Supported HTML Subset

Describes the support for HTML markup in text widgets.

Qt’s text widgets are able to display rich text, specified using a subset of HTML 4 markup. Widgets that use QTextDocument , such as QLabel and QTextEdit, are able to display rich text specified in this way.

Using HTML Markup in Text Widgets

Widgets automatically detect HTML markup and display rich text accordingly. For example, setting a label’s text property with the string "<b>Hello</b> <i>Qt!</i>" will result in the label displaying text like this: Hello Qt!

When HTML markup is used for text, Qt follows the rules defined by the HTML 4 specification. This includes default properties for text layout, such as the direction of the text flow (left-to-right) which can be changed by applying the dir :ref:` <Supported-HTML-Subset>` attribute to blocks of text.

Supported Tags

The following table lists the HTML tags supported by Qt’s rich text engine.

Note

The functionality implemented for tags listed below is a subset of the full HTML 4 specification. Not all attributes are supported, see comments for each tag.

Tag	Description	Comment
a	Anchor or link	Supports the href and name attributes.
address	Address
b	Bold
big	Larger font
blockquote	Indented paragraph
body	Document body	Supports the bgcolor attribute, which can be a Qt color name or a #RRGGBB color specification.
br	Line break
center	Centered paragraph
cite	Inline citation	Same as i.
code	Code	Same as tt.
dd	Definition data
dfn	Definition	Same as i.
div	Document division	Supports the standard block attributes .
dl	Definition list	Supports the standard block attributes .
dt	Definition term	Supports the standard block attributes .
em	Emphasized	Same as i.
font	Font size, family, and/or color	Supports the following attributes: size, face, and color (Qt color names or #RRGGBB).
h1	Level 1 heading	Supports the standard block attributes .
h2	Level 2 heading	Supports the standard block attributes .
h3	Level 3 heading	Supports the standard block attributes .
h4	Level 4 heading	Supports the standard block attributes .
h5	Level 5 heading	Supports the standard block attributes .
h6	Level 6 heading	Supports the standard block attributes .
head	Document header
hr	Horizontal line	Supports the width attribute, which can be specified as an absolute or relative (%) value.
html	HTML document
i	Italic
img	Image	Supports the src, source (for Qt 3 compatibility), width, and height attributes.
kbd	User-entered text
meta	Meta-information	If a text encoding is specified using the meta tag, it is picked up by Qt::codecForHtml(). Likewise, if an encoding is specified to toHtml() , the encoding is stored using a meta tag, for example: <meta http-equiv="Content-Type" content="text/html; charset=EUC-JP" />
li	List item
nobr	Non-breakable text
ol	Ordered list	Supports the standard list attributes .
p	Paragraph	Left-aligned by default. Supports the standard block attributes .
pre	Preformated text
qt	Qt rich-text document	Synonym for html. Provided for compatibility with earlier versions of Qt.
s	Strikethrough
samp	Sample code	Same as tt.
small	Small font
span	Grouped elements
strong	Strong	Same as b.
sub	Subscript
sup	Superscript
table	Table	Supports the following attributes: border, bgcolor (Qt color names or #RRGGBB), cellspacing, cellpadding, width (absolute or relative), and height.
tbody	Table body	Does nothing.
td	Table data cell	Supports the standard table cell attributes .
tfoot	Table footer	Does nothing.
th	Table header cell	Supports the standard table cell attributes .
thead	Table header	If the thead tag is specified, it is used when printing tables that span multiple pages.
title	Document title	The value specified using the title tag is available through metaInformation() .
tr	Table row	Supports the bgcolor attribute, which can be a Qt color name or a #RRGGBB color specification.
tt	Typewrite font
u	Underlined
ul	Unordered list	Supports the standard list attributes .
var	Variable	Same as i.

Block Attributes

The following attributes are supported by the div, dl, dt, h1, h2, h3, h4, h5, h6, p tags:

• align (left, right, center, justify)

• dir (ltr, rtl)

List Attributes

The following attribute is supported by the ol and ul tags:

• type (1, a, A, square, disc, circle)

Table Cell Attributes

The following attributes are supported by the td and th tags:

• width (absolute, relative, or no-value)

• bgcolor (Qt color names or #RRGGBB)

• colspan

• rowspan

• align (left, right, center, justify)

• valign (top, middle, bottom)

CSS Properties

The following table lists the CSS properties supported by Qt’s rich text engine:

Property	Values	Description
background-color	<color>	Background color for elements
background-image	<uri>	Background image for elements
color	<color>	Text foreground color
font-family	<family name>	Font family name
font-size	[ small | medium | large | x-large | xx-large ] | <size>pt | <size>px	Font size relative to the document font, or specified in points or pixels
font-style	[ normal | italic | oblique ]
font-weight	[ normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 ]	Specifies the font weight used for text, where normal and bold are mapped to the corresponding QFont weights. Numeric values are 8 times the equivalent QFont weight values.
text-decoration	none | [ underline || overline || line-through ]	Additional text effects
font	[ [ <’font-style’> || <’font-weight’> ]? <’font-size’> <’font-family’> ]	Font shorthand property
text-indent	<length>px	First line text indentation in pixels
white-space	normal | pre | nowrap | pre-wrap	Declares how whitespace in HTML is handled.
margin-top	<length>px	Top paragraph margin in pixels
margin-bottom	<length>px	Bottom paragraph margin in pixels
margin-left	<length>px	Left paragraph margin in pixels
margin-right	<length>px	Right paragraph margin in pixels
padding-top	<length>px	Top table cell padding in pixels
padding-bottom	<length>px	Bottom table cell padding in pixels
padding-left	<length>px	Left table cell padding in pixels
padding-right	<length>px	Right table cell padding in pixels
padding	<length>px	Shorthand for setting all the padding properties at once.
vertical-align	baseline | sub | super | middle | top | bottom	Vertical text alignment. For vertical alignment in text table cells only middle, top, and bottom apply.
border-collapse	collapse | separate	Border Collapse mode for text tables. If set to collapse, cell-spacing will not be applied.
border-color	<color>	Border color for text tables and table cells.
border-top-color	<color>	Top border color for table cells.
border-bottom-color	<color>	Bottom border color for table cells.
border-left-color	<color>	Left border color for table cells.
border-right-color	<color>	Right border color for table cells.
border-style	none | dotted | dashed | dot-dash | dot-dot-dash | solid | double | groove | ridge | inset | outset	Border style for text tables and table cells.
border-top-style	<border-style>	Top border style for table cells.
border-bottom-style	<border-style>	Bottom border style for table cells.
border-left-style	<border-style>	Left border style for table cells.
border-right-style	<border-style>	Right border style for table cells.
border-width	<width>px	Width of table or cell border
border-top-width	<length>px	Top border width for table cells.
border-bottom-width	<length>px	Bottom border width for table cells.
border-left-width	<length>px	Left border width for table cells.
border-right-width	<length>px	Right border width for table cells.
border-top	<width>px <border-style> <border-color>	Shorthand for setting top border width, style and color
border-bottom	<width>px <border-style> <border-color>	Shorthand for setting bottom border width, style and color
border-left	<width>px <border-style> <border-color>	Shorthand for setting left border width, style and color
border-right	<width>px <border-style> <border-color>	Shorthand for setting right border width, style and color
border-top	<width>px <border-style> <border-color>	Shorthand for setting top border width, style and color
border-bottom	<width>px <border-style> <border-color>	Shorthand for setting bottom border width, style and color
border	<width>px <border-style> <border-color>	Shorthand for setting all four border’s width, style and color
background	[ <’background-color’> || <’background-image’> ]	Background shorthand property
page-break-before	[ auto | always ]	Make it possible to enforce a page break before the paragraph/table
page-break-after	[ auto | always ]	Make it possible to enforce a page break after the paragraph/table
float	[ left | right | none ]	Specifies where an image or a text will be placed in another element. Note that the float property is only supported for tables and images.
text-transform	[ uppercase | lowercase ]	Select the transformation that will be performed on the text prior to displaying it.
font-kerning	[ normal | none ]	Enables or disables kerning between text characters.
font-variant	small-caps	Perform the smallcaps transformation on the text prior to displaying it.
word-spacing	<width>px	Specifies an alternate spacing between each word.
line-height	<number>[% | px | pt | cm]	Specifies the height of a line. It can be one of the following: fixed line height in pixels, points, or centimeters. a percentage of the current font size.

Qt-specific CSS properties

Besides the standard CSS properties listed earlier, the following Qt-specific properties can also be used to style a text block:

Property	Values	Description
-qt-block-indent	<number>	Indents the text block by the specified no. spaces.
-qt-list-indent	<number>	Indents the list items by the specified no. of spaces.
-qt-list-number-prefix	<string>	Prefixes the given string to list number in an HTML ordered list.
-qt-list-number-suffix	<string>	Suffixes the given string to list number in an HTML ordered list.
-qt-paragraph-type	empty	Hides the text block.
-qt-table-type	root | frame	root renders the text blocks inline without borders and indentation, whereas frame renders them on a new line with a frame around.
-qt-user-state	<number>	Adds it as user data for the text block.

Supported CSS Selectors

All CSS 2.1 selector classes are supported except pseudo-class selectors such as :first-child, :visited and :hover.