gecko-dev/dom/base/nsIStyleSheetLinkingElement.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/. */
#ifndef nsIStyleSheetLinkingElement_h__
#define nsIStyleSheetLinkingElement_h__


#include "nsISupports.h"
#include "mozilla/StyleSheet.h"
#include "mozilla/Result.h"

class nsICSSLoaderObserver;
class nsIURI;

#define NS_ISTYLESHEETLINKINGELEMENT_IID          \
{ 0xa8b79f3b, 0x9d18, 0x4f9c, \
  { 0xb1, 0xaa, 0x8c, 0x9b, 0x1b, 0xaa, 0xac, 0xad } }

class nsIStyleSheetLinkingElement : public nsISupports {
public:
  enum class ForceUpdate
  {
    Yes,
    No,
  };

  enum class IsAlternate
  {
    Yes,
    No,
  };

  enum class Completed
  {
    Yes,
    No,
  };

  struct Update
  {
  private:
    bool mWillNotify;
    bool mIsAlternate;

  public:
    Update()
      : mWillNotify(false)
      , mIsAlternate(false)
    { }

    Update(Completed aCompleted, IsAlternate aIsAlternate)
      : mWillNotify(aCompleted == Completed::No)
      , mIsAlternate(aIsAlternate == IsAlternate::Yes)
    { }

    bool WillNotify() const
    {
      return mWillNotify;
    }

    bool ShouldBlock() const
    {
      if (!mWillNotify) {
        return false;
      }

      return !mIsAlternate;
    }
  };

  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISTYLESHEETLINKINGELEMENT_IID)

  /**
   * Used to make the association between a style sheet and
   * the element that linked it to the document.
   *
   * @param aStyleSheet the style sheet associated with this
   *                    element.
   */
  virtual void SetStyleSheet(mozilla::StyleSheet* aStyleSheet) = 0;

  /**
   * Used to obtain the style sheet linked in by this element.
   *
   * @return the style sheet associated with this element.
   */
  virtual mozilla::StyleSheet* GetStyleSheet() = 0;

  /**
   * Initialize the stylesheet linking element. If aDontLoadStyle is
   * true the element will ignore the first modification to the
   * element that would cause a stylesheet to be loaded. Subsequent
   * modifications to the element will not be ignored.
   */
  virtual void InitStyleLinkElement(bool aDontLoadStyle) = 0;

  /**
   * Tells this element to update the stylesheet.
   *
   * @param aObserver    observer to notify once the stylesheet is loaded.
   *                     This will be passed to the CSSLoader
   * @param aForceUpdate whether we wand to force the update, flushing the
   *                     cached version if any.
   */
  virtual mozilla::Result<Update, nsresult>
    UpdateStyleSheet(nsICSSLoaderObserver* aObserver,
                     ForceUpdate = ForceUpdate::No) = 0;

  /**
   * Tells this element whether to update the stylesheet when the
   * element's properties change.
   *
   * @param aEnableUpdates update on changes or not.
   */
  virtual void SetEnableUpdates(bool aEnableUpdates) = 0;

  /**
   * Gets the charset that the element claims the style sheet is in.
   * Can return empty string to indicate that we have no charset
   * information.
   *
   * @param aCharset the charset
   */
  virtual void GetCharset(nsAString& aCharset) = 0;

  /**
   * Tells this element to use a different base URI. This is used for
   * proper loading of xml-stylesheet processing instructions in XUL overlays
   * and is only currently used by nsXMLStylesheetPI.
   *
   * @param aNewBaseURI the new base URI, nullptr to use the default base URI.
   */
  virtual void OverrideBaseURI(nsIURI* aNewBaseURI) = 0;

  // This doesn't entirely belong here since they only make sense for
  // some types of linking elements, but it's a better place than
  // anywhere else.
  virtual void SetLineNumber(uint32_t aLineNumber) = 0;

  /**
   * Get the line number, as previously set by SetLineNumber.
   *
   * @return the line number of this element; or 1 if no line number
   *         was set
   */
  virtual uint32_t GetLineNumber() = 0;
};

NS_DEFINE_STATIC_IID_ACCESSOR(nsIStyleSheetLinkingElement,
                              NS_ISTYLESHEETLINKINGELEMENT_IID)

#endif // nsILinkingElement_h__