chrome/browser/resources/pdf/open_pdf_params_parser.js

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

(function() {

'use strict';

/**
 * Parses the open pdf parameters passed in the url to set initial viewport
 * settings for opening the pdf.
 */
window.OpenPDFParamsParser = class {
  /**
   * @param {function(Object)} postMessageCallback
   *     Function called to fetch information for a named destination.
   */
  constructor(postMessageCallback) {
    /** @private {!Array<!Object>} */
    this.outstandingRequests_ = [];

    /** @private {!function(Object)} */
    this.postMessageCallback_ = postMessageCallback;
  }

  /**
   * Parse zoom parameter of open PDF parameters. The PDF should be opened at
   * the specified zoom level.
   *
   * @param {string} paramValue zoom value.
   * @return {Object} Map with zoom parameters (zoom and position).
   * @private
   */
  parseZoomParam_(paramValue) {
    const paramValueSplit = paramValue.split(',');
    if (paramValueSplit.length != 1 && paramValueSplit.length != 3)
      return {};

    // User scale of 100 means zoom value of 100% i.e. zoom factor of 1.0.
    const zoomFactor = parseFloat(paramValueSplit[0]) / 100;
    if (Number.isNaN(zoomFactor))
      return {};

    // Handle #zoom=scale.
    if (paramValueSplit.length == 1) {
      return {'zoom': zoomFactor};
    }

    // Handle #zoom=scale,left,top.
    const position = {
      x: parseFloat(paramValueSplit[1]),
      y: parseFloat(paramValueSplit[2])
    };
    return {'position': position, 'zoom': zoomFactor};
  }

  /**
   * Parse view parameter of open PDF parameters. The PDF should be opened at
   * the specified fitting type mode and position.
   *
   * @param {string} paramValue view value.
   * @return {Object} Map with view parameters (view and viewPosition).
   * @private
   */
  parseViewParam_(paramValue) {
    const viewModeComponents = paramValue.toLowerCase().split(',');
    if (viewModeComponents.length < 1)
      return {};

    const params = {};
    const viewMode = viewModeComponents[0];
    let acceptsPositionParam;
    if (viewMode === 'fit') {
      params['view'] = FittingType.FIT_TO_PAGE;
      acceptsPositionParam = false;
    } else if (viewMode === 'fith') {
      params['view'] = FittingType.FIT_TO_WIDTH;
      acceptsPositionParam = true;
    } else if (viewMode === 'fitv') {
      params['view'] = FittingType.FIT_TO_HEIGHT;
      acceptsPositionParam = true;
    }

    if (!acceptsPositionParam || viewModeComponents.length < 2)
      return params;

    const position = parseFloat(viewModeComponents[1]);
    if (!Number.isNaN(position))
      params['viewPosition'] = position;

    return params;
  }

  /**
   * Parse the parameters encoded in the fragment of a URL into a dictionary.
   *
   * @param {string} url to parse
   * @return {Object} Key-value pairs of URL parameters
   * @private
   */
  parseUrlParams_(url) {
    const params = {};

    const paramIndex = url.search('#');
    if (paramIndex == -1)
      return params;

    const paramTokens = url.substring(paramIndex + 1).split('&');
    if ((paramTokens.length == 1) && (paramTokens[0].search('=') == -1)) {
      // Handle the case of http://foo.com/bar#NAMEDDEST. This is not
      // explicitly mentioned except by example in the Adobe
      // "PDF Open Parameters" document.
      params['nameddest'] = paramTokens[0];
      return params;
    }

    for (const paramToken of paramTokens) {
      const keyValueSplit = paramToken.split('=');
      if (keyValueSplit.length != 2)
        continue;
      params[keyValueSplit[0]] = keyValueSplit[1];
    }

    return params;
  }

  /**
   * Parse PDF url parameters used for controlling the state of UI. These need
   * to be available when the UI is being initialized, rather than when the PDF
   * is finished loading.
   *
   * @param {string} url that needs to be parsed.
   * @return {Object} parsed url parameters.
   */
  getUiUrlParams(url) {
    const params = this.parseUrlParams_(url);
    const uiParams = {toolbar: true};

    if ('toolbar' in params && params['toolbar'] == 0)
      uiParams.toolbar = false;

    return uiParams;
  }

  /**
   * Parse PDF url parameters. These parameters are mentioned in the url
   * and specify actions to be performed when opening pdf files.
   * See http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/
   * pdfs/pdf_open_parameters.pdf for details.
   *
   * @param {string} url that needs to be parsed.
   * @param {Function} callback function to be called with viewport info.
   */
  getViewportFromUrlParams(url, callback) {
    const params = {};
    params['url'] = url;

    const urlParams = this.parseUrlParams_(url);

    if ('page' in urlParams) {
      // |pageNumber| is 1-based, but goToPage() take a zero-based page number.
      const pageNumber = parseInt(urlParams['page'], 10);
      if (!Number.isNaN(pageNumber) && pageNumber > 0)
        params['page'] = pageNumber - 1;
    }

    if ('view' in urlParams)
      Object.assign(params, this.parseViewParam_(urlParams['view']));

    if ('zoom' in urlParams)
      Object.assign(params, this.parseZoomParam_(urlParams['zoom']));

    if (params.page === undefined && 'nameddest' in urlParams) {
      this.outstandingRequests_.push({callback: callback, params: params});
      this.postMessageCallback_({
        type: 'getNamedDestination',
        namedDestination: urlParams['nameddest']
      });
    } else {
      callback(params);
    }
  }

  /**
   * This is called when a named destination is received and the page number
   * corresponding to the request for which a named destination is passed.
   *
   * @param {number} pageNumber The page corresponding to the named destination
   *    requested.
   */
  onNamedDestinationReceived(pageNumber) {
    const outstandingRequest = this.outstandingRequests_.shift();
    if (pageNumber != -1)
      outstandingRequest.params.page = pageNumber;
    outstandingRequest.callback(outstandingRequest.params);
  }
};

}());