a24ad28d75
It was pointed out the the old name felt confusing, so let's just rename the getter since it's an internal property anyway.
123 lines
4.0 KiB
JavaScript
123 lines
4.0 KiB
JavaScript
/* Copyright 2017 Mozilla Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import { BaseViewer } from "./base_viewer.js";
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import { shadow } from "pdfjs-lib";
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class PDFSinglePageViewer extends BaseViewer {
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constructor(options) {
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super(options);
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this.eventBus._on("pagesinit", evt => {
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// Since the pages are placed in a `DocumentFragment`, make sure that
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// the current page becomes visible upon loading of the document.
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this._ensurePageViewVisible();
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});
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}
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get _viewerElement() {
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// Since we only want to display *one* page at a time when using the
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// `PDFSinglePageViewer`, we cannot append them to the `viewer` DOM element.
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// Instead, they are placed in a `DocumentFragment`, and only the current
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// page is displayed in the viewer (refer to `this._ensurePageViewVisible`).
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return shadow(this, "_viewerElement", this._shadowViewer);
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}
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_resetView() {
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super._resetView();
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this._previousPageNumber = 1;
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this._shadowViewer = document.createDocumentFragment();
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this._updateScrollDown = null;
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}
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_ensurePageViewVisible() {
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const pageView = this._pages[this._currentPageNumber - 1];
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const previousPageView = this._pages[this._previousPageNumber - 1];
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const viewerNodes = this.viewer.childNodes;
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switch (viewerNodes.length) {
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case 0: // Should *only* occur on initial loading.
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this.viewer.appendChild(pageView.div);
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break;
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case 1: // The normal page-switching case.
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if (viewerNodes[0] !== previousPageView.div) {
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throw new Error(
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"_ensurePageViewVisible: Unexpected previously visible page."
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);
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}
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if (pageView === previousPageView) {
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break; // The correct page is already visible.
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}
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// Switch visible pages, and reset the viewerContainer scroll position.
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this._shadowViewer.appendChild(previousPageView.div);
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this.viewer.appendChild(pageView.div);
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this.container.scrollTop = 0;
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break;
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default:
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throw new Error(
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"_ensurePageViewVisible: Only one page should be visible at a time."
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);
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}
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this._previousPageNumber = this._currentPageNumber;
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}
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_scrollUpdate() {
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if (this._updateScrollDown) {
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this._updateScrollDown();
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}
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super._scrollUpdate();
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}
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_scrollIntoView({ pageDiv, pageSpot = null, pageNumber = null }) {
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if (pageNumber) {
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// Ensure that `this._currentPageNumber` is correct.
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this._setCurrentPageNumber(pageNumber);
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}
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const scrolledDown = this._currentPageNumber >= this._previousPageNumber;
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this._ensurePageViewVisible();
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// Ensure that rendering always occurs, to avoid showing a blank page,
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// even if the current position doesn't change when the page is scrolled.
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this.update();
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super._scrollIntoView({ pageDiv, pageSpot, pageNumber });
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// Since scrolling is tracked using `requestAnimationFrame`, update the
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// scroll direction during the next `this._scrollUpdate` invocation.
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this._updateScrollDown = () => {
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this.scroll.down = scrolledDown;
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this._updateScrollDown = null;
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};
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}
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_getVisiblePages() {
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return this._getCurrentVisiblePage();
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}
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_updateHelper(visiblePages) {}
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get _isScrollModeHorizontal() {
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// The Scroll/Spread modes are never used in `PDFSinglePageViewer`.
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return shadow(this, "_isScrollModeHorizontal", false);
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}
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_updateScrollMode() {}
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_updateSpreadMode() {}
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}
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export { PDFSinglePageViewer };
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