gecko-dev/dom/base/nsStyleLinkElement.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * A base class which implements nsIStyleSheetLinkingElement and can
 * be subclassed by various content nodes that want to load
 * stylesheets (<style>, <link>, processing instructions, etc).
 */

#ifndef nsStyleLinkElement_h___
#define nsStyleLinkElement_h___

#include "mozilla/Attributes.h"
#include "mozilla/CORSMode.h"
#include "mozilla/StyleSheetInlines.h"
#include "mozilla/Unused.h"
#include "nsCOMPtr.h"
#include "nsIStyleSheetLinkingElement.h"
#include "nsTArray.h"

class nsIURI;

namespace mozilla {
class CSSStyleSheet;
namespace dom {
class Document;
class ShadowRoot;
}  // namespace dom
}  // namespace mozilla

class nsStyleLinkElement : public nsIStyleSheetLinkingElement {
 public:
  nsStyleLinkElement();
  virtual ~nsStyleLinkElement();

  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override = 0;

  mozilla::StyleSheet* GetSheet() const { return mStyleSheet; }

  // nsIStyleSheetLinkingElement
  void SetStyleSheet(mozilla::StyleSheet* aStyleSheet) override;
  mozilla::StyleSheet* GetStyleSheet() override;
  void InitStyleLinkElement(bool aDontLoadStyle) override;

  mozilla::Result<Update, nsresult> UpdateStyleSheet(
      nsICSSLoaderObserver*) override;

  void SetEnableUpdates(bool aEnableUpdates) override;
  void GetCharset(nsAString& aCharset) override;

  void OverrideBaseURI(nsIURI* aNewBaseURI) override;
  void SetLineNumber(uint32_t aLineNumber) override;
  uint32_t GetLineNumber() override;
  void SetColumnNumber(uint32_t aColumnNumber) override;
  uint32_t GetColumnNumber() override;

  enum RelValue {
    ePREFETCH = 0x00000001,
    eDNS_PREFETCH = 0x00000002,
    eSTYLESHEET = 0x00000004,
    eNEXT = 0x00000008,
    eALTERNATE = 0x00000010,
    ePRECONNECT = 0x00000020,
    // NOTE: 0x40 is unused
    ePRELOAD = 0x00000080
  };

  // The return value is a bitwise or of 0 or more RelValues.
  static uint32_t ParseLinkTypes(const nsAString& aTypes);

  void UpdateStyleSheetInternal() {
    mozilla::Unused << UpdateStyleSheetInternal(nullptr, nullptr);
  }

 protected:
  /**
   * @param aOldDocument   should be non-null only if we're updating because we
   *                       removed the node from the document.
   * @param aOldShadowRoot should be non-null only if we're updating because we
   *                       removed the node from a shadow tree.
   * @param aForceUpdate true will force the update even if the URI has not
   *                     changed.  This should be used in cases when something
   *                     about the content that affects the resulting sheet
   *                     changed but the URI may not have changed.
   *
   * TODO(emilio): Should probably pass a single DocumentOrShadowRoot.
   */
  mozilla::Result<Update, nsresult> UpdateStyleSheetInternal(
      mozilla::dom::Document* aOldDocument,
      mozilla::dom::ShadowRoot* aOldShadowRoot, ForceUpdate = ForceUpdate::No);

  // Gets a suitable title and media for SheetInfo out of an element, which
  // needs to be `this`.
  //
  // NOTE(emilio): Needs nsString instead of nsAString because of
  // CompressWhitespace.
  static void GetTitleAndMediaForElement(const mozilla::dom::Element&,
                                         nsString& aTitle, nsString& aMedia);

  // Returns whether the type attribute specifies the text/css mime type.
  static bool IsCSSMimeTypeAttribute(const mozilla::dom::Element&);

  virtual mozilla::Maybe<SheetInfo> GetStyleSheetInfo() = 0;

  // CC methods
  void Unlink();
  void Traverse(nsCycleCollectionTraversalCallback& cb);

 private:
  /**
   * @param aOldDocument should be non-null only if we're updating because we
   *                     removed the node from the document.
   * @param aOldShadowRoot The ShadowRoot that used to contain the style.
   *                     Passed as a parameter because on an update, the node
   *                     is removed from the tree before the sheet is removed
   *                     from the ShadowRoot.
   * @param aForceUpdate true will force the update even if the URI has not
   *                     changed.  This should be used in cases when something
   *                     about the content that affects the resulting sheet
   *                     changed but the URI may not have changed.
   */
  mozilla::Result<Update, nsresult> DoUpdateStyleSheet(
      mozilla::dom::Document* aOldDocument,
      mozilla::dom::ShadowRoot* aOldShadowRoot, nsICSSLoaderObserver* aObserver,
      ForceUpdate);

  RefPtr<mozilla::StyleSheet> mStyleSheet;

 protected:
  nsCOMPtr<nsIPrincipal> mTriggeringPrincipal;
  bool mDontLoadStyle;
  bool mUpdatesEnabled;
  uint32_t mLineNumber;
  uint32_t mColumnNumber;
};

#endif /* nsStyleLinkElement_h___ */