QTextDocument Class
The QTextDocument class holds formatted text. More...
| Header: | #include <QTextDocument> |
| qmake: | QT += gui |
| Inherits: | QObject |
Note: All functions in this class are reentrant.
Public Types
| enum | FindFlag { FindBackward, FindCaseSensitively, FindWholeWords } |
| enum | MetaInformation { DocumentTitle, DocumentUrl } |
| enum | ResourceType { UnknownResource, HtmlResource, ImageResource, StyleSheetResource, MarkdownResource, UserResource } |
| enum | Stacks { UndoStack, RedoStack, UndoAndRedoStacks } |
Properties
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Public Functions
| QUrl | baseUrl() const |
| int | blockCount() const |
| QFont | defaultFont() const |
| QString | defaultStyleSheet() const |
| QTextOption | defaultTextOption() const |
| qreal | documentMargin() const |
| qreal | indentWidth() const |
| bool | isModified() const |
| bool | isUndoRedoEnabled() const |
| int | maximumBlockCount() const |
| QSizeF | pageSize() const |
| void | setBaseUrl(const QUrl &url) |
| void | setDefaultFont(const QFont &font) |
| void | setDefaultStyleSheet(const QString &sheet) |
| void | setDefaultTextOption(const QTextOption &option) |
| void | setDocumentMargin(qreal margin) |
| void | setIndentWidth(qreal width) |
| void | setMaximumBlockCount(int maximum) |
| void | setPageSize(const QSizeF &size) |
| void | setTextWidth(qreal width) |
| void | setUndoRedoEnabled(bool enable) |
| void | setUseDesignMetrics(bool b) |
| QSizeF | size() const |
| qreal | textWidth() const |
| bool | useDesignMetrics() const |
Public Slots
| void | setModified(bool m = true) |
Signals
| void | baseUrlChanged(const QUrl &url) |
Detailed Description
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 and other meta-information can be obtained by calling the metaInformation() function. For documents that are exposed to users through the QTextEdit class, the document title is also available via the QTextEdit::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. The following are the undo/redo operations of a QTextDocument:
- Insertion or removal of characters. A sequence of insertions or removals within the same text block are regarded as a single undo/redo operation.
- Insertion or removal of text blocks. Sequences of insertion or removals in a single operation (e.g., by selecting and then deleting text) are regarded as a single undo/redo operation.
- Text character format changes.
- Text block format changes.
- Text block group format changes.
See also QTextCursor, QTextEdit, Rich Text Processing, and Text Object Example.
Member Type Documentation
enum QTextDocument::FindFlag
This enum describes the options available to QTextDocument's find function. The options can be OR-ed together from the following list:
| Constant | Value | Description |
|---|---|---|
QTextDocument::FindBackward | 0x00001 | Search backwards instead of forwards. |
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. |
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. |
QTextDocument::DocumentUrl | 1 | The url of the document. The loadResource() function uses this url as the base when loading relative resources. |
See also metaInformation() and setMetaInformation().
enum QTextDocument::ResourceType
This enum describes the types of resources that can be loaded by QTextDocument's loadResource() function or by QTextBrowser::setSource().
| Constant | Value | Description |
|---|---|---|
QTextDocument::UnknownResource | 0 | No resource is loaded, or the resource type is not known. |
QTextDocument::HtmlResource | 1 | The resource contains HTML. |
QTextDocument::ImageResource | 2 | The resource contains image data. Currently supported data types are QVariant::Pixmap and QVariant::Image. If the corresponding variant is of type QVariant::ByteArray then Qt attempts to load the image using QImage::loadFromData. QVariant::Icon is currently not supported. The icon needs to be converted to one of the supported types first, for example using QIcon::pixmap. |
QTextDocument::StyleSheetResource | 3 | The resource contains CSS. |
QTextDocument::MarkdownResource | 4 | The resource contains Markdown. |
QTextDocument::UserResource | 100 | The first available value for user defined resource types. |
See also loadResource() and QTextBrowser::sourceType().
enum QTextDocument::Stacks
| Constant | Value | Description |
|---|---|---|
QTextDocument::UndoStack | 0x01 | The undo stack. |
QTextDocument::RedoStack | 0x02 | The redo stack. |
QTextDocument::UndoAndRedoStacks | UndoStack | RedoStack | Both the undo and redo stacks. |
Property Documentation
baseUrl : QUrl
This property holds the base URL used to resolve relative resource URLs within the document.
Resource URLs are resolved to be within the same directory as the target of the base URL meaning any portion of the path after the last '/' will be ignored.
| Base URL | Relative URL | Resolved URL |
|---|---|---|
| file:///path/to/content | images/logo.png | file:///path/to/images/logo.png |
| file:///path/to/content/ | images/logo.png | file:///path/to/content/images/logo.png |
| file:///path/to/content/index.html | images/logo.png | file:///path/to/content/images/logo.png |
| file:///path/to/content/images/ | ../images/logo.png | file:///path/to/content/images/logo.png |
This property was introduced in Qt 5.3.
Access functions:
| QUrl | baseUrl() const |
| void | setBaseUrl(const QUrl &url) |
Notifier signal:
| void | baseUrlChanged(const QUrl &url) |
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 |
See also lineCount() and characterCount().
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) |
documentMargin : qreal
The margin around the document. The default is 4.
This property was introduced in Qt 4.5.
Access functions:
| qreal | documentMargin() const |
| void | setDocumentMargin(qreal margin) |
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
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
The units are determined by the underlying paint device. The size is measured in logical pixels when painting to the screen, and in points (1/72 inch) when painting to a printer.
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.
Using design metrics makes a layout have a width that is no longer dependent on hinting and pixel-rounding. This means that WYSIWYG text layout becomes possible because the width scales much more linearly based on paintdevice metrics than it would otherwise.
By default, this property is false.
This property was introduced in Qt 4.1.
Access functions:
| bool | useDesignMetrics() const |
| void | setUseDesignMetrics(bool b) |