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 }  // namespace dom
  20 namespace fontlist {
  21 struct Family;
  22 }  // namespace fontlist
  23 }  // namespace mozilla
  24 class gfxUserFontEntry;
  25
  26 namespace mozilla {
  27
  28 /**
  29  * A PostTraversalTask is a task to be performed immediately after a Servo
  30  * traversal.  There are just a few tasks we need to perform, so we use this
  31  * class rather than Runnables, to avoid virtual calls and some allocations.
  32  *
  33  * A PostTraversalTask is only safe to run immediately after the Servo
  34  * traversal, since it can hold raw pointers to DOM objects.
  35  */
  36 class PostTraversalTask {
  37  public:
  38   static PostTraversalTask ResolveFontFaceLoadedPromise(
  39       dom::FontFace* aFontFace) {
  40     auto task = PostTraversalTask(Type::ResolveFontFaceLoadedPromise);
  41     task.mTarget = aFontFace;
  42     return task;
  43   }
  44
  45   static PostTraversalTask RejectFontFaceLoadedPromise(dom::FontFace* aFontFace,
  46                                                        nsresult aResult) {
  47     auto task = PostTraversalTask(Type::ResolveFontFaceLoadedPromise);
  48     task.mTarget = aFontFace;
  49     task.mResult = aResult;
  50     return task;
  51   }
  52
  53   static PostTraversalTask DispatchLoadingEventAndReplaceReadyPromise(
  54       dom::FontFaceSet* aFontFaceSet) {
  55     auto task =
  56         PostTraversalTask(Type::DispatchLoadingEventAndReplaceReadyPromise);
  57     task.mTarget = aFontFaceSet;
  58     return task;
  59   }
  60
  61   static PostTraversalTask DispatchFontFaceSetCheckLoadingFinishedAfterDelay(
  62       dom::FontFaceSet* aFontFaceSet) {
  63     auto task = PostTraversalTask(
  64         Type::DispatchFontFaceSetCheckLoadingFinishedAfterDelay);
  65     task.mTarget = aFontFaceSet;
  66     return task;
  67   }
  68
  69   static PostTraversalTask LoadFontEntry(gfxUserFontEntry* aFontEntry) {
  70     auto task = PostTraversalTask(Type::LoadFontEntry);
  71     task.mTarget = aFontEntry;
  72     return task;
  73   }
  74
  75   static PostTraversalTask InitializeFamily(fontlist::Family* aFamily) {
  76     auto task = PostTraversalTask(Type::InitializeFamily);
  77     task.mTarget = aFamily;
  78     return task;
  79   }
  80
  81   static PostTraversalTask FontInfoUpdate(ServoStyleSet* aSet) {
  82     auto task = PostTraversalTask(Type::FontInfoUpdate);
  83     task.mTarget = aSet;
  84     return task;
  85   }
  86
  87   void Run();
  88
  89  private:
  90   // For any new raw pointer type that we need to store in a PostTraversalTask,
  91   // please add an assertion that class' destructor that we are not in a Servo
  92   // traversal, to protect against the possibility of having dangling pointers.
  93   enum class Type {
  94     // mTarget (FontFace*)
  95     ResolveFontFaceLoadedPromise,
  96
  97     // mTarget (FontFace*)
  98     // mResult
  99     RejectFontFaceLoadedPromise,
 100
 101     // mTarget (FontFaceSet*)
 102     DispatchLoadingEventAndReplaceReadyPromise,
 103
 104     // mTarget (FontFaceSet*)
 105     DispatchFontFaceSetCheckLoadingFinishedAfterDelay,
 106
 107     // mTarget (gfxUserFontEntry*)
 108     LoadFontEntry,
 109
 110     // mTarget (fontlist::Family*)
 111     InitializeFamily,
 112
 113     // mTarget (ServoStyleSet*)
 114     FontInfoUpdate,
 115   };
 116
 117   explicit PostTraversalTask(Type aType)
 118       : mType(aType), mTarget(nullptr), mResult(NS_OK) {}
 119
 120   Type mType;
 121   void* mTarget;
 122   nsresult mResult;
 123 };
 124
 125 }  // namespace mozilla
 126
 127 #endif  // mozilla_PostTraversalTask_h