chrome/browser/resources/pdf/open_pdf_params_parser.ts - chromium/src - Git at Google

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

 import {assert} from 'chrome://resources/js/assert.js';

 import type {NamedDestinationMessageData, Point, Rect} from './constants.js';
 import {FittingType} from './constants.js';
 import type {Size} from './viewport.js';

 export interface OpenPdfParams {
   boundingBox?: Rect;
   page?: number;
   position?: Point;
   url?: string;
   view?: FittingType;
   viewPosition?: number;
   zoom?: number;
 }

 export enum ViewMode {
   FIT = 'fit',
   FIT_B = 'fitb',
   FIT_BH = 'fitbh',
   FIT_BV = 'fitbv',
   FIT_H = 'fith',
   FIT_R = 'fitr',
   FIT_V = 'fitv',
   XYZ = 'xyz',
 }

 const FRAGMENT_DIRECTIVE_DELIMITER = ':~:';

 type GetNamedDestinationCallback = (name: string) =>
     Promise<NamedDestinationMessageData>;

 type GetPageBoundingBoxCallback = (page: number) => Promise<Rect>;

 // Parses the open pdf parameters passed in the url to set initial viewport
 // settings for opening the pdf.
 export class OpenPdfParamsParser {
   private getNamedDestinationCallback_: GetNamedDestinationCallback;
   private getPageBoundingBoxCallback_: GetPageBoundingBoxCallback;
   private pageCount_?: number;
   private viewportDimensions_?: Size;

   /**
    * @param getNamedDestinationCallback Function called to fetch information for
    *     a named destination.
    * @param getPageBoundingBoxCallback Function called to fetch information for
    *     a page's bounding box.
    */
   constructor(
       getNamedDestinationCallback: GetNamedDestinationCallback,
       getPageBoundingBoxCallback: GetPageBoundingBoxCallback) {
     this.getNamedDestinationCallback_ = getNamedDestinationCallback;
     this.getPageBoundingBoxCallback_ = getPageBoundingBoxCallback;
   }

   /**
    * Calculate the zoom level needed for making viewport focus on a rectangular
    * area in the PDF document.
    * @param size The dimensions of the rectangular area to be focused on.
    * @return The zoom level needed for focusing on the rectangular area. A zoom
    *     level of 0 indicates that the zoom level cannot be calculated with the
    *     given information.
    */
   private calculateRectZoomLevel_(size: Size): number {
     if (size.height === 0 || size.width === 0) {
       return 0;
     }

     assert(this.viewportDimensions_);
     return Math.min(
         this.viewportDimensions_.height / size.height,
         this.viewportDimensions_.width / size.width);
   }

   /**
    * Parse zoom parameter of open PDF parameters. The PDF should be opened at
    * the specified zoom level.
    * @return Map with zoom parameters (zoom and position).
    */
   private parseZoomParam_(paramValue: string): OpenPdfParams {
     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 paramValue Params to parse.
    * @param pageNumber Page number for bounding box, if there is a fit bounding
    *     box param. `pageNumber` is 1-indexed and must be bounded by 1 and the
    *     number of pages in the PDF, inclusive.
    * @return Map with view parameters (view and viewPosition).
    */
   private async parseViewParam_(paramValue: string, pageNumber: number):
       Promise<OpenPdfParams> {
     assert(pageNumber > 0);
     if (this.pageCount_) {
       assert(pageNumber <= this.pageCount_);
     }

     const viewModeComponents = paramValue.toLowerCase().split(',');
     if (viewModeComponents.length === 0) {
       return {};
     }

     const params: OpenPdfParams = {};
     const viewMode = viewModeComponents[0]!;
     let acceptsPositionParam = false;

     // Note that `pageNumber` is 1-indexed, but PDF Viewer is 0-indexed.
     switch (viewMode) {
       case ViewMode.FIT:
         params['view'] = FittingType.FIT_TO_PAGE;
         break;
       case ViewMode.FIT_H:
         params['view'] = FittingType.FIT_TO_WIDTH;
         acceptsPositionParam = true;
         break;
       case ViewMode.FIT_V:
         params['view'] = FittingType.FIT_TO_HEIGHT;
         acceptsPositionParam = true;
         break;
       case ViewMode.FIT_B:
         if (this.pageCount_) {
           params['view'] = FittingType.FIT_TO_BOUNDING_BOX;
           params['boundingBox'] =
               await this.getPageBoundingBoxCallback_(pageNumber - 1);
         }
         break;
       case ViewMode.FIT_BH:
         if (this.pageCount_) {
           params['view'] = FittingType.FIT_TO_BOUNDING_BOX_WIDTH;
           params['boundingBox'] =
               await this.getPageBoundingBoxCallback_(pageNumber - 1);
           acceptsPositionParam = true;
         }
         break;
       case ViewMode.FIT_BV:
         if (this.pageCount_) {
           params['view'] = FittingType.FIT_TO_BOUNDING_BOX_HEIGHT;
           params['boundingBox'] =
               await this.getPageBoundingBoxCallback_(pageNumber - 1);
           acceptsPositionParam = true;
         }
         break;
       case ViewMode.FIT_R:
       case ViewMode.XYZ:
         // Should have already been handled in `parseNameddestViewParam_()`.
         break;
       default:
         // Invalid view parameter, do nothing.
     }

     if (!acceptsPositionParam || viewModeComponents.length === 1) {
       return params;
     }

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

     return params;
   }

   /**
    * Parse view parameters which come from nameddest.
    * @param paramValue Params to parse.
    * @param pageNumber Page number for bounding box, if there is a fit bounding
    *     box param.
    * @return Map with view parameters.
    */
   private async parseNameddestViewParam_(
       paramValue: string, pageNumber: number): Promise<OpenPdfParams> {
     const viewModeComponents = paramValue.toLowerCase().split(',');
     assert(viewModeComponents.length > 0);
     const viewMode = viewModeComponents[0]!;
     const params: OpenPdfParams = {};

     if (viewMode === ViewMode.XYZ && viewModeComponents.length === 4) {
       const x = parseFloat(viewModeComponents[1]!);
       const y = parseFloat(viewModeComponents[2]!);
       const zoom = parseFloat(viewModeComponents[3]!);

       // If zoom is originally 0 for the XYZ view, it is guaranteed to be
       // transformed into "null" by the backend.
       assert(zoom !== 0);

       if (!Number.isNaN(zoom)) {
         params['zoom'] = zoom;
       }
       if (!Number.isNaN(x) || !Number.isNaN(y)) {
         params['position'] = {x: x, y: y};
       }
       return params;
     }

     if (viewMode === ViewMode.FIT_R && viewModeComponents.length === 5) {
       assert(this.viewportDimensions_ !== undefined);
       let x1 = parseFloat(viewModeComponents[1]!);
       let y1 = parseFloat(viewModeComponents[2]!);
       let x2 = parseFloat(viewModeComponents[3]!);
       let y2 = parseFloat(viewModeComponents[4]!);
       if (!Number.isNaN(x1) && !Number.isNaN(y1) && !Number.isNaN(x2) &&
           !Number.isNaN(y2)) {
         if (x1 > x2) {
           [x1, x2] = [x2, x1];
         }
         if (y1 > y2) {
           [y1, y2] = [y2, y1];
         }
         const rectSize = {width: x2 - x1, height: y2 - y1};
         params['position'] = {x: x1, y: y1};
         const zoom = this.calculateRectZoomLevel_(rectSize);
         if (zoom !== 0) {
           params['zoom'] = zoom;
         }
       }
       return params;
     }

     return this.parseViewParam_(paramValue, pageNumber);
   }

   /** Parse the parameters encoded in the fragment of a URL. */
   private parseUrlParams_(url: string): URLSearchParams {
     const hash = new URL(url).hash;
     const params = new URLSearchParams(hash.substring(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.
     if (Array.from(params).length === 1) {
       const key = Array.from(params.keys())[0]!;
       if (params.get(key) === '') {
         params.append('nameddest', key);
         params.delete(key);
       }
     }

     return params;
   }

   /** Store the number of pages. */
   setPageCount(pageCount: number) {
     this.pageCount_ = pageCount;
   }

   /** Store current viewport's dimensions. */
   setViewportDimensions(dimensions: Size) {
     this.viewportDimensions_ = dimensions;
   }

   /**
    * @param url that needs to be parsed.
    * @return Whether the toolbar UI element should be shown.
    */
   shouldShowToolbar(url: string): boolean {
     const urlParams = this.parseUrlParams_(url);
     const navpanes = urlParams.get('navpanes');
     const toolbar = urlParams.get('toolbar');

     // If navpanes is set to '1', then the toolbar must be shown, regardless of
     // the value of toolbar.
     return navpanes === '1' || toolbar !== '0';
   }

   /**
    * @param url that needs to be parsed.
    * @param sidenavCollapsed the default sidenav state if there are no
    *     overriding open parameters.
    * @return Whether the sidenav UI element should be shown.
    */
   shouldShowSidenav(url: string, sidenavCollapsed: boolean): boolean {
     const urlParams = this.parseUrlParams_(url);
     const navpanes = urlParams.get('navpanes');
     const toolbar = urlParams.get('toolbar');

     // If there are no relevant open parameters, default to the original value.
     if (navpanes === null && toolbar === null) {
       return !sidenavCollapsed;
     }

     return navpanes === '1';
   }

   /**
    * Fetch text fragment directives that appear in the PDF URL if any.
    *
    * @param url that needs to be parsed.
    * @return The text fragment directives or an empty array if they do not
    *     exist.
    */
   getTextFragments(url: string): string[] {
     // The hash of the URL object decodes the escaped characters in our
     // fragment. So in order to keep characters such as `,` or `-` which could
     // be part of the prefix or suffix, the fragment of the URL needs to be
     // fetched directly from the `url` string instead of using the URL
     // interface.
     const hashSplit = url.split('#');
     if (hashSplit.length !== 2) {
       return [];
     }
     const hash = hashSplit[1];
     assert(hash !== undefined);

     // Handle the case of text directives included in the URL.
     const fragmentDirectiveSplit = hash.split(FRAGMENT_DIRECTIVE_DELIMITER);
     if (fragmentDirectiveSplit.length !== 2) {
       return [];
     }
     const fragmentDirective = fragmentDirectiveSplit[1];
     assert(fragmentDirective !== undefined);

     // Loop through the directive split at character `&` in case of multiple
     // text directives. This cannot be done with URLSearchParams since the `get`
     // and `getAll` functions decode the parameter values which can result in a
     // broken text fragment parse.
     const textFragmentDirectives: string[] = [];
     for (const param of fragmentDirective.split('&')) {
       const [key, value] = param.split('=');
       if (key === 'text' && value) {
         textFragmentDirectives.push(value);
       }
     }
     return textFragmentDirectives;
   }

   /**
    * 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 url that needs to be parsed.
    */
   async getViewportFromUrlParams(url: string): Promise<OpenPdfParams> {
     const params: OpenPdfParams = {url};

     const urlParams = this.parseUrlParams_(url);

     // `pageNumber` is 1-based.
     let pageNumber = 1;
     if (urlParams.has('page')) {
       pageNumber = parseInt(urlParams.get('page')!, 10);
       if (!Number.isNaN(pageNumber) && this.pageCount_) {
         // If necessary, clip `pageNumber` to stay within bounds.
         if (pageNumber < 1) {
           pageNumber = 1;
         } else if (pageNumber > this.pageCount_) {
           pageNumber = this.pageCount_;
         }
         // goToPage() takes a zero-based page index.
         params['page'] = pageNumber - 1;
       }
     }

     if (urlParams.has('view')) {
       Object.assign(
           params,
           await this.parseViewParam_(urlParams.get('view')!, pageNumber));
     }

     if (urlParams.has('zoom')) {
       Object.assign(params, this.parseZoomParam_(urlParams.get('zoom')!));
     }

     if (params.page === undefined && urlParams.has('nameddest')) {
       const data =
           await this.getNamedDestinationCallback_(urlParams.get('nameddest')!);

       if (data.pageNumber !== -1) {
         params.page = data.pageNumber;
         pageNumber = data.pageNumber;
       }

       if (data.namedDestinationView) {
         Object.assign(
             params,
             await this.parseNameddestViewParam_(
                 data.namedDestinationView, pageNumber));
       }
       return params;
     }
     return params;
   }
 }
	// Copyright 2014 The Chromium Authors
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import {assert} from 'chrome://resources/js/assert.js';

	import type {NamedDestinationMessageData, Point, Rect} from './constants.js';
	import {FittingType} from './constants.js';
	import type {Size} from './viewport.js';

	export interface OpenPdfParams {
	boundingBox?: Rect;
	page?: number;
	position?: Point;
	url?: string;
	view?: FittingType;
	viewPosition?: number;
	zoom?: number;
	}

	export enum ViewMode {
	FIT = 'fit',
	FIT_B = 'fitb',
	FIT_BH = 'fitbh',
	FIT_BV = 'fitbv',
	FIT_H = 'fith',
	FIT_R = 'fitr',
	FIT_V = 'fitv',
	XYZ = 'xyz',
	}

	const FRAGMENT_DIRECTIVE_DELIMITER = ':~:';

	type GetNamedDestinationCallback = (name: string) =>
	Promise<NamedDestinationMessageData>;

	type GetPageBoundingBoxCallback = (page: number) => Promise<Rect>;

	// Parses the open pdf parameters passed in the url to set initial viewport
	// settings for opening the pdf.
	export class OpenPdfParamsParser {
	private getNamedDestinationCallback_: GetNamedDestinationCallback;
	private getPageBoundingBoxCallback_: GetPageBoundingBoxCallback;
	private pageCount_?: number;
	private viewportDimensions_?: Size;

	/**
	* @param getNamedDestinationCallback Function called to fetch information for
	* a named destination.
	* @param getPageBoundingBoxCallback Function called to fetch information for
	* a page's bounding box.
	*/
	constructor(
	getNamedDestinationCallback: GetNamedDestinationCallback,
	getPageBoundingBoxCallback: GetPageBoundingBoxCallback) {
	this.getNamedDestinationCallback_ = getNamedDestinationCallback;
	this.getPageBoundingBoxCallback_ = getPageBoundingBoxCallback;
	}

	/**
	* Calculate the zoom level needed for making viewport focus on a rectangular
	* area in the PDF document.
	* @param size The dimensions of the rectangular area to be focused on.
	* @return The zoom level needed for focusing on the rectangular area. A zoom
	* level of 0 indicates that the zoom level cannot be calculated with the
	* given information.
	*/
	private calculateRectZoomLevel_(size: Size): number {
	if (size.height === 0 \|\| size.width === 0) {
	return 0;
	}

	assert(this.viewportDimensions_);
	return Math.min(
	this.viewportDimensions_.height / size.height,
	this.viewportDimensions_.width / size.width);
	}

	/**
	* Parse zoom parameter of open PDF parameters. The PDF should be opened at
	* the specified zoom level.
	* @return Map with zoom parameters (zoom and position).
	*/
	private parseZoomParam_(paramValue: string): OpenPdfParams {
	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 paramValue Params to parse.
	* @param pageNumber Page number for bounding box, if there is a fit bounding
	* box param. `pageNumber` is 1-indexed and must be bounded by 1 and the
	* number of pages in the PDF, inclusive.
	* @return Map with view parameters (view and viewPosition).
	*/
	private async parseViewParam_(paramValue: string, pageNumber: number):
	Promise<OpenPdfParams> {
	assert(pageNumber > 0);
	if (this.pageCount_) {
	assert(pageNumber <= this.pageCount_);
	}

	const viewModeComponents = paramValue.toLowerCase().split(',');
	if (viewModeComponents.length === 0) {
	return {};
	}

	const params: OpenPdfParams = {};
	const viewMode = viewModeComponents[0]!;
	let acceptsPositionParam = false;

	// Note that `pageNumber` is 1-indexed, but PDF Viewer is 0-indexed.
	switch (viewMode) {
	case ViewMode.FIT:
	params['view'] = FittingType.FIT_TO_PAGE;
	break;
	case ViewMode.FIT_H:
	params['view'] = FittingType.FIT_TO_WIDTH;
	acceptsPositionParam = true;
	break;
	case ViewMode.FIT_V:
	params['view'] = FittingType.FIT_TO_HEIGHT;
	acceptsPositionParam = true;
	break;
	case ViewMode.FIT_B:
	if (this.pageCount_) {
	params['view'] = FittingType.FIT_TO_BOUNDING_BOX;
	params['boundingBox'] =
	await this.getPageBoundingBoxCallback_(pageNumber - 1);
	}
	break;
	case ViewMode.FIT_BH:
	if (this.pageCount_) {
	params['view'] = FittingType.FIT_TO_BOUNDING_BOX_WIDTH;
	params['boundingBox'] =
	await this.getPageBoundingBoxCallback_(pageNumber - 1);
	acceptsPositionParam = true;
	}
	break;
	case ViewMode.FIT_BV:
	if (this.pageCount_) {
	params['view'] = FittingType.FIT_TO_BOUNDING_BOX_HEIGHT;
	params['boundingBox'] =
	await this.getPageBoundingBoxCallback_(pageNumber - 1);
	acceptsPositionParam = true;
	}
	break;
	case ViewMode.FIT_R:
	case ViewMode.XYZ:
	// Should have already been handled in `parseNameddestViewParam_()`.
	break;
	default:
	// Invalid view parameter, do nothing.
	}

	if (!acceptsPositionParam \|\| viewModeComponents.length === 1) {
	return params;
	}

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

	return params;
	}

	/**
	* Parse view parameters which come from nameddest.
	* @param paramValue Params to parse.
	* @param pageNumber Page number for bounding box, if there is a fit bounding
	* box param.
	* @return Map with view parameters.
	*/
	private async parseNameddestViewParam_(
	paramValue: string, pageNumber: number): Promise<OpenPdfParams> {
	const viewModeComponents = paramValue.toLowerCase().split(',');
	assert(viewModeComponents.length > 0);
	const viewMode = viewModeComponents[0]!;
	const params: OpenPdfParams = {};

	if (viewMode === ViewMode.XYZ && viewModeComponents.length === 4) {
	const x = parseFloat(viewModeComponents[1]!);
	const y = parseFloat(viewModeComponents[2]!);
	const zoom = parseFloat(viewModeComponents[3]!);

	// If zoom is originally 0 for the XYZ view, it is guaranteed to be
	// transformed into "null" by the backend.
	assert(zoom !== 0);

	if (!Number.isNaN(zoom)) {
	params['zoom'] = zoom;
	}
	if (!Number.isNaN(x) \|\| !Number.isNaN(y)) {
	params['position'] = {x: x, y: y};
	}
	return params;
	}

	if (viewMode === ViewMode.FIT_R && viewModeComponents.length === 5) {
	assert(this.viewportDimensions_ !== undefined);
	let x1 = parseFloat(viewModeComponents[1]!);
	let y1 = parseFloat(viewModeComponents[2]!);
	let x2 = parseFloat(viewModeComponents[3]!);
	let y2 = parseFloat(viewModeComponents[4]!);
	if (!Number.isNaN(x1) && !Number.isNaN(y1) && !Number.isNaN(x2) &&
	!Number.isNaN(y2)) {
	if (x1 > x2) {
	[x1, x2] = [x2, x1];
	}
	if (y1 > y2) {
	[y1, y2] = [y2, y1];
	}
	const rectSize = {width: x2 - x1, height: y2 - y1};
	params['position'] = {x: x1, y: y1};
	const zoom = this.calculateRectZoomLevel_(rectSize);
	if (zoom !== 0) {
	params['zoom'] = zoom;
	}
	}
	return params;
	}

	return this.parseViewParam_(paramValue, pageNumber);
	}

	/** Parse the parameters encoded in the fragment of a URL. */
	private parseUrlParams_(url: string): URLSearchParams {
	const hash = new URL(url).hash;
	const params = new URLSearchParams(hash.substring(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.
	if (Array.from(params).length === 1) {
	const key = Array.from(params.keys())[0]!;
	if (params.get(key) === '') {
	params.append('nameddest', key);
	params.delete(key);
	}
	}

	return params;
	}

	/** Store the number of pages. */
	setPageCount(pageCount: number) {
	this.pageCount_ = pageCount;
	}

	/** Store current viewport's dimensions. */
	setViewportDimensions(dimensions: Size) {
	this.viewportDimensions_ = dimensions;
	}

	/**
	* @param url that needs to be parsed.
	* @return Whether the toolbar UI element should be shown.
	*/
	shouldShowToolbar(url: string): boolean {
	const urlParams = this.parseUrlParams_(url);
	const navpanes = urlParams.get('navpanes');
	const toolbar = urlParams.get('toolbar');

	// If navpanes is set to '1', then the toolbar must be shown, regardless of
	// the value of toolbar.
	return navpanes === '1' \|\| toolbar !== '0';
	}

	/**
	* @param url that needs to be parsed.
	* @param sidenavCollapsed the default sidenav state if there are no
	* overriding open parameters.
	* @return Whether the sidenav UI element should be shown.
	*/
	shouldShowSidenav(url: string, sidenavCollapsed: boolean): boolean {
	const urlParams = this.parseUrlParams_(url);
	const navpanes = urlParams.get('navpanes');
	const toolbar = urlParams.get('toolbar');

	// If there are no relevant open parameters, default to the original value.
	if (navpanes === null && toolbar === null) {
	return !sidenavCollapsed;
	}

	return navpanes === '1';
	}

	/**
	* Fetch text fragment directives that appear in the PDF URL if any.
	*
	* @param url that needs to be parsed.
	* @return The text fragment directives or an empty array if they do not
	* exist.
	*/
	getTextFragments(url: string): string[] {
	// The hash of the URL object decodes the escaped characters in our
	// fragment. So in order to keep characters such as `,` or `-` which could
	// be part of the prefix or suffix, the fragment of the URL needs to be
	// fetched directly from the `url` string instead of using the URL
	// interface.
	const hashSplit = url.split('#');
	if (hashSplit.length !== 2) {
	return [];
	}
	const hash = hashSplit[1];
	assert(hash !== undefined);

	// Handle the case of text directives included in the URL.
	const fragmentDirectiveSplit = hash.split(FRAGMENT_DIRECTIVE_DELIMITER);
	if (fragmentDirectiveSplit.length !== 2) {
	return [];
	}
	const fragmentDirective = fragmentDirectiveSplit[1];
	assert(fragmentDirective !== undefined);

	// Loop through the directive split at character `&` in case of multiple
	// text directives. This cannot be done with URLSearchParams since the `get`
	// and `getAll` functions decode the parameter values which can result in a
	// broken text fragment parse.
	const textFragmentDirectives: string[] = [];
	for (const param of fragmentDirective.split('&')) {
	const [key, value] = param.split('=');
	if (key === 'text' && value) {
	textFragmentDirectives.push(value);
	}
	}
	return textFragmentDirectives;
	}

	/**
	* 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 url that needs to be parsed.
	*/
	async getViewportFromUrlParams(url: string): Promise<OpenPdfParams> {
	const params: OpenPdfParams = {url};

	const urlParams = this.parseUrlParams_(url);

	// `pageNumber` is 1-based.
	let pageNumber = 1;
	if (urlParams.has('page')) {
	pageNumber = parseInt(urlParams.get('page')!, 10);
	if (!Number.isNaN(pageNumber) && this.pageCount_) {
	// If necessary, clip `pageNumber` to stay within bounds.
	if (pageNumber < 1) {
	pageNumber = 1;
	} else if (pageNumber > this.pageCount_) {
	pageNumber = this.pageCount_;
	}
	// goToPage() takes a zero-based page index.
	params['page'] = pageNumber - 1;
	}
	}

	if (urlParams.has('view')) {
	Object.assign(
	params,
	await this.parseViewParam_(urlParams.get('view')!, pageNumber));
	}

	if (urlParams.has('zoom')) {
	Object.assign(params, this.parseZoomParam_(urlParams.get('zoom')!));
	}

	if (params.page === undefined && urlParams.has('nameddest')) {
	const data =
	await this.getNamedDestinationCallback_(urlParams.get('nameddest')!);

	if (data.pageNumber !== -1) {
	params.page = data.pageNumber;
	pageNumber = data.pageNumber;
	}

	if (data.namedDestinationView) {
	Object.assign(
	params,
	await this.parseNameddestViewParam_(
	data.namedDestinationView, pageNumber));
	}
	return params;
	}
	return params;
	}
	}