forked from AuroraMiddleware/gtk
d7b175a3fb
Commit b52966a318 stopped the parser from
handling various deprecated pseudoclasses, which were aliases of others,
but it did not update the documentation to reflect that they were gone.
965 lines
33 KiB
XML
965 lines
33 KiB
XML
<?xml version="1.0"?>
|
||
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
|
||
"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
|
||
]>
|
||
<refentry id="chap-css-overview">
|
||
<refmeta>
|
||
<refentrytitle>GTK+ CSS</refentrytitle>
|
||
<manvolnum>3</manvolnum>
|
||
<refmiscinfo>GTK Library</refmiscinfo>
|
||
</refmeta>
|
||
|
||
<refnamediv>
|
||
<refname>GTK+ CSS</refname>
|
||
<refpurpose>
|
||
Overview of CSS in GTK+
|
||
</refpurpose>
|
||
</refnamediv>
|
||
|
||
|
||
<!--
|
||
Formatting conventions:
|
||
We use
|
||
|
||
‑ U+2011 Non-breaking Hyphen
|
||
U+00A0 No-break Space
|
||
|
||
to control line breaks in the Name and Value columns.
|
||
We use
|
||
|
||
〈 U+2329 Left-pointing Angle Bracket
|
||
〉 U+232A Right-pointing Angle Bracket
|
||
|
||
for indicating non-terminals in syntax productions.
|
||
|
||
We use <literallayout> for syntax productions, and each line is put in a <code>
|
||
(the latter is a workaround for deficiences in the developer.gnome.org post-processing).
|
||
-->
|
||
|
||
<refsect1 id="css-overview">
|
||
<title>Overview of CSS in GTK+</title>
|
||
|
||
<para>
|
||
This chapter describes in detail how GTK+ uses CSS for styling
|
||
and layout.
|
||
</para>
|
||
|
||
<para>
|
||
We loosely follow the CSS
|
||
<ulink url="https://www.w3.org/TR/css-values/#value-defs">value definition</ulink>
|
||
specification in the formatting of syntax productions.
|
||
<simplelist>
|
||
<member>Nonterminals are enclosed in angle backets (〈〉), all other strings that are not listed here are literals</member>
|
||
<member>Juxtaposition means all components must occur, in the given order</member>
|
||
<member>A double ampersand (&&) means all components must occur, in any order</member>
|
||
<member>A double bar (||) means one or more of the components must occur, in any order</member>
|
||
<member>A single bar (|) indicates an alternative; exactly one of the components must occur</member>
|
||
<member>Brackets ([]) are used for grouping</member>
|
||
<member>A question mark (?) means that the preceding component is optional</member>
|
||
<member>An asterisk (*) means zero or more copies of the preceding component</member>
|
||
<member>A plus (+) means one or more copies of the preceding component</member>
|
||
<member>A number in curly braces ({n}) means that the preceding component occurs exactly n times</member>
|
||
<member>Two numbers in curly braces ({m,n}) mean that the preceding component occurs at least m times and at most n times</member>
|
||
</simplelist>
|
||
</para>
|
||
|
||
<refsect2>
|
||
<title>CSS nodes</title>
|
||
|
||
<para>
|
||
GTK+ applies the style information found in style sheets by matching
|
||
the selectors against a tree of nodes. Each node in the tree has a
|
||
name, a state and possibly style classes. The children of each node
|
||
are linearly ordered.
|
||
</para>
|
||
|
||
<para>
|
||
Every widget has one or more of these CSS nodes, and determines their
|
||
name, state, style classes and how they are layed out as children and
|
||
siblings in the overall node tree. The documentation for each widget
|
||
explains what CSS nodes it has.
|
||
</para>
|
||
|
||
<example>
|
||
<title>The CSS nodes of a GtkScale</title>
|
||
<programlisting><![CDATA[
|
||
scale[.fine-tune]
|
||
├── marks.top
|
||
│ ├── mark
|
||
┊ ┊
|
||
│ ╰── mark
|
||
├── trough
|
||
│ ├── slider
|
||
│ ├── [highlight]
|
||
│ ╰── [fill]
|
||
╰── marks.bottom
|
||
├── mark
|
||
┊
|
||
╰── mark
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Style sheets</title>
|
||
|
||
<para>
|
||
The basic structure of the style sheets understood by GTK+ is
|
||
a series of statements, which are either rule sets or “@-rules”,
|
||
separated by whitespace.
|
||
</para>
|
||
|
||
<para>
|
||
A rule set consists of a selector and a declaration block, which is
|
||
a series of declarations enclosed in curly braces. The declarations
|
||
are separated by semicolons. Multiple selectors can share the same
|
||
declaration block, by putting all the separators in front of the block,
|
||
separated by commas.
|
||
</para>
|
||
|
||
<example>
|
||
<title>A rule set with two selectors</title>
|
||
<programlisting><![CDATA[
|
||
button, entry {
|
||
color: #ff00ea;
|
||
font: Comic Sans 12
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Importing style sheets</title>
|
||
|
||
<para>
|
||
GTK+ supports the CSS @import rule, in order to load another
|
||
style sheet in addition to the currently parsed one.
|
||
</para>
|
||
|
||
<para>
|
||
The syntax for @import rules is as follows:
|
||
</para>
|
||
|
||
<literallayout><code>〈import rule〉 = @import [ 〈url〉 | 〈string〉] ;</code>
|
||
<code>〈url〉 = url( 〈string〉)</code>
|
||
</literallayout>
|
||
|
||
<example><title>An example for using the @import rule</title>
|
||
<programlisting><![CDATA[
|
||
@import url("path/to/common.css");
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
To learn more about the @import rule, you can read the
|
||
<ulink url="https://www.w3.org/TR/css3-cascade/#at-import">Cascading</ulink>
|
||
module of the CSS specification.
|
||
</para>
|
||
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Selectors</title>
|
||
|
||
<para>
|
||
Selectors work very similar to the way they do in CSS.
|
||
</para>
|
||
|
||
<para>
|
||
All widgets have one or more CSS nodes with element names and style
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||
classes. When style classes are used in selectors, they have to be prefixed
|
||
with a period. Widget names can be used in selectors like IDs. When used
|
||
in a selector, widget names must be prefixed with a # character.
|
||
</para>
|
||
|
||
<para>
|
||
In more complicated situations, selectors can be combined in various ways.
|
||
To require that a node satisfies several conditions, combine several selectors
|
||
into one by concatenating them. To only match a node when it occurs inside some
|
||
other node, write the two selectors after each other, separated by whitespace.
|
||
To restrict the match to direct children of the parent node, insert a >
|
||
character between the two selectors.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Theme labels that are descendants of a window</title>
|
||
<programlisting><![CDATA[
|
||
window label {
|
||
background-color: #898989
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme notebooks, and anything within</title>
|
||
<programlisting><![CDATA[
|
||
notebook {
|
||
background-color: #a939f0
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme combo boxes, and entries that are direct children of a notebook</title>
|
||
<programlisting><![CDATA[
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||
combobox,
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||
notebook > entry {
|
||
color: @fg_color;
|
||
background-color: #1209a2
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme any widget within a GtkBox</title>
|
||
<programlisting><![CDATA[
|
||
box * {
|
||
font: Sans 20
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme a label named title-label</title>
|
||
<programlisting><![CDATA[
|
||
label#title-label {
|
||
font: Sans 15
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme any widget named main-entry</title>
|
||
<programlisting><![CDATA[
|
||
#main-entry {
|
||
background-color: #f0a810
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme all widgets with the style class entry</title>
|
||
<programlisting><![CDATA[
|
||
.entry {
|
||
color: #39f1f9;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme the entry of a GtkSpinButton</title>
|
||
<programlisting><![CDATA[
|
||
spinbutton entry {
|
||
color: 900185;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
It is possible to select CSS nodes depending on their position amongst
|
||
their siblings by applying pseudo-classes to the selector, like :first-child,
|
||
:last-child or :nth-child(even). When used in selectors, pseudo-classes
|
||
must be prefixed with a : character.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Theme labels in the first notebook tab</title>
|
||
<programlisting><![CDATA[
|
||
notebook tab:first-child label {
|
||
color: #89d012;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
Another use of pseudo-classes is to match widgets depending on their
|
||
state. The available pseudo-classes for widget states are :active, :hover
|
||
:disabled, :selected, :focus, :indeterminate, :checked and :backdrop.
|
||
In addition, the following pseudo-classes don't have a direct equivalent
|
||
as a widget state: :dir(ltr) and :dir(rtl) (for text direction), :link and
|
||
:visited (for links) and :drop(active) (for highlighting drop targets).
|
||
Widget state pseudo-classes may only apply to the last element in a selector.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Theme pressed buttons</title>
|
||
<programlisting><![CDATA[
|
||
button:active {
|
||
background-color: #0274d9;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme buttons with the mouse pointer over it</title>
|
||
<programlisting><![CDATA[
|
||
button:hover {
|
||
background-color: #3085a9;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme insensitive widgets</title>
|
||
<programlisting><![CDATA[
|
||
*:disabled {
|
||
background-color: #320a91;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme checkbuttons that are checked</title>
|
||
<programlisting><![CDATA[
|
||
checkbutton:checked {
|
||
background-color: #56f9a0;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme focused labels</title>
|
||
<programlisting><![CDATA[
|
||
label:focus {
|
||
background-color: #b4940f;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Theme indeterminate checkbuttons</title>
|
||
<programlisting><![CDATA[
|
||
checkbutton:indeterminate {
|
||
background-color: #20395a;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
To determine the effective style for a widget, all the matching rule
|
||
sets are merged. As in CSS, rules apply by specificity, so the rules
|
||
whose selectors more closely match a node will take precedence
|
||
over the others.
|
||
</para>
|
||
|
||
<para>
|
||
The full syntax for selectors understood by GTK+ can be found in the
|
||
table below. The main difference to CSS is that GTK+ does not currently
|
||
support attribute selectors.
|
||
</para>
|
||
|
||
<table>
|
||
<title>Selector syntax</title>
|
||
<tgroup cols="4">
|
||
<thead>
|
||
<row><entry>Pattern</entry><entry>Matches</entry><entry>Reference</entry><entry>Notes</entry></row>
|
||
</thead>
|
||
<tbody>
|
||
<row>
|
||
<entry>*</entry>
|
||
<entry>any node</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#universal-selector">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E</entry>
|
||
<entry>any node with name E</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#type-selectors">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E.class</entry>
|
||
<entry>any E node with the given style class</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#class-html">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E#id</entry>
|
||
<entry>any E node with the given ID</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#id-selectors">CSS</ulink></entry>
|
||
<entry>GTK+ uses the widget name as ID</entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:nth‑child(〈nth‑child〉)</entry>
|
||
<entry>any E node which is the n-th child of its parent node</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#structural-pseudos">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:nth‑last‑child(〈nth‑child〉)</entry>
|
||
<entry>any E node which is the n-th child of its parent node, counting from the end</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#structural-pseudos">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:first‑child</entry>
|
||
<entry>any E node which is the first child of its parent node</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#structural-pseudos">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:last‑child</entry>
|
||
<entry>any E node which is the last child of its parent node</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#structural-pseudos">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:only‑child</entry>
|
||
<entry>any E node which is the only child of its parent node</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#structural-pseudos">CSS</ulink></entry>
|
||
<entry>Equivalent to E:first-child:last-child</entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:link, E:visited</entry>
|
||
<entry>any E node which represents a hyperlink, not yet visited (:link) or already visited (:visited)</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#link">CSS</ulink></entry>
|
||
<entry>Corresponds to GTK_STATE_FLAG_LINK and GTK_STATE_FLAGS_VISITED</entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:active, E:hover, E:focus</entry>
|
||
<entry>any E node which is part of a widget with the corresponding state</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#useraction-pseudos">CSS</ulink></entry>
|
||
<entry>Correspond to GTK_STATE_FLAG_ACTIVE, GTK_STATE_FLAG_PRELIGHT and GTK_STATE_FLAGS_FOCUSED respectively</entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:disabled</entry>
|
||
<entry>any E node which is part of a widget which is disabled</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#UIstates">CSS</ulink></entry>
|
||
<entry>Corresponds to GTK_STATE_FLAG_INSENSITIVE</entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:checked</entry>
|
||
<entry>any E node which is part of a widget (e.g. radio- or checkbuttons) which is checked</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#UIstates">CSS</ulink></entry>
|
||
<entry>Corresponds to GTK_STATE_FLAG_CHECKED</entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:indeterminate</entry>
|
||
<entry>any E node which is part of a widget (e.g. radio- or checkbuttons) which is in an indeterminate state</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#indeterminate">CSS3</ulink>,
|
||
<ulink url="https://drafts.csswg.org/selectors/#indeterminate">CSS4</ulink></entry>
|
||
<entry>Corresponds to GTK_STATE_FLAG_INCONSISTENT</entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:backdrop, E:selected</entry>
|
||
<entry>any E node which is part of a widget with the corresponding state</entry>
|
||
<entry></entry>
|
||
<entry>Corresponds to GTK_STATE_FLAG_BACKDROP, GTK_STATE_FLAG_SELECTED</entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:not(〈selector〉)</entry>
|
||
<entry>any E node which does not match the simple selector 〈selector〉</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#negation">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:dir(ltr), E:dir(rtl)</entry>
|
||
<entry>any E node that has the corresponding text direction</entry>
|
||
<entry><ulink url="https://drafts.csswg.org/selectors/#the-dir-pseudo">CSS4</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E:drop(active)</entry>
|
||
<entry>any E node that is an active drop target for a current DND operation</entry>
|
||
<entry><ulink url="https://drafts.csswg.org/selectors/#drag-pseudos">CSS4</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E F</entry>
|
||
<entry>any F node which is a descendent of an E node</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#descendent-combinators">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E > F</entry>
|
||
<entry>any F node which is a child of an E node</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#child-combinators">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E ~ F</entry>
|
||
<entry>any F node which is preceded by an E node</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#general-sibling-combinators">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>E + F</entry>
|
||
<entry>any F node which is immediately preceded by an E node</entry>
|
||
<entry><ulink url="https://www.w3.org/TR/css3-selectors/#adjacent-sibling-combinators">CSS</ulink></entry>
|
||
<entry></entry>
|
||
</row>
|
||
</tbody>
|
||
</tgroup>
|
||
</table>
|
||
|
||
<literallayout><code>〈nth-child〉 = even | odd | 〈integer〉 | 〈integer〉n | 〈integer〉n [ + | - ] 〈integer〉</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
To learn more about selectors in CSS, read the
|
||
<ulink url="https://www.w3.org/TR/css3-selectors/">Selectors</ulink>
|
||
module of the CSS specification.
|
||
</para>
|
||
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Colors</title>
|
||
|
||
<para>
|
||
CSS allows to specify colors in various ways, using numeric
|
||
values or names from a predefined list of colors.
|
||
</para>
|
||
|
||
<literallayout><code>〈color〉 = currentColor | transparent | 〈color name〉 | 〈rgb color〉 | 〈rgba color〉 | 〈hex color〉 | 〈gtk color〉</code>
|
||
<code>〈rgb color 〉 = rgb( 〈number〉, 〈number〉, 〈number〉 ) | rgb( 〈percentage〉, 〈percentage〉, 〈percentage〉 )</code>
|
||
<code>〈rgba color 〉 = rgba(〈number〉, 〈number〉, 〈number〉, 〈alpha value〉) | rgba( 〈percentage〉, 〈percentage〉, 〈percentage〉, 〈alpha value〉 )</code>
|
||
<code>〈hex color〉 = #〈hex digits〉</code>
|
||
<code>〈alpha value〉 = 〈number〉</code>, clamped to values between 0 and 1
|
||
</literallayout>
|
||
|
||
<para>
|
||
The keyword currentColor resolves to the current value of the
|
||
color property when used in another property, and to the inherited value
|
||
of the color property when used in the color property itself.
|
||
</para>
|
||
|
||
<para>
|
||
The keyword transparent can be considered a shorthand for rgba(0,0,0,0).
|
||
</para>
|
||
|
||
<para>
|
||
For a list of valid color names and for more background on colors in
|
||
CSS, see the <ulink url="https://www.w3.org/TR/css3-color/#svg-color">Color</ulink>
|
||
module of the CSS specification.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Specifying colors in various ways</title>
|
||
<programlisting><![CDATA[
|
||
color: transparent;
|
||
background-color: red;
|
||
border-top-color: rgb(128,57,0);
|
||
border-left-color: rgba(10%,20%,30%,0.5);
|
||
border-right-color: #ff00cc;
|
||
border-bottom-color: #ffff0000cccc;
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
GTK+ adds several additional ways to specify colors.
|
||
</para>
|
||
|
||
<literallayout><code>〈gtk color〉 = 〈symbolic color〉 | 〈color expression〉| 〈win32 color〉</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
The first is a reference to a color defined via a @define-color rule.
|
||
The syntax for @define-color rules is as follows:
|
||
</para>
|
||
|
||
<literallayout><code>〈define color rule〉 = @define-color 〈name〉 〈color〉</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
To refer to the color defined by a @define-color rule,
|
||
use the name from the rule, prefixed with @.
|
||
</para>
|
||
|
||
<literallayout><code>〈symbolic color〉 = @〈name〉</code>
|
||
</literallayout>
|
||
|
||
<example><title>An example for defining colors</title>
|
||
<programlisting><![CDATA[
|
||
@define-color bg_color #f9a039;
|
||
|
||
* {
|
||
background-color: @bg_color;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
GTK+ also supports color expressions, which allow colors to be transformed
|
||
to new ones and can be nested, providing a rich language to define colors.
|
||
Color expressions resemble functions, taking 1 or more colors and in some
|
||
cases a number as arguments.
|
||
</para>
|
||
<para>
|
||
shade() leaves the color unchanged when the number is 1 and transforms it
|
||
to black or white as the number approaches 0 or 2 respectively. For mix(),
|
||
0 or 1 return the unaltered 1st or 2nd color respectively; numbers between
|
||
0 and 1 return blends of the two; and numbers below 0 or above 1 intensify
|
||
the RGB components of the 1st or 2nd color respectively. alpha() takes a
|
||
number from 0 to 1 and applies that as the opacity of the supplied color.
|
||
</para>
|
||
|
||
<literallayout><code>〈color expression〉 = lighter(〈color〉) | darker(〈color〉) | shade(〈color〉,〈number〉) | alpha(〈color〉,〈number〉) | mix(〈color〉,〈color〉,〈number〉)</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
On Windows, GTK+ allows to refer to system colors, as follows:
|
||
</para>
|
||
|
||
<literallayout><code>〈win32 color〉 = -gtk-win32-color( 〈name〉, 〈integer〉)</code>
|
||
</literallayout>
|
||
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Images</title>
|
||
|
||
<para>
|
||
CSS allows to specify images in various ways, for backgrounds
|
||
and borders.
|
||
</para>
|
||
|
||
<literallayout><code>〈image〉 = 〈url〉 | 〈crossfade〉 | 〈alternatives〉 | 〈gradient〉 | 〈gtk image〉</code>
|
||
<code>〈crossfade〉 = cross-fade( 〈percentage〉, 〈image〉, 〈image〉)</code>
|
||
<code>〈alternatives〉 = image([ 〈image〉, ]* [ 〈image〉 | 〈color〉 ])</code>
|
||
<code>〈gradient〉 = 〈linear gradient〉 | 〈radial gradient〉</code>
|
||
<code>〈linear gradient〉 = [ linear-gradient | repeating-linear-gradient ] (</code>
|
||
<code> [ [ 〈angle〉 | to 〈side or corner〉 ] , ]?</code>
|
||
<code> 〈color stops〉 )</code>
|
||
<code>〈radial gradient〉 = [ radial‑gradient | repeating‑radial‑gradient ] (</code>
|
||
<code> [ [ 〈shape〉 || 〈size〉 ] [ at 〈position〉 ]? , | at 〈position〉, ]?</code>
|
||
<code> 〈color stops〉 )</code>
|
||
<code>〈side or corner〉 = [ left | right ] || [ top | bottom ]</code>
|
||
<code>〈color stops〉 = 〈color stop〉 [ , 〈color stop〉]+</code>
|
||
<code>〈color stop〉 = 〈color〉 [ 〈percentage〉 | 〈length〉 ]?</code>
|
||
<code>〈shape〉 = circle | ellipse</code>
|
||
<code>〈size〉 = 〈extent keyword〉 | 〈length〉 | [ 〈length〉 | 〈percentage〉 ]{1,2}</code>
|
||
<code>〈extent keyword〉 = closest-size | farthest-side | closest-corner | farthest-corner</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
The simplest way to specify an image in CSS is to load an image
|
||
file from a URL. CSS does not specify anything about supported file
|
||
formats; within GTK+, you can expect at least PNG, JPEG and SVG to
|
||
work. The full list of supported image formats is determined by the
|
||
available gdk-pixbuf image loaders and may vary between systems.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Loading an image file</title>
|
||
<programlisting><![CDATA[
|
||
button {
|
||
background-image: url("water-lily.png");
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
A crossfade lets you specify an image as an intermediate between two
|
||
images. Crossfades are specified in the draft of the level 4
|
||
<ulink url="https://www.w3.org/TR/css4-images">Image</ulink>
|
||
module of the CSS specification.
|
||
</para>
|
||
|
||
<para>
|
||
</para>
|
||
|
||
<example>
|
||
<title>Crossfading two images</title>
|
||
<programlisting><![CDATA[
|
||
button {
|
||
background-image: cross-fade(50%, url("water-lily.png"), url("buffalo.jpg"));
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
The image() syntax provides a way to specify fallbacks in case an image
|
||
format may not be supported. Multiple fallback images can be specified,
|
||
and will be tried in turn until one can be loaded successfully. The
|
||
last fallback may be a color, which will be rendered as a solid color
|
||
image.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Image fallback</title>
|
||
<programlisting><![CDATA[
|
||
button {
|
||
background-image: image(url("fancy.svg"), url("plain.png"), green);
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
Gradients are images that smoothly fades from one color to another. CSS
|
||
provides ways to specify repeating and non-repeating linear and radial
|
||
gradients. Radial gradients can be circular, or axis-aligned ellipses.
|
||
</para>
|
||
|
||
<para>
|
||
A linear gradient is created by specifying a gradient line and then several
|
||
colors placed along that line. The gradient line may be specified using
|
||
an angle, or by using direction keywords.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Linear gradients</title>
|
||
<programlisting><![CDATA[
|
||
button {
|
||
background-image: linear-gradient(45deg, yellow, blue);
|
||
}
|
||
label {
|
||
background-image: linear-gradient(to top right, blue 20%, #f0f 80%);
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
A radial gradient is created by specifying a center point and one or two
|
||
radii. The radii may be given explicitly as lengths or percentages or
|
||
indirectly, by keywords that specify how the end circle or ellipsis
|
||
should be positioned relative to the area it is derawn in.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Radial gradients</title>
|
||
<programlisting><![CDATA[
|
||
button {
|
||
background-image: radial-gradient(ellipse at center, yellow 0%, green 100%);
|
||
}
|
||
label {
|
||
background-image: radial-gradient(circle farthest-side at left bottom, red, yellow 50px, green);
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
To learn more about gradients in CSS, including details of how color stops
|
||
are placed on the gradient line and keywords for specifying radial sizes,
|
||
you can read the
|
||
<ulink url="https://www.w3.org/TR/css3-images/#gradients">Image</ulink>
|
||
module of the CSS specification.
|
||
</para>
|
||
|
||
<para>
|
||
GTK+ extends the CSS syntax for images and also uses it for specifying icons.
|
||
</para>
|
||
|
||
<literallayout><code>〈gtk image〉 = 〈themed icon〉 | 〈scaled image〉 | 〈recolored image〉 | 〈win32 theme part〉</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
GTK+ has extensive support for loading icons from icon themes. It is
|
||
accessible from CSS with the -gtk-icontheme syntax.
|
||
</para>
|
||
|
||
<literallayout><code>〈themed icon〉 = -gtk-icontheme( 〈icon name〉 )</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
The specified icon name is used to look up a themed icon, while taking
|
||
into account the values of the -gtk-icon-theme and -gtk-icon-palette
|
||
properties. This kind of image is mainly used as value of the
|
||
-gtk-icon-source property.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Using themed icons in CSS</title>
|
||
<programlisting><![CDATA[
|
||
spinner {
|
||
-gtk-icon-source: -gtk-icontheme('process-working-symbolic');
|
||
-gtk-icon-palette: success blue, warning #fc3, error magenta;
|
||
}
|
||
arrow.fancy {
|
||
-gtk-icon-source: -gtk-icontheme('pan-down');
|
||
-gtk-icon-theme: 'Oxygen';
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
GTK+ supports scaled rendering on hi-resolution displays. This works
|
||
best if images can specify normal and hi-resolution variants. From
|
||
CSS, this can be done with the -gtk-scaled syntax.
|
||
</para>
|
||
|
||
<literallayout><code>〈scaled image〉 = -gtk-scaled( 〈image〉[, 〈image〉]* )</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
While -gtk-scaled accepts multiple higher-resolution variants, in
|
||
practice, it will mostly be used to specify a regular image and one
|
||
variant for scale 2.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Scaled images in CSS</title>
|
||
<programlisting><![CDATA[
|
||
arrow {
|
||
-gtk-icon-source: -gtk-scaled(url('my-arrow.png'),
|
||
url('my-arrow@2.png'));
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<literallayout><code>〈recolored image〉 = -gtk-recolor( 〈url〉[, 〈color palette〉] )</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
Symbolic icons from the icon theme are recolored according to the
|
||
-gtk-icon-palette property. The recoloring is sometimes needed for images
|
||
that are not part of an icon theme, and the -gtk-recolor syntax makes
|
||
this available. -gtk-recolor requires a url as first argument. The
|
||
remaining arguments specify the color palette to use. If the palette
|
||
is not explicitly specified, the current value of the -gtk-icon-palette
|
||
property is used.
|
||
</para>
|
||
|
||
<example>
|
||
<title>Recoloring an image</title>
|
||
<programlisting><![CDATA[
|
||
arrow {
|
||
-gtk-icon-source: -gtk-recolor(url('check.svg'), success blue, error rgb(255,0,0));
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
<para>
|
||
On Windows, GTK+ allows to refer to system theme parts as images, as follows:
|
||
</para>
|
||
|
||
<literallayout><code>〈win32 theme part〉 = -gtk-win32-theme-part( 〈name〉, 〈integer〉 〈integer〉</code>
|
||
<code> [, [ over( 〈integer〉 〈integer〉 [ , 〈alpha value〉]? ) | margins( 〈integer〉{1,4} ) ] ]* )</code>
|
||
</literallayout>
|
||
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Transitions</title>
|
||
|
||
<para>
|
||
CSS defines a mechanism by which changes in CSS property values can
|
||
be made to take effect gradually, instead of all at once. GTK+ supports
|
||
these transitions as well.
|
||
</para>
|
||
|
||
<para>
|
||
To enable a transition for a property when a rule set takes effect, it
|
||
needs to be listed in the transition-property property in that rule set.
|
||
Only animatable properties can be listed in the transition-property.
|
||
</para>
|
||
|
||
<para>
|
||
The details of a transition can modified with the transition-duration,
|
||
transition-timing-function and transition-delay properties.
|
||
</para>
|
||
|
||
<para>
|
||
To learn more about transitions, you can read the
|
||
<ulink url="www.w3.org/TR/css3-transitions/">Transitions</ulink>
|
||
module of the CSS specification.
|
||
</para>
|
||
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Animations</title>
|
||
|
||
<para>
|
||
In addition to transitions, which are triggered by changes of the underlying
|
||
node tree, CSS also supports defined animations. While transitions specify how
|
||
property values change from one value to a new value, animations explicitly
|
||
define intermediate property values in keyframes.
|
||
</para>
|
||
|
||
<para>
|
||
Keyframes are defined with an @-rule which contains one or more of rule sets
|
||
with special selectors. Property declarations for nonanimatable properties
|
||
are ignored in these rule sets (with the exception of animation properties).
|
||
</para>
|
||
|
||
<literallayout><code>〈keyframe rule〉 = @keyframes 〈name〉 { 〈animation rule〉 }</code>
|
||
<code>〈animation rule〉 = 〈animation selector〉 { 〈declaration〉* }</code>
|
||
<code>〈animation selector〉 = 〈single animation selector〉 [ , 〈single animation selector ]*</code>
|
||
<code>〈single animation selector〉 = from | to | 〈percentage〉</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
To enable an animation, the name of the keyframes must be set as the value
|
||
of the animation-name property. The details of the animation can modified
|
||
with the animation-duration, animation-timing-function, animation-iteration-count
|
||
and other animation properties.
|
||
</para>
|
||
|
||
<example>
|
||
<title>A CSS animation</title>
|
||
<programlisting><![CDATA[
|
||
@keyframes spin {
|
||
to { -gtk-icon-transform: rotate(1turn); }
|
||
}
|
||
|
||
spinner {
|
||
animation-name: spin;
|
||
animation-duration: 1s;
|
||
animation-timing-function: linear;
|
||
animation-iteration-count: infinite;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
<para>
|
||
To learn more about animations, you can read the
|
||
<ulink url="www.w3.org/TR/css3-animations/">Animations</ulink>
|
||
module of the CSS specification.
|
||
</para>
|
||
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Key bindings</title>
|
||
|
||
<para>
|
||
In order to extend key bindings affecting different widgets,
|
||
GTK+ supports the @binding-set rule to parse a set of bind/unbind
|
||
directives. Note that in order to take effect, the binding sets
|
||
defined in this way must be associated with rule sets by setting
|
||
the -gtk-key-bindings property.
|
||
</para>
|
||
|
||
<para>
|
||
The syntax for @binding-set rules is as follows:
|
||
</para>
|
||
|
||
<literallayout><code>〈binding set rule〉 = @binding-set 〈binding name〉{ [ [ 〈binding〉 | 〈unbinding〉] ; ]* }</code>
|
||
<code>〈binding〉 = bind "〈accelerator〉" { 〈signal emission〉* }</code>
|
||
<code>〈signal emission〉 = "〈signal name〉" ( [ 〈argument〉[ , 〈argument〉]* ]? }</code>
|
||
<code>〈unbinding〉 = unbind "〈accelerator〉" ;</code>
|
||
</literallayout>
|
||
|
||
<para>
|
||
where 〈accelerator〉 is a string that can be parsed by gtk_accelerator_parse(),
|
||
〈signal name〉 is the name of a keybinding signal of the widget in question,
|
||
and the 〈argument〉 list must be according to the signals declaration.
|
||
</para>
|
||
|
||
<example>
|
||
<title>An example for using the @binding-set rule</title>
|
||
<programlisting><![CDATA[
|
||
@binding-set binding-set1 {
|
||
bind "<alt>Left" { "move-cursor" (visual-positions, -3, 0) };
|
||
unbind "End";
|
||
};
|
||
|
||
@binding-set binding-set2 {
|
||
bind "<alt>Right" { "move-cursor" (visual-positions, 3, 0) };
|
||
bind "<alt>KP_space" { "delete-from-cursor" (whitespace, 1)
|
||
"insert-at-cursor" (" ") };
|
||
};
|
||
|
||
entry {
|
||
-gtk-key-bindings: binding-set1, binding-set2;
|
||
}
|
||
]]></programlisting>
|
||
</example>
|
||
|
||
</refsect2>
|
||
|
||
</refsect1>
|
||
</refentry>
|