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66 строки
1.8 KiB
Plaintext
66 строки
1.8 KiB
Plaintext
Notes on DOM style support, or: Everything you ever wanted to know
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about Perignon, but managed to avoid asking.
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Data Structures:
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----------------
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Style data is represented by sets of disjoint trees, rooted on the
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innermost element type (simple selector). The sets are stored in a
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hash table. It's easier to understand with a picture, so here goes.
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Legend:
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-- ``enclosing''
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| ``sibling''
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(=...) ``rule''
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Style data:
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H1 { color:blue }
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H1 A { color:red }
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H1 B A { color:green }
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B A { color:purple }
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A:link { color:orange }
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.A { color:forclassA }
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A -- B (=color:purple) -- H1 (=color:green)
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| |
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| H1 (=color:red)
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A:link (=color:orange)
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.A (=color:forclassA)
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H1 (=color:blue)
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Note that there are no rules on the ``A'' selector. If the only rule
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in the sheet for ``A'' was the ``A:visited'' one, a dummy selector
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would be added, since the hash table is keyed on the pseudo-less
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selector.
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Classes (".H1") and IDs ("#H1") are chained in the sibling list with
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their like-named tags.
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A selector can correspond to a tag, class or id, depending on the
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value of the type field. If a class selector applies to the magic
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``all'' class, it will have no extra field. Otherwise, the extra
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field will be the tag selector. If a tag selector has an ID as well,
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it will be found in the extra field.
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JSSS:
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-----
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Perignon currently depends on JSSS to populate it, but someday I should
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implement DOM_StyleParseRule for the heathens that just use CSS.
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CSS2:
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-----
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I don't do CSS2 selectors yet. I don't yet know how much I care about
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that, because I don't yet know what CSS2 selectors are. =)
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Questions:
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----------
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- Do visited links get A:link properties as well? They don't appear to in
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the current implementation, but to my mind they should (unless, of course,
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such properties are overridden by A:visited rules).
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