pdfjs-dist/lib/display/font_loader.js

/**
 * @licstart The following is the entire license notice for the
 * Javascript code in this page
 *
 * Copyright 2020 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.
 *
 * @licend The above is the entire license notice for the
 * Javascript code in this page
 */
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.FontLoader = exports.FontFaceObject = void 0;

var _util = require("../shared/util.js");

class BaseFontLoader {
  constructor({
    docId,
    onUnsupportedFeature
  }) {
    if (this.constructor === BaseFontLoader) {
      (0, _util.unreachable)("Cannot initialize BaseFontLoader.");
    }

    this.docId = docId;
    this._onUnsupportedFeature = onUnsupportedFeature;
    this.nativeFontFaces = [];
    this.styleElement = null;
  }

  addNativeFontFace(nativeFontFace) {
    this.nativeFontFaces.push(nativeFontFace);
    document.fonts.add(nativeFontFace);
  }

  insertRule(rule) {
    let styleElement = this.styleElement;

    if (!styleElement) {
      styleElement = this.styleElement = document.createElement("style");
      styleElement.id = `PDFJS_FONT_STYLE_TAG_${this.docId}`;
      document.documentElement.getElementsByTagName("head")[0].appendChild(styleElement);
    }

    const styleSheet = styleElement.sheet;
    styleSheet.insertRule(rule, styleSheet.cssRules.length);
  }

  clear() {
    this.nativeFontFaces.forEach(function (nativeFontFace) {
      document.fonts.delete(nativeFontFace);
    });
    this.nativeFontFaces.length = 0;

    if (this.styleElement) {
      this.styleElement.remove();
      this.styleElement = null;
    }
  }

  async bind(font) {
    if (font.attached || font.missingFile) {
      return;
    }

    font.attached = true;

    if (this.isFontLoadingAPISupported) {
      const nativeFontFace = font.createNativeFontFace();

      if (nativeFontFace) {
        this.addNativeFontFace(nativeFontFace);

        try {
          await nativeFontFace.loaded;
        } catch (ex) {
          this._onUnsupportedFeature({
            featureId: _util.UNSUPPORTED_FEATURES.errorFontLoadNative
          });

          (0, _util.warn)(`Failed to load font '${nativeFontFace.family}': '${ex}'.`);
          font.disableFontFace = true;
          throw ex;
        }
      }

      return;
    }

    const rule = font.createFontFaceRule();

    if (rule) {
      this.insertRule(rule);

      if (this.isSyncFontLoadingSupported) {
        return;
      }

      await new Promise(resolve => {
        const request = this._queueLoadingCallback(resolve);

        this._prepareFontLoadEvent([rule], [font], request);
      });
    }
  }

  _queueLoadingCallback(callback) {
    (0, _util.unreachable)("Abstract method `_queueLoadingCallback`.");
  }

  get isFontLoadingAPISupported() {
    const supported = typeof document !== "undefined" && !!document.fonts;
    return (0, _util.shadow)(this, "isFontLoadingAPISupported", supported);
  }

  get isSyncFontLoadingSupported() {
    (0, _util.unreachable)("Abstract method `isSyncFontLoadingSupported`.");
  }

  get _loadTestFont() {
    (0, _util.unreachable)("Abstract method `_loadTestFont`.");
  }

  _prepareFontLoadEvent(rules, fontsToLoad, request) {
    (0, _util.unreachable)("Abstract method `_prepareFontLoadEvent`.");
  }

}

let FontLoader;
exports.FontLoader = FontLoader;
{
  exports.FontLoader = FontLoader = class GenericFontLoader extends BaseFontLoader {
    constructor(docId) {
      super(docId);
      this.loadingContext = {
        requests: [],
        nextRequestId: 0
      };
      this.loadTestFontId = 0;
    }

    get isSyncFontLoadingSupported() {
      let supported = false;

      if (typeof navigator === "undefined") {
        supported = true;
      } else {
        const m = /Mozilla\/5.0.*?rv:(\d+).*? Gecko/.exec(navigator.userAgent);

        if (m && m[1] >= 14) {
          supported = true;
        }
      }

      return (0, _util.shadow)(this, "isSyncFontLoadingSupported", supported);
    }

    _queueLoadingCallback(callback) {
      function completeRequest() {
        (0, _util.assert)(!request.done, "completeRequest() cannot be called twice.");
        request.done = true;

        while (context.requests.length > 0 && context.requests[0].done) {
          const otherRequest = context.requests.shift();
          setTimeout(otherRequest.callback, 0);
        }
      }

      const context = this.loadingContext;
      const request = {
        id: `pdfjs-font-loading-${context.nextRequestId++}`,
        done: false,
        complete: completeRequest,
        callback
      };
      context.requests.push(request);
      return request;
    }

    get _loadTestFont() {
      const getLoadTestFont = function () {
        return atob("T1RUTwALAIAAAwAwQ0ZGIDHtZg4AAAOYAAAAgUZGVE1lkzZwAAAEHAAAABxHREVGABQA" + "FQAABDgAAAAeT1MvMlYNYwkAAAEgAAAAYGNtYXABDQLUAAACNAAAAUJoZWFk/xVFDQAA" + "ALwAAAA2aGhlYQdkA+oAAAD0AAAAJGhtdHgD6AAAAAAEWAAAAAZtYXhwAAJQAAAAARgA" + "AAAGbmFtZVjmdH4AAAGAAAAAsXBvc3T/hgAzAAADeAAAACAAAQAAAAEAALZRFsRfDzz1" + "AAsD6AAAAADOBOTLAAAAAM4KHDwAAAAAA+gDIQAAAAgAAgAAAAAAAAABAAADIQAAAFoD" + "6AAAAAAD6AABAAAAAAAAAAAAAAAAAAAAAQAAUAAAAgAAAAQD6AH0AAUAAAKKArwAAACM" + "AooCvAAAAeAAMQECAAACAAYJAAAAAAAAAAAAAQAAAAAAAAAAAAAAAFBmRWQAwAAuAC4D" + "IP84AFoDIQAAAAAAAQAAAAAAAAAAACAAIAABAAAADgCuAAEAAAAAAAAAAQAAAAEAAAAA" + "AAEAAQAAAAEAAAAAAAIAAQAAAAEAAAAAAAMAAQAAAAEAAAAAAAQAAQAAAAEAAAAAAAUA" + "AQAAAAEAAAAAAAYAAQAAAAMAAQQJAAAAAgABAAMAAQQJAAEAAgABAAMAAQQJAAIAAgAB" + "AAMAAQQJAAMAAgABAAMAAQQJAAQAAgABAAMAAQQJAAUAAgABAAMAAQQJAAYAAgABWABY" + "AAAAAAAAAwAAAAMAAAAcAAEAAAAAADwAAwABAAAAHAAEACAAAAAEAAQAAQAAAC7//wAA" + "AC7////TAAEAAAAAAAABBgAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" + "AAAAAAAAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" + "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" + "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" + "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" + "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAMAAAAAAAD/gwAyAAAAAQAAAAAAAAAAAAAAAAAA" + "AAABAAQEAAEBAQJYAAEBASH4DwD4GwHEAvgcA/gXBIwMAYuL+nz5tQXkD5j3CBLnEQAC" + "AQEBIVhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYAAABAQAADwACAQEEE/t3" + "Dov6fAH6fAT+fPp8+nwHDosMCvm1Cvm1DAz6fBQAAAAAAAABAAAAAMmJbzEAAAAAzgTj" + "FQAAAADOBOQpAAEAAAAAAAAADAAUAAQAAAABAAAAAgABAAAAAAAAAAAD6AAAAAAAAA==");
      };

      return (0, _util.shadow)(this, "_loadTestFont", getLoadTestFont());
    }

    _prepareFontLoadEvent(rules, fonts, request) {
      function int32(data, offset) {
        return data.charCodeAt(offset) << 24 | data.charCodeAt(offset + 1) << 16 | data.charCodeAt(offset + 2) << 8 | data.charCodeAt(offset + 3) & 0xff;
      }

      function spliceString(s, offset, remove, insert) {
        const chunk1 = s.substring(0, offset);
        const chunk2 = s.substring(offset + remove);
        return chunk1 + insert + chunk2;
      }

      let i, ii;
      const canvas = document.createElement("canvas");
      canvas.width = 1;
      canvas.height = 1;
      const ctx = canvas.getContext("2d");
      let called = 0;

      function isFontReady(name, callback) {
        called++;

        if (called > 30) {
          (0, _util.warn)("Load test font never loaded.");
          callback();
          return;
        }

        ctx.font = "30px " + name;
        ctx.fillText(".", 0, 20);
        const imageData = ctx.getImageData(0, 0, 1, 1);

        if (imageData.data[3] > 0) {
          callback();
          return;
        }

        setTimeout(isFontReady.bind(null, name, callback));
      }

      const loadTestFontId = `lt${Date.now()}${this.loadTestFontId++}`;
      let data = this._loadTestFont;
      const COMMENT_OFFSET = 976;
      data = spliceString(data, COMMENT_OFFSET, loadTestFontId.length, loadTestFontId);
      const CFF_CHECKSUM_OFFSET = 16;
      const XXXX_VALUE = 0x58585858;
      let checksum = int32(data, CFF_CHECKSUM_OFFSET);

      for (i = 0, ii = loadTestFontId.length - 3; i < ii; i += 4) {
        checksum = checksum - XXXX_VALUE + int32(loadTestFontId, i) | 0;
      }

      if (i < loadTestFontId.length) {
        checksum = checksum - XXXX_VALUE + int32(loadTestFontId + "XXX", i) | 0;
      }

      data = spliceString(data, CFF_CHECKSUM_OFFSET, 4, (0, _util.string32)(checksum));
      const url = `url(data:font/opentype;base64,${btoa(data)});`;
      const rule = `@font-face {font-family:"${loadTestFontId}";src:${url}}`;
      this.insertRule(rule);
      const names = [];

      for (i = 0, ii = fonts.length; i < ii; i++) {
        names.push(fonts[i].loadedName);
      }

      names.push(loadTestFontId);
      const div = document.createElement("div");
      div.style.visibility = "hidden";
      div.style.width = div.style.height = "10px";
      div.style.position = "absolute";
      div.style.top = div.style.left = "0px";

      for (i = 0, ii = names.length; i < ii; ++i) {
        const span = document.createElement("span");
        span.textContent = "Hi";
        span.style.fontFamily = names[i];
        div.appendChild(span);
      }

      document.body.appendChild(div);
      isFontReady(loadTestFontId, function () {
        document.body.removeChild(div);
        request.complete();
      });
    }

  };
}

class FontFaceObject {
  constructor(translatedData, {
    isEvalSupported = true,
    disableFontFace = false,
    ignoreErrors = false,
    onUnsupportedFeature = null,
    fontRegistry = null
  }) {
    this.compiledGlyphs = Object.create(null);

    for (const i in translatedData) {
      this[i] = translatedData[i];
    }

    this.isEvalSupported = isEvalSupported !== false;
    this.disableFontFace = disableFontFace === true;
    this.ignoreErrors = ignoreErrors === true;
    this._onUnsupportedFeature = onUnsupportedFeature;
    this.fontRegistry = fontRegistry;
  }

  createNativeFontFace() {
    if (!this.data || this.disableFontFace) {
      return null;
    }

    const nativeFontFace = new FontFace(this.loadedName, this.data, {});

    if (this.fontRegistry) {
      this.fontRegistry.registerFont(this);
    }

    return nativeFontFace;
  }

  createFontFaceRule() {
    if (!this.data || this.disableFontFace) {
      return null;
    }

    const data = (0, _util.bytesToString)(new Uint8Array(this.data));
    const url = `url(data:${this.mimetype};base64,${btoa(data)});`;
    const rule = `@font-face {font-family:"${this.loadedName}";src:${url}}`;

    if (this.fontRegistry) {
      this.fontRegistry.registerFont(this, url);
    }

    return rule;
  }

  getPathGenerator(objs, character) {
    if (this.compiledGlyphs[character] !== undefined) {
      return this.compiledGlyphs[character];
    }

    let cmds, current;

    try {
      cmds = objs.get(this.loadedName + "_path_" + character);
    } catch (ex) {
      if (!this.ignoreErrors) {
        throw ex;
      }

      if (this._onUnsupportedFeature) {
        this._onUnsupportedFeature({
          featureId: _util.UNSUPPORTED_FEATURES.errorFontGetPath
        });
      }

      (0, _util.warn)(`getPathGenerator - ignoring character: "${ex}".`);
      return this.compiledGlyphs[character] = function (c, size) {};
    }

    if (this.isEvalSupported && _util.IsEvalSupportedCached.value) {
      let args,
          js = "";

      for (let i = 0, ii = cmds.length; i < ii; i++) {
        current = cmds[i];

        if (current.args !== undefined) {
          args = current.args.join(",");
        } else {
          args = "";
        }

        js += "c." + current.cmd + "(" + args + ");\n";
      }

      return this.compiledGlyphs[character] = new Function("c", "size", js);
    }

    return this.compiledGlyphs[character] = function (c, size) {
      for (let i = 0, ii = cmds.length; i < ii; i++) {
        current = cmds[i];

        if (current.cmd === "scale") {
          current.args = [size, -size];
        }

        c[current.cmd].apply(c, current.args);
      }
    };
  }

}

exports.FontFaceObject = FontFaceObject;