path: root/toolkit/actors/PrintingChild.sys.mjs

/* vim: set ts=2 sw=2 sts=2 et 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/. */

const lazy = {};

ChromeUtils.defineESModuleGetters(lazy, {
  DeferredTask: "resource://gre/modules/DeferredTask.sys.mjs",
  ReaderMode: "resource://gre/modules/ReaderMode.sys.mjs",
  setTimeout: "resource://gre/modules/Timer.sys.mjs",
});

let gPendingPreviewsMap = new Map();

export class PrintingChild extends JSWindowActorChild {
  actorCreated() {
    // When the print preview page is loaded, the actor will change, so update
    // the state/progress listener to the new actor.
    let listener = gPendingPreviewsMap.get(this.browsingContext.id);
    if (listener) {
      listener.actor = this;
    }
    this.contentWindow.addEventListener("scroll", this);
  }

  didDestroy() {
    this._scrollTask?.disarm();
    this.contentWindow?.removeEventListener("scroll", this);
  }

  handleEvent(event) {
    switch (event.type) {
      case "PrintingError": {
        let win = event.target.defaultView;
        let wbp = win.getInterface(Ci.nsIWebBrowserPrint);
        let nsresult = event.detail;
        this.sendAsyncMessage("Printing:Error", {
          isPrinting: wbp.doingPrint,
          nsresult,
        });
        break;
      }

      case "scroll":
        if (!this._scrollTask) {
          this._scrollTask = new lazy.DeferredTask(
            () => this.updateCurrentPage(),
            16,
            16
          );
        }
        this._scrollTask.arm();
        break;
    }
  }

  receiveMessage(message) {
    let data = message.data;
    switch (message.name) {
      case "Printing:Preview:Navigate": {
        this.navigate(data.navType, data.pageNum);
        break;
      }

      case "Printing:Preview:ParseDocument": {
        return this.parseDocument(
          data.URL,
          Services.wm.getOuterWindowWithId(data.windowID)
        );
      }
    }

    return undefined;
  }

  async parseDocument(URL, contentWindow) {
    // The document in 'contentWindow' will be simplified and the resulting nodes
    // will be inserted into this.contentWindow.
    let thisWindow = this.contentWindow;

    // By using ReaderMode primitives, we parse given document and place the
    // resulting JS object into the DOM of current browser.
    let article;
    try {
      article = await lazy.ReaderMode.parseDocument(contentWindow.document);
    } catch (ex) {
      console.error(ex);
    }

    await new Promise(resolve => {
      // We make use of a web progress listener in order to know when the content we inject
      // into the DOM has finished rendering. If our layout engine is still painting, we
      // will wait for MozAfterPaint event to be fired.
      let actor = thisWindow.windowGlobalChild.getActor("Printing");
      let webProgressListener = {
        onStateChange(webProgress, req, flags, status) {
          if (flags & Ci.nsIWebProgressListener.STATE_STOP) {
            webProgress.removeProgressListener(webProgressListener);
            let domUtils = contentWindow.windowUtils;
            // Here we tell the parent that we have parsed the document successfully
            // using ReaderMode primitives and we are able to enter on preview mode.
            if (domUtils.isMozAfterPaintPending) {
              let onPaint = function () {
                contentWindow.removeEventListener("MozAfterPaint", onPaint);
                actor.sendAsyncMessage("Printing:Preview:ReaderModeReady");
                resolve();
              };
              contentWindow.addEventListener("MozAfterPaint", onPaint);
              // This timer is needed for when display list invalidation doesn't invalidate.
              lazy.setTimeout(() => {
                contentWindow.removeEventListener("MozAfterPaint", onPaint);
                actor.sendAsyncMessage("Printing:Preview:ReaderModeReady");
                resolve();
              }, 100);
            } else {
              actor.sendAsyncMessage("Printing:Preview:ReaderModeReady");
              resolve();
            }
          }
        },

        QueryInterface: ChromeUtils.generateQI([
          "nsIWebProgressListener",
          "nsISupportsWeakReference",
          "nsIObserver",
        ]),
      };

      // Here we QI the docShell into a nsIWebProgress passing our web progress listener in.
      let webProgress = thisWindow.docShell
        .QueryInterface(Ci.nsIInterfaceRequestor)
        .getInterface(Ci.nsIWebProgress);
      webProgress.addProgressListener(
        webProgressListener,
        Ci.nsIWebProgress.NOTIFY_STATE_REQUEST
      );

      let document = thisWindow.document;
      document.head.innerHTML = "";

      // Set base URI of document. Print preview code will read this value to
      // populate the URL field in print settings so that it doesn't show
      // "about:blank" as its URI.
      let headBaseElement = document.createElement("base");
      headBaseElement.setAttribute("href", URL);
      document.head.appendChild(headBaseElement);

      // Create link element referencing aboutReader.css and append it to head
      let headStyleElement = document.createElement("link");
      headStyleElement.setAttribute("rel", "stylesheet");
      headStyleElement.setAttribute(
        "href",
        "chrome://global/skin/aboutReader.css"
      );
      headStyleElement.setAttribute("type", "text/css");
      document.head.appendChild(headStyleElement);

      // Create link element referencing simplifyMode.css and append it to head
      headStyleElement = document.createElement("link");
      headStyleElement.setAttribute("rel", "stylesheet");
      headStyleElement.setAttribute(
        "href",
        "chrome://global/content/simplifyMode.css"
      );
      headStyleElement.setAttribute("type", "text/css");
      document.head.appendChild(headStyleElement);

      document.body.innerHTML = "";

      // Create container div (main element) and append it to body
      let containerElement = document.createElement("div");
      containerElement.setAttribute("class", "container");
      document.body.appendChild(containerElement);

      // Reader Mode might return null if there's a failure when parsing the document.
      // We'll render the error message for the Simplify Page document when that happens.
      if (article) {
        // Set title of document
        document.title = article.title;

        // Create header div and append it to container
        let headerElement = document.createElement("div");
        headerElement.setAttribute("class", "reader-header");
        headerElement.setAttribute("class", "header");
        containerElement.appendChild(headerElement);

        // Jam the article's title and byline into header div
        let titleElement = document.createElement("h1");
        titleElement.setAttribute("class", "reader-title");
        titleElement.textContent = article.title;
        headerElement.appendChild(titleElement);

        let bylineElement = document.createElement("div");
        bylineElement.setAttribute("class", "reader-credits credits");
        bylineElement.textContent = article.byline;
        headerElement.appendChild(bylineElement);

        // Display header element
        headerElement.style.display = "block";

        // Create content div and append it to container
        let contentElement = document.createElement("div");
        contentElement.setAttribute("class", "content");
        containerElement.appendChild(contentElement);

        // Jam the article's content into content div
        let readerContent = document.createElement("div");
        readerContent.setAttribute("class", "moz-reader-content");
        contentElement.appendChild(readerContent);

        let articleUri = Services.io.newURI(article.url);
        let parserUtils = Cc["@mozilla.org/parserutils;1"].getService(
          Ci.nsIParserUtils
        );
        let contentFragment = parserUtils.parseFragment(
          article.content,
          Ci.nsIParserUtils.SanitizerDropForms |
            Ci.nsIParserUtils.SanitizerAllowStyle,
          false,
          articleUri,
          readerContent
        );

        readerContent.appendChild(contentFragment);

        // Display reader content element
        readerContent.style.display = "block";
      } else {
        const l10n = new Localization(["toolkit/about/aboutReader.ftl"], true);
        const errorMessage = l10n.formatValueSync("about-reader-load-error");

        document.title = errorMessage;

        // Create reader message div and append it to body
        let readerMessageElement = document.createElement("div");
        readerMessageElement.setAttribute("class", "reader-message");
        readerMessageElement.textContent = errorMessage;
        containerElement.appendChild(readerMessageElement);

        // Display reader message element
        readerMessageElement.style.display = "block";
      }
    });
  }

  updateCurrentPage() {
    let cv = this.docShell.contentViewer;
    cv.QueryInterface(Ci.nsIWebBrowserPrint);
    this.sendAsyncMessage("Printing:Preview:CurrentPage", {
      currentPage: cv.printPreviewCurrentPageNumber,
    });
  }

  navigate(navType, pageNum) {
    let cv = this.docShell.contentViewer;
    cv.QueryInterface(Ci.nsIWebBrowserPrint);
    cv.printPreviewScrollToPage(navType, pageNum);
  }
}