gecko-dev/browser/modules/PageInfoListener.jsm

/* 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/. */

var EXPORTED_SYMBOLS = ["PageInfoListener"];

ChromeUtils.import("resource://gre/modules/Services.jsm");
ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");

XPCOMUtils.defineLazyModuleGetters(this, {
  Feeds: "resource:///modules/Feeds.jsm",
  PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.jsm",
  setTimeout: "resource://gre/modules/Timer.jsm"
});

var PageInfoListener = {
  /* nsIMessageListener */
  receiveMessage(message) {
    let strings = message.data.strings;
    let window;

    let frameOuterWindowID = message.data.frameOuterWindowID;

    // If inside frame then get the frame's window and document.
    if (frameOuterWindowID != undefined) {
      window = Services.wm.getOuterWindowWithId(frameOuterWindowID);
    } else {
      window = message.target.content;
    }

    let document = window.document;

    let pageInfoData = {metaViewRows: this.getMetaInfo(document),
                        docInfo: this.getDocumentInfo(document),
                        feeds: this.getFeedsInfo(document, strings),
                        windowInfo: this.getWindowInfo(window)};

    message.target.sendAsyncMessage("PageInfo:data", pageInfoData);

    // Separate step so page info dialog isn't blank while waiting for this to finish.
    this.getMediaInfo(document, window, strings, message.target);
  },

  getMetaInfo(document) {
    let metaViewRows = [];

    // Get the meta tags from the page.
    let metaNodes = document.getElementsByTagName("meta");

    for (let metaNode of metaNodes) {
      metaViewRows.push([metaNode.name || metaNode.httpEquiv || metaNode.getAttribute("property"),
                        metaNode.content]);
    }

    return metaViewRows;
  },

  getWindowInfo(window) {
    let windowInfo = {};
    windowInfo.isTopWindow = window == window.top;

    let hostName = null;
    try {
      hostName = Services.io.newURI(window.location.href).displayHost;
    } catch (exception) { }

    windowInfo.hostName = hostName;
    return windowInfo;
  },

  getDocumentInfo(document) {
    let docInfo = {};
    docInfo.title = document.title;
    docInfo.location = document.location.toString();
    try {
      docInfo.location = Services.io.newURI(document.location.toString()).displaySpec;
    } catch (exception) { }
    docInfo.referrer = document.referrer;
    try {
      if (document.referrer) {
        docInfo.referrer = Services.io.newURI(document.referrer).displaySpec;
      }
    } catch (exception) { }
    docInfo.compatMode = document.compatMode;
    docInfo.contentType = document.contentType;
    docInfo.characterSet = document.characterSet;
    docInfo.lastModified = document.lastModified;
    docInfo.principal = document.nodePrincipal;

    let documentURIObject = {};
    documentURIObject.spec = document.documentURIObject.spec;
    docInfo.documentURIObject = documentURIObject;

    docInfo.isContentWindowPrivate = PrivateBrowsingUtils.isContentWindowPrivate(document.ownerGlobal);

    return docInfo;
  },

  getFeedsInfo(document, strings) {
    let feeds = [];
    // Get the feeds from the page.
    let linkNodes = document.getElementsByTagName("link");
    let length = linkNodes.length;
    for (let i = 0; i < length; i++) {
      let link = linkNodes[i];
      if (!link.href) {
        continue;
      }
      let rel = link.rel && link.rel.toLowerCase();
      let rels = {};

      if (rel) {
        for (let relVal of rel.split(/\s+/)) {
          rels[relVal] = true;
        }
      }

      if (rels.feed || (link.type && rels.alternate && !rels.stylesheet)) {
        let type = Feeds.isValidFeed(link, document.nodePrincipal, "feed" in rels);
        if (type) {
          type = strings[type] || strings["application/rss+xml"];
          feeds.push([link.title, type, link.href]);
        }
      }
    }
    return feeds;
  },

  // Only called once to get the media tab's media elements from the content page.
  getMediaInfo(document, window, strings, mm) {
    let frameList = this.goThroughFrames(document, window);
    this.processFrames(document, frameList, strings, mm);
  },

  goThroughFrames(document, window) {
    let frameList = [document];
    if (window && window.frames.length > 0) {
      let num = window.frames.length;
      for (let i = 0; i < num; i++) {
        // Recurse through the frames.
        frameList.concat(this.goThroughFrames(window.frames[i].document,
                                              window.frames[i]));
      }
    }
    return frameList;
  },

  async processFrames(document, frameList, strings, mm) {
    let nodeCount = 0;
    let content = document.ownerGlobal;
    for (let doc of frameList) {
      let iterator = doc.createTreeWalker(doc, content.NodeFilter.SHOW_ELEMENT);

      // Goes through all the elements on the doc. imageViewRows takes only the media elements.
      while (iterator.nextNode()) {
        let mediaItems = this.getMediaItems(document, strings, iterator.currentNode);

        if (mediaItems.length) {
          mm.sendAsyncMessage("PageInfo:mediaData",
                           {mediaItems, isComplete: false});
        }

        if (++nodeCount % 500 == 0) {
          // setTimeout every 500 elements so we don't keep blocking the content process.
          await new Promise(resolve => setTimeout(resolve, 10));
        }
      }
    }
    // Send that page info media fetching has finished.
    mm.sendAsyncMessage("PageInfo:mediaData", {isComplete: true});
  },

  getMediaItems(document, strings, elem) {
    // Check for images defined in CSS (e.g. background, borders)
    let computedStyle = elem.ownerGlobal.getComputedStyle(elem);
    // A node can have multiple media items associated with it - for example,
    // multiple background images.
    let mediaItems = [];
    let content = document.ownerGlobal;

    let addImage = (url, type, alt, el, isBg) => {
      let element = this.serializeElementInfo(document, url, type, alt, el, isBg);
      mediaItems.push([url, type, alt, element, isBg]);
    };

    if (computedStyle) {
      let addImgFunc = (label, urls) => {
        for (let url of urls) {
          addImage(url, label, strings.notSet, elem, true);
        }
      };
      // FIXME: This is missing properties. See the implementation of
      // getCSSImageURLs for a list of properties.
      //
      // If you don't care about the message you can also pass "all" here and
      // get all the ones the browser knows about.
      addImgFunc(strings.mediaBGImg, computedStyle.getCSSImageURLs("background-image"));
      addImgFunc(strings.mediaBorderImg, computedStyle.getCSSImageURLs("border-image-source"));
      addImgFunc(strings.mediaListImg, computedStyle.getCSSImageURLs("list-style-image"));
      addImgFunc(strings.mediaCursor, computedStyle.getCSSImageURLs("cursor"));
    }

    // One swi^H^H^Hif-else to rule them all.
    if (elem instanceof content.HTMLImageElement) {
      addImage(elem.src, strings.mediaImg,
               (elem.hasAttribute("alt")) ? elem.alt : strings.notSet, elem, false);
    } else if (elem instanceof content.SVGImageElement) {
      try {
        // Note: makeURLAbsolute will throw if either the baseURI is not a valid URI
        //       or the URI formed from the baseURI and the URL is not a valid URI.
        if (elem.href.baseVal) {
          let href = Services.io.newURI(elem.href.baseVal, null, Services.io.newURI(elem.baseURI)).spec;
          addImage(href, strings.mediaImg, "", elem, false);
        }
      } catch (e) { }
    } else if (elem instanceof content.HTMLVideoElement) {
      addImage(elem.currentSrc, strings.mediaVideo, "", elem, false);
    } else if (elem instanceof content.HTMLAudioElement) {
      addImage(elem.currentSrc, strings.mediaAudio, "", elem, false);
    } else if (elem instanceof content.HTMLLinkElement) {
      if (elem.rel && /\bicon\b/i.test(elem.rel)) {
        addImage(elem.href, strings.mediaLink, "", elem, false);
      }
    } else if (elem instanceof content.HTMLInputElement || elem instanceof content.HTMLButtonElement) {
      if (elem.type.toLowerCase() == "image") {
        addImage(elem.src, strings.mediaInput,
                 (elem.hasAttribute("alt")) ? elem.alt : strings.notSet, elem, false);
      }
    } else if (elem instanceof content.HTMLObjectElement) {
      addImage(elem.data, strings.mediaObject, this.getValueText(elem), elem, false);
    } else if (elem instanceof content.HTMLEmbedElement) {
      addImage(elem.src, strings.mediaEmbed, "", elem, false);
    }

    return mediaItems;
  },

  /**
   * Set up a JSON element object with all the instanceOf and other infomation that
   * makePreview in pageInfo.js uses to figure out how to display the preview.
   */

  serializeElementInfo(document, url, type, alt, item, isBG) {
    let result = {};
    let content = document.ownerGlobal;

    let imageText;
    if (!isBG &&
        !(item instanceof content.SVGImageElement) &&
        !(document instanceof content.ImageDocument)) {
      imageText = item.title || item.alt;

      if (!imageText && !(item instanceof content.HTMLImageElement)) {
        imageText = this.getValueText(item);
      }
    }

    result.imageText = imageText;
    result.longDesc = item.longDesc;
    result.numFrames = 1;

    if (item instanceof content.HTMLObjectElement ||
      item instanceof content.HTMLEmbedElement ||
      item instanceof content.HTMLLinkElement) {
      result.mimeType = item.type;
    }

    if (!result.mimeType && !isBG && item instanceof Ci.nsIImageLoadingContent) {
      // Interface for image loading content.
      let imageRequest = item.getRequest(Ci.nsIImageLoadingContent.CURRENT_REQUEST);
      if (imageRequest) {
        result.mimeType = imageRequest.mimeType;
        let image = !(imageRequest.imageStatus & imageRequest.STATUS_ERROR) && imageRequest.image;
        if (image) {
          result.numFrames = image.numFrames;
        }
      }
    }

    // If we have a data url, get the MIME type from the url.
    if (!result.mimeType && url.startsWith("data:")) {
      let dataMimeType = /^data:(image\/[^;,]+)/i.exec(url);
      if (dataMimeType)
        result.mimeType = dataMimeType[1].toLowerCase();
    }

    result.HTMLLinkElement = item instanceof content.HTMLLinkElement;
    result.HTMLInputElement = item instanceof content.HTMLInputElement;
    result.HTMLImageElement = item instanceof content.HTMLImageElement;
    result.HTMLObjectElement = item instanceof content.HTMLObjectElement;
    result.SVGImageElement = item instanceof content.SVGImageElement;
    result.HTMLVideoElement = item instanceof content.HTMLVideoElement;
    result.HTMLAudioElement = item instanceof content.HTMLAudioElement;

    if (isBG) {
      // Items that are showing this image as a background
      // image might not necessarily have a width or height,
      // so we'll dynamically generate an image and send up the
      // natural dimensions.
      let img = content.document.createElement("img");
      img.src = url;
      result.naturalWidth = img.naturalWidth;
      result.naturalHeight = img.naturalHeight;
    } else {
      // Otherwise, we can use the current width and height
      // of the image.
      result.width = item.width;
      result.height = item.height;
    }

    if (item instanceof content.SVGImageElement) {
      result.SVGImageElementWidth = item.width.baseVal.value;
      result.SVGImageElementHeight = item.height.baseVal.value;
    }

    result.baseURI = item.baseURI;

    return result;
  },

  // Other Misc Stuff
  // Modified from the Links Panel v2.3, http://segment7.net/mozilla/links/links.html
  // parse a node to extract the contents of the node
  getValueText(node) {

    let valueText = "";
    let content = node.ownerGlobal;

    // Form input elements don't generally contain information that is useful to our callers, so return nothing.
    if (node instanceof content.HTMLInputElement ||
        node instanceof content.HTMLSelectElement ||
        node instanceof content.HTMLTextAreaElement) {
      return valueText;
    }

    // Otherwise recurse for each child.
    let length = node.childNodes.length;

    for (let i = 0; i < length; i++) {
      let childNode = node.childNodes[i];
      let nodeType = childNode.nodeType;

      // Text nodes are where the goods are.
      if (nodeType == content.Node.TEXT_NODE) {
        valueText += " " + childNode.nodeValue;
      } else if (nodeType == content.Node.ELEMENT_NODE) {
        // And elements can have more text inside them.
        // Images are special, we want to capture the alt text as if the image weren't there.
        if (childNode instanceof content.HTMLImageElement) {
          valueText += " " + this.getAltText(childNode);
        } else {
          valueText += " " + this.getValueText(childNode);
        }
      }
    }

    return this.stripWS(valueText);
  },

  // Copied from the Links Panel v2.3, http://segment7.net/mozilla/links/links.html.
  // Traverse the tree in search of an img or area element and grab its alt tag.
  getAltText(node) {
    let altText = "";

    if (node.alt) {
      return node.alt;
    }
    let length = node.childNodes.length;
    for (let i = 0; i < length; i++) {
      if ((altText = this.getAltText(node.childNodes[i]) != undefined)) { // stupid js warning...
        return altText;
      }
    }
    return "";
  },

  // Copied from the Links Panel v2.3, http://segment7.net/mozilla/links/links.html.
  // Strip leading and trailing whitespace, and replace multiple consecutive whitespace characters with a single space.
  stripWS(text) {
    let middleRE = /\s+/g;
    let endRE = /(^\s+)|(\s+$)/g;

    text = text.replace(middleRE, " ");
    return text.replace(endRE, "");
  }
};