pdfjs-dist/lib/display/text_layer.js

/* Copyright 2017 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';
var sharedUtil = require('../shared/util.js');
var displayDOMUtils = require('./dom_utils.js');
var Util = sharedUtil.Util;
var createPromiseCapability = sharedUtil.createPromiseCapability;
var CustomStyle = displayDOMUtils.CustomStyle;
var getDefaultSetting = displayDOMUtils.getDefaultSetting;
var renderTextLayer = function renderTextLayerClosure() {
 var MAX_TEXT_DIVS_TO_RENDER = 100000;
 var NonWhitespaceRegexp = /\S/;
 function isAllWhitespace(str) {
  return !NonWhitespaceRegexp.test(str);
 }
 var styleBuf = [
  'left: ',
  0,
  'px; top: ',
  0,
  'px; font-size: ',
  0,
  'px; font-family: ',
  '',
  ';'
 ];
 function appendText(task, geom, styles) {
  var textDiv = document.createElement('div');
  var textDivProperties = {
   style: null,
   angle: 0,
   canvasWidth: 0,
   isWhitespace: false,
   originalTransform: null,
   paddingBottom: 0,
   paddingLeft: 0,
   paddingRight: 0,
   paddingTop: 0,
   scale: 1
  };
  task._textDivs.push(textDiv);
  if (isAllWhitespace(geom.str)) {
   textDivProperties.isWhitespace = true;
   task._textDivProperties.set(textDiv, textDivProperties);
   return;
  }
  var tx = Util.transform(task._viewport.transform, geom.transform);
  var angle = Math.atan2(tx[1], tx[0]);
  var style = styles[geom.fontName];
  if (style.vertical) {
   angle += Math.PI / 2;
  }
  var fontHeight = Math.sqrt(tx[2] * tx[2] + tx[3] * tx[3]);
  var fontAscent = fontHeight;
  if (style.ascent) {
   fontAscent = style.ascent * fontAscent;
  } else if (style.descent) {
   fontAscent = (1 + style.descent) * fontAscent;
  }
  var left;
  var top;
  if (angle === 0) {
   left = tx[4];
   top = tx[5] - fontAscent;
  } else {
   left = tx[4] + fontAscent * Math.sin(angle);
   top = tx[5] - fontAscent * Math.cos(angle);
  }
  styleBuf[1] = left;
  styleBuf[3] = top;
  styleBuf[5] = fontHeight;
  styleBuf[7] = style.fontFamily;
  textDivProperties.style = styleBuf.join('');
  textDiv.setAttribute('style', textDivProperties.style);
  textDiv.textContent = geom.str;
  if (getDefaultSetting('pdfBug')) {
   textDiv.dataset.fontName = geom.fontName;
  }
  if (angle !== 0) {
   textDivProperties.angle = angle * (180 / Math.PI);
  }
  if (geom.str.length > 1) {
   if (style.vertical) {
    textDivProperties.canvasWidth = geom.height * task._viewport.scale;
   } else {
    textDivProperties.canvasWidth = geom.width * task._viewport.scale;
   }
  }
  task._textDivProperties.set(textDiv, textDivProperties);
  if (task._enhanceTextSelection) {
   var angleCos = 1, angleSin = 0;
   if (angle !== 0) {
    angleCos = Math.cos(angle);
    angleSin = Math.sin(angle);
   }
   var divWidth = (style.vertical ? geom.height : geom.width) * task._viewport.scale;
   var divHeight = fontHeight;
   var m, b;
   if (angle !== 0) {
    m = [
     angleCos,
     angleSin,
     -angleSin,
     angleCos,
     left,
     top
    ];
    b = Util.getAxialAlignedBoundingBox([
     0,
     0,
     divWidth,
     divHeight
    ], m);
   } else {
    b = [
     left,
     top,
     left + divWidth,
     top + divHeight
    ];
   }
   task._bounds.push({
    left: b[0],
    top: b[1],
    right: b[2],
    bottom: b[3],
    div: textDiv,
    size: [
     divWidth,
     divHeight
    ],
    m: m
   });
  }
 }
 function render(task) {
  if (task._canceled) {
   return;
  }
  var textLayerFrag = task._container;
  var textDivs = task._textDivs;
  var capability = task._capability;
  var textDivsLength = textDivs.length;
  if (textDivsLength > MAX_TEXT_DIVS_TO_RENDER) {
   task._renderingDone = true;
   capability.resolve();
   return;
  }
  var canvas = document.createElement('canvas');
  canvas.mozOpaque = true;
  var ctx = canvas.getContext('2d', { alpha: false });
  var lastFontSize;
  var lastFontFamily;
  for (var i = 0; i < textDivsLength; i++) {
   var textDiv = textDivs[i];
   var textDivProperties = task._textDivProperties.get(textDiv);
   if (textDivProperties.isWhitespace) {
    continue;
   }
   var fontSize = textDiv.style.fontSize;
   var fontFamily = textDiv.style.fontFamily;
   if (fontSize !== lastFontSize || fontFamily !== lastFontFamily) {
    ctx.font = fontSize + ' ' + fontFamily;
    lastFontSize = fontSize;
    lastFontFamily = fontFamily;
   }
   var width = ctx.measureText(textDiv.textContent).width;
   textLayerFrag.appendChild(textDiv);
   var transform = '';
   if (textDivProperties.canvasWidth !== 0 && width > 0) {
    textDivProperties.scale = textDivProperties.canvasWidth / width;
    transform = 'scaleX(' + textDivProperties.scale + ')';
   }
   if (textDivProperties.angle !== 0) {
    transform = 'rotate(' + textDivProperties.angle + 'deg) ' + transform;
   }
   if (transform !== '') {
    textDivProperties.originalTransform = transform;
    CustomStyle.setProp('transform', textDiv, transform);
   }
   task._textDivProperties.set(textDiv, textDivProperties);
  }
  task._renderingDone = true;
  capability.resolve();
 }
 function expand(task) {
  var bounds = task._bounds;
  var viewport = task._viewport;
  var expanded = expandBounds(viewport.width, viewport.height, bounds);
  for (var i = 0; i < expanded.length; i++) {
   var div = bounds[i].div;
   var divProperties = task._textDivProperties.get(div);
   if (divProperties.angle === 0) {
    divProperties.paddingLeft = bounds[i].left - expanded[i].left;
    divProperties.paddingTop = bounds[i].top - expanded[i].top;
    divProperties.paddingRight = expanded[i].right - bounds[i].right;
    divProperties.paddingBottom = expanded[i].bottom - bounds[i].bottom;
    task._textDivProperties.set(div, divProperties);
    continue;
   }
   var e = expanded[i], b = bounds[i];
   var m = b.m, c = m[0], s = m[1];
   var points = [
    [
     0,
     0
    ],
    [
     0,
     b.size[1]
    ],
    [
     b.size[0],
     0
    ],
    b.size
   ];
   var ts = new Float64Array(64);
   points.forEach(function (p, i) {
    var t = Util.applyTransform(p, m);
    ts[i + 0] = c && (e.left - t[0]) / c;
    ts[i + 4] = s && (e.top - t[1]) / s;
    ts[i + 8] = c && (e.right - t[0]) / c;
    ts[i + 12] = s && (e.bottom - t[1]) / s;
    ts[i + 16] = s && (e.left - t[0]) / -s;
    ts[i + 20] = c && (e.top - t[1]) / c;
    ts[i + 24] = s && (e.right - t[0]) / -s;
    ts[i + 28] = c && (e.bottom - t[1]) / c;
    ts[i + 32] = c && (e.left - t[0]) / -c;
    ts[i + 36] = s && (e.top - t[1]) / -s;
    ts[i + 40] = c && (e.right - t[0]) / -c;
    ts[i + 44] = s && (e.bottom - t[1]) / -s;
    ts[i + 48] = s && (e.left - t[0]) / s;
    ts[i + 52] = c && (e.top - t[1]) / -c;
    ts[i + 56] = s && (e.right - t[0]) / s;
    ts[i + 60] = c && (e.bottom - t[1]) / -c;
   });
   var findPositiveMin = function (ts, offset, count) {
    var result = 0;
    for (var i = 0; i < count; i++) {
     var t = ts[offset++];
     if (t > 0) {
      result = result ? Math.min(t, result) : t;
     }
    }
    return result;
   };
   var boxScale = 1 + Math.min(Math.abs(c), Math.abs(s));
   divProperties.paddingLeft = findPositiveMin(ts, 32, 16) / boxScale;
   divProperties.paddingTop = findPositiveMin(ts, 48, 16) / boxScale;
   divProperties.paddingRight = findPositiveMin(ts, 0, 16) / boxScale;
   divProperties.paddingBottom = findPositiveMin(ts, 16, 16) / boxScale;
   task._textDivProperties.set(div, divProperties);
  }
 }
 function expandBounds(width, height, boxes) {
  var bounds = boxes.map(function (box, i) {
   return {
    x1: box.left,
    y1: box.top,
    x2: box.right,
    y2: box.bottom,
    index: i,
    x1New: undefined,
    x2New: undefined
   };
  });
  expandBoundsLTR(width, bounds);
  var expanded = new Array(boxes.length);
  bounds.forEach(function (b) {
   var i = b.index;
   expanded[i] = {
    left: b.x1New,
    top: 0,
    right: b.x2New,
    bottom: 0
   };
  });
  boxes.map(function (box, i) {
   var e = expanded[i], b = bounds[i];
   b.x1 = box.top;
   b.y1 = width - e.right;
   b.x2 = box.bottom;
   b.y2 = width - e.left;
   b.index = i;
   b.x1New = undefined;
   b.x2New = undefined;
  });
  expandBoundsLTR(height, bounds);
  bounds.forEach(function (b) {
   var i = b.index;
   expanded[i].top = b.x1New;
   expanded[i].bottom = b.x2New;
  });
  return expanded;
 }
 function expandBoundsLTR(width, bounds) {
  bounds.sort(function (a, b) {
   return a.x1 - b.x1 || a.index - b.index;
  });
  var fakeBoundary = {
   x1: -Infinity,
   y1: -Infinity,
   x2: 0,
   y2: Infinity,
   index: -1,
   x1New: 0,
   x2New: 0
  };
  var horizon = [{
    start: -Infinity,
    end: Infinity,
    boundary: fakeBoundary
   }];
  bounds.forEach(function (boundary) {
   var i = 0;
   while (i < horizon.length && horizon[i].end <= boundary.y1) {
    i++;
   }
   var j = horizon.length - 1;
   while (j >= 0 && horizon[j].start >= boundary.y2) {
    j--;
   }
   var horizonPart, affectedBoundary;
   var q, k, maxXNew = -Infinity;
   for (q = i; q <= j; q++) {
    horizonPart = horizon[q];
    affectedBoundary = horizonPart.boundary;
    var xNew;
    if (affectedBoundary.x2 > boundary.x1) {
     xNew = affectedBoundary.index > boundary.index ? affectedBoundary.x1New : boundary.x1;
    } else if (affectedBoundary.x2New === undefined) {
     xNew = (affectedBoundary.x2 + boundary.x1) / 2;
    } else {
     xNew = affectedBoundary.x2New;
    }
    if (xNew > maxXNew) {
     maxXNew = xNew;
    }
   }
   boundary.x1New = maxXNew;
   for (q = i; q <= j; q++) {
    horizonPart = horizon[q];
    affectedBoundary = horizonPart.boundary;
    if (affectedBoundary.x2New === undefined) {
     if (affectedBoundary.x2 > boundary.x1) {
      if (affectedBoundary.index > boundary.index) {
       affectedBoundary.x2New = affectedBoundary.x2;
      }
     } else {
      affectedBoundary.x2New = maxXNew;
     }
    } else if (affectedBoundary.x2New > maxXNew) {
     affectedBoundary.x2New = Math.max(maxXNew, affectedBoundary.x2);
    }
   }
   var changedHorizon = [], lastBoundary = null;
   for (q = i; q <= j; q++) {
    horizonPart = horizon[q];
    affectedBoundary = horizonPart.boundary;
    var useBoundary = affectedBoundary.x2 > boundary.x2 ? affectedBoundary : boundary;
    if (lastBoundary === useBoundary) {
     changedHorizon[changedHorizon.length - 1].end = horizonPart.end;
    } else {
     changedHorizon.push({
      start: horizonPart.start,
      end: horizonPart.end,
      boundary: useBoundary
     });
     lastBoundary = useBoundary;
    }
   }
   if (horizon[i].start < boundary.y1) {
    changedHorizon[0].start = boundary.y1;
    changedHorizon.unshift({
     start: horizon[i].start,
     end: boundary.y1,
     boundary: horizon[i].boundary
    });
   }
   if (boundary.y2 < horizon[j].end) {
    changedHorizon[changedHorizon.length - 1].end = boundary.y2;
    changedHorizon.push({
     start: boundary.y2,
     end: horizon[j].end,
     boundary: horizon[j].boundary
    });
   }
   for (q = i; q <= j; q++) {
    horizonPart = horizon[q];
    affectedBoundary = horizonPart.boundary;
    if (affectedBoundary.x2New !== undefined) {
     continue;
    }
    var used = false;
    for (k = i - 1; !used && k >= 0 && horizon[k].start >= affectedBoundary.y1; k--) {
     used = horizon[k].boundary === affectedBoundary;
    }
    for (k = j + 1; !used && k < horizon.length && horizon[k].end <= affectedBoundary.y2; k++) {
     used = horizon[k].boundary === affectedBoundary;
    }
    for (k = 0; !used && k < changedHorizon.length; k++) {
     used = changedHorizon[k].boundary === affectedBoundary;
    }
    if (!used) {
     affectedBoundary.x2New = maxXNew;
    }
   }
   Array.prototype.splice.apply(horizon, [
    i,
    j - i + 1
   ].concat(changedHorizon));
  });
  horizon.forEach(function (horizonPart) {
   var affectedBoundary = horizonPart.boundary;
   if (affectedBoundary.x2New === undefined) {
    affectedBoundary.x2New = Math.max(width, affectedBoundary.x2);
   }
  });
 }
 function TextLayerRenderTask(textContent, container, viewport, textDivs, enhanceTextSelection) {
  this._textContent = textContent;
  this._container = container;
  this._viewport = viewport;
  this._textDivs = textDivs || [];
  this._textDivProperties = new WeakMap();
  this._renderingDone = false;
  this._canceled = false;
  this._capability = createPromiseCapability();
  this._renderTimer = null;
  this._bounds = [];
  this._enhanceTextSelection = !!enhanceTextSelection;
 }
 TextLayerRenderTask.prototype = {
  get promise() {
   return this._capability.promise;
  },
  cancel: function TextLayer_cancel() {
   this._canceled = true;
   if (this._renderTimer !== null) {
    clearTimeout(this._renderTimer);
    this._renderTimer = null;
   }
   this._capability.reject('canceled');
  },
  _render: function TextLayer_render(timeout) {
   var textItems = this._textContent.items;
   var textStyles = this._textContent.styles;
   for (var i = 0, len = textItems.length; i < len; i++) {
    appendText(this, textItems[i], textStyles);
   }
   if (!timeout) {
    render(this);
   } else {
    var self = this;
    this._renderTimer = setTimeout(function () {
     render(self);
     self._renderTimer = null;
    }, timeout);
   }
  },
  expandTextDivs: function TextLayer_expandTextDivs(expandDivs) {
   if (!this._enhanceTextSelection || !this._renderingDone) {
    return;
   }
   if (this._bounds !== null) {
    expand(this);
    this._bounds = null;
   }
   for (var i = 0, ii = this._textDivs.length; i < ii; i++) {
    var div = this._textDivs[i];
    var divProperties = this._textDivProperties.get(div);
    if (divProperties.isWhitespace) {
     continue;
    }
    if (expandDivs) {
     var transform = '', padding = '';
     if (divProperties.scale !== 1) {
      transform = 'scaleX(' + divProperties.scale + ')';
     }
     if (divProperties.angle !== 0) {
      transform = 'rotate(' + divProperties.angle + 'deg) ' + transform;
     }
     if (divProperties.paddingLeft !== 0) {
      padding += ' padding-left: ' + divProperties.paddingLeft / divProperties.scale + 'px;';
      transform += ' translateX(' + -divProperties.paddingLeft / divProperties.scale + 'px)';
     }
     if (divProperties.paddingTop !== 0) {
      padding += ' padding-top: ' + divProperties.paddingTop + 'px;';
      transform += ' translateY(' + -divProperties.paddingTop + 'px)';
     }
     if (divProperties.paddingRight !== 0) {
      padding += ' padding-right: ' + divProperties.paddingRight / divProperties.scale + 'px;';
     }
     if (divProperties.paddingBottom !== 0) {
      padding += ' padding-bottom: ' + divProperties.paddingBottom + 'px;';
     }
     if (padding !== '') {
      div.setAttribute('style', divProperties.style + padding);
     }
     if (transform !== '') {
      CustomStyle.setProp('transform', div, transform);
     }
    } else {
     div.style.padding = 0;
     CustomStyle.setProp('transform', div, divProperties.originalTransform || '');
    }
   }
  }
 };
 function renderTextLayer(renderParameters) {
  var task = new TextLayerRenderTask(renderParameters.textContent, renderParameters.container, renderParameters.viewport, renderParameters.textDivs, renderParameters.enhanceTextSelection);
  task._render(renderParameters.timeout);
  return task;
 }
 return renderTextLayer;
}();
exports.renderTextLayer = renderTextLayer;