layout/style/PreloadedStyleSheet.cpp

   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 /* a CSS style sheet returned from nsIStyleSheetService.preloadSheet */
   8
   9 #include "PreloadedStyleSheet.h"
  10
  11 #include "mozilla/css/Loader.h"
  12 #include "mozilla/dom/Promise.h"
  13 #include "nsICSSLoaderObserver.h"
  14 #include "nsLayoutUtils.h"
  15
  16 namespace mozilla {
  17
  18 PreloadedStyleSheet::PreloadedStyleSheet(nsIURI* aURI,
  19                                          css::SheetParsingMode aParsingMode)
  20     : mLoaded(false), mURI(aURI), mParsingMode(aParsingMode) {}
  21
  22 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(PreloadedStyleSheet)
  23   NS_INTERFACE_MAP_ENTRY(nsIPreloadedStyleSheet)
  24   NS_INTERFACE_MAP_ENTRY(nsISupports)
  25 NS_INTERFACE_MAP_END
  26
  27 NS_IMPL_CYCLE_COLLECTING_ADDREF(PreloadedStyleSheet)
  28 NS_IMPL_CYCLE_COLLECTING_RELEASE(PreloadedStyleSheet)
  29
  30 NS_IMPL_CYCLE_COLLECTION(PreloadedStyleSheet, mSheet)
  31
  32 nsresult PreloadedStyleSheet::GetSheet(StyleSheet** aResult) {
  33   *aResult = nullptr;
  34
  35   MOZ_DIAGNOSTIC_ASSERT(mLoaded);
  36
  37   if (!mSheet) {
  38     auto loader = MakeRefPtr<css::Loader>();
  39     auto result = loader->LoadSheetSync(mURI, mParsingMode,
  40                                         css::Loader::UseSystemPrincipal::Yes);
  41     if (result.isErr()) {
  42       return result.unwrapErr();
  43     }
  44     mSheet = result.unwrap();
  45   }
  46
  47   *aResult = mSheet;
  48   return NS_OK;
  49 }
  50
  51 nsresult PreloadedStyleSheet::Preload() {
  52   MOZ_DIAGNOSTIC_ASSERT(!mLoaded);
  53   mLoaded = true;
  54   StyleSheet* sheet;
  55   return GetSheet(&sheet);
  56 }
  57
  58 NS_IMPL_ISUPPORTS(PreloadedStyleSheet::StylesheetPreloadObserver,
  59                   nsICSSLoaderObserver)
  60
  61 NS_IMETHODIMP
  62 PreloadedStyleSheet::StylesheetPreloadObserver::StyleSheetLoaded(
  63     StyleSheet* aSheet, bool aWasDeferred, nsresult aStatus) {
  64   MOZ_DIAGNOSTIC_ASSERT(!mPreloadedSheet->mLoaded);
  65   mPreloadedSheet->mLoaded = true;
  66
  67   if (NS_FAILED(aStatus)) {
  68     mPromise->MaybeReject(aStatus);
  69   } else {
  70     mPromise->MaybeResolve(mPreloadedSheet);
  71   }
  72
  73   return NS_OK;
  74 }
  75
  76 // Note: After calling this method, the preloaded sheet *must not* be used
  77 // until the observer is notified that the sheet has finished loading.
  78 nsresult PreloadedStyleSheet::PreloadAsync(NotNull<dom::Promise*> aPromise) {
  79   MOZ_DIAGNOSTIC_ASSERT(!mLoaded);
  80
  81   auto loader = MakeRefPtr<css::Loader>();
  82   auto obs = MakeRefPtr<StylesheetPreloadObserver>(aPromise, this);
  83   auto result = loader->LoadSheet(mURI, mParsingMode,
  84                                   css::Loader::UseSystemPrincipal::No, obs);
  85   if (result.isErr()) {
  86     return result.unwrapErr();
  87   }
  88   mSheet = result.unwrap();
  89   return NS_OK;
  90 }
  91
  92 }  // namespace mozilla