Merge pull request #10539 from Snuffleupagus/fallback-disableFontFace-v2

[api-minor] Fallback to the built-in font renderer when font loading fails

src/core/document.js

@@ -666,6 +666,10 @@ class PDFDocument {
     });
   }
 
+  fontFallback(id, handler) {
+    return this.catalog.fontFallback(id, handler);
+  }
+
   cleanup() {
     return this.catalog.cleanup();
   }

src/core/evaluator.js

@@ -610,37 +610,18 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
       });
     },
 
-    handleText: function PartialEvaluator_handleText(chars, state) {
-      var font = state.font;
-      var glyphs = font.charsToGlyphs(chars);
-      var isAddToPathSet = !!(state.textRenderingMode &
+    handleText(chars, state) {
+      const font = state.font;
+      const glyphs = font.charsToGlyphs(chars);
+
+      if (font.data) {
+        const isAddToPathSet = !!(state.textRenderingMode &
                                   TextRenderingMode.ADD_TO_PATH_FLAG);
-      if (font.data && (isAddToPathSet || this.options.disableFontFace ||
-                        state.fillColorSpace.name === 'Pattern')) {
-        var buildPath = (fontChar) => {
-          if (!font.renderer.hasBuiltPath(fontChar)) {
-            var path = font.renderer.getPathJs(fontChar);
-            this.handler.send('commonobj', [
-              font.loadedName + '_path_' + fontChar,
-              'FontPath',
-              path
-            ]);
-          }
-        };
-
-        for (var i = 0, ii = glyphs.length; i < ii; i++) {
-          var glyph = glyphs[i];
-          buildPath(glyph.fontChar);
-
-          // If the glyph has an accent we need to build a path for its
-          // fontChar too, otherwise CanvasGraphics_paintChar will fail.
-          var accent = glyph.accent;
-          if (accent && accent.fontChar) {
-            buildPath(accent.fontChar);
+        if (isAddToPathSet || state.fillColorSpace.name === 'Pattern' ||
+            font.disableFontFace || this.options.disableFontFace) {
+          PartialEvaluator.buildFontPaths(font, glyphs, this.handler);
         }
       }
-      }
-
       return glyphs;
     },
 
@@ -2623,6 +2604,30 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
     },
   };
 
+  PartialEvaluator.buildFontPaths = function(font, glyphs, handler) {
+    function buildPath(fontChar) {
+      if (font.renderer.hasBuiltPath(fontChar)) {
+        return;
+      }
+      handler.send('commonobj', [
+        `${font.loadedName}_path_${fontChar}`,
+        'FontPath',
+        font.renderer.getPathJs(fontChar),
+      ]);
+    }
+
+    for (const glyph of glyphs) {
+      buildPath(glyph.fontChar);
+
+      // If the glyph has an accent we need to build a path for its
+      // fontChar too, otherwise CanvasGraphics_paintChar will fail.
+      const accent = glyph.accent;
+      if (accent && accent.fontChar) {
+        buildPath(accent.fontChar);
+      }
+    }
+  };
+
   return PartialEvaluator;
 })();
 
@@ -2639,14 +2644,31 @@ var TranslatedFont = (function TranslatedFontClosure() {
       if (this.sent) {
         return;
       }
-      var fontData = this.font.exportData();
+      this.sent = true;
+
       handler.send('commonobj', [
         this.loadedName,
         'Font',
-        fontData
+        this.font.exportData(),
       ]);
-      this.sent = true;
     },
+
+    fallback(handler) {
+      if (!this.font.data) {
+        return;
+      }
+      // When font loading failed, fall back to the built-in font renderer.
+      this.font.disableFontFace = true;
+      // An arbitrary number of text rendering operators could have been
+      // encountered between the point in time when the 'Font' message was sent
+      // to the main-thread, and the point in time when the 'FontFallback'
+      // message was received on the worker-thread.
+      // To ensure that all 'FontPath's are available on the main-thread, when
+      // font loading failed, attempt to resend *all* previously parsed glyphs.
+      const glyphs = this.font.glyphCacheValues;
+      PartialEvaluator.buildFontPaths(this.font, glyphs, handler);
+    },
+
     loadType3Data(evaluator, resources, parentOperatorList, task) {
       if (!this.font.isType3Font) {
         throw new Error('Must be a Type3 font.');

src/core/fonts.js

@@ -1159,6 +1159,8 @@ var Font = (function FontClosure() {
     font: null,
     mimetype: null,
     encoding: null,
+    disableFontFace: false,
+
     get renderer() {
       var renderer = FontRendererFactory.create(this, SEAC_ANALYSIS_ENABLED);
       return shadow(this, 'renderer', renderer);
@@ -2944,6 +2946,10 @@ var Font = (function FontClosure() {
       // Enter the translated string into the cache
       return (charsCache[charsCacheKey] = glyphs);
     },
+
+    get glyphCacheValues() {
+      return Object.values(this.glyphCache);
+    },
   };
 
   return Font;

src/core/obj.js

@@ -490,6 +490,22 @@ class Catalog {
     return shadow(this, 'javaScript', javaScript);
   }
 
+  fontFallback(id, handler) {
+    const promises = [];
+    this.fontCache.forEach(function(promise) {
+      promises.push(promise);
+    });
+
+    return Promise.all(promises).then((translatedFonts) => {
+      for (const translatedFont of translatedFonts) {
+        if (translatedFont.loadedName === id) {
+          translatedFont.fallback(handler);
+          return;
+        }
+      }
+    });
+  }
+
   cleanup() {
     this.pageKidsCountCache.clear();
 

src/core/pdf_manager.js

@@ -68,6 +68,10 @@ class BasePdfManager {
     return this.pdfDocument.getPage(pageIndex);
   }
 
+  fontFallback(id, handler) {
+    return this.pdfDocument.fontFallback(id, handler);
+  }
+
   cleanup() {
     return this.pdfDocument.cleanup();
   }

src/core/worker.js

@@ -667,6 +667,10 @@ var WorkerMessageHandler = {
       });
     });
 
+    handler.on('FontFallback', function(data) {
+      return pdfManager.fontFallback(data.id, handler);
+    });
+
     handler.on('Cleanup', function wphCleanup(data) {
       return pdfManager.cleanup();
     });

src/display/api.js

@@ -1676,7 +1676,10 @@ class WorkerTransport {
     this.messageHandler = messageHandler;
     this.loadingTask = loadingTask;
     this.commonObjs = new PDFObjects();
-    this.fontLoader = new FontLoader(loadingTask.docId);
+    this.fontLoader = new FontLoader({
+      docId: loadingTask.docId,
+      onUnsupportedFeature: this._onUnsupportedFeature.bind(this),
+    });
     this._params = params;
     this.CMapReaderFactory = new params.CMapReaderFactory({
       baseUrl: params.cMapUrl,
@@ -1944,11 +1947,16 @@ class WorkerTransport {
             onUnsupportedFeature: this._onUnsupportedFeature.bind(this),
             fontRegistry,
           });
-          const fontReady = (fontObjs) => {
-            this.commonObjs.resolve(id, font);
-          };
 
-          this.fontLoader.bind([font], fontReady);
+          this.fontLoader.bind(font).then(() => {
+            this.commonObjs.resolve(id, font);
+          }, (reason) => {
+            messageHandler.sendWithPromise('FontFallback', {
+              id,
+            }).finally(() => {
+              this.commonObjs.resolve(id, font);
+            });
+          });
           break;
         case 'FontPath':
           this.commonObjs.resolve(id, exportedData);

src/display/font_loader.js

@@ -19,18 +19,15 @@ import {
 } from '../shared/util';
 
 class BaseFontLoader {
-  constructor(docId) {
+  constructor({ docId, onUnsupportedFeature, }) {
     if (this.constructor === BaseFontLoader) {
       unreachable('Cannot initialize BaseFontLoader.');
     }
     this.docId = docId;
+    this._onUnsupportedFeature = onUnsupportedFeature;
 
     this.nativeFontFaces = [];
     this.styleElement = null;
-    this.loadingContext = {
-      requests: [],
-      nextRequestId: 0,
-    };
   }
 
   addNativeFontFace(nativeFontFace) {
@@ -64,22 +61,10 @@ class BaseFontLoader {
     }
   }
 
-  bind(fonts, callback) {
-    const rules = [];
-    const fontsToLoad = [];
-    const fontLoadPromises = [];
-    const getNativeFontPromise = function(nativeFontFace) {
-      // Return a promise that is always fulfilled, even when the font fails to
-      // load.
-      return nativeFontFace.loaded.catch(function(reason) {
-        warn(`Failed to load font "${nativeFontFace.family}": ${reason}`);
-      });
-    };
-
-    for (const font of fonts) {
+  async bind(font) {
     // Add the font to the DOM only once; skip if the font is already loaded.
     if (font.attached || font.missingFile) {
-        continue;
+      return;
     }
     font.attached = true;
 
@@ -87,49 +72,37 @@ class BaseFontLoader {
       const nativeFontFace = font.createNativeFontFace();
       if (nativeFontFace) {
         this.addNativeFontFace(nativeFontFace);
-          fontLoadPromises.push(getNativeFontPromise(nativeFontFace));
+        try {
+          await nativeFontFace.loaded;
+        } catch (ex) {
+          this._onUnsupportedFeature({ featureId: UNSUPPORTED_FEATURES.font, });
+          warn(`Failed to load font '${nativeFontFace.family}': '${ex}'.`);
+
+          // When font loading failed, fall back to the built-in font renderer.
+          font.disableFontFace = true;
+          throw ex;
         }
-      } else {
+      }
+      return; // The font was, asynchronously, loaded.
+    }
+
+    // !this.isFontLoadingAPISupported
     const rule = font.createFontFaceRule();
     if (rule) {
       this.insertRule(rule);
-          rules.push(rule);
-          fontsToLoad.push(font);
-        }
-      }
-    }
 
-    const request = this._queueLoadingCallback(callback);
-    if (this.isFontLoadingAPISupported) {
-      Promise.all(fontLoadPromises).then(request.complete);
-    } else if (rules.length > 0 && !this.isSyncFontLoadingSupported) {
-      this._prepareFontLoadEvent(rules, fontsToLoad, request);
-    } else {
-      request.complete();
+      if (this.isSyncFontLoadingSupported) {
+        return; // The font was, synchronously, loaded.
+      }
+      return new Promise((resolve) => {
+        const request = this._queueLoadingCallback(resolve);
+        this._prepareFontLoadEvent([rule], [font], request);
+      });
     }
   }
 
   _queueLoadingCallback(callback) {
-    function completeRequest() {
-      assert(!request.done, 'completeRequest() cannot be called twice.');
-      request.done = true;
-
-      // Sending all completed requests in order of how they were queued.
-      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;
+    unreachable('Abstract method `_queueLoadingCallback`.');
   }
 
   get isFontLoadingAPISupported() {
@@ -168,6 +141,10 @@ FontLoader = class MozcentralFontLoader extends BaseFontLoader {
 FontLoader = class GenericFontLoader extends BaseFontLoader {
   constructor(docId) {
     super(docId);
+    this.loadingContext = {
+      requests: [],
+      nextRequestId: 0,
+    };
     this.loadTestFontId = 0;
   }
 
@@ -205,6 +182,29 @@ FontLoader = class GenericFontLoader extends BaseFontLoader {
     return shadow(this, 'isSyncFontLoadingSupported', supported);
   }
 
+  _queueLoadingCallback(callback) {
+    function completeRequest() {
+      assert(!request.done, 'completeRequest() cannot be called twice.');
+      request.done = true;
+
+      // Sending all completed requests in order of how they were queued.
+      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() {
       // This is a CFF font with 1 glyph for '.' that fills its entire width and

src/shared/compatibility.js

@@ -23,11 +23,6 @@ if ((typeof PDFJSDev === 'undefined' ||
 
 globalScope._pdfjsCompatibilityChecked = true;
 
-// In the Chrome extension, most of the polyfills are unnecessary.
-// We support down to Chrome 49, because it's still commonly used by Windows XP
-// users - https://github.com/mozilla/pdf.js/issues/9397
-if (typeof PDFJSDev === 'undefined' || !PDFJSDev.test('CHROME')) {
-
 const isNodeJS = require('./is_node');
 
 const hasDOM = typeof window === 'object' && typeof document === 'object';
@@ -199,14 +194,15 @@ const hasDOM = typeof window === 'object' && typeof document === 'object';
   Number.isInteger = require('core-js/fn/number/is-integer');
 })();
 
-// Support: IE, Safari<8, Chrome<32
+// Support: IE, Safari<11, Chrome<63
 (function checkPromise() {
   if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('IMAGE_DECODERS')) {
     // The current image decoders are synchronous, hence `Promise` shouldn't
     // need to be polyfilled for the IMAGE_DECODERS build target.
     return;
   }
-  if (globalScope.Promise) {
+  if (globalScope.Promise && (globalScope.Promise.prototype &&
+                              globalScope.Promise.prototype.finally)) {
     return;
   }
   globalScope.Promise = require('core-js/fn/promise');
@@ -254,8 +250,6 @@ const hasDOM = typeof window === 'object' && typeof document === 'object';
   require('core-js/es6/symbol');
 })();
 
-} // End of !PDFJSDev.test('CHROME')
-
 // Provides support for String.prototype.padStart in legacy browsers.
 // Support: IE, Chrome<57
 (function checkStringPadStart() {