зеркало из https://github.com/mozilla/gecko-dev.git
142 строки
4.4 KiB
C++
142 строки
4.4 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* a CSS style sheet returned from nsIStyleSheetService.preloadSheet */
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#include "PreloadedStyleSheet.h"
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#include "mozilla/css/Loader.h"
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#include "mozilla/dom/Promise.h"
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#include "nsICSSLoaderObserver.h"
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#include "nsLayoutUtils.h"
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namespace mozilla {
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PreloadedStyleSheet::PreloadedStyleSheet(nsIURI* aURI,
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css::SheetParsingMode aParsingMode)
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: mLoaded(false)
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, mURI(aURI)
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, mParsingMode(aParsingMode)
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{
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}
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/* static */ nsresult
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PreloadedStyleSheet::Create(nsIURI* aURI,
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css::SheetParsingMode aParsingMode,
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PreloadedStyleSheet** aResult)
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{
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*aResult = nullptr;
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RefPtr<PreloadedStyleSheet> preloadedSheet =
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new PreloadedStyleSheet(aURI, aParsingMode);
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preloadedSheet.forget(aResult);
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return NS_OK;
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}
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NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(PreloadedStyleSheet)
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NS_INTERFACE_MAP_ENTRY(nsIPreloadedStyleSheet)
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NS_INTERFACE_MAP_ENTRY(nsISupports)
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NS_INTERFACE_MAP_END
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NS_IMPL_CYCLE_COLLECTING_ADDREF(PreloadedStyleSheet)
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NS_IMPL_CYCLE_COLLECTING_RELEASE(PreloadedStyleSheet)
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NS_IMPL_CYCLE_COLLECTION(PreloadedStyleSheet, mGecko, mServo)
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nsresult
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PreloadedStyleSheet::GetSheet(StyleBackendType aType, StyleSheet** aResult)
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{
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*aResult = nullptr;
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MOZ_DIAGNOSTIC_ASSERT(mLoaded);
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RefPtr<StyleSheet>& sheet =
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aType == StyleBackendType::Gecko ? mGecko : mServo;
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if (!sheet) {
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RefPtr<css::Loader> loader = new css::Loader(aType, nullptr);
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nsresult rv = loader->LoadSheetSync(mURI, mParsingMode, true, &sheet);
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NS_ENSURE_SUCCESS(rv, rv);
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MOZ_ASSERT(sheet);
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}
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*aResult = sheet;
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return NS_OK;
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}
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nsresult
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PreloadedStyleSheet::Preload()
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{
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MOZ_DIAGNOSTIC_ASSERT(!mLoaded);
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// The nsIStyleSheetService.preloadSheet API doesn't tell us which backend
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// the sheet will be used with, and it seems wasteful to eagerly create
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// both a CSSStyleSheet and a ServoStyleSheet. So instead, we guess that
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// the sheet type we will want matches the current value of the stylo pref,
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// and preload a sheet of that type.
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//
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// If we guess wrong, we will re-load the sheet later with the requested type,
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// and we won't really have front loaded the loading time as the name
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// "preload" might suggest. Also, in theory we could get different data from
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// fetching the URL again, but for the usage patterns of this API this is
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// unlikely, and it doesn't seem worth trying to store the contents of the URL
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// and duplicating a bunch of css::Loader's logic.
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auto type = nsLayoutUtils::StyloEnabled() ? StyleBackendType::Servo
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: StyleBackendType::Gecko;
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mLoaded = true;
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StyleSheet* sheet;
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return GetSheet(type, &sheet);
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}
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NS_IMPL_ISUPPORTS(PreloadedStyleSheet::StylesheetPreloadObserver,
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nsICSSLoaderObserver)
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NS_IMETHODIMP
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PreloadedStyleSheet::StylesheetPreloadObserver::StyleSheetLoaded(
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StyleSheet* aSheet, bool aWasAlternate, nsresult aStatus)
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{
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MOZ_DIAGNOSTIC_ASSERT(!mPreloadedSheet->mLoaded);
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mPreloadedSheet->mLoaded = true;
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if (NS_FAILED(aStatus)) {
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mPromise->MaybeReject(aStatus);
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} else {
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mPromise->MaybeResolve(mPreloadedSheet);
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}
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return NS_OK;
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}
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// Note: After calling this method, the preloaded sheet *must not* be used
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// until the observer is notified that the sheet has finished loading.
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nsresult
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PreloadedStyleSheet::PreloadAsync(NotNull<dom::Promise*> aPromise)
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{
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MOZ_DIAGNOSTIC_ASSERT(!mLoaded);
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// As with the Preload() method, we can't be sure that the sheet will only be
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// used with the backend that we're preloading it for now. If it's used with
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// a different backend later, it will be synchronously loaded for that
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// backend the first time it's used.
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auto type = nsLayoutUtils::StyloEnabled() ? StyleBackendType::Servo
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: StyleBackendType::Gecko;
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RefPtr<StyleSheet>& sheet =
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type == StyleBackendType::Gecko ? mGecko : mServo;
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RefPtr<css::Loader> loader = new css::Loader(type, nullptr);
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RefPtr<StylesheetPreloadObserver> obs =
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new StylesheetPreloadObserver(aPromise, this);
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return loader->LoadSheet(mURI, mParsingMode, false, obs, &sheet);
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}
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} // namespace mozilla
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