layout/style/nsIStyleRuleProcessor.h

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  38
  39 /*
  40  * internal abstract interface for containers (roughly origins within
  41  * the CSS cascade) that provide style rules matching an element or
  42  * pseudo-element
  43  */
  44
  45 #ifndef nsIStyleRuleProcessor_h___
  46 #define nsIStyleRuleProcessor_h___
  47
  48 #include "nsISupports.h"
  49 #include "nsChangeHint.h"
  50 #include "nsIContent.h"
  51
  52 struct RuleProcessorData;
  53 struct ElementRuleProcessorData;
  54 struct PseudoElementRuleProcessorData;
  55 struct AnonBoxRuleProcessorData;
  56 #ifdef MOZ_XUL
  57 struct XULTreeRuleProcessorData;
  58 #endif
  59 struct StateRuleProcessorData;
  60 struct AttributeRuleProcessorData;
  61 class nsPresContext;
  62
  63 // IID for the nsIStyleRuleProcessor interface
  64 // {b8e44bbe-aaac-4125-8ab2-0f42802e14ad}
  65 #define NS_ISTYLE_RULE_PROCESSOR_IID     \
  66 { 0xb8e44bbe, 0xaaac, 0x4125, \
  67  { 0x8a, 0xb2, 0x0f, 0x42, 0x80, 0x2e, 0x14, 0xad } }
  68
  69
  70 /* The style rule processor interface is a mechanism to separate the matching
  71  * of style rules from style sheet instances.
  72  * Simple style sheets can and will act as their own processor.
  73  * Sheets where rule ordering interlaces between multiple sheets, will need to
  74  * share a single rule processor between them (CSS sheets do this for cascading order)
  75  *
  76  * @see nsIStyleRule (for significantly more detailed comments)
  77  */
  78 class nsIStyleRuleProcessor : public nsISupports {
  79 public:
  80   NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISTYLE_RULE_PROCESSOR_IID)
  81
  82   // Shorthand for:
  83   //  nsCOMArray<nsIStyleRuleProcessor>::nsCOMArrayEnumFunc
  84   typedef PRBool (* EnumFunc)(nsIStyleRuleProcessor*, void*);
  85
  86   /**
  87    * Find the |nsIStyleRule|s matching the given content node and
  88    * position the given |nsRuleWalker| at the |nsRuleNode| in the rule
  89    * tree representing that ordered list of rules (with higher
  90    * precedence being farther from the root of the lexicographic tree).
  91    */
  92   virtual void RulesMatching(ElementRuleProcessorData* aData) = 0;
  93
  94   /**
  95    * Just like the previous |RulesMatching|, except for a given content
  96    * node <em>and pseudo-element</em>.
  97    */
  98   virtual void RulesMatching(PseudoElementRuleProcessorData* aData) = 0;
  99
 100   /**
 101    * Just like the previous |RulesMatching|, except for a given anonymous box.
 102    */
 103   virtual void RulesMatching(AnonBoxRuleProcessorData* aData) = 0;
 104
 105 #ifdef MOZ_XUL
 106   /**
 107    * Just like the previous |RulesMatching|, except for a given content
 108    * node <em>and tree pseudo</em>.
 109    */
 110   virtual void RulesMatching(XULTreeRuleProcessorData* aData) = 0;
 111 #endif
 112
 113   /**
 114    * Return whether style can depend on a change of the given document state.
 115    *
 116    * Document states are defined in nsIDocument.h.
 117    */
 118   virtual PRBool
 119     HasDocumentStateDependentStyle(StateRuleProcessorData* aData) = 0;
 120
 121   /**
 122    * Return how (as described by nsRestyleHint) style can depend on a
 123    * change of the given content state on the given content node.  This
 124    * test is used for optimization only, and may err on the side of
 125    * reporting more dependencies than really exist.
 126    *
 127    * Event states are defined in nsIEventStateManager.h.
 128    */
 129   virtual nsRestyleHint
 130     HasStateDependentStyle(StateRuleProcessorData* aData) = 0;
 131
 132   /**
 133    * This method will be called twice for every attribute change.
 134    * During the first call, aData->mAttrHasChanged will be false and
 135    * the attribute change will not have happened yet.  During the
 136    * second call, aData->mAttrHasChanged will be true and the
 137    * change will have already happened.  The bitwise OR of the two
 138    * return values must describe the style changes that are needed due
 139    * to the attribute change.  It's up to the rule processor
 140    * implementation to decide how to split the bits up amongst the two
 141    * return values.  For example, it could return the bits needed by
 142    * rules that might stop matching the node from the first call and
 143    * the bits needed by rules that might have started matching the
 144    * node from the second call.  This test is used for optimization
 145    * only, and may err on the side of reporting more dependencies than
 146    * really exist.
 147    */
 148   virtual nsRestyleHint
 149     HasAttributeDependentStyle(AttributeRuleProcessorData* aData) = 0;
 150
 151   /**
 152    * Do any processing that needs to happen as a result of a change in
 153    * the characteristics of the medium, and return whether this rule
 154    * processor's rules have changed (e.g., because of media queries).
 155    */
 156   virtual PRBool MediumFeaturesChanged(nsPresContext* aPresContext) = 0;
 157 };
 158
 159 NS_DEFINE_STATIC_IID_ACCESSOR(nsIStyleRuleProcessor,
 160                               NS_ISTYLE_RULE_PROCESSOR_IID)
 161
 162 #endif /* nsIStyleRuleProcessor_h___ */