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.

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.

TagDescriptionComment
aAnchor or linkSupports the href and name attributes.
addressAddress
bBold
bigLarger font
blockquoteIndented paragraph
bodyDocument bodySupports the bgcolor attribute, which can be a Qt color name or a #RRGGBB color specification.
brLine break
centerCentered paragraph
citeInline citationSame as i.
codeCodeSame as tt.
ddDefinition data
dfnDefinitionSame as i.
divDocument divisionSupports the standard block attributes.
dlDefinition listSupports the standard block attributes.
dtDefinition termSupports the standard block attributes.
emEmphasizedSame as i.
fontFont size, family, and/or colorSupports the following attributes: size, face, and color (Qt color names or #RRGGBB).
h1Level 1 headingSupports the standard block attributes.
h2Level 2 headingSupports the standard block attributes.
h3Level 3 headingSupports the standard block attributes.
h4Level 4 headingSupports the standard block attributes.
h5Level 5 headingSupports the standard block attributes.
h6Level 6 headingSupports the standard block attributes.
headDocument header
hrHorizontal lineSupports the width attribute, which can be specified as an absolute or relative (%) value.
htmlHTML document
iItalic
imgImageSupports the src, source (for Qt 3 compatibility), width, and height attributes.
kbdUser-entered text
metaMeta-informationIf 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" />
liList item
nobrNon-breakable text
olOrdered listSupports the standard list attributes.
pParagraphLeft-aligned by default. Supports the standard block attributes.
prePreformated text
qtQt rich-text documentSynonym for html. Provided for compatibility with earlier versions of Qt.
sStrikethrough
sampSample codeSame as tt.
smallSmall font
spanGrouped elements
strongStrongSame as b.
subSubscript
supSuperscript
tableTableSupports the following attributes: border, bgcolor (Qt color names or #RRGGBB), cellspacing, cellpadding, width (absolute or relative), and height.
tbodyTable bodyDoes nothing.
tdTable data cellSupports the standard table cell attributes.
tfootTable footerDoes nothing.
thTable header cellSupports the standard table cell attributes.
theadTable headerIf the thead tag is specified, it is used when printing tables that span multiple pages.
titleDocument titleThe value specified using the title tag is available through QTextDocument::metaInformation().
trTable rowSupports the bgcolor attribute, which can be a Qt color name or a #RRGGBB color specification.
ttTypewrite font
uUnderlined
ulUnordered listSupports the standard list attributes.
varVariableSame 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:

PropertyValuesDescription
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>pxFont 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-decorationnone | [ underline || overline || line-through ]Additional text effects
font[ [ <'font-style'> || <'font-weight'> ]? <'font-size'> <'font-family'> ]Font shorthand property
text-indent<length>pxFirst line text indentation in pixels
white-spacenormal | pre | nowrap | pre-wrapDeclares how whitespace in HTML is handled.
margin-top<length>pxTop paragraph margin in pixels
margin-bottom<length>pxBottom paragraph margin in pixels
margin-left<length>pxLeft paragraph margin in pixels
margin-right<length>pxRight paragraph margin in pixels
padding-top<length>pxTop table cell padding in pixels
padding-bottom<length>pxBottom table cell padding in pixels
padding-left<length>pxLeft table cell padding in pixels
padding-right<length>pxRight table cell padding in pixels
padding<length>pxShorthand for setting all the padding properties at once.
vertical-alignbaseline | sub | super | middle | top | bottomVertical text alignment. For vertical alignment in text table cells only middle, top, and bottom apply.
border-collapsecollapse | separateBorder 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-stylenone | dotted | dashed | dot-dash | dot-dot-dash | solid | double | groove | ridge | inset | outsetBorder 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>pxWidth of table or cell border
border-top-width<length>pxTop border width for table cells.
border-bottom-width<length>pxBottom border width for table cells.
border-left-width<length>pxLeft border width for table cells.
border-right-width<length>pxRight 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-variantsmall-capsPerform the smallcaps transformation on the text prior to displaying it.
word-spacing<width>pxSpecifies 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:

PropertyValuesDescription
-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-typeemptyHides the text block.
-qt-table-typeroot | frameroot 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.

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