diff --git a/src/core/fonts.js b/src/core/fonts.js
index ebf84af211115..8b8ec434d3377 100644
--- a/src/core/fonts.js
+++ b/src/core/fonts.js
@@ -57,6 +57,7 @@ import {
 import { IdentityToUnicodeMap, ToUnicodeMap } from "./to_unicode_map.js";
 import { CFFFont } from "./cff_font.js";
 import { FontRendererFactory } from "./font_renderer.js";
+import { GlyfTable } from "./glyf.js";
 import { IdentityCMap } from "./cmap.js";
 import { OpenTypeFileBuilder } from "./opentype_file_builder.js";
 import { readUint32 } from "./core_utils.js";
@@ -2323,6 +2324,51 @@ class Font {
     font.pos = (font.start || 0) + tables.maxp.offset;
     const version = font.getInt32();
     const numGlyphs = font.getUint16();
+
+    if (
+      properties.scaleFactors &&
+      properties.scaleFactors.length === numGlyphs &&
+      isTrueType
+    ) {
+      const { scaleFactors } = properties;
+      const isGlyphLocationsLong = int16(
+        tables.head.data[50],
+        tables.head.data[51]
+      );
+
+      const glyphs = new GlyfTable({
+        glyfTable: tables.glyf.data,
+        isGlyphLocationsLong,
+        locaTable: tables.loca.data,
+        numGlyphs,
+      });
+      glyphs.scale(scaleFactors);
+
+      const { glyf, loca, isLocationLong } = glyphs.write();
+      tables.glyf.data = glyf;
+      tables.loca.data = loca;
+
+      if (isLocationLong !== !!isGlyphLocationsLong) {
+        tables.head.data[50] = 0;
+        tables.head.data[51] = isLocationLong ? 1 : 0;
+      }
+
+      const metrics = tables.hmtx.data;
+
+      for (let i = 0; i < numGlyphs; i++) {
+        const j = 4 * i;
+        const advanceWidth = Math.round(
+          scaleFactors[i] * int16(metrics[j], metrics[j + 1])
+        );
+        metrics[j] = (advanceWidth >> 8) & 0xff;
+        metrics[j + 1] = advanceWidth & 0xff;
+        const lsb = Math.round(
+          scaleFactors[i] * signedInt16(metrics[j + 2], metrics[j + 3])
+        );
+        writeSignedInt16(metrics, j + 2, lsb);
+      }
+    }
+
     // Glyph 0 is duplicated and appended.
     let numGlyphsOut = numGlyphs + 1;
     let dupFirstEntry = true;
diff --git a/src/core/glyf.js b/src/core/glyf.js
new file mode 100644
index 0000000000000..4027214da6c58
--- /dev/null
+++ b/src/core/glyf.js
@@ -0,0 +1,708 @@
+/* Copyright 2021 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.
+ */
+
+const ON_CURVE_POINT = 1 << 0;
+const X_SHORT_VECTOR = 1 << 1;
+const Y_SHORT_VECTOR = 1 << 2;
+const REPEAT_FLAG = 1 << 3;
+const X_IS_SAME_OR_POSITIVE_X_SHORT_VECTOR = 1 << 4;
+const Y_IS_SAME_OR_POSITIVE_Y_SHORT_VECTOR = 1 << 5;
+const OVERLAP_SIMPLE = 1 << 6;
+
+const ARG_1_AND_2_ARE_WORDS = 1 << 0;
+const ARGS_ARE_XY_VALUES = 1 << 1;
+// const ROUND_XY_TO_GRID = 1 << 2;
+const WE_HAVE_A_SCALE = 1 << 3;
+const MORE_COMPONENTS = 1 << 5;
+const WE_HAVE_AN_X_AND_Y_SCALE = 1 << 6;
+const WE_HAVE_A_TWO_BY_TWO = 1 << 7;
+const WE_HAVE_INSTRUCTIONS = 1 << 8;
+// const USE_MY_METRICS = 1 << 9;
+// const OVERLAP_COMPOUND = 1 << 10;
+// const SCALED_COMPONENT_OFFSET = 1 << 11;
+// const UNSCALED_COMPONENT_OFFSET = 1 << 12;
+
+/**
+ * GlyfTable object represents a glyf table containing glyph information:
+ *  - glyph header (xMin, yMin, xMax, yMax);
+ *  - contours if any;
+ *  - components if the glyph is a composite.
+ *
+ * It's possible to re-scale each glyph in order to have a new font which
+ * exactly fits an other one: the goal is to be able to build some substitution
+ * font for well-known fonts (Myriad, Arial, ...).
+ *
+ * A full description of glyf table can be found here
+ * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6glyf.html
+ */
+class GlyfTable {
+  constructor({ glyfTable, isGlyphLocationsLong, locaTable, numGlyphs }) {
+    this.glyphs = [];
+    const loca = new DataView(
+      locaTable.buffer,
+      locaTable.byteOffset,
+      locaTable.byteLength
+    );
+    const glyf = new DataView(
+      glyfTable.buffer,
+      glyfTable.byteOffset,
+      glyfTable.byteLength
+    );
+    const offsetSize = isGlyphLocationsLong ? 4 : 2;
+    let prev = isGlyphLocationsLong ? loca.getUint32(0) : 2 * loca.getUint16(0);
+    let pos = 0;
+    for (let i = 0; i < numGlyphs; i++) {
+      pos += offsetSize;
+      const next = isGlyphLocationsLong
+        ? loca.getUint32(pos)
+        : 2 * loca.getUint16(pos);
+      if (next === prev) {
+        this.glyphs.push(new Glyph({}));
+        continue;
+      }
+
+      const glyph = Glyph.parse(prev, glyf);
+      this.glyphs.push(glyph);
+
+      prev = next;
+    }
+  }
+
+  getSize() {
+    return this.glyphs.reduce((a, g) => {
+      const size = g.getSize();
+      // Round to next multiple of 4 if needed.
+      return a + ((size + 3) & ~3);
+    }, 0);
+  }
+
+  write() {
+    const totalSize = this.getSize();
+    const glyfTable = new DataView(new ArrayBuffer(totalSize));
+    const isLocationLong = totalSize > /* 0xffff * 2 */ 0x1fffe;
+    const offsetSize = isLocationLong ? 4 : 2;
+    const locaTable = new DataView(
+      new ArrayBuffer((this.glyphs.length + 1) * offsetSize)
+    );
+
+    if (isLocationLong) {
+      locaTable.setUint32(0, 0);
+    } else {
+      locaTable.setUint16(0, 0);
+    }
+
+    let pos = 0;
+    let locaIndex = 0;
+    for (const glyph of this.glyphs) {
+      pos += glyph.write(pos, glyfTable);
+      // Round to next multiple of 4 if needed.
+      pos = (pos + 3) & ~3;
+
+      locaIndex += offsetSize;
+      if (isLocationLong) {
+        locaTable.setUint32(locaIndex, pos);
+      } else {
+        locaTable.setUint16(locaIndex, pos >> 1);
+      }
+    }
+
+    return {
+      isLocationLong,
+      loca: new Uint8Array(locaTable.buffer),
+      glyf: new Uint8Array(glyfTable.buffer),
+    };
+  }
+
+  scale(factors) {
+    for (let i = 0, ii = this.glyphs.length; i < ii; i++) {
+      this.glyphs[i].scale(factors[i]);
+    }
+  }
+}
+
+class Glyph {
+  constructor({ header = null, simple = null, composites = null }) {
+    this.header = header;
+    this.simple = simple;
+    this.composites = composites;
+  }
+
+  static parse(pos, glyf) {
+    const [read, header] = GlyphHeader.parse(pos, glyf);
+    pos += read;
+
+    if (header.numberOfContours < 0) {
+      // Composite glyph.
+      const composites = [];
+      while (true) {
+        const [n, composite] = CompositeGlyph.parse(pos, glyf);
+        pos += n;
+        composites.push(composite);
+        if (!(composite.flags & MORE_COMPONENTS)) {
+          break;
+        }
+      }
+
+      return new Glyph({ header, composites });
+    }
+
+    const simple = SimpleGlyph.parse(pos, glyf, header.numberOfContours);
+
+    return new Glyph({ header, simple });
+  }
+
+  getSize() {
+    if (!this.header) {
+      return 0;
+    }
+    const size = this.simple
+      ? this.simple.getSize()
+      : this.composites.reduce((a, c) => a + c.getSize(), 0);
+    return this.header.getSize() + size;
+  }
+
+  write(pos, buf) {
+    if (!this.header) {
+      return 0;
+    }
+
+    const spos = pos;
+    pos += this.header.write(pos, buf);
+    if (this.simple) {
+      pos += this.simple.write(pos, buf);
+    } else {
+      for (const composite of this.composites) {
+        pos += composite.write(pos, buf);
+      }
+    }
+
+    return pos - spos;
+  }
+
+  scale(factor) {
+    if (!this.header) {
+      return;
+    }
+
+    const xMiddle = (this.header.xMin + this.header.xMax) / 2;
+    this.header.scale(xMiddle, factor);
+    if (this.simple) {
+      this.simple.scale(xMiddle, factor);
+    } else {
+      for (const composite of this.composites) {
+        composite.scale(xMiddle, factor);
+      }
+    }
+  }
+}
+
+class GlyphHeader {
+  constructor({ numberOfContours, xMin, yMin, xMax, yMax }) {
+    this.numberOfContours = numberOfContours;
+    this.xMin = xMin;
+    this.yMin = yMin;
+    this.xMax = xMax;
+    this.yMax = yMax;
+  }
+
+  static parse(pos, glyf) {
+    return [
+      10,
+      new GlyphHeader({
+        numberOfContours: glyf.getInt16(pos),
+        xMin: glyf.getInt16(pos + 2),
+        yMin: glyf.getInt16(pos + 4),
+        xMax: glyf.getInt16(pos + 6),
+        yMax: glyf.getInt16(pos + 8),
+      }),
+    ];
+  }
+
+  getSize() {
+    return 10;
+  }
+
+  write(pos, buf) {
+    buf.setInt16(pos, this.numberOfContours);
+    buf.setInt16(pos + 2, this.xMin);
+    buf.setInt16(pos + 4, this.yMin);
+    buf.setInt16(pos + 6, this.xMax);
+    buf.setInt16(pos + 8, this.yMax);
+
+    return 10;
+  }
+
+  scale(x, factor) {
+    this.xMin = Math.round(x + (this.xMin - x) * factor);
+    this.xMax = Math.round(x + (this.xMax - x) * factor);
+  }
+}
+
+class Contour {
+  constructor({ flags, xCoordinates, yCoordinates }) {
+    this.xCoordinates = xCoordinates;
+    this.yCoordinates = yCoordinates;
+    this.flags = flags;
+  }
+}
+
+class SimpleGlyph {
+  constructor({ contours, instructions }) {
+    this.contours = contours;
+    this.instructions = instructions;
+  }
+
+  static parse(pos, glyf, numberOfContours) {
+    const endPtsOfContours = [];
+    for (let i = 0; i < numberOfContours; i++) {
+      const endPt = glyf.getUint16(pos);
+      pos += 2;
+      endPtsOfContours.push(endPt);
+    }
+    const numberOfPt = endPtsOfContours[numberOfContours - 1] + 1;
+    const instructionLength = glyf.getUint16(pos);
+    pos += 2;
+    const instructions = new Uint8Array(glyf).slice(
+      pos,
+      pos + instructionLength
+    );
+    pos += instructionLength;
+
+    const flags = [];
+    for (let i = 0; i < numberOfPt; pos++, i++) {
+      let flag = glyf.getUint8(pos);
+      flags.push(flag);
+      if (flag & REPEAT_FLAG) {
+        const count = glyf.getUint8(++pos);
+        flag = flag ^ REPEAT_FLAG;
+        for (let m = 0; m < count; m++) {
+          flags.push(flag);
+        }
+        i += count;
+      }
+    }
+
+    const allXCoordinates = [];
+    let xCoordinates = [];
+    let yCoordinates = [];
+    let pointFlags = [];
+    const contours = [];
+    let endPtsOfContoursIndex = 0;
+    let lastCoordinate = 0;
+
+    // Get x coordinates.
+    for (let i = 0; i < numberOfPt; i++) {
+      const flag = flags[i];
+      if (flag & X_SHORT_VECTOR) {
+        // 8-bits unsigned value.
+        const x = glyf.getUint8(pos++);
+        lastCoordinate += flag & X_IS_SAME_OR_POSITIVE_X_SHORT_VECTOR ? x : -x;
+        xCoordinates.push(lastCoordinate);
+      } else if (flag & X_IS_SAME_OR_POSITIVE_X_SHORT_VECTOR) {
+        // IS_SAME.
+        xCoordinates.push(lastCoordinate);
+      } else {
+        lastCoordinate += glyf.getInt16(pos);
+        pos += 2;
+        xCoordinates.push(lastCoordinate);
+      }
+
+      if (endPtsOfContours[endPtsOfContoursIndex] === i) {
+        // Next entry is the first one of a new contour.
+        endPtsOfContoursIndex++;
+        allXCoordinates.push(xCoordinates);
+        xCoordinates = [];
+      }
+    }
+
+    lastCoordinate = 0;
+    endPtsOfContoursIndex = 0;
+    for (let i = 0; i < numberOfPt; i++) {
+      const flag = flags[i];
+      if (flag & Y_SHORT_VECTOR) {
+        // 8-bits unsigned value.
+        const y = glyf.getUint8(pos++);
+        lastCoordinate += flag & Y_IS_SAME_OR_POSITIVE_Y_SHORT_VECTOR ? y : -y;
+        yCoordinates.push(lastCoordinate);
+      } else if (flag & Y_IS_SAME_OR_POSITIVE_Y_SHORT_VECTOR) {
+        // IS_SAME.
+        yCoordinates.push(lastCoordinate);
+      } else {
+        lastCoordinate += glyf.getInt16(pos);
+        pos += 2;
+        yCoordinates.push(lastCoordinate);
+      }
+
+      pointFlags.push((flag & ON_CURVE_POINT) | (flag & OVERLAP_SIMPLE));
+
+      if (endPtsOfContours[endPtsOfContoursIndex] === i) {
+        // Next entry is the first one of a new contour.
+        xCoordinates = allXCoordinates[endPtsOfContoursIndex];
+        endPtsOfContoursIndex++;
+        contours.push(
+          new Contour({
+            flags: pointFlags,
+            xCoordinates,
+            yCoordinates,
+          })
+        );
+        yCoordinates = [];
+        pointFlags = [];
+      }
+    }
+
+    return new SimpleGlyph({
+      contours,
+      instructions,
+    });
+  }
+
+  getSize() {
+    let size = this.contours.length * 2 + 2 + this.instructions.length;
+    let lastX = 0;
+    let lastY = 0;
+    for (const contour of this.contours) {
+      size += contour.flags.length;
+      for (let i = 0, ii = contour.xCoordinates.length; i < ii; i++) {
+        const x = contour.xCoordinates[i];
+        const y = contour.yCoordinates[i];
+        let abs = Math.abs(x - lastX);
+        if (abs > 255) {
+          size += 2;
+        } else if (abs > 0) {
+          size += 1;
+        }
+        lastX = x;
+
+        abs = Math.abs(y - lastY);
+        if (abs > 255) {
+          size += 2;
+        } else if (abs > 0) {
+          size += 1;
+        }
+        lastY = y;
+      }
+    }
+    return size;
+  }
+
+  write(pos, buf) {
+    const spos = pos;
+    const xCoordinates = [];
+    const yCoordinates = [];
+    const flags = [];
+    let lastX = 0;
+    let lastY = 0;
+
+    for (const contour of this.contours) {
+      for (let i = 0, ii = contour.xCoordinates.length; i < ii; i++) {
+        let flag = contour.flags[i];
+        const x = contour.xCoordinates[i];
+        let delta = x - lastX;
+        if (delta === 0) {
+          flag = flag | X_IS_SAME_OR_POSITIVE_X_SHORT_VECTOR;
+          xCoordinates.push(0);
+        } else {
+          const abs = Math.abs(delta);
+          if (abs <= 255) {
+            flag =
+              flag |
+              (delta >= 0
+                ? X_SHORT_VECTOR | X_IS_SAME_OR_POSITIVE_X_SHORT_VECTOR
+                : X_SHORT_VECTOR);
+            xCoordinates.push(abs);
+          } else {
+            xCoordinates.push(delta);
+          }
+        }
+        lastX = x;
+
+        const y = contour.yCoordinates[i];
+        delta = y - lastY;
+        if (delta === 0) {
+          flag = flag | Y_IS_SAME_OR_POSITIVE_Y_SHORT_VECTOR;
+          yCoordinates.push(0);
+        } else {
+          const abs = Math.abs(delta);
+          if (abs <= 255) {
+            flag =
+              flag |
+              (delta >= 0
+                ? Y_SHORT_VECTOR | Y_IS_SAME_OR_POSITIVE_Y_SHORT_VECTOR
+                : Y_SHORT_VECTOR);
+            yCoordinates.push(abs);
+          } else {
+            yCoordinates.push(delta);
+          }
+        }
+        lastY = y;
+
+        flags.push(flag);
+      }
+
+      // Write endPtsOfContours entry.
+      buf.setUint16(pos, xCoordinates.length - 1);
+      pos += 2;
+    }
+
+    // Write instructionLength.
+    buf.setUint16(pos, this.instructions.length);
+    pos += 2;
+    if (this.instructions.length) {
+      // Write instructions.
+      new Uint8Array(buf.buffer, 0, buf.buffer.byteLength).set(
+        this.instructions,
+        pos
+      );
+      pos += this.instructions.length;
+    }
+
+    // Write flags.
+    for (const flag of flags) {
+      buf.setUint8(pos++, flag);
+    }
+
+    // Write xCoordinates.
+    for (let i = 0, ii = xCoordinates.length; i < ii; i++) {
+      const x = xCoordinates[i];
+      const flag = flags[i];
+      if (flag & X_SHORT_VECTOR) {
+        buf.setUint8(pos++, x);
+      } else if (!(flag & X_IS_SAME_OR_POSITIVE_X_SHORT_VECTOR)) {
+        buf.setInt16(pos, x);
+        pos += 2;
+      }
+    }
+
+    // Write yCoordinates.
+    for (let i = 0, ii = yCoordinates.length; i < ii; i++) {
+      const y = yCoordinates[i];
+      const flag = flags[i];
+      if (flag & Y_SHORT_VECTOR) {
+        buf.setUint8(pos++, y);
+      } else if (!(flag & Y_IS_SAME_OR_POSITIVE_Y_SHORT_VECTOR)) {
+        buf.setInt16(pos, y);
+        pos += 2;
+      }
+    }
+
+    return pos - spos;
+  }
+
+  scale(x, factor) {
+    for (const contour of this.contours) {
+      if (contour.xCoordinates.length === 0) {
+        continue;
+      }
+
+      for (let i = 0, ii = contour.xCoordinates.length; i < ii; i++) {
+        contour.xCoordinates[i] = Math.round(
+          x + (contour.xCoordinates[i] - x) * factor
+        );
+      }
+    }
+  }
+}
+
+class CompositeGlyph {
+  constructor({
+    flags,
+    glyphIndex,
+    argument1,
+    argument2,
+    transf,
+    instructions,
+  }) {
+    this.flags = flags;
+    this.glyphIndex = glyphIndex;
+    this.argument1 = argument1;
+    this.argument2 = argument2;
+    this.transf = transf;
+    this.instructions = instructions;
+  }
+
+  static parse(pos, glyf) {
+    const spos = pos;
+    const transf = [];
+    let flags = glyf.getUint16(pos);
+    const glyphIndex = glyf.getUint16(pos + 2);
+    pos += 4;
+
+    let argument1, argument2;
+    if (flags & ARG_1_AND_2_ARE_WORDS) {
+      if (flags & ARGS_ARE_XY_VALUES) {
+        argument1 = glyf.getInt16(pos);
+        argument2 = glyf.getInt16(pos + 2);
+      } else {
+        argument1 = glyf.getUint16(pos);
+        argument2 = glyf.getUint16(pos + 2);
+      }
+      pos += 4;
+      flags = flags ^ ARG_1_AND_2_ARE_WORDS;
+    } else {
+      argument1 = glyf.getUint8(pos);
+      argument2 = glyf.getUint8(pos + 1);
+      if (flags & ARGS_ARE_XY_VALUES) {
+        const abs1 = argument1 & 0x7f;
+        argument1 = argument1 & 0x80 ? -abs1 : abs1;
+
+        const abs2 = argument2 & 0x7f;
+        argument2 = argument2 & 0x80 ? -abs2 : abs2;
+      }
+      pos += 2;
+    }
+
+    if (flags & WE_HAVE_A_SCALE) {
+      // Single F2.14.
+      transf.push(glyf.getUint16(pos));
+      pos += 2;
+    } else if (flags & WE_HAVE_AN_X_AND_Y_SCALE) {
+      // Two F2.14.
+      transf.push(glyf.getUint16(pos), glyf.getUint16(pos + 2));
+      pos += 4;
+    } else if (flags & WE_HAVE_A_TWO_BY_TWO) {
+      // Four F2.14.
+      transf.push(
+        glyf.getUint16(pos),
+        glyf.getUint16(pos + 2),
+        glyf.getUint16(pos + 4),
+        glyf.getUint16(pos + 6)
+      );
+      pos += 8;
+    }
+
+    let instructions = null;
+    if (flags & WE_HAVE_INSTRUCTIONS) {
+      const instructionLength = glyf.getUint16(pos);
+      pos += 2;
+      instructions = new Uint8Array(glyf).slice(pos, pos + instructionLength);
+      pos += instructionLength;
+    }
+
+    return [
+      pos - spos,
+      new CompositeGlyph({
+        flags,
+        glyphIndex,
+        argument1,
+        argument2,
+        transf,
+        instructions,
+      }),
+    ];
+  }
+
+  getSize() {
+    let size = 2 + 2 + this.transf.length * 2;
+    if (this.flags & WE_HAVE_INSTRUCTIONS) {
+      size += 2 + this.instructions.length;
+    }
+
+    size += 2;
+    if (this.flags & 2) {
+      // Arguments are signed.
+      if (
+        !(
+          this.argument1 >= -128 &&
+          this.argument1 <= 127 &&
+          this.argument2 >= -128 &&
+          this.argument2 <= 127
+        )
+      ) {
+        size += 2;
+      }
+    } else {
+      if (
+        !(
+          this.argument1 >= 0 &&
+          this.argument1 <= 255 &&
+          this.argument2 >= 0 &&
+          this.argument2 <= 255
+        )
+      ) {
+        size += 2;
+      }
+    }
+
+    return size;
+  }
+
+  write(pos, buf) {
+    const spos = pos;
+
+    if (this.flags & ARGS_ARE_XY_VALUES) {
+      // Arguments are signed.
+      if (
+        !(
+          this.argument1 >= -128 &&
+          this.argument1 <= 127 &&
+          this.argument2 >= -128 &&
+          this.argument2 <= 127
+        )
+      ) {
+        this.flags = this.flags | ARG_1_AND_2_ARE_WORDS;
+      }
+    } else {
+      if (
+        !(
+          this.argument1 >= 0 &&
+          this.argument1 <= 255 &&
+          this.argument2 >= 0 &&
+          this.argument2 <= 255
+        )
+      ) {
+        this.flags = this.flags | ARG_1_AND_2_ARE_WORDS;
+      }
+    }
+
+    buf.setUint16(pos, this.flags);
+    buf.setUint16(pos + 2, this.glyphIndex);
+    pos += 4;
+
+    if (this.flags & ARG_1_AND_2_ARE_WORDS) {
+      if (this.flags & ARGS_ARE_XY_VALUES) {
+        buf.setInt16(pos, this.argument1);
+        buf.setInt16(pos + 2, this.argument2);
+      } else {
+        buf.setUint16(pos, this.argument1);
+        buf.setUint16(pos + 2, this.argument2);
+      }
+      pos += 4;
+    } else {
+      buf.setUint8(pos, this.argument1);
+      buf.setUint8(pos + 1, this.argument2);
+      pos += 2;
+    }
+
+    if (this.flags & WE_HAVE_INSTRUCTIONS) {
+      buf.setUint16(pos, this.instructions.length);
+      pos += 2;
+      // Write instructions.
+      if (this.instructions.length) {
+        new Uint8Array(buf.buffer, 0, buf.buffer.byteLength).set(
+          this.instructions,
+          pos
+        );
+        pos += this.instructions.length;
+      }
+    }
+
+    return pos - spos;
+  }
+
+  scale(x, factor) {}
+}
+
+export { GlyfTable };