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epubreader/vendor/pdfjs/lib/text_layer_builder.js

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2020-04-21 20:37:42 +00:00
/* 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.
*/
'use strict';
(function (root, factory) {
if (typeof define === 'function' && define.amd) {
define('pdfjs-web/text_layer_builder', ['exports', 'pdfjs-web/dom_events',
'pdfjs-web/pdfjs'], factory);
} else if (typeof exports !== 'undefined') {
factory(exports, require('./dom_events.js'), require('./pdfjs.js'));
} else {
factory((root.pdfjsWebTextLayerBuilder = {}), root.pdfjsWebDOMEvents,
root.pdfjsWebPDFJS);
}
}(this, function (exports, domEvents, pdfjsLib) {
var 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 {PDFFindController} findController
* @property {boolean} enhanceTextSelection - Option to turn on improved
* text selection.
*/
/**
* TextLayerBuilder provides text-selection functionality for the PDF.
* It does this by creating overlay divs over the PDF text. These divs
* contain text that matches the PDF text they are overlaying. This object
* also provides a way to highlight text that is being searched for.
* @class
*/
var TextLayerBuilder = (function TextLayerBuilderClosure() {
function TextLayerBuilder(options) {
this.textLayerDiv = options.textLayerDiv;
this.eventBus = options.eventBus || domEvents.getGlobalEventBus();
this.textContent = null;
this.renderingDone = false;
this.pageIdx = options.pageIndex;
this.pageNumber = this.pageIdx + 1;
this.matches = [];
this.viewport = options.viewport;
this.textDivs = [];
this.findController = options.findController || null;
this.textLayerRenderTask = null;
this.enhanceTextSelection = options.enhanceTextSelection;
this._bindMouse();
}
TextLayerBuilder.prototype = {
/**
* @private
*/
_finishRendering: function TextLayerBuilder_finishRendering() {
this.renderingDone = true;
if (!this.enhanceTextSelection) {
var endOfContent = document.createElement('div');
endOfContent.className = 'endOfContent';
this.textLayerDiv.appendChild(endOfContent);
}
this.eventBus.dispatch('textlayerrendered', {
source: this,
pageNumber: this.pageNumber,
numTextDivs: this.textDivs.length,
});
},
/**
* Renders the text layer.
* @param {number} timeout (optional) if specified, the rendering waits
* for specified amount of ms.
*/
render: function TextLayerBuilder_render(timeout) {
if (!this.textContent || this.renderingDone) {
return;
}
this.cancel();
this.textDivs = [];
var textLayerFrag = document.createDocumentFragment();
this.textLayerRenderTask = pdfjsLib.renderTextLayer({
textContent: this.textContent,
container: textLayerFrag,
viewport: this.viewport,
textDivs: this.textDivs,
timeout: timeout,
enhanceTextSelection: this.enhanceTextSelection,
});
this.textLayerRenderTask.promise.then(function () {
this.textLayerDiv.appendChild(textLayerFrag);
this._finishRendering();
this.updateMatches();
}.bind(this), function (reason) {
// cancelled or failed to render text layer -- skipping errors
});
},
/**
* Cancels rendering of the text layer.
*/
cancel: function TextLayerBuilder_cancel() {
if (this.textLayerRenderTask) {
this.textLayerRenderTask.cancel();
this.textLayerRenderTask = null;
}
},
setTextContent: function TextLayerBuilder_setTextContent(textContent) {
this.cancel();
this.textContent = textContent;
},
convertMatches: function TextLayerBuilder_convertMatches(matches,
matchesLength) {
var i = 0;
var iIndex = 0;
var bidiTexts = this.textContent.items;
var end = bidiTexts.length - 1;
var queryLen = (this.findController === null ?
0 : this.findController.state.query.length);
var ret = [];
if (!matches) {
return ret;
}
for (var m = 0, len = matches.length; m < len; m++) {
// Calculate the start position.
var matchIdx = matches[m];
// Loop over the divIdxs.
while (i !== end && matchIdx >= (iIndex + bidiTexts[i].str.length)) {
iIndex += bidiTexts[i].str.length;
i++;
}
if (i === bidiTexts.length) {
console.error('Could not find a matching mapping');
}
var match = {
begin: {
divIdx: i,
offset: matchIdx - iIndex
}
};
// Calculate the end position.
if (matchesLength) { // multiterm search
matchIdx += matchesLength[m];
} else { // phrase search
matchIdx += queryLen;
}
// Somewhat the same array as above, but use > instead of >= to get
// the end position right.
while (i !== end && matchIdx > (iIndex + bidiTexts[i].str.length)) {
iIndex += bidiTexts[i].str.length;
i++;
}
match.end = {
divIdx: i,
offset: matchIdx - iIndex
};
ret.push(match);
}
return ret;
},
renderMatches: function TextLayerBuilder_renderMatches(matches) {
// Early exit if there is nothing to render.
if (matches.length === 0) {
return;
}
var bidiTexts = this.textContent.items;
var textDivs = this.textDivs;
var prevEnd = null;
var pageIdx = this.pageIdx;
var isSelectedPage = (this.findController === null ?
false : (pageIdx === this.findController.selected.pageIdx));
var selectedMatchIdx = (this.findController === null ?
-1 : this.findController.selected.matchIdx);
var highlightAll = (this.findController === null ?
false : this.findController.state.highlightAll);
var infinity = {
divIdx: -1,
offset: undefined
};
function beginText(begin, className) {
var divIdx = begin.divIdx;
textDivs[divIdx].textContent = '';
appendTextToDiv(divIdx, 0, begin.offset, className);
}
function appendTextToDiv(divIdx, fromOffset, toOffset, className) {
var div = textDivs[divIdx];
var content = bidiTexts[divIdx].str.substring(fromOffset, toOffset);
var node = document.createTextNode(content);
if (className) {
var span = document.createElement('span');
span.className = className;
span.appendChild(node);
div.appendChild(span);
return;
}
div.appendChild(node);
}
var i0 = selectedMatchIdx, i1 = i0 + 1;
if (highlightAll) {
i0 = 0;
i1 = matches.length;
} else if (!isSelectedPage) {
// Not highlighting all and this isn't the selected page, so do nothing.
return;
}
for (var i = i0; i < i1; i++) {
var match = matches[i];
var begin = match.begin;
var end = match.end;
var isSelected = (isSelectedPage && i === selectedMatchIdx);
var highlightSuffix = (isSelected ? ' selected' : '');
if (this.findController) {
this.findController.updateMatchPosition(pageIdx, i, textDivs,
begin.divIdx);
}
// Match inside new div.
if (!prevEnd || begin.divIdx !== prevEnd.divIdx) {
// If there was a previous div, then add the text at the end.
if (prevEnd !== null) {
appendTextToDiv(prevEnd.divIdx, prevEnd.offset, infinity.offset);
}
// Clear the divs and set the content until the starting point.
beginText(begin);
} else {
appendTextToDiv(prevEnd.divIdx, prevEnd.offset, begin.offset);
}
if (begin.divIdx === end.divIdx) {
appendTextToDiv(begin.divIdx, begin.offset, end.offset,
'highlight' + highlightSuffix);
} else {
appendTextToDiv(begin.divIdx, begin.offset, infinity.offset,
'highlight begin' + highlightSuffix);
for (var n0 = begin.divIdx + 1, n1 = end.divIdx; n0 < n1; n0++) {
textDivs[n0].className = 'highlight middle' + highlightSuffix;
}
beginText(end, 'highlight end' + highlightSuffix);
}
prevEnd = end;
}
if (prevEnd) {
appendTextToDiv(prevEnd.divIdx, prevEnd.offset, infinity.offset);
}
},
updateMatches: function TextLayerBuilder_updateMatches() {
// Only show matches when all rendering is done.
if (!this.renderingDone) {
return;
}
// Clear all matches.
var matches = this.matches;
var textDivs = this.textDivs;
var bidiTexts = this.textContent.items;
var clearedUntilDivIdx = -1;
// Clear all current matches.
for (var i = 0, len = matches.length; i < len; i++) {
var match = matches[i];
var begin = Math.max(clearedUntilDivIdx, match.begin.divIdx);
for (var n = begin, end = match.end.divIdx; n <= end; n++) {
var div = textDivs[n];
div.textContent = bidiTexts[n].str;
div.className = '';
}
clearedUntilDivIdx = match.end.divIdx + 1;
}
if (this.findController === null || !this.findController.active) {
return;
}
// Convert the matches on the page controller into the match format
// used for the textLayer.
var pageMatches, pageMatchesLength;
if (this.findController !== null) {
pageMatches = this.findController.pageMatches[this.pageIdx] || null;
pageMatchesLength = (this.findController.pageMatchesLength) ?
this.findController.pageMatchesLength[this.pageIdx] || null : null;
}
this.matches = this.convertMatches(pageMatches, pageMatchesLength);
this.renderMatches(this.matches);
},
/**
* Fixes text selection: adds additional div where mouse was clicked.
* This reduces flickering of the content if mouse slowly dragged down/up.
* @private
*/
_bindMouse: function TextLayerBuilder_bindMouse() {
var div = this.textLayerDiv;
var self = this;
var expandDivsTimer = null;
div.addEventListener('mousedown', function (e) {
if (self.enhanceTextSelection && self.textLayerRenderTask) {
self.textLayerRenderTask.expandTextDivs(true);
if ((typeof PDFJSDev === 'undefined' ||
!PDFJSDev.test('FIREFOX || MOZCENTRAL')) &&
expandDivsTimer) {
clearTimeout(expandDivsTimer);
expandDivsTimer = null;
}
return;
}
var end = div.querySelector('.endOfContent');
if (!end) {
return;
}
if (typeof PDFJSDev === 'undefined' ||
!PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
// On non-Firefox browsers, the selection will feel better if the height
// of the endOfContent div will be adjusted to start at mouse click
// location -- this will avoid flickering when selections moves up.
// However it does not work when selection started on empty space.
var adjustTop = e.target !== div;
if (typeof PDFJSDev === 'undefined' || PDFJSDev.test('GENERIC')) {
adjustTop = adjustTop && window.getComputedStyle(end).
getPropertyValue('-moz-user-select') !== 'none';
}
if (adjustTop) {
var divBounds = div.getBoundingClientRect();
var r = Math.max(0, (e.pageY - divBounds.top) / divBounds.height);
end.style.top = (r * 100).toFixed(2) + '%';
}
}
end.classList.add('active');
});
div.addEventListener('mouseup', function (e) {
if (self.enhanceTextSelection && self.textLayerRenderTask) {
if (typeof PDFJSDev === 'undefined' ||
!PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
expandDivsTimer = setTimeout(function() {
if (self.textLayerRenderTask) {
self.textLayerRenderTask.expandTextDivs(false);
}
expandDivsTimer = null;
}, EXPAND_DIVS_TIMEOUT);
} else {
self.textLayerRenderTask.expandTextDivs(false);
}
return;
}
var end = div.querySelector('.endOfContent');
if (!end) {
return;
}
if (typeof PDFJSDev === 'undefined' ||
!PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
end.style.top = '';
}
end.classList.remove('active');
});
},
};
return TextLayerBuilder;
})();
/**
* @constructor
* @implements IPDFTextLayerFactory
*/
function DefaultTextLayerFactory() {}
DefaultTextLayerFactory.prototype = {
/**
* @param {HTMLDivElement} textLayerDiv
* @param {number} pageIndex
* @param {PageViewport} viewport
* @param {boolean} enhanceTextSelection
* @returns {TextLayerBuilder}
*/
createTextLayerBuilder: function (textLayerDiv, pageIndex, viewport,
enhanceTextSelection) {
return new TextLayerBuilder({
textLayerDiv: textLayerDiv,
pageIndex: pageIndex,
viewport: viewport,
enhanceTextSelection: enhanceTextSelection
});
}
};
exports.TextLayerBuilder = TextLayerBuilder;
exports.DefaultTextLayerFactory = DefaultTextLayerFactory;
}));