 4.2.

void QTextDocument::redo ()   [slot]

This is an overloaded member function, provided for convenience.

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.

int QTextDocument::revision () const

Returns the document's revision (if undo is enabled).

The revision is guaranteed to increase when a document that is not modified is edited.

This function was introduced in Qt 4.4.

See also QTextBlock::revision() and isModified().

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 documentLayoutChanged().

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".

Note: It is the responsibility of the caller to make sure that the text is correctly decoded when a QString containing HTML is created and passed to setHtml().

See also setPlainText() and Supported HTML Subset.

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.

See also Supported HTML Subset.

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 ( QTextCursor * cursor )

Undoes the last editing operation on the document if undo is available. The provided cursor is positioned at the end of the location where the edition operation was undone.

See the Qt Undo Framework documentation for details.

This function was introduced in Qt 4.2.

See also undoAvailable() and isUndoRedoEnabled().

void QTextDocument::undo ()   [slot]

This is an overloaded member function, provided for convenience.

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

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

See the Qt Undo Framework documentation for details.

See also undo() and isUndoRedoEnabled().

void QTextDocument::undoCommandAdded ()   [signal]

This signal is emitted every time a new level of undo is added to the QTextDocument.

This function was introduced in Qt 4.4.