forked from AuroraMiddleware/gtk
80 lines
4.4 KiB
Markdown
80 lines
4.4 KiB
Markdown
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# CSS in GTK {#css}
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This chapter describes how GTK uses CSS for styling and layout.
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It is not meant to be an explanation of CSS from first principles,
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but focuses on listing supported CSS features and differences
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between Web CSS and GTK.
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There is plenty of introductory documentation available that
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can be used to learn about CSS in general. In the tables below
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we include links to the official specs that can be used to look
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up the definition of individual selectors and properties.
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## CSS nodes
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GTK applies the style information found in style sheets by matching
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the selectors against a tree of nodes. Each node in the tree has a
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name, a state and possibly style classes. The children of each node
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are linearly ordered.
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Every widget has one or more of these CSS nodes, and determines their
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name, state, style classes and how they are layed out as children and
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siblings in the overall node tree. The documentation for each widget
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explains what CSS nodes it has.
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### The CSS nodes of a GtkScale
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```
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scale[.fine-tune]
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├── marks.top
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│ ├── mark
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┊ ┊
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│ ╰── mark
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├── trough
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│ ├── slider
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│ ├── [highlight]
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│ ╰── [fill]
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╰── marks.bottom
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├── mark
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┊
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╰── mark
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```
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## Selectors
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Selectors work very similar to the way they do on the web.
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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
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with a period. Widget names can be used in selectors like IDs. When used
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in a selector, widget names must be prefixed with a # character.
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### GTK CSS Selectors
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| Pattern | Reference | Notes |
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|:--------|:----------|:------|
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| * | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#universal-selector) | |
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| E | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#type-selectors) | |
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| E.class | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#class-html) | |
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| E#id | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#id-selectors) | |
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| E:nth-child(n) | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#structural-pseudos) | |
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| E:nth-last-child(n) | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#structural-pseudos) | |
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| E:first-child | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#structural-pseudos) | |
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| E:last-child | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#structural-pseudos) | |
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| E:only-child | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#structural-pseudos) | |
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| E:link, E:visited | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#link) | Corresponds to GTK_STATE_FLAG_LINK and GTK_STATE_FLAGS_VISITED |
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| E:active, E:hover, E:focus | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#useraction-pseudos) | Correspond to GTK_STATE_FLAG_ACTIVE, GTK_STATE_FLAG_PRELIGHT, GTK_STATE_FLAGS_FOCUSED |
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| E:focus-within | [CSS Selector Level 4](https://drafts.csswg.org/selectors/#focus-within-pseudo) | Set on all ancestors of the focus widget, unlike CSS |
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| E:focus-visible | [CSS Selector Level 4](https://drafts.csswg.org/selectors/#focus-within-pseudo) | Set on focus widget and all ancestors, unlike CSS |
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| E:disabled | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#UIstates) | Corresponds to GTK_STATE_FLAG_INSENSITIVE |
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| E:disabled | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#UIstates) | Corresponds to GTK_STATE_FLAG_CHECKED |
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| E:indeterminate | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#indeterminate) | Corresponds to GTK_STATE_FLAG_INCONSISTENT |
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| E:backdrop, E:selected | | Corresponds to GTK_STATE_FLAG_BACKDROP, GTK_STATE_FLAG_SELECTED |
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| E:not(selector) | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#negation) | |
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| E:dir(ltr), E:dir(rtl) | [CSS Selector Level 4](https://drafts.csswg.org/selectors/#the-dir-pseudo) | |
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| E:drop(active) | [CSS Selector Level 4](https://drafts.csswg.org/selectors/#drag-pseudos) | |
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| E F | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#descendent-combinators) | |
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| E > F | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#child-combinators) | |
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| E ~ F | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#general-sibling-combinators) | |
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| E + F | [CSS Selector Level 3](https://www.w3.org/TR/css3-selectors/#adjacent-sibling-combinators) | |
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