@cantoo/pdf-lib
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Create and modify PDF files with JavaScript
93 lines • 2.61 kB
JavaScript
/*
* Copyright 2012 Mozilla Foundation
*
* The Stream class contained in this file is a TypeScript port of the
* JavaScript Stream class in Mozilla's pdf.js project, made available
* under the Apache 2.0 open source license.
*/
class Stream {
constructor(buffer, start, length) {
this.bytes = buffer;
this.start = start || 0;
this.pos = this.start;
this.end = !!start && !!length ? start + length : this.bytes.length;
}
get length() {
return this.end - this.start;
}
get isEmpty() {
return this.length === 0;
}
getByte() {
if (this.pos >= this.end) {
return -1;
}
return this.bytes[this.pos++];
}
getUint16() {
const b0 = this.getByte();
const b1 = this.getByte();
if (b0 === -1 || b1 === -1) {
return -1;
}
return (b0 << 8) + b1;
}
getInt32() {
const b0 = this.getByte();
const b1 = this.getByte();
const b2 = this.getByte();
const b3 = this.getByte();
return (b0 << 24) + (b1 << 16) + (b2 << 8) + b3;
}
// Returns subarray of original buffer, should only be read.
getBytes(length, forceClamped = false) {
const bytes = this.bytes;
const pos = this.pos;
const strEnd = this.end;
if (!length) {
const subarray = bytes.subarray(pos, strEnd);
// `this.bytes` is always a `Uint8Array` here.
return forceClamped ? new Uint8ClampedArray(subarray) : subarray;
}
else {
let end = pos + length;
if (end > strEnd) {
end = strEnd;
}
this.pos = end;
const subarray = bytes.subarray(pos, end);
// `this.bytes` is always a `Uint8Array` here.
return forceClamped ? new Uint8ClampedArray(subarray) : subarray;
}
}
peekByte() {
const peekedByte = this.getByte();
this.pos--;
return peekedByte;
}
peekBytes(length, forceClamped = false) {
const bytes = this.getBytes(length, forceClamped);
this.pos -= bytes.length;
return bytes;
}
skip(n) {
if (!n) {
n = 1;
}
this.pos += n;
}
reset() {
this.pos = this.start;
}
moveStart() {
this.start = this.pos;
}
makeSubStream(start, length) {
return new Stream(this.bytes, start, length);
}
decode() {
return this.bytes;
}
}
export default Stream;
//# sourceMappingURL=Stream.js.map