The Tor Browser / file comparison
comparison: layout/style/nsIStyleRule.h
layout/style/nsIStyleRule.h
- branch
- TOR_BUG_3246
- changeset 6
- 8bccb770b82d
equal
deleted
inserted
replaced
| -1:000000000000 | 0:287ecf39efb4 |
|---|---|
| 1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 /* | |
| 7 * internal abstract interface for objects providing immutable style | |
| 8 * information | |
| 9 */ | |
| 10 | |
| 11 #ifndef nsIStyleRule_h___ | |
| 12 #define nsIStyleRule_h___ | |
| 13 | |
| 14 #include <stdio.h> | |
| 15 | |
| 16 #include "nsISupports.h" | |
| 17 | |
| 18 struct nsRuleData; | |
| 19 | |
| 20 // IID for the nsIStyleRule interface {f75f3f70-435d-43a6-a01b-65970489ca26} | |
| 21 #define NS_ISTYLE_RULE_IID \ | |
| 22 { 0xf75f3f70, 0x435d, 0x43a6, \ | |
| 23 { 0xa0, 0x1b, 0x65, 0x97, 0x04, 0x89, 0xca, 0x26 } } | |
| 24 | |
| 25 /** | |
| 26 * An object implementing |nsIStyleRule| (henceforth, a rule) represents | |
| 27 * immutable stylistic information that either applies or does not apply | |
| 28 * to a given element. It belongs to an object or group of objects that | |
| 29 * implement |nsIStyleSheet| and |nsIStyleRuleProcessor| (henceforth, a | |
| 30 * sheet). | |
| 31 * | |
| 32 * A rule becomes relevant to the computation of style data when | |
| 33 * |nsIStyleRuleProcessor::RulesMatching| creates a rule node that | |
| 34 * points to the rule. (A rule node, |nsRuleNode|, is a node in the | |
| 35 * rule tree, which is a lexicographic tree indexed by rules. The path | |
| 36 * from the root of the rule tree to the |nsRuleNode| for a given | |
| 37 * |nsStyleContext| contains exactly the rules that match the element | |
| 38 * that the style context is for, in priority (weight, origin, | |
| 39 * specificity) order.) | |
| 40 * | |
| 41 * The computation of style data uses the rule tree, which calls | |
| 42 * |nsIStyleRule::MapRuleInfoInto| below. | |
| 43 * | |
| 44 * It is worth emphasizing that the data represented by a rule | |
| 45 * implementation are immutable. When the data need to be changed, a | |
| 46 * new rule object must be created. Failing to do this will lead to | |
| 47 * bugs in the handling of dynamic style changes, since the rule tree | |
| 48 * caches the results of |MapRuleInfoInto|. | |
| 49 * | |
| 50 * |nsIStyleRule| objects are owned by |nsRuleNode| objects (in addition | |
| 51 * to typically being owned by their sheet), which are in turn garbage | |
| 52 * collected (with the garbage collection roots being style contexts). | |
| 53 */ | |
| 54 | |
| 55 | |
| 56 class nsIStyleRule : public nsISupports { | |
| 57 public: | |
| 58 NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISTYLE_RULE_IID) | |
| 59 | |
| 60 /** | |
| 61 * |nsIStyleRule::MapRuleInfoInto| is a request to copy all stylistic | |
| 62 * data represented by the rule that: | |
| 63 * + are relevant for any structs in |aRuleData->mSIDs| (style | |
| 64 * struct ID bits) | |
| 65 * + are not already filled into the data struct | |
| 66 * into the appropriate data struct in |aRuleData|. It is important | |
| 67 * that only empty data are filled in, since the rule tree is walked | |
| 68 * from highest priority rule to least, so that the walk can stop if | |
| 69 * all needed data are found. Thus overwriting non-empty data will | |
| 70 * break CSS cascading rules. | |
| 71 */ | |
| 72 virtual void MapRuleInfoInto(nsRuleData* aRuleData)=0; | |
| 73 | |
| 74 #ifdef DEBUG | |
| 75 virtual void List(FILE* out = stdout, int32_t aIndent = 0) const = 0; | |
| 76 #endif | |
| 77 }; | |
| 78 | |
| 79 NS_DEFINE_STATIC_IID_ACCESSOR(nsIStyleRule, NS_ISTYLE_RULE_IID) | |
| 80 | |
| 81 #endif /* nsIStyleRule_h___ */ |
