roi-theme/wp-content/plugins/PDFEmbedder-premium-secure/assets/js/viewer/text_layer_builder.js

/* Copyright 2012 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// eslint-disable-next-line max-len
/** @typedef {import("../src/display/display_utils").PageViewport} PageViewport */
/** @typedef {import("./event_utils").EventBus} EventBus */
/** @typedef {import("./text_highlighter").TextHighlighter} TextHighlighter */
// eslint-disable-next-line max-len
/** @typedef {import("./text_accessibility.js").TextAccessibilityManager} TextAccessibilityManager */

import { renderTextLayer } from 'pdfjs-dist';

const EXPAND_DIVS_TIMEOUT = 300; // ms

/**
 * @typedef {Object} TextLayerBuilderOptions
 * @property {HTMLDivElement} textLayerDiv - The text layer container.
 * @property {EventBus} eventBus - The application event bus.
 * @property {number} pageIndex - The page index.
 * @property {PageViewport} viewport - The viewport of the text layer.
 * @property {TextHighlighter} highlighter - Optional object that will handle
 *   highlighting text from the find controller.
 * @property {boolean} enhanceTextSelection - Option to turn on improved
 *   text selection.
 * @property {TextAccessibilityManager} [accessibilityManager]
 */

/**
 * The text layer builder provides text selection functionality for the PDF.
 * It does this by creating overlay divs over the PDF's text. These divs
 * contain text that matches the PDF text they are overlaying.
 */
class TextLayerBuilder {
	constructor({
		textLayerDiv,
		eventBus,
		pageIndex,
		viewport,
		highlighter = null,
		enhanceTextSelection = false,
		accessibilityManager = null,
	}) {
		this.textLayerDiv = textLayerDiv;
		this.eventBus = eventBus;
		this.textContent = null;
		this.textContentItemsStr = [];
		this.textContentStream = null;
		this.renderingDone = false;
		this.pageNumber = pageIndex + 1;
		this.viewport = viewport;
		this.textDivs = [];
		this.textLayerRenderTask = null;
		this.highlighter = highlighter;
		this.enhanceTextSelection = enhanceTextSelection;
		this.accessibilityManager = accessibilityManager;

		this._bindMouse();
	}

	/**
	 * @private
	 */
	_finishRendering() {
		this.renderingDone = true;

		if (!this.enhanceTextSelection) {
			const endOfContent = document.createElement('div');
			endOfContent.className = 'endOfContent';
			this.textLayerDiv.append(endOfContent);
		}

		this.eventBus.dispatch('textlayerrendered', {
			source: this,
			pageNumber: this.pageNumber,
			numTextDivs: this.textDivs.length,
		});
	}

	/**
	 * Renders the text layer.
	 *
	 * @param {number} [timeout] - Wait for a specified amount of milliseconds
	 *                             before rendering.
	 */
	render(timeout = 0) {
		if (
			!(this.textContent || this.textContentStream) ||
			this.renderingDone
		) {
			return;
		}
		this.cancel();

		this.textDivs.length = 0;
		this.highlighter?.setTextMapping(
			this.textDivs,
			this.textContentItemsStr,
		);
		this.accessibilityManager?.setTextMapping(this.textDivs);

		const textLayerFrag = document.createDocumentFragment();
		this.textLayerRenderTask = renderTextLayer({
			textContent: this.textContent,
			textContentStream: this.textContentStream,
			container: textLayerFrag,
			viewport: this.viewport,
			textDivs: this.textDivs,
			textContentItemsStr: this.textContentItemsStr,
			timeout,
			enhanceTextSelection: this.enhanceTextSelection,
		});
		this.textLayerRenderTask.promise.then(
			() => {
				this.textLayerDiv.append(textLayerFrag);
				this._finishRendering();
				this.highlighter?.enable();
				this.accessibilityManager?.enable();
			},
			function (reason) {
				// Cancelled or failed to render text layer; skipping errors.
			},
		);
	}

	/**
	 * Cancel rendering of the text layer.
	 */
	cancel() {
		if (this.textLayerRenderTask) {
			this.textLayerRenderTask.cancel();
			this.textLayerRenderTask = null;
		}
		this.highlighter?.disable();
		this.accessibilityManager?.disable();
	}

	setTextContentStream(readableStream) {
		this.cancel();
		this.textContentStream = readableStream;
	}

	setTextContent(textContent) {
		this.cancel();
		this.textContent = textContent;
	}

	/**
	 * Improves text selection by adding an additional div where the mouse was
	 * clicked. This reduces flickering of the content if the mouse is slowly
	 * dragged up or down.
	 *
	 * @private
	 */
	_bindMouse() {
		const div = this.textLayerDiv;
		let expandDivsTimer = null;

		div.addEventListener('mousedown', (evt) => {
			if (this.enhanceTextSelection && this.textLayerRenderTask) {
				this.textLayerRenderTask.expandTextDivs(true);
				if (
					(typeof PDFJSDev === 'undefined' ||
						!PDFJSDev.test('MOZCENTRAL')) &&
					expandDivsTimer
				) {
					clearTimeout(expandDivsTimer);
					expandDivsTimer = null;
				}
				return;
			}

			const end = div.querySelector('.endOfContent');
			if (!end) {
				return;
			}
			if (
				typeof PDFJSDev === 'undefined' ||
				!PDFJSDev.test('MOZCENTRAL')
			) {
				// On non-Firefox browsers, the selection will feel better if the height
				// of the `endOfContent` div is adjusted to start at mouse click
				// location. This avoids flickering when the selection moves up.
				// However it does not work when selection is started on empty space.
				let adjustTop = evt.target !== div;
				if (
					typeof PDFJSDev === 'undefined' ||
					PDFJSDev.test('GENERIC')
				) {
					adjustTop =
						adjustTop &&
						window
							.getComputedStyle(end)
							.getPropertyValue('-moz-user-select') !== 'none';
				}
				if (adjustTop) {
					const divBounds = div.getBoundingClientRect();
					const r = Math.max(
						0,
						(evt.pageY - divBounds.top) / divBounds.height,
					);
					end.style.top = (r * 100).toFixed(2) + '%';
				}
			}
			end.classList.add('active');
		});

		div.addEventListener('mouseup', () => {
			if (this.enhanceTextSelection && this.textLayerRenderTask) {
				if (
					typeof PDFJSDev === 'undefined' ||
					!PDFJSDev.test('MOZCENTRAL')
				) {
					expandDivsTimer = setTimeout(() => {
						if (this.textLayerRenderTask) {
							this.textLayerRenderTask.expandTextDivs(false);
						}
						expandDivsTimer = null;
					}, EXPAND_DIVS_TIMEOUT);
				} else {
					this.textLayerRenderTask.expandTextDivs(false);
				}
				return;
			}

			const end = div.querySelector('.endOfContent');
			if (!end) {
				return;
			}
			if (
				typeof PDFJSDev === 'undefined' ||
				!PDFJSDev.test('MOZCENTRAL')
			) {
				end.style.top = '';
			}
			end.classList.remove('active');
		});
	}
}

export { TextLayerBuilder };