firefox/devtools/server/actors/highlighters.js

/* 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/. */

"use strict";

const { Actor } = require("devtools/shared/protocol");
const { customHighlighterSpec } = require("devtools/shared/specs/highlighters");
const { TYPES } = ChromeUtils.importESModule(
  "resource://devtools/shared/highlighters.mjs",
  { global: "contextual" }
);

const EventEmitter = require("devtools/shared/event-emitter");

loader.lazyRequireGetter(
  this,
  "isXUL",
  "resource://devtools/server/actors/highlighters/utils/markup.js",
  true
);

/**
 * The registration mechanism for highlighters provides a quick way to
 * have modular highlighters instead of a hard coded list.
 */
const highlighterTypes = new Map();

/**
 * Returns `true` if a highlighter for the given `typeName` is registered,
 * `false` otherwise.
 */
const isTypeRegistered = typeName => highlighterTypes.has(typeName);
exports.isTypeRegistered = isTypeRegistered;

/**
 * Registers a given constructor as highlighter, for the `typeName` given.
 */
const registerHighlighter = (typeName, modulePath) => {
  if (highlighterTypes.has(typeName)) {
    throw Error(`${typeName} is already registered.`);
  }

  highlighterTypes.set(typeName, modulePath);
};

/**
 * CustomHighlighterActor is a generic Actor that instantiates a custom implementation of
 * a highlighter class given its type name which must be registered in `highlighterTypes`.
 * CustomHighlighterActor proxies calls to methods of the highlighter class instance:
 * constructor(targetActor), show(node, options), hide(), destroy()
 */
exports.CustomHighlighterActor = class CustomHighligherActor extends Actor {
  /**
   * Create a highlighter instance given its typeName.
   */
  constructor(parent, typeName) {
    super(parent.conn, customHighlighterSpec);

    this._parent = parent;

    const modulePath = highlighterTypes.get(typeName);
    if (!modulePath) {
      const list = [...highlighterTypes.keys()];

      throw new Error(`${typeName} isn't a valid highlighter class (${list})`);
    }

    const constructor = require(modulePath)[typeName];
    // The assumption is that custom highlighters either need the canvasframe
    // container to append their elements and thus a non-XUL window or they have
    // to define a static XULSupported flag that indicates that the highlighter
    // supports XUL windows. Otherwise, bail out.
    if (!isXUL(this._parent.targetActor.window) || constructor.XULSupported) {
      this._highlighterEnv = new HighlighterEnvironment();
      this._highlighterEnv.initFromTargetActor(parent.targetActor);
      this._highlighter = new constructor(this._highlighterEnv, parent);
      if (this._highlighter.on) {
        this._highlighter.on(
          "highlighter-event",
          this._onHighlighterEvent.bind(this)
        );
      }
    } else {
      throw new Error(
        "Custom " + typeName + "highlighter cannot be created in a XUL window"
      );
    }
  }

  destroy() {
    super.destroy();
    this.finalize();
    this._parent = null;
  }

  release() {}

  /**
   * Get current instance of the highlighter object.
   */
  get instance() {
    return this._highlighter;
  }

  /**
   * Show the highlighter.
   * This calls through to the highlighter instance's |show(node, options)|
   * method.
   *
   * Most custom highlighters are made to highlight DOM nodes, hence the first
   * NodeActor argument (NodeActor as in devtools/server/actor/inspector).
   * Note however that some highlighters use this argument merely as a context
   * node: The SelectorHighlighter for instance uses it as a base node to run the
   * provided CSS selector on.
   *
   * @param {NodeActor} The node to be highlighted
   * @param {Object} Options for the custom highlighter
   * @return {Boolean} True, if the highlighter has been successfully shown
   */
  show(node, options) {
    if (!this._highlighter) {
      return null;
    }

    const rawNode = node?.rawNode;

    return this._highlighter.show(rawNode, options);
  }

  /**
   * Hide the highlighter if it was shown before
   */
  hide() {
    if (this._highlighter) {
      this._highlighter.hide();
    }
  }

  /**
   * Upon receiving an event from the highlighter, forward it to the client.
   */
  _onHighlighterEvent(data) {
    this.emit("highlighter-event", data);
  }

  /**
   * Destroy the custom highlighter implementation.
   * This method is called automatically just before the actor is destroyed.
   */
  finalize() {
    if (this._highlighter) {
      if (this._highlighter.off) {
        this._highlighter.off(
          "highlighter-event",
          this._onHighlighterEvent.bind(this)
        );
      }
      this._highlighter.destroy();
      this._highlighter = null;
    }

    if (this._highlighterEnv) {
      this._highlighterEnv.destroy();
      this._highlighterEnv = null;
    }
  }
};

/**
 * The HighlighterEnvironment is an object that holds all the required data for
 * highlighters to work: the window, docShell, event listener target, ...
 * It also emits "will-navigate", "navigate" and "window-ready" events,
 * similarly to the WindowGlobalTargetActor.
 *
 * It can be initialized either from a WindowGlobalTargetActor (which is the
 * most frequent way of using it, since highlighters are initialized by
 * CustomHighlighterActor, which has a targetActor reference).
 * It can also be initialized just with a window object (which is
 * useful for when a highlighter is used outside of the devtools server context.
 */

class HighlighterEnvironment extends EventEmitter {
  initFromTargetActor(targetActor) {
    this._targetActor = targetActor;

    const relayedEvents = [
      "window-ready",
      "navigate",
      "will-navigate",
      "use-simple-highlighters-updated",
    ];

    this._abortController = new AbortController();
    const signal = this._abortController.signal;
    for (const event of relayedEvents) {
      this._targetActor.on(event, this.relayTargetEvent.bind(this, event), {
        signal,
      });
    }
  }

  initFromWindow(win) {
    this._win = win;

    // We need a progress listener to know when the window will navigate/has
    // navigated.
    const self = this;
    this.listener = {
      QueryInterface: ChromeUtils.generateQI([
        "nsIWebProgressListener",
        "nsISupportsWeakReference",
      ]),

      onStateChange(progress, request, flag) {
        const isStart = flag & Ci.nsIWebProgressListener.STATE_START;
        const isStop = flag & Ci.nsIWebProgressListener.STATE_STOP;
        const isWindow = flag & Ci.nsIWebProgressListener.STATE_IS_WINDOW;
        const isDocument = flag & Ci.nsIWebProgressListener.STATE_IS_DOCUMENT;

        if (progress.DOMWindow !== win) {
          return;
        }

        if (isDocument && isStart) {
          // One of the earliest events that tells us a new URI is being loaded
          // in this window.
          self.emit("will-navigate", {
            window: win,
            isTopLevel: true,
          });
        }
        if (isWindow && isStop) {
          self.emit("navigate", {
            window: win,
            isTopLevel: true,
          });
        }
      },
    };

    this.webProgress.addProgressListener(
      this.listener,
      Ci.nsIWebProgress.NOTIFY_STATE_WINDOW |
        Ci.nsIWebProgress.NOTIFY_STATE_DOCUMENT
    );
  }

  get isInitialized() {
    return this._win || this._targetActor;
  }

  get isXUL() {
    return isXUL(this.window);
  }

  get useSimpleHighlightersForReducedMotion() {
    return this._targetActor?._useSimpleHighlightersForReducedMotion;
  }

  get window() {
    if (!this.isInitialized) {
      throw new Error(
        "Initialize HighlighterEnvironment with a targetActor " +
          "or window first"
      );
    }
    const win = this._targetActor ? this._targetActor.window : this._win;

    try {
      return Cu.isDeadWrapper(win) ? null : win;
    } catch (e) {
      // win is null
      return null;
    }
  }

  get document() {
    return this.window && this.window.document;
  }

  get docShell() {
    return this.window && this.window.docShell;
  }

  get webProgress() {
    return (
      this.docShell &&
      this.docShell
        .QueryInterface(Ci.nsIInterfaceRequestor)
        .getInterface(Ci.nsIWebProgress)
    );
  }

  /**
   * Get the right target for listening to events on the page.
   * - If the environment was initialized from a WindowGlobalTargetActor
   *   *and* if we're in the Browser Toolbox (to inspect Firefox Desktop): the
   *   targetActor is the RootActor, in which case, the window property can be
   *   used to listen to events.
   * - With Firefox Desktop, the targetActor is a WindowGlobalTargetActor, and we use
   *   the chromeEventHandler which gives us a target we can use to listen to
   *   events, even from nested iframes.
   * - If the environment was initialized from a window, we also use the
   *   chromeEventHandler.
   */
  get pageListenerTarget() {
    if (this._targetActor && this._targetActor.isRootActor) {
      return this.window;
    }
    return this.docShell && this.docShell.chromeEventHandler;
  }

  relayTargetEvent(name, data) {
    this.emit(name, data);
  }

  destroy() {
    if (this._abortController) {
      this._abortController.abort();
      this._abortController = null;
    }

    // In case the environment was initialized from a window, we need to remove
    // the progress listener.
    if (this._win) {
      try {
        this.webProgress.removeProgressListener(this.listener);
      } catch (e) {
        // Which may fail in case the window was already destroyed.
      }
    }

    this._targetActor = null;
    this._win = null;
  }
}
exports.HighlighterEnvironment = HighlighterEnvironment;

// This constant object is created to make the calls array more
// readable. Otherwise, linting rules force some array defs to span 4
// lines instead, which is much harder to parse.
const HIGHLIGHTERS = {
  [TYPES.ACCESSIBLE]: "devtools/server/actors/highlighters/accessible",
  [TYPES.BOXMODEL]: "devtools/server/actors/highlighters/box-model",
  [TYPES.GRID]: "devtools/server/actors/highlighters/css-grid",
  [TYPES.TRANSFORM]: "devtools/server/actors/highlighters/css-transform",
  [TYPES.EYEDROPPER]: "devtools/server/actors/highlighters/eye-dropper",
  [TYPES.FLEXBOX]: "devtools/server/actors/highlighters/flexbox",
  [TYPES.FONTS]: "devtools/server/actors/highlighters/fonts",
  [TYPES.GEOMETRY]: "devtools/server/actors/highlighters/geometry-editor",
  [TYPES.MEASURING]: "devtools/server/actors/highlighters/measuring-tool",
  [TYPES.PAUSED_DEBUGGER]:
    "devtools/server/actors/highlighters/paused-debugger",
  [TYPES.RULERS]: "devtools/server/actors/highlighters/rulers",
  [TYPES.SELECTOR]: "devtools/server/actors/highlighters/selector",
  [TYPES.SHAPES]: "devtools/server/actors/highlighters/shapes",
  [TYPES.TABBING_ORDER]: "devtools/server/actors/highlighters/tabbing-order",
  [TYPES.VIEWPORT_SIZE]: "devtools/server/actors/highlighters/viewport-size",
  [TYPES.VIEWPORT_SIZE_ON_RESIZE]:
    "devtools/server/actors/highlighters/viewport-size-on-resize",
};
for (const [typeName, modulePath] of Object.entries(HIGHLIGHTERS)) {
  registerHighlighter(typeName, modulePath);
}