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Cache the TextDecoder/TextEncoder instances used when compiling/decompiling font-data #21806

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Merged
timvandermeij merged 1 commit into from
Aug 20, 2026
+31 −24
Merged

Cache the TextDecoder/TextEncoder instances used when compiling/decompiling font-data #21806

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7 changes: 4 additions & 3 deletions src/core/obj_bin_transform_core.js
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Original file line number Diff line number Diff line change
Expand Up @@ -17,12 +17,13 @@ import { assert, FeatureTest } from "../shared/util.js";
import {
CSS_FONT_INFO,
FONT_INFO,
InfoUtils,
PATTERN_INFO,
SYSTEM_FONT_INFO,
} from "../shared/obj_bin_transform_utils.js";

function compileCssFontInfo(info) {
const encoder = new TextEncoder();
const { encoder } = InfoUtils;
const encodedStrings = {};
let stringsLength = 0;
for (const prop of CSS_FONT_INFO.strings) {
Expand All @@ -48,7 +49,7 @@ function compileCssFontInfo(info) {
}

function compileSystemFontInfo(info) {
const encoder = new TextEncoder();
const { encoder } = InfoUtils;
const encodedStrings = {};
let stringsLength = 0;
for (const prop of SYSTEM_FONT_INFO.strings) {
Expand Down Expand Up @@ -106,7 +107,7 @@ function compileFontInfo(font) {
? compileCssFontInfo(font.cssFontInfo)
: null;

const encoder = new TextEncoder();
const { encoder } = InfoUtils;
const encodedStrings = {};
let stringsLength = 0;
for (const prop of FONT_INFO.strings) {
Expand Down
27 changes: 10 additions & 17 deletions src/display/obj_bin_transform_display.js
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Original file line number Diff line number Diff line change
Expand Up @@ -17,15 +17,14 @@ import { assert, BBOX_INIT, FeatureTest, Util } from "../shared/util.js";
import {
CSS_FONT_INFO,
FONT_INFO,
InfoUtils,
PATTERN_INFO,
SYSTEM_FONT_INFO,
} from "../shared/obj_bin_transform_utils.js";

class CssFontInfo {
#buffer;

#decoder = new TextDecoder();

#view;

constructor(buffer) {
Expand All @@ -35,14 +34,13 @@ class CssFontInfo {

#readString(index) {
assert(index < CSS_FONT_INFO.strings.length, "Invalid string index");
const { decoder } = InfoUtils;
let offset = 0;
for (let i = 0; i < index; i++) {
offset += this.#view.getUint32(offset) + 4;
}
const length = this.#view.getUint32(offset);
return this.#decoder.decode(
new Uint8Array(this.#buffer, offset + 4, length)
);
return decoder.decode(new Uint8Array(this.#buffer, offset + 4, length));
}

get fontFamily() {
Expand All @@ -61,8 +59,6 @@ class CssFontInfo {
class SystemFontInfo {
#buffer;

#decoder = new TextDecoder();

#view;

constructor(buffer) {
Expand All @@ -76,14 +72,13 @@ class SystemFontInfo {

#readString(index) {
assert(index < SYSTEM_FONT_INFO.strings.length, "Invalid string index");
const { decoder } = InfoUtils;
let offset = 5;
for (let i = 0; i < index; i++) {
offset += this.#view.getUint32(offset) + 4;
}
const length = this.#view.getUint32(offset);
return this.#decoder.decode(
new Uint8Array(this.#buffer, offset + 4, length)
);
return decoder.decode(new Uint8Array(this.#buffer, offset + 4, length));
}

get css() {
Expand All @@ -103,15 +98,16 @@ class SystemFontInfo {
}

get style() {
const { decoder } = InfoUtils;
let offset = 1;
offset += 4 + this.#view.getUint32(offset);
const styleLength = this.#view.getUint32(offset);
const style = this.#decoder.decode(
const style = decoder.decode(
new Uint8Array(this.#buffer, offset + 4, styleLength)
);
offset += 4 + styleLength;
const weightLength = this.#view.getUint32(offset);
const weight = this.#decoder.decode(
const weight = decoder.decode(
new Uint8Array(this.#buffer, offset + 4, weightLength)
);
return { style, weight };
Expand All @@ -121,8 +117,6 @@ class SystemFontInfo {
class FontInfo {
#buffer;

#decoder = new TextDecoder();

#view;

constructor({ buffer, extra }) {
Expand Down Expand Up @@ -242,14 +236,13 @@ class FontInfo {

#readString(index) {
assert(index < FONT_INFO.strings.length, "Invalid string index");
const { decoder } = InfoUtils;
let offset = FONT_INFO.OFFSET_STRINGS + 4;
for (let i = 0; i < index; i++) {
offset += this.#view.getUint32(offset) + 4;
}
const length = this.#view.getUint32(offset);
return this.#decoder.decode(
new Uint8Array(this.#buffer, offset + 4, length)
);
return decoder.decode(new Uint8Array(this.#buffer, offset + 4, length));
}

get fallbackName() {
Expand Down
14 changes: 13 additions & 1 deletion src/shared/obj_bin_transform_utils.js
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,8 @@
* limitations under the License.
*/

import { shadow } from "./util.js";

class CSS_FONT_INFO {
static strings = ["fontFamily", "fontWeight", "italicAngle"];
}
Expand Down Expand Up @@ -68,4 +70,14 @@ class PATTERN_INFO {
static N_FIGURES = 16; // number of figures
}

export { CSS_FONT_INFO, FONT_INFO, PATTERN_INFO, SYSTEM_FONT_INFO };
class InfoUtils {
static get decoder() {
return shadow(this, "decoder", new TextDecoder());
}

static get encoder() {
return shadow(this, "encoder", new TextEncoder());
}
}

export { CSS_FONT_INFO, FONT_INFO, InfoUtils, PATTERN_INFO, SYSTEM_FONT_INFO };
7 changes: 4 additions & 3 deletions test/unit/obj_bin_transform_spec.js
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ import {
SystemFontInfo,
} from "../../src/display/obj_bin_transform_display.js";
import { FeatureTest } from "../../src/shared/util.js";
import { InfoUtils } from "../../src/shared/obj_bin_transform_utils.js";

describe("obj_bin_transform", function () {
describe("Font data", function () {
Expand Down Expand Up @@ -80,7 +81,7 @@ describe("obj_bin_transform", function () {
describe("font data serialization and deserialization", function () {
describe("CssFontInfo", function () {
it("must roundtrip correctly for CssFontInfo", function () {
const encoder = new TextEncoder();
const { encoder } = InfoUtils;
let sizeEstimate = 0;
for (const string of ["Sample Family", "not a number", "angle"]) {
sizeEstimate += 4 + encoder.encode(string).length;
Expand All @@ -97,7 +98,7 @@ describe("obj_bin_transform", function () {

describe("SystemFontInfo", function () {
it("must roundtrip correctly for SystemFontInfo", function () {
const encoder = new TextEncoder();
const { encoder } = InfoUtils;
let sizeEstimate = 1 + 4;
for (const string of [
"some string",
Expand Down Expand Up @@ -127,7 +128,7 @@ describe("obj_bin_transform", function () {
describe("FontInfo", function () {
it("must roundtrip correctly for FontInfo", function () {
let sizeEstimate = 92; // fixed offset until the strings
const encoder = new TextEncoder();
const { encoder } = InfoUtils;
sizeEstimate += 4 + 4 * (4 + encoder.encode("string").length);
sizeEstimate += 4 + 4; // cssFontInfo and systemFontInfo
sizeEstimate += 4 + fontInfo.data.length;
Expand Down