Supported HTML Subset
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 attribute to blocks of text.
Supported Tags
The following table lists the HTML tags supported by Qt's rich text engine:
| 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 QTextDocument::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 QTextDocument::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)colspanrowspanalign(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:
|
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.