pdf.js/src/core/binary_cmap.js
Jonas Jenwald bc7aa8a585 Re-factor some String.fromCharCode usage in the src/core/binary_cmap.js file
We can replace one case of `apply` with rest parameters, and avoid doing repeated `String.fromCharCode` calls within a loop.
2023-04-21 12:21:31 +02:00

327 lines
9.0 KiB
JavaScript

/* Copyright 2012 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.
*/
import { FormatError } from "../shared/util.js";
function hexToInt(a, size) {
let n = 0;
for (let i = 0; i <= size; i++) {
n = (n << 8) | a[i];
}
return n >>> 0;
}
function hexToStr(a, size) {
// This code is hot. Special-case some common values to avoid creating an
// object with subarray().
if (size === 1) {
return String.fromCharCode(a[0], a[1]);
}
if (size === 3) {
return String.fromCharCode(a[0], a[1], a[2], a[3]);
}
return String.fromCharCode(...a.subarray(0, size + 1));
}
function addHex(a, b, size) {
let c = 0;
for (let i = size; i >= 0; i--) {
c += a[i] + b[i];
a[i] = c & 255;
c >>= 8;
}
}
function incHex(a, size) {
let c = 1;
for (let i = size; i >= 0 && c > 0; i--) {
c += a[i];
a[i] = c & 255;
c >>= 8;
}
}
const MAX_NUM_SIZE = 16;
const MAX_ENCODED_NUM_SIZE = 19; // ceil(MAX_NUM_SIZE * 7 / 8)
class BinaryCMapStream {
constructor(data) {
this.buffer = data;
this.pos = 0;
this.end = data.length;
this.tmpBuf = new Uint8Array(MAX_ENCODED_NUM_SIZE);
}
readByte() {
if (this.pos >= this.end) {
return -1;
}
return this.buffer[this.pos++];
}
readNumber() {
let n = 0;
let last;
do {
const b = this.readByte();
if (b < 0) {
throw new FormatError("unexpected EOF in bcmap");
}
last = !(b & 0x80);
n = (n << 7) | (b & 0x7f);
} while (!last);
return n;
}
readSigned() {
const n = this.readNumber();
return n & 1 ? ~(n >>> 1) : n >>> 1;
}
readHex(num, size) {
num.set(this.buffer.subarray(this.pos, this.pos + size + 1));
this.pos += size + 1;
}
readHexNumber(num, size) {
let last;
const stack = this.tmpBuf;
let sp = 0;
do {
const b = this.readByte();
if (b < 0) {
throw new FormatError("unexpected EOF in bcmap");
}
last = !(b & 0x80);
stack[sp++] = b & 0x7f;
} while (!last);
let i = size,
buffer = 0,
bufferSize = 0;
while (i >= 0) {
while (bufferSize < 8 && stack.length > 0) {
buffer |= stack[--sp] << bufferSize;
bufferSize += 7;
}
num[i] = buffer & 255;
i--;
buffer >>= 8;
bufferSize -= 8;
}
}
readHexSigned(num, size) {
this.readHexNumber(num, size);
const sign = num[size] & 1 ? 255 : 0;
let c = 0;
for (let i = 0; i <= size; i++) {
c = ((c & 1) << 8) | num[i];
num[i] = (c >> 1) ^ sign;
}
}
readString() {
const len = this.readNumber(),
buf = new Array(len);
for (let i = 0; i < len; i++) {
buf[i] = this.readNumber();
}
return String.fromCharCode(...buf);
}
}
class BinaryCMapReader {
async process(data, cMap, extend) {
const stream = new BinaryCMapStream(data);
const header = stream.readByte();
cMap.vertical = !!(header & 1);
let useCMap = null;
const start = new Uint8Array(MAX_NUM_SIZE);
const end = new Uint8Array(MAX_NUM_SIZE);
const char = new Uint8Array(MAX_NUM_SIZE);
const charCode = new Uint8Array(MAX_NUM_SIZE);
const tmp = new Uint8Array(MAX_NUM_SIZE);
let code;
let b;
while ((b = stream.readByte()) >= 0) {
const type = b >> 5;
if (type === 7) {
// metadata, e.g. comment or usecmap
switch (b & 0x1f) {
case 0:
stream.readString(); // skipping comment
break;
case 1:
useCMap = stream.readString();
break;
}
continue;
}
const sequence = !!(b & 0x10);
const dataSize = b & 15;
if (dataSize + 1 > MAX_NUM_SIZE) {
throw new Error("BinaryCMapReader.process: Invalid dataSize.");
}
const ucs2DataSize = 1;
const subitemsCount = stream.readNumber();
switch (type) {
case 0: // codespacerange
stream.readHex(start, dataSize);
stream.readHexNumber(end, dataSize);
addHex(end, start, dataSize);
cMap.addCodespaceRange(
dataSize + 1,
hexToInt(start, dataSize),
hexToInt(end, dataSize)
);
for (let i = 1; i < subitemsCount; i++) {
incHex(end, dataSize);
stream.readHexNumber(start, dataSize);
addHex(start, end, dataSize);
stream.readHexNumber(end, dataSize);
addHex(end, start, dataSize);
cMap.addCodespaceRange(
dataSize + 1,
hexToInt(start, dataSize),
hexToInt(end, dataSize)
);
}
break;
case 1: // notdefrange
stream.readHex(start, dataSize);
stream.readHexNumber(end, dataSize);
addHex(end, start, dataSize);
stream.readNumber(); // code
// undefined range, skipping
for (let i = 1; i < subitemsCount; i++) {
incHex(end, dataSize);
stream.readHexNumber(start, dataSize);
addHex(start, end, dataSize);
stream.readHexNumber(end, dataSize);
addHex(end, start, dataSize);
stream.readNumber(); // code
// nop
}
break;
case 2: // cidchar
stream.readHex(char, dataSize);
code = stream.readNumber();
cMap.mapOne(hexToInt(char, dataSize), code);
for (let i = 1; i < subitemsCount; i++) {
incHex(char, dataSize);
if (!sequence) {
stream.readHexNumber(tmp, dataSize);
addHex(char, tmp, dataSize);
}
code = stream.readSigned() + (code + 1);
cMap.mapOne(hexToInt(char, dataSize), code);
}
break;
case 3: // cidrange
stream.readHex(start, dataSize);
stream.readHexNumber(end, dataSize);
addHex(end, start, dataSize);
code = stream.readNumber();
cMap.mapCidRange(
hexToInt(start, dataSize),
hexToInt(end, dataSize),
code
);
for (let i = 1; i < subitemsCount; i++) {
incHex(end, dataSize);
if (!sequence) {
stream.readHexNumber(start, dataSize);
addHex(start, end, dataSize);
} else {
start.set(end);
}
stream.readHexNumber(end, dataSize);
addHex(end, start, dataSize);
code = stream.readNumber();
cMap.mapCidRange(
hexToInt(start, dataSize),
hexToInt(end, dataSize),
code
);
}
break;
case 4: // bfchar
stream.readHex(char, ucs2DataSize);
stream.readHex(charCode, dataSize);
cMap.mapOne(
hexToInt(char, ucs2DataSize),
hexToStr(charCode, dataSize)
);
for (let i = 1; i < subitemsCount; i++) {
incHex(char, ucs2DataSize);
if (!sequence) {
stream.readHexNumber(tmp, ucs2DataSize);
addHex(char, tmp, ucs2DataSize);
}
incHex(charCode, dataSize);
stream.readHexSigned(tmp, dataSize);
addHex(charCode, tmp, dataSize);
cMap.mapOne(
hexToInt(char, ucs2DataSize),
hexToStr(charCode, dataSize)
);
}
break;
case 5: // bfrange
stream.readHex(start, ucs2DataSize);
stream.readHexNumber(end, ucs2DataSize);
addHex(end, start, ucs2DataSize);
stream.readHex(charCode, dataSize);
cMap.mapBfRange(
hexToInt(start, ucs2DataSize),
hexToInt(end, ucs2DataSize),
hexToStr(charCode, dataSize)
);
for (let i = 1; i < subitemsCount; i++) {
incHex(end, ucs2DataSize);
if (!sequence) {
stream.readHexNumber(start, ucs2DataSize);
addHex(start, end, ucs2DataSize);
} else {
start.set(end);
}
stream.readHexNumber(end, ucs2DataSize);
addHex(end, start, ucs2DataSize);
stream.readHex(charCode, dataSize);
cMap.mapBfRange(
hexToInt(start, ucs2DataSize),
hexToInt(end, ucs2DataSize),
hexToStr(charCode, dataSize)
);
}
break;
default:
throw new Error(`BinaryCMapReader.process - unknown type: ${type}`);
}
}
if (useCMap) {
return extend(useCMap);
}
return cMap;
}
}
export { BinaryCMapReader };