Simplify the way to pass the glyph drawing instructions from the worker to the main thread

calixteman · pull[bot] · commit 1844583faea6 · 2024-07-21T12:40:11.000Z
and remove the use of eval in the font loader.
diff --git a/src/core/evaluator.js b/src/core/evaluator.js
@@ -4391,6 +4391,15 @@ class PartialEvaluator {
       }
     }
 
+    let fontMatrix = dict.getArray("FontMatrix");
+    if (
+      !Array.isArray(fontMatrix) ||
+      fontMatrix.length !== 6 ||
+      fontMatrix.some(x => typeof x !== "number")
+    ) {
+      fontMatrix = FONT_IDENTITY_MATRIX;
+    }
+
     const properties = {
       type,
       name: fontName.name,
@@ -4403,7 +4412,7 @@ class PartialEvaluator {
       loadedName: baseDict.loadedName,
       composite,
       fixedPitch: false,
-      fontMatrix: dict.getArray("FontMatrix") || FONT_IDENTITY_MATRIX,
+      fontMatrix,
       firstChar,
       lastChar,
       toUnicode,
diff --git a/src/core/font_renderer.js b/src/core/font_renderer.js
@@ -16,6 +16,7 @@
 import {
   bytesToString,
   FONT_IDENTITY_MATRIX,
+  FontRenderOps,
   FormatError,
   unreachable,
   warn,
@@ -180,13 +181,13 @@ function lookupCmap(ranges, unicode) {
 
 function compileGlyf(code, cmds, font) {
   function moveTo(x, y) {
-    cmds.push({ cmd: "moveTo", args: [x, y] });
+    cmds.add(FontRenderOps.MOVE_TO, [x, y]);
   }
   function lineTo(x, y) {
-    cmds.push({ cmd: "lineTo", args: [x, y] });
+    cmds.add(FontRenderOps.LINE_TO, [x, y]);
   }
   function quadraticCurveTo(xa, ya, x, y) {
-    cmds.push({ cmd: "quadraticCurveTo", args: [xa, ya, x, y] });
+    cmds.add(FontRenderOps.QUADRATIC_CURVE_TO, [xa, ya, x, y]);
   }
 
   let i = 0;
@@ -247,20 +248,22 @@ function compileGlyf(code, cmds, font) {
       if (subglyph) {
         // TODO: the transform should be applied only if there is a scale:
         // https://github.com/freetype/freetype/blob/edd4fedc5427cf1cf1f4b045e53ff91eb282e9d4/src/truetype/ttgload.c#L1205
-        cmds.push(
-          { cmd: "save" },
-          {
-            cmd: "transform",
-            args: [scaleX, scale01, scale10, scaleY, x, y],
-          }
-        );
+        cmds.add(FontRenderOps.SAVE);
+        cmds.add(FontRenderOps.TRANSFORM, [
+          scaleX,
+          scale01,
+          scale10,
+          scaleY,
+          x,
+          y,
+        ]);
 
         if (!(flags & 0x02)) {
           // TODO: we must use arg1 and arg2 to make something similar to:
           // https://github.com/freetype/freetype/blob/edd4fedc5427cf1cf1f4b045e53ff91eb282e9d4/src/truetype/ttgload.c#L1209
         }
         compileGlyf(subglyph, cmds, font);
-        cmds.push({ cmd: "restore" });
+        cmds.add(FontRenderOps.RESTORE);
       }
     } while (flags & 0x20);
   } else {
@@ -365,13 +368,13 @@ function compileGlyf(code, cmds, font) {
 
 function compileCharString(charStringCode, cmds, font, glyphId) {
   function moveTo(x, y) {
-    cmds.push({ cmd: "moveTo", args: [x, y] });
+    cmds.add(FontRenderOps.MOVE_TO, [x, y]);
   }
   function lineTo(x, y) {
-    cmds.push({ cmd: "lineTo", args: [x, y] });
+    cmds.add(FontRenderOps.LINE_TO, [x, y]);
   }
   function bezierCurveTo(x1, y1, x2, y2, x, y) {
-    cmds.push({ cmd: "bezierCurveTo", args: [x1, y1, x2, y2, x, y] });
+    cmds.add(FontRenderOps.BEZIER_CURVE_TO, [x1, y1, x2, y2, x, y]);
   }
 
   const stack = [];
@@ -544,7 +547,8 @@ function compileCharString(charStringCode, cmds, font, glyphId) {
             const bchar = stack.pop();
             y = stack.pop();
             x = stack.pop();
-            cmds.push({ cmd: "save" }, { cmd: "translate", args: [x, y] });
+            cmds.add(FontRenderOps.SAVE);
+            cmds.add(FontRenderOps.TRANSLATE, [x, y]);
             let cmap = lookupCmap(
               font.cmap,
               String.fromCharCode(font.glyphNameMap[StandardEncoding[achar]])
@@ -555,7 +559,7 @@ function compileCharString(charStringCode, cmds, font, glyphId) {
               font,
               cmap.glyphId
             );
-            cmds.push({ cmd: "restore" });
+            cmds.add(FontRenderOps.RESTORE);
 
             cmap = lookupCmap(
               font.cmap,
@@ -741,6 +745,27 @@ function compileCharString(charStringCode, cmds, font, glyphId) {
 
 const NOOP = [];
 
+class Commands {
+  cmds = [];
+
+  add(cmd, args) {
+    if (args) {
+      if (args.some(arg => typeof arg !== "number")) {
+        warn(
+          `Commands.add - "${cmd}" has at least one non-number arg: "${args}".`
+        );
+        // "Fix" the wrong args by replacing them with 0.
+        const newArgs = args.map(arg => (typeof arg === "number" ? arg : 0));
+        this.cmds.push(cmd, ...newArgs);
+      } else {
+        this.cmds.push(cmd, ...args);
+      }
+    } else {
+      this.cmds.push(cmd);
+    }
+  }
+}
+
 class CompiledFont {
   constructor(fontMatrix) {
     if (this.constructor === CompiledFont) {
@@ -757,8 +782,10 @@ class CompiledFont {
     let fn = this.compiledGlyphs[glyphId];
     if (!fn) {
       try {
-        fn = this.compileGlyph(this.glyphs[glyphId], glyphId);
-        this.compiledGlyphs[glyphId] = fn;
+        fn = this.compiledGlyphs[glyphId] = this.compileGlyph(
+          this.glyphs[glyphId],
+          glyphId
+        );
       } catch (ex) {
         // Avoid attempting to re-compile a corrupt glyph.
         this.compiledGlyphs[glyphId] = NOOP;
@@ -793,16 +820,14 @@ class CompiledFont {
       }
     }
 
-    const cmds = [
-      { cmd: "save" },
-      { cmd: "transform", args: fontMatrix.slice() },
-      { cmd: "scale", args: ["size", "-size"] },
-    ];
+    const cmds = new Commands();
+    cmds.add(FontRenderOps.SAVE);
+    cmds.add(FontRenderOps.TRANSFORM, fontMatrix.slice());
+    cmds.add(FontRenderOps.SCALE);
     this.compileGlyphImpl(code, cmds, glyphId);
+    cmds.add(FontRenderOps.RESTORE);
 
-    cmds.push({ cmd: "restore" });
-
-    return cmds;
+    return cmds.cmds;
   }
 
   compileGlyphImpl() {
diff --git a/src/display/api.js b/src/display/api.js
@@ -169,8 +169,8 @@ const DefaultStandardFontDataFactory =
  *   pixels, i.e. width * height. Images above this value will not be rendered.
  *   Use -1 for no limit, which is also the default value.
  * @property {boolean} [isEvalSupported] - Determines if we can evaluate strings
- *   as JavaScript. Primarily used to improve performance of font rendering, and
- *   when parsing PDF functions. The default value is `true`.
+ *   as JavaScript. Primarily used to improve performance of PDF functions.
+ *   The default value is `true`.
  * @property {boolean} [isOffscreenCanvasSupported] - Determines if we can use
  *   `OffscreenCanvas` in the worker. Primarily used to improve performance of
  *   image conversion/rendering.
@@ -384,7 +384,6 @@ function getDocument(src) {
   };
   const transportParams = {
     ignoreErrors,
-    isEvalSupported,
     disableFontFace,
     fontExtraProperties,
     enableXfa,
@@ -2744,7 +2743,6 @@ class WorkerTransport {
               ? (font, url) => globalThis.FontInspector.fontAdded(font, url)
               : null;
           const font = new FontFaceObject(exportedData, {
-            isEvalSupported: params.isEvalSupported,
             disableFontFace: params.disableFontFace,
             ignoreErrors: params.ignoreErrors,
             inspectFont,
diff --git a/src/display/font_loader.js b/src/display/font_loader.js
@@ -16,7 +16,7 @@
 import {
   assert,
   bytesToString,
-  FeatureTest,
+  FontRenderOps,
   isNodeJS,
   shadow,
   string32,
@@ -362,19 +362,13 @@ class FontLoader {
 class FontFaceObject {
   constructor(
     translatedData,
-    {
-      isEvalSupported = true,
-      disableFontFace = false,
-      ignoreErrors = false,
-      inspectFont = null,
-    }
+    { disableFontFace = false, ignoreErrors = false, inspectFont = null }
   ) {
     this.compiledGlyphs = Object.create(null);
     // importing translated data
     for (const i in translatedData) {
       this[i] = translatedData[i];
     }
-    this.isEvalSupported = isEvalSupported !== false;
     this.disableFontFace = disableFontFace === true;
     this.ignoreErrors = ignoreErrors === true;
     this._inspectFont = inspectFont;
@@ -440,35 +434,85 @@ class FontFaceObject {
         throw ex;
       }
       warn(`getPathGenerator - ignoring character: "${ex}".`);
+    }
 
+    if (!Array.isArray(cmds) || cmds.length === 0) {
       return (this.compiledGlyphs[character] = function (c, size) {
         // No-op function, to allow rendering to continue.
       });
     }
 
-    // If we can, compile cmds into JS for MAXIMUM SPEED...
-    if (this.isEvalSupported && FeatureTest.isEvalSupported) {
-      const jsBuf = [];
-      for (const current of cmds) {
-        const args = current.args !== undefined ? current.args.join(",") : "";
-        jsBuf.push("c.", current.cmd, "(", args, ");\n");
+    const commands = [];
+    for (let i = 0, ii = cmds.length; i < ii; ) {
+      switch (cmds[i++]) {
+        case FontRenderOps.BEZIER_CURVE_TO:
+          {
+            const [a, b, c, d, e, f] = cmds.slice(i, i + 6);
+            commands.push(ctx => ctx.bezierCurveTo(a, b, c, d, e, f));
+            i += 6;
+          }
+          break;
+        case FontRenderOps.MOVE_TO:
+          {
+            const [a, b] = cmds.slice(i, i + 2);
+            commands.push(ctx => ctx.moveTo(a, b));
+            i += 2;
+          }
+          break;
+        case FontRenderOps.LINE_TO:
+          {
+            const [a, b] = cmds.slice(i, i + 2);
+            commands.push(ctx => ctx.lineTo(a, b));
+            i += 2;
+          }
+          break;
+        case FontRenderOps.QUADRATIC_CURVE_TO:
+          {
+            const [a, b, c, d] = cmds.slice(i, i + 4);
+            commands.push(ctx => ctx.quadraticCurveTo(a, b, c, d));
+            i += 4;
+          }
+          break;
+        case FontRenderOps.RESTORE:
+          commands.push(ctx => ctx.restore());
+          break;
+        case FontRenderOps.SAVE:
+          commands.push(ctx => ctx.save());
+          break;
+        case FontRenderOps.SCALE:
+          // The scale command must be at the third position, after save and
+          // transform (for the font matrix) commands (see also
+          // font_renderer.js).
+          // The goal is to just scale the canvas and then run the commands loop
+          // without the need to pass the size parameter to each command.
+          assert(
+            commands.length === 2,
+            "Scale command is only valid at the third position."
+          );
+          break;
+        case FontRenderOps.TRANSFORM:
+          {
+            const [a, b, c, d, e, f] = cmds.slice(i, i + 6);
+            commands.push(ctx => ctx.transform(a, b, c, d, e, f));
+            i += 6;
+          }
+          break;
+        case FontRenderOps.TRANSLATE:
+          {
+            const [a, b] = cmds.slice(i, i + 2);
+            commands.push(ctx => ctx.translate(a, b));
+            i += 2;
+          }
+          break;
       }
-      // eslint-disable-next-line no-new-func
-      return (this.compiledGlyphs[character] = new Function(
-        "c",
-        "size",
-        jsBuf.join("")
-      ));
-    }
-    // ... but fall back on using Function.prototype.apply() if we're
-    // blocked from using eval() for whatever reason (like CSP policies).
-    return (this.compiledGlyphs[character] = function (c, size) {
-      for (const current of cmds) {
-        if (current.cmd === "scale") {
-          current.args = [size, -size];
-        }
-        // eslint-disable-next-line prefer-spread
-        c[current.cmd].apply(c, current.args);
+    }
+
+    return (this.compiledGlyphs[character] = function glyphDrawer(ctx, size) {
+      commands[0](ctx);
+      commands[1](ctx);
+      ctx.scale(size, -size);
+      for (let i = 2, ii = commands.length; i < ii; i++) {
+        commands[i](ctx);
       }
     });
   }
diff --git a/src/shared/util.js b/src/shared/util.js
@@ -1073,6 +1073,18 @@ function getUuid() {
 
 const AnnotationPrefix = "pdfjs_internal_id_";
 
+const FontRenderOps = {
+  BEZIER_CURVE_TO: 0,
+  MOVE_TO: 1,
+  LINE_TO: 2,
+  QUADRATIC_CURVE_TO: 3,
+  RESTORE: 4,
+  SAVE: 5,
+  SCALE: 6,
+  TRANSFORM: 7,
+  TRANSLATE: 8,
+};
+
 export {
   AbortException,
   AnnotationActionEventType,
@@ -1095,6 +1107,7 @@ export {
   DocumentActionEventType,
   FeatureTest,
   FONT_IDENTITY_MATRIX,
+  FontRenderOps,
   FormatError,
   getModificationDate,
   getUuid,
