layout/style/PostTraversalTask.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_PostTraversalTask_h
   8 #define mozilla_PostTraversalTask_h
   9
  10 #include "nscore.h"
  11
  12 /* a task to be performed immediately after a Servo traversal */
  13
  14 namespace mozilla {
  15 class ServoStyleSet;
  16 namespace dom {
  17 class FontFace;
  18 class FontFaceSet;
  19 class FontFaceSetImpl;
  20 }  // namespace dom
  21 namespace fontlist {
  22 struct Family;
  23 }  // namespace fontlist
  24 }  // namespace mozilla
  25 class gfxUserFontEntry;
  26
  27 namespace mozilla {
  28
  29 /**
  30  * A PostTraversalTask is a task to be performed immediately after a Servo
  31  * traversal.  There are just a few tasks we need to perform, so we use this
  32  * class rather than Runnables, to avoid virtual calls and some allocations.
  33  *
  34  * A PostTraversalTask is only safe to run immediately after the Servo
  35  * traversal, since it can hold raw pointers to DOM objects.
  36  */
  37 class PostTraversalTask {
  38  public:
  39   static PostTraversalTask ResolveFontFaceLoadedPromise(
  40       dom::FontFace* aFontFace) {
  41     auto task = PostTraversalTask(Type::ResolveFontFaceLoadedPromise);
  42     task.mTarget = aFontFace;
  43     return task;
  44   }
  45
  46   static PostTraversalTask RejectFontFaceLoadedPromise(dom::FontFace* aFontFace,
  47                                                        nsresult aResult) {
  48     auto task = PostTraversalTask(Type::ResolveFontFaceLoadedPromise);
  49     task.mTarget = aFontFace;
  50     task.mResult = aResult;
  51     return task;
  52   }
  53
  54   static PostTraversalTask DispatchLoadingEventAndReplaceReadyPromise(
  55       dom::FontFaceSet* aFontFaceSet) {
  56     auto task =
  57         PostTraversalTask(Type::DispatchLoadingEventAndReplaceReadyPromise);
  58     task.mTarget = aFontFaceSet;
  59     return task;
  60   }
  61
  62   static PostTraversalTask DispatchFontFaceSetCheckLoadingFinishedAfterDelay(
  63       dom::FontFaceSetImpl* aFontFaceSet) {
  64     auto task = PostTraversalTask(
  65         Type::DispatchFontFaceSetCheckLoadingFinishedAfterDelay);
  66     task.mTarget = aFontFaceSet;
  67     return task;
  68   }
  69
  70   static PostTraversalTask LoadFontEntry(gfxUserFontEntry* aFontEntry) {
  71     auto task = PostTraversalTask(Type::LoadFontEntry);
  72     task.mTarget = aFontEntry;
  73     return task;
  74   }
  75
  76   static PostTraversalTask InitializeFamily(fontlist::Family* aFamily) {
  77     auto task = PostTraversalTask(Type::InitializeFamily);
  78     task.mTarget = aFamily;
  79     return task;
  80   }
  81
  82   static PostTraversalTask FontInfoUpdate(ServoStyleSet* aSet) {
  83     auto task = PostTraversalTask(Type::FontInfoUpdate);
  84     task.mTarget = aSet;
  85     return task;
  86   }
  87
  88   void Run();
  89
  90  private:
  91   // For any new raw pointer type that we need to store in a PostTraversalTask,
  92   // please add an assertion that class' destructor that we are not in a Servo
  93   // traversal, to protect against the possibility of having dangling pointers.
  94   enum class Type {
  95     // mTarget (FontFace*)
  96     ResolveFontFaceLoadedPromise,
  97
  98     // mTarget (FontFace*)
  99     // mResult
 100     RejectFontFaceLoadedPromise,
 101
 102     // mTarget (FontFaceSet*)
 103     DispatchLoadingEventAndReplaceReadyPromise,
 104
 105     // mTarget (FontFaceSetImpl*)
 106     DispatchFontFaceSetCheckLoadingFinishedAfterDelay,
 107
 108     // mTarget (gfxUserFontEntry*)
 109     LoadFontEntry,
 110
 111     // mTarget (fontlist::Family*)
 112     InitializeFamily,
 113
 114     // mTarget (ServoStyleSet*)
 115     FontInfoUpdate,
 116   };
 117
 118   explicit PostTraversalTask(Type aType)
 119       : mType(aType), mTarget(nullptr), mResult(NS_OK) {}
 120
 121   Type mType;
 122   void* mTarget;
 123   nsresult mResult;
 124 };
 125
 126 }  // namespace mozilla
 127
 128 #endif  // mozilla_PostTraversalTask_h