Test files for APNG can be found at the following locations:
This page hosts a formal specification of PNG (Portable Network Graphics) file using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All JavaScript code generated by Kaitai Struct depends on the Kaitai Struct runtime library for JavaScript. You must add this dependency to your project before you can parse or serialize any data.
The JavaScript runtime library is available at npm:
npm install kaitai-structSee the usage examples in the JavaScript notes.
Parse structure from an ArrayBuffer:
var arrayBuffer = ...;
var data = new Png(new KaitaiStream(arrayBuffer));
After that, one can get various attributes from the structure by accessing fields or properties like:
data.magic // => get magic
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
(function (root, factory) {
if (typeof define === 'function' && define.amd) {
define(['exports', 'kaitai-struct/KaitaiStream'], factory);
} else if (typeof exports === 'object' && exports !== null && typeof exports.nodeType !== 'number') {
factory(exports, require('kaitai-struct/KaitaiStream'));
} else {
factory(root.Png || (root.Png = {}), root.KaitaiStream);
}
})(typeof self !== 'undefined' ? self : this, function (Png_, KaitaiStream) {
/**
* Test files for APNG can be found at the following locations:
*
* * <https://philip.html5.org/tests/apng/tests.html>
* * <http://littlesvr.ca/apng/>
*/
var Png = (function() {
Png.BlendOpValues = Object.freeze({
SOURCE: 0,
OVER: 1,
0: "SOURCE",
1: "OVER",
});
Png.ColorType = Object.freeze({
GREYSCALE: 0,
TRUECOLOR: 2,
INDEXED: 3,
GREYSCALE_ALPHA: 4,
TRUECOLOR_ALPHA: 6,
0: "GREYSCALE",
2: "TRUECOLOR",
3: "INDEXED",
4: "GREYSCALE_ALPHA",
6: "TRUECOLOR_ALPHA",
});
Png.CompressionMethods = Object.freeze({
ZLIB: 0,
0: "ZLIB",
});
Png.DisposeOpValues = Object.freeze({
NONE: 0,
BACKGROUND: 1,
PREVIOUS: 2,
0: "NONE",
1: "BACKGROUND",
2: "PREVIOUS",
});
Png.FilterMethod = Object.freeze({
BASE: 0,
0: "BASE",
});
Png.InterlaceMethod = Object.freeze({
NONE: 0,
ADAM7: 1,
0: "NONE",
1: "ADAM7",
});
Png.PhysUnit = Object.freeze({
UNKNOWN: 0,
METER: 1,
0: "UNKNOWN",
1: "METER",
});
function Png(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root || this;
this._read();
}
Png.prototype._read = function() {
this.magic = this._io.readBytes(8);
if (!((KaitaiStream.byteArrayCompare(this.magic, new Uint8Array([137, 80, 78, 71, 13, 10, 26, 10])) == 0))) {
throw new KaitaiStream.ValidationNotEqualError(new Uint8Array([137, 80, 78, 71, 13, 10, 26, 10]), this.magic, this._io, "/seq/0");
}
this.ihdrLen = this._io.readU4be();
if (!(this.ihdrLen == 13)) {
throw new KaitaiStream.ValidationNotEqualError(13, this.ihdrLen, this._io, "/seq/1");
}
this.ihdrType = this._io.readBytes(4);
if (!((KaitaiStream.byteArrayCompare(this.ihdrType, new Uint8Array([73, 72, 68, 82])) == 0))) {
throw new KaitaiStream.ValidationNotEqualError(new Uint8Array([73, 72, 68, 82]), this.ihdrType, this._io, "/seq/2");
}
this.ihdr = new IhdrChunk(this._io, this, this._root);
this.ihdrCrc = this._io.readU4be();
this.chunks = [];
var i = 0;
do {
var _ = new Chunk(this._io, this, this._root);
this.chunks.push(_);
i++;
} while (!( ((_.type == "IEND") || (this._io.isEof())) ));
}
/**
* @see {@link https://stackoverflow.com/questions/4242402/the-fireworks-png-format-any-insight-any-libs/51683285#51683285|Source}
*/
var AdobeFireworksChunk = Png.AdobeFireworksChunk = (function() {
function AdobeFireworksChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
AdobeFireworksChunk.prototype._read = function() {
this._raw_previewData = this._io.readBytesFull();
this.previewData = KaitaiStream.processZlib(this._raw_previewData);
}
return AdobeFireworksChunk;
})();
/**
* @see {@link https://www.w3.org/TR/png/#acTL-chunk|Source}
*/
var AnimationControlChunk = Png.AnimationControlChunk = (function() {
function AnimationControlChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
AnimationControlChunk.prototype._read = function() {
this.numFrames = this._io.readU4be();
this.numPlays = this._io.readU4be();
}
/**
* Number of frames, must be equal to the number of `fcTL` chunks (i.e.
* `frame_control_chunk` objects)
*/
/**
* Number of times to loop, 0 indicates infinite looping.
*/
return AnimationControlChunk;
})();
/**
* @see {@link https://github.com/skeeto/scratch/tree/58470254f4a95cdf7a53888e405c851c21eb2cae/pngattach|Source}
* @see {@link https://nullprogram.com/blog/2021/12/31/|A new protocol and tool for PNG file attachments}
*/
var AtchChunk = Png.AtchChunk = (function() {
AtchChunk.CompressionAttachMethods = Object.freeze({
NONE: 0,
ZLIB: 1,
0: "NONE",
1: "ZLIB",
});
function AtchChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
AtchChunk.prototype._read = function() {
this.fileName = KaitaiStream.bytesToStr(this._io.readBytesTerm(0, false, true, true), "UTF-8");
var _ = this.fileName;
if (!( ((_.length != 0) && (_.substring(0, 1) != ".")) )) {
throw new KaitaiStream.ValidationExprError(this.fileName, this._io, "/types/atch_chunk/seq/0");
}
this.compression = this._io.readU1();
if (!Object.prototype.hasOwnProperty.call(Png.AtchChunk.CompressionAttachMethods, this.compression)) {
throw new KaitaiStream.ValidationNotInEnumError(this.compression, this._io, "/types/atch_chunk/seq/1");
}
if (this.compression == Png.AtchChunk.CompressionAttachMethods.NONE) {
this.dataPlain = this._io.readBytesFull();
}
if (this.compression == Png.AtchChunk.CompressionAttachMethods.ZLIB) {
this._raw_dataZlib = this._io.readBytesFull();
this.dataZlib = KaitaiStream.processZlib(this._raw_dataZlib);
}
}
Object.defineProperty(AtchChunk.prototype, 'data', {
get: function() {
if (this._m_data !== undefined)
return this._m_data;
this._m_data = (this.compression == Png.AtchChunk.CompressionAttachMethods.NONE ? this.dataPlain : this.dataZlib);
return this._m_data;
}
});
/**
* From the [official
* specification](https://github.com/skeeto/scratch/tree/58470254f4a95cdf7a53888e405c851c21eb2cae/pngattach#atch-chunk-specification):
*
* > The name can be any length that fits in the chunk, and should be
* > encoded with UTF-8. It's up to each implementation to determine how
* > to appropriately interpret the bytestring for the local system.
*
* > The name must be at least one byte long, not counting the null
* > terminator. It cannot begin with a period (`0x2e`), nor contain
* > control bytes (anything less than `0x20`), nor slash (`0x2f`), nor
* > backslash (`0x5c`), i.e. no directory hierarchies.
*
* As of Kaitai Struct 0.11, we cannot easily check whether a string
* contains certain characters, so we only enforce that the file name is
* not empty and that it doesn't start with a period.
*/
return AtchChunk;
})();
/**
* Background chunk stores default background color to display this
* image against. Contents depend on `color_type` of the image.
* @see {@link https://www.w3.org/TR/png/#11bKGD|Source}
*/
var BkgdChunk = Png.BkgdChunk = (function() {
function BkgdChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
BkgdChunk.prototype._read = function() {
switch (this._root.ihdr.colorType) {
case Png.ColorType.GREYSCALE:
this.bkgd = new BkgdGreyscale(this._io, this, this._root);
break;
case Png.ColorType.GREYSCALE_ALPHA:
this.bkgd = new BkgdGreyscale(this._io, this, this._root);
break;
case Png.ColorType.INDEXED:
this.bkgd = new BkgdIndexed(this._io, this, this._root);
break;
case Png.ColorType.TRUECOLOR:
this.bkgd = new BkgdTruecolor(this._io, this, this._root);
break;
case Png.ColorType.TRUECOLOR_ALPHA:
this.bkgd = new BkgdTruecolor(this._io, this, this._root);
break;
}
}
return BkgdChunk;
})();
/**
* Background chunk for greyscale images.
*/
var BkgdGreyscale = Png.BkgdGreyscale = (function() {
function BkgdGreyscale(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
BkgdGreyscale.prototype._read = function() {
this.value = this._io.readU2be();
}
return BkgdGreyscale;
})();
/**
* Background chunk for images with indexed palette.
*/
var BkgdIndexed = Png.BkgdIndexed = (function() {
function BkgdIndexed(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
BkgdIndexed.prototype._read = function() {
this.paletteIndex = this._io.readU1();
}
return BkgdIndexed;
})();
/**
* Background chunk for truecolor images.
*/
var BkgdTruecolor = Png.BkgdTruecolor = (function() {
function BkgdTruecolor(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
BkgdTruecolor.prototype._read = function() {
this.red = this._io.readU2be();
this.green = this._io.readU2be();
this.blue = this._io.readU2be();
}
return BkgdTruecolor;
})();
var ChrmChromaticity = Png.ChrmChromaticity = (function() {
function ChrmChromaticity(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
ChrmChromaticity.prototype._read = function() {
this.xInt = this._io.readU4be();
this.yInt = this._io.readU4be();
}
Object.defineProperty(ChrmChromaticity.prototype, 'x', {
get: function() {
if (this._m_x !== undefined)
return this._m_x;
this._m_x = this.xInt / 100000.0;
return this._m_x;
}
});
Object.defineProperty(ChrmChromaticity.prototype, 'y', {
get: function() {
if (this._m_y !== undefined)
return this._m_y;
this._m_y = this.yInt / 100000.0;
return this._m_y;
}
});
return ChrmChromaticity;
})();
/**
* @see {@link https://www.w3.org/TR/png/#11cHRM|Source}
*/
var ChrmChunk = Png.ChrmChunk = (function() {
function ChrmChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
ChrmChunk.prototype._read = function() {
this.whitePoint = new ChrmChromaticity(this._io, this, this._root);
this.red = new ChrmChromaticity(this._io, this, this._root);
this.green = new ChrmChromaticity(this._io, this, this._root);
this.blue = new ChrmChromaticity(this._io, this, this._root);
}
return ChrmChunk;
})();
var Chunk = Png.Chunk = (function() {
function Chunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
Chunk.prototype._read = function() {
this.len = this._io.readU4be();
this.typeRaw = this._io.readBytes(4);
var _ = this.typeRaw;
if (!( (( (( ((_[0] >= 65) && (_[0] <= 90)) ) || ( ((_[0] >= 97) && (_[0] <= 122)) )) ) && ( (( ((_[1] >= 65) && (_[1] <= 90)) ) || ( ((_[1] >= 97) && (_[1] <= 122)) )) ) && ( (( ((_[2] >= 65) && (_[2] <= 90)) ) || ( ((_[2] >= 97) && (_[2] <= 122)) )) ) && ( (( ((_[3] >= 65) && (_[3] <= 90)) ) || ( ((_[3] >= 97) && (_[3] <= 122)) )) )) )) {
throw new KaitaiStream.ValidationExprError(this.typeRaw, this._io, "/types/chunk/seq/1");
}
switch (this.type) {
case "PLTE":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new PlteChunk(_io__raw_body, this, this._root);
break;
case "acTL":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new AnimationControlChunk(_io__raw_body, this, this._root);
break;
case "atCh":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new AtchChunk(_io__raw_body, this, this._root);
break;
case "bKGD":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new BkgdChunk(_io__raw_body, this, this._root);
break;
case "cHRM":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new ChrmChunk(_io__raw_body, this, this._root);
break;
case "cICP":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new CicpChunk(_io__raw_body, this, this._root);
break;
case "cLLI":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new ClliChunk(_io__raw_body, this, this._root);
break;
case "fcTL":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new FrameControlChunk(_io__raw_body, this, this._root);
break;
case "fdAT":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new FrameDataChunk(_io__raw_body, this, this._root);
break;
case "gAMA":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new GamaChunk(_io__raw_body, this, this._root);
break;
case "iTXt":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new InternationalTextChunk(_io__raw_body, this, this._root);
break;
case "mDCV":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new MdcvChunk(_io__raw_body, this, this._root);
break;
case "mkBS":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new AdobeFireworksChunk(_io__raw_body, this, this._root);
break;
case "mkTS":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new AdobeFireworksChunk(_io__raw_body, this, this._root);
break;
case "pHYs":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new PhysChunk(_io__raw_body, this, this._root);
break;
case "prVW":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new AdobeFireworksChunk(_io__raw_body, this, this._root);
break;
case "sRGB":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new SrgbChunk(_io__raw_body, this, this._root);
break;
case "skMf":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new EvernoteSkmfChunk(_io__raw_body, this, this._root);
break;
case "skRf":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new EvernoteSkrfChunk(_io__raw_body, this, this._root);
break;
case "tEXt":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new TextChunk(_io__raw_body, this, this._root);
break;
case "tIME":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new TimeChunk(_io__raw_body, this, this._root);
break;
case "zTXt":
this._raw_body = this._io.readBytes(this.len);
var _io__raw_body = new KaitaiStream(this._raw_body);
this.body = new CompressedTextChunk(_io__raw_body, this, this._root);
break;
default:
this.body = this._io.readBytes(this.len);
break;
}
this.crc = this._io.readU4be();
}
/**
* false = critical chunk, true = ancillary chunk
*/
Object.defineProperty(Chunk.prototype, 'isAncillary', {
get: function() {
if (this._m_isAncillary !== undefined)
return this._m_isAncillary;
this._m_isAncillary = (this.typeRaw[0] & 32) != 0;
return this._m_isAncillary;
}
});
/**
* false = public chunk (defined by the W3C), true = private chunk (can
* be defined by anyone)
*/
Object.defineProperty(Chunk.prototype, 'isPrivate', {
get: function() {
if (this._m_isPrivate !== undefined)
return this._m_isPrivate;
this._m_isPrivate = (this.typeRaw[1] & 32) != 0;
return this._m_isPrivate;
}
});
/**
* Defines whether the chunk may be copied if the image data (i.e.
* pixels) is modified. This tells PNG editors how to handle unknown
* chunks - see section [14.2 Behavior of PNG
* editors](https://www.w3.org/TR/2025/REC-png-3-20250624/#14Ordering) in
* the official specification.
*/
Object.defineProperty(Chunk.prototype, 'isSafeToCopy', {
get: function() {
if (this._m_isSafeToCopy !== undefined)
return this._m_isSafeToCopy;
this._m_isSafeToCopy = (this.typeRaw[3] & 32) != 0;
return this._m_isSafeToCopy;
}
});
/**
* Should be `false`, i.e. all chunk types should have uppercase third
* letters (the lowercase third letter is reserved for possible future
* extensions to the PNG standard)
*/
Object.defineProperty(Chunk.prototype, 'reservedBit', {
get: function() {
if (this._m_reservedBit !== undefined)
return this._m_reservedBit;
this._m_reservedBit = (this.typeRaw[2] & 32) != 0;
return this._m_reservedBit;
}
});
Object.defineProperty(Chunk.prototype, 'type', {
get: function() {
if (this._m_type !== undefined)
return this._m_type;
this._m_type = KaitaiStream.bytesToStr(this.typeRaw, "ASCII");
return this._m_type;
}
});
/**
* Each byte of a chunk type is restricted to the hexadecimal values
* 0x41..0x5a and 0x61..0x7a, i.e. uppercase and lowercase ASCII letters
* (`A-Z` and `a-z`).
* @see {@link https://www.w3.org/TR/2025/REC-png-3-20250624/#table51|Source}
*/
return Chunk;
})();
/**
* @see {@link https://www.w3.org/TR/png/#cICP-chunk|Source}
* @see {@link https://w3c.github.io/png/Implementation_Report_3e/#cicp|Source}
*/
var CicpChunk = Png.CicpChunk = (function() {
function CicpChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
CicpChunk.prototype._read = function() {
this.colorPrimaries = this._io.readU1();
this.transferFunction = this._io.readU1();
this.matrixCoefficients = this._io.readU1();
if (!(this.matrixCoefficients == 0)) {
throw new KaitaiStream.ValidationNotEqualError(0, this.matrixCoefficients, this._io, "/types/cicp_chunk/seq/2");
}
this.videoFullRangeFlag = this._io.readU1();
if (!( ((this.videoFullRangeFlag == 0) || (this.videoFullRangeFlag == 1)) )) {
throw new KaitaiStream.ValidationNotAnyOfError(this.videoFullRangeFlag, this._io, "/types/cicp_chunk/seq/3");
}
}
/**
* values above 22 are reserved, see
* <https://github.com/pnggroup/pngcheck/blob/bd33ad6490269df07cac81e5305f4ebf56c2b637/pngcheck.c#L3322-L3325>
*/
/**
* values above 18 are reserved, see
* <https://github.com/pnggroup/pngcheck/blob/bd33ad6490269df07cac81e5305f4ebf56c2b637/pngcheck.c#L3326-L3329>
*/
/**
* From the [official
* specification](https://www.w3.org/TR/2025/REC-png-3-20250624/#cICP-chunk):
*
* > RGB is currently the only supported color model in PNG, and as such
* > `Matrix Coefficients` shall be set to `0`.
*/
/**
* From the [official
* specification](https://www.w3.org/TR/2025/REC-png-3-20250624/#cICP-chunk):
*
* > If `Video Full Range Flag` value is `1`, then the image is a
* > full-range image. Typically, images in the RGB color representation
* > are stored in the full-range signal quantization, therefore the vast
* > majority of computer graphics and web images, including those used
* > in traditional PNG workflows, are full-range images.
*
* > If `Video Full Range Flag` value is `0`, then the image is a
* > narrow-range image.
*/
return CicpChunk;
})();
/**
* @see {@link https://www.w3.org/TR/png/#cLLI-chunk|Source}
* @see {@link https://w3c.github.io/png/Implementation_Report_3e/#light|Source}
*/
var ClliChunk = Png.ClliChunk = (function() {
function ClliChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
ClliChunk.prototype._read = function() {
this.maxContentLightLevelInt = this._io.readU4be();
this.maxFrameAverageLightLevelInt = this._io.readU4be();
}
/**
* Maximum Content Light Level (MaxCLL), in cd/m^2
*/
Object.defineProperty(ClliChunk.prototype, 'maxContentLightLevel', {
get: function() {
if (this._m_maxContentLightLevel !== undefined)
return this._m_maxContentLightLevel;
this._m_maxContentLightLevel = this.maxContentLightLevelInt * 0.0001;
return this._m_maxContentLightLevel;
}
});
/**
* Maximum Frame Average Light Level (MaxFALL), in cd/m^2
*/
Object.defineProperty(ClliChunk.prototype, 'maxFrameAverageLightLevel', {
get: function() {
if (this._m_maxFrameAverageLightLevel !== undefined)
return this._m_maxFrameAverageLightLevel;
this._m_maxFrameAverageLightLevel = this.maxFrameAverageLightLevelInt * 0.0001;
return this._m_maxFrameAverageLightLevel;
}
});
return ClliChunk;
})();
var CompressedText = Png.CompressedText = (function() {
function CompressedText(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
CompressedText.prototype._read = function() {
this.value = KaitaiStream.bytesToStr(this._io.readBytesFull(), "ISO-8859-1");
}
/**
* Text string (the "value" of this key-value pair).
*
* Although it is not null-terminated (unlike the keyword), it must not
* contain a zero byte (U+0000 NULL character). A newline should be
* represented by a single U+000A LINE FEED (LF) character (aka `\n`).
* The remaining control characters (U+0001..U+0009, U+000B..0+001F,
* U+007F..U+009F) are discouraged.
*/
return CompressedText;
})();
/**
* Compressed textual data (`zTXt`) chunk effectively allows you to store
* key-value string pairs in the PNG container, compressing the "value" part
* (which can be quite lengthy) with zlib compression.
*
* The `zTXt` and `tEXt` chunks are semantically equivalent, but the `zTXt`
* chunk is recommended for storing large blocks of text.
* @see {@link https://www.w3.org/TR/png/#11zTXt|Source}
*/
var CompressedTextChunk = Png.CompressedTextChunk = (function() {
function CompressedTextChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
CompressedTextChunk.prototype._read = function() {
this.keyword = KaitaiStream.bytesToStr(this._io.readBytesTerm(0, false, true, true), "ISO-8859-1");
this.compressionMethod = this._io.readU1();
if (!(this.compressionMethod == Png.CompressionMethods.ZLIB)) {
throw new KaitaiStream.ValidationNotEqualError(Png.CompressionMethods.ZLIB, this.compressionMethod, this._io, "/types/compressed_text_chunk/seq/1");
}
this._raw__raw_text = this._io.readBytesFull();
this._raw_text = KaitaiStream.processZlib(this._raw__raw_text);
var _io__raw_text = new KaitaiStream(this._raw_text);
this.text = new CompressedText(_io__raw_text, this, this._root);
}
/**
* Indicates the type of information represented by the text string.
*
* Keywords must consist exclusively of printable ISO-8859-1 (Latin-1)
* characters and spaces; that is, only code points 0x20-0x7E and
* 0xA1-0xFF are allowed. To reduce the chances for human misreading of a
* keyword, leading spaces, trailing spaces, and consecutive spaces are
* not permitted.
* @see {@link https://www.w3.org/TR/2025/REC-png-3-20250624/#11keywords|Source}
*/
return CompressedTextChunk;
})();
/**
* @see {@link https://web.archive.org/web/20210302212148/https://discussion.evernote.com/forums/topic/88532-how-to-extract-annotation-information-from-annotated-evernoteskitch-images/#comment-451501|Source}
*/
var EvernoteSkmfChunk = Png.EvernoteSkmfChunk = (function() {
function EvernoteSkmfChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
EvernoteSkmfChunk.prototype._read = function() {
this.json = KaitaiStream.bytesToStr(this._io.readBytesFull(), "UTF-8");
}
/**
* JSON document with information about editable annotations (text,
* lines, paths, etc.) in Evernote/Skitch.
*
* It refers to the original image stored in the `skRf` chunk (which
* usually follows immediately after `skMf`) via the
* `.children[0].children[0].uri` JSON property. This has the format
* `"skitch+uuid:///$UUID"`, where `$UUID` is a random UUIDv4 value that
* matches the `uuid` field in `evernote_skrf_chunk` (i.e. in the first
* 16 bytes of the `skRf` chunk).
*/
return EvernoteSkmfChunk;
})();
/**
* @see {@link https://web.archive.org/web/20210302212148/https://discussion.evernote.com/forums/topic/88532-how-to-extract-annotation-information-from-annotated-evernoteskitch-images/#comment-451501|Source}
*/
var EvernoteSkrfChunk = Png.EvernoteSkrfChunk = (function() {
function EvernoteSkrfChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
EvernoteSkrfChunk.prototype._read = function() {
this.uuid = this._io.readBytes(16);
this.origImg = this._io.readBytesFull();
}
/**
* Random UUIDv4 value used to identify the image. It is referenced by
* the `skMf` chunk - see the documentation for the `json` field in
* `evernote_skmf_chunk`.
*/
/**
* The original source image without annotations. It's usually a PNG
* image as well, but it can also be a JPEG or possibly other formats.
*/
return EvernoteSkrfChunk;
})();
/**
* @see {@link https://www.w3.org/TR/png/#fcTL-chunk|Source}
*/
var FrameControlChunk = Png.FrameControlChunk = (function() {
function FrameControlChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
FrameControlChunk.prototype._read = function() {
this.sequenceNumber = this._io.readU4be();
this.width = this._io.readU4be();
if (!(this.width >= 1)) {
throw new KaitaiStream.ValidationLessThanError(1, this.width, this._io, "/types/frame_control_chunk/seq/1");
}
if (!(this.width <= this._root.ihdr.width)) {
throw new KaitaiStream.ValidationGreaterThanError(this._root.ihdr.width, this.width, this._io, "/types/frame_control_chunk/seq/1");
}
this.height = this._io.readU4be();
if (!(this.height >= 1)) {
throw new KaitaiStream.ValidationLessThanError(1, this.height, this._io, "/types/frame_control_chunk/seq/2");
}
if (!(this.height <= this._root.ihdr.height)) {
throw new KaitaiStream.ValidationGreaterThanError(this._root.ihdr.height, this.height, this._io, "/types/frame_control_chunk/seq/2");
}
this.xOffset = this._io.readU4be();
if (!(this.xOffset <= this._root.ihdr.width - this.width)) {
throw new KaitaiStream.ValidationGreaterThanError(this._root.ihdr.width - this.width, this.xOffset, this._io, "/types/frame_control_chunk/seq/3");
}
this.yOffset = this._io.readU4be();
if (!(this.yOffset <= this._root.ihdr.height - this.height)) {
throw new KaitaiStream.ValidationGreaterThanError(this._root.ihdr.height - this.height, this.yOffset, this._io, "/types/frame_control_chunk/seq/4");
}
this.delayNum = this._io.readU2be();
this.delayDen = this._io.readU2be();
this.disposeOp = this._io.readU1();
if (!Object.prototype.hasOwnProperty.call(Png.DisposeOpValues, this.disposeOp)) {
throw new KaitaiStream.ValidationNotInEnumError(this.disposeOp, this._io, "/types/frame_control_chunk/seq/7");
}
this.blendOp = this._io.readU1();
if (!Object.prototype.hasOwnProperty.call(Png.BlendOpValues, this.blendOp)) {
throw new KaitaiStream.ValidationNotInEnumError(this.blendOp, this._io, "/types/frame_control_chunk/seq/8");
}
}
/**
* Time to display this frame, in seconds
*/
Object.defineProperty(FrameControlChunk.prototype, 'delay', {
get: function() {
if (this._m_delay !== undefined)
return this._m_delay;
this._m_delay = this.delayNum / (this.delayDen == 0 ? 100.0 : this.delayDen);
return this._m_delay;
}
});
/**
* Sequence number of the animation chunk, starting from 0.
*
* The `fcTL` and `fdAT` chunks have a 4-byte sequence number. Both chunk
* types share the sequence. The purpose of this number is to detect (and
* optionally correct) sequence errors in an Animated PNG, since the PNG
* specification does not impose ordering restrictions on ancillary
* chunks (which means that a PNG editor is technically allowed to
* reorder them arbitrarily, see [14.2 Behavior of PNG
* editors](https://www.w3.org/TR/png/#14Ordering) in the spec).
*
* The first `fcTL` chunk must contain sequence number 0, and the
* sequence numbers in the remaining `fcTL` and `fdAT` chunks must be in
* ascending order, with no gaps or duplicates.
*/
/**
* Width of the following frame
*/
/**
* Height of the following frame
*/
/**
* X position at which to render the following frame
*/
/**
* Y position at which to render the following frame
*/
/**
* Frame delay fraction numerator
*/
/**
* Frame delay fraction denominator
*/
/**
* Type of frame area disposal to be done after rendering this frame
*/
/**
* Type of frame area rendering for this frame
*/
return FrameControlChunk;
})();
/**
* @see {@link https://www.w3.org/TR/png/#fdAT-chunk|Source}
*/
var FrameDataChunk = Png.FrameDataChunk = (function() {
function FrameDataChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
FrameDataChunk.prototype._read = function() {
this.sequenceNumber = this._io.readU4be();
this.frameData = this._io.readBytesFull();
}
/**
* Sequence number of the animation chunk, starting from 0.
*
* The `fcTL` and `fdAT` chunks have a 4-byte sequence number. Both chunk
* types share the sequence. The purpose of this number is to detect (and
* optionally correct) sequence errors in an Animated PNG, since the PNG
* specification does not impose ordering restrictions on ancillary
* chunks (which means that a PNG editor is technically allowed to
* reorder them arbitrarily, see [14.2 Behavior of PNG
* editors](https://www.w3.org/TR/png/#14Ordering) in the spec).
*
* The first `fcTL` chunk must contain sequence number 0, and the
* sequence numbers in the remaining `fcTL` and `fdAT` chunks must be in
* ascending order, with no gaps or duplicates.
*/
/**
* Frame data for the frame. At least one `fdAT` chunk is required for
* each frame, except for the first frame, if that frame is represented
* by an `IDAT` chunk. The compressed datastream for each frame is the
* concatenation of the contents of the data fields of all the `fdAT`
* chunks within a frame.
*/
return FrameDataChunk;
})();
/**
* @see {@link https://www.w3.org/TR/png/#11gAMA|Source}
*/
var GamaChunk = Png.GamaChunk = (function() {
function GamaChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
GamaChunk.prototype._read = function() {
this.gammaInt = this._io.readU4be();
var _ = this.gammaInt;
if (!(_ != 0)) {
throw new KaitaiStream.ValidationExprError(this.gammaInt, this._io, "/types/gama_chunk/seq/0");
}
}
/**
* Image gamma, typically 0.45455 = 1/2.2
*/
Object.defineProperty(GamaChunk.prototype, 'gamma', {
get: function() {
if (this._m_gamma !== undefined)
return this._m_gamma;
this._m_gamma = this.gammaInt / 100000.0;
return this._m_gamma;
}
});
/**
* Inverse of the image gamma (1 / gamma), typically 2.2 (not considering
* rounding)
*/
Object.defineProperty(GamaChunk.prototype, 'invGamma', {
get: function() {
if (this._m_invGamma !== undefined)
return this._m_invGamma;
this._m_invGamma = 100000.0 / this.gammaInt;
return this._m_invGamma;
}
});
/**
* Image gamma multiplied by 100000 (a gamma value of 1/2.2 is stored as
* 45455)
*/
return GamaChunk;
})();
/**
* @see {@link https://www.w3.org/TR/png/#11IHDR|Source}
*/
var IhdrChunk = Png.IhdrChunk = (function() {
function IhdrChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
IhdrChunk.prototype._read = function() {
this.width = this._io.readU4be();
if (!(this.width >= 1)) {
throw new KaitaiStream.ValidationLessThanError(1, this.width, this._io, "/types/ihdr_chunk/seq/0");
}
this.height = this._io.readU4be();
if (!(this.height >= 1)) {
throw new KaitaiStream.ValidationLessThanError(1, this.height, this._io, "/types/ihdr_chunk/seq/1");
}
this.bitDepth = this._io.readU1();
if (!( ((this.bitDepth == 1) || (this.bitDepth == 2) || (this.bitDepth == 4) || (this.bitDepth == 8) || (this.bitDepth == 16)) )) {
throw new KaitaiStream.ValidationNotAnyOfError(this.bitDepth, this._io, "/types/ihdr_chunk/seq/2");
}
this.colorType = this._io.readU1();
if (!Object.prototype.hasOwnProperty.call(Png.ColorType, this.colorType)) {
throw new KaitaiStream.ValidationNotInEnumError(this.colorType, this._io, "/types/ihdr_chunk/seq/3");
}
this.compressionMethod = this._io.readU1();
if (!Object.prototype.hasOwnProperty.call(Png.CompressionMethods, this.compressionMethod)) {
throw new KaitaiStream.ValidationNotInEnumError(this.compressionMethod, this._io, "/types/ihdr_chunk/seq/4");
}
this.filterMethod = this._io.readU1();
if (!Object.prototype.hasOwnProperty.call(Png.FilterMethod, this.filterMethod)) {
throw new KaitaiStream.ValidationNotInEnumError(this.filterMethod, this._io, "/types/ihdr_chunk/seq/5");
}
this.interlaceMethod = this._io.readU1();
if (!Object.prototype.hasOwnProperty.call(Png.InterlaceMethod, this.interlaceMethod)) {
throw new KaitaiStream.ValidationNotInEnumError(this.interlaceMethod, this._io, "/types/ihdr_chunk/seq/6");
}
}
return IhdrChunk;
})();
var InternationalText = Png.InternationalText = (function() {
function InternationalText(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
InternationalText.prototype._read = function() {
this.value = KaitaiStream.bytesToStr(this._io.readBytesFull(), "UTF-8");
}
/**
* Text string (the "value" of this key-value pair), written in language
* specified in `_parent.language_tag`.
*
* Although it is not null-terminated (unlike other textual data in the
* `iTXt` chunk), it must not contain a zero byte
* (U+0000 NULL character). A newline should be represented by a single
* U+000A LINE FEED (LF) character (aka `\n`). The remaining control
* characters (U+0001..U+0009, U+000B..0+001F, U+007F..U+009F) are
* discouraged.
*/
return InternationalText;
})();
/**
* International textual data (`iTXt`) chunk effectively allows you to store
* key-value string pairs in the PNG container.
*
* The "key" part (`keyword`) is restricted to printable ISO-8859-1 (Latin-1)
* characters and spaces. The translated keyword and the "value" part
* (`text`) are stored in UTF-8 and thus can store text in any language -
* this language can be indicated via the language tag (`language_tag`).
* @see {@link https://www.w3.org/TR/png/#11iTXt|Source}
*/
var InternationalTextChunk = Png.InternationalTextChunk = (function() {
function InternationalTextChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
InternationalTextChunk.prototype._read = function() {
this.keyword = KaitaiStream.bytesToStr(this._io.readBytesTerm(0, false, true, true), "ISO-8859-1");
this.compressionFlag = this._io.readU1();
if (!( ((this.compressionFlag == 0) || (this.compressionFlag == 1)) )) {
throw new KaitaiStream.ValidationNotAnyOfError(this.compressionFlag, this._io, "/types/international_text_chunk/seq/1");
}
this.compressionMethod = this._io.readU1();
if (!(this.compressionMethod == (this.compressionFlag == 1 ? Png.CompressionMethods.ZLIB : this.compressionMethod))) {
throw new KaitaiStream.ValidationNotEqualError((this.compressionFlag == 1 ? Png.CompressionMethods.ZLIB : this.compressionMethod), this.compressionMethod, this._io, "/types/international_text_chunk/seq/2");
}
this.languageTag = KaitaiStream.bytesToStr(this._io.readBytesTerm(0, false, true, true), "ASCII");
this.translatedKeyword = KaitaiStream.bytesToStr(this._io.readBytesTerm(0, false, true, true), "UTF-8");
if (this.compressionFlag == 0) {
this._raw_textPlain = this._io.readBytesFull();
var _io__raw_textPlain = new KaitaiStream(this._raw_textPlain);
this.textPlain = new InternationalText(_io__raw_textPlain, this, this._root);
}
if (this.compressionFlag == 1) {
this._raw__raw_textZlib = this._io.readBytesFull();
this._raw_textZlib = KaitaiStream.processZlib(this._raw__raw_textZlib);
var _io__raw_textZlib = new KaitaiStream(this._raw_textZlib);
this.textZlib = new InternationalText(_io__raw_textZlib, this, this._root);
}
}
/**
* Text string (the "value" of this key-value pair), written in language
* specified in `language_tag`.
*
* Although it is not null-terminated (unlike other textual data in the
* `iTXt` chunk), it must not contain a zero byte
* (U+0000 NULL character). A newline should be represented by a single
* U+000A LINE FEED (LF) character (aka `\n`). The remaining control
* characters (U+0001..U+0009, U+000B..0+001F, U+007F..U+009F) are
* discouraged.
*/
Object.defineProperty(InternationalTextChunk.prototype, 'text', {
get: function() {
if (this._m_text !== undefined)
return this._m_text;
this._m_text = (this.compressionFlag == 0 ? this.textPlain : this.textZlib).value;
return this._m_text;
}
});
/**
* Indicates the type of information represented by the text string.
*
* Keywords must consist exclusively of printable ISO-8859-1 (Latin-1)
* characters and spaces; that is, only code points 0x20-0x7E and
* 0xA1-0xFF are allowed. To reduce the chances for human misreading of a
* keyword, leading spaces, trailing spaces, and consecutive spaces are
* not permitted.
* @see {@link https://www.w3.org/TR/2025/REC-png-3-20250624/#11keywords|Source}
*/
/**
* 0 = text is uncompressed, 1 = text is compressed with a
* method specified in `compression_method`.
*/
/**
* Human language used in the `translated_keyword` and `text` fields.
*
* From the [official
* specification](https://www.w3.org/TR/2025/REC-png-3-20250624/#11iTXt):
*
* > The language tag is a well-formed language tag defined by [RFC 5646:
* > BCP 47: Tags for Identifying
* > Languages](https://www.rfc-editor.org/info/rfc5646/). Unlike the
* > keyword, the language tag is case-insensitive. Subtags must appear
* > in the [IANA language subtag
* > registry](https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry).
* > If the language tag is empty, the language is unspecified. Examples
* > of language tags include: `en`, `en-GB`, `es-419`, `zh-Hans`,
* > `zh-Hans-CN`, `tlh-Cyrl-AQ`, `ar-AE-u-nu-latn`, and `x-private`.
*/
/**
* The keyword (`keyword`) translated into the language specified in
* `language_tag`.
*
* It must not contain a zero byte (U+0000 NULL character). Line breaks
* should not appear. The remaining control characters (U+0001..U+0009,
* U+000B..0+001F, U+007F..U+009F) are discouraged.
*/
return InternationalTextChunk;
})();
var MdcvChromaticity = Png.MdcvChromaticity = (function() {
function MdcvChromaticity(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
MdcvChromaticity.prototype._read = function() {
this.xInt = this._io.readU2be();
this.yInt = this._io.readU2be();
}
Object.defineProperty(MdcvChromaticity.prototype, 'x', {
get: function() {
if (this._m_x !== undefined)
return this._m_x;
this._m_x = this.xInt * 0.00002;
return this._m_x;
}
});
Object.defineProperty(MdcvChromaticity.prototype, 'y', {
get: function() {
if (this._m_y !== undefined)
return this._m_y;
this._m_y = this.yInt * 0.00002;
return this._m_y;
}
});
return MdcvChromaticity;
})();
/**
* @see {@link https://www.w3.org/TR/png/#mDCV-chunk|Source}
* @see {@link https://w3c.github.io/png/Implementation_Report_3e/#mastering|Source}
*/
var MdcvChunk = Png.MdcvChunk = (function() {
function MdcvChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
MdcvChunk.prototype._read = function() {
this.red = new MdcvChromaticity(this._io, this, this._root);
this.green = new MdcvChromaticity(this._io, this, this._root);
this.blue = new MdcvChromaticity(this._io, this, this._root);
this.whitePoint = new MdcvChromaticity(this._io, this, this._root);
this.maxLuminanceInt = this._io.readU4be();
this.minLuminanceInt = this._io.readU4be();
}
/**
* Maximum luminance in cd/m^2
*/
Object.defineProperty(MdcvChunk.prototype, 'maxLuminance', {
get: function() {
if (this._m_maxLuminance !== undefined)
return this._m_maxLuminance;
this._m_maxLuminance = this.maxLuminanceInt * 0.0001;
return this._m_maxLuminance;
}
});
/**
* Minimum luminance in cd/m^2
*/
Object.defineProperty(MdcvChunk.prototype, 'minLuminance', {
get: function() {
if (this._m_minLuminance !== undefined)
return this._m_minLuminance;
this._m_minLuminance = this.minLuminanceInt * 0.0001;
return this._m_minLuminance;
}
});
return MdcvChunk;
})();
/**
* Physical pixel dimensions (`pHYs`) chunk specifies the intended physical
* size of the pixels (in meters) or pixel aspect ratio for display of the
* image.
* @see {@link https://www.w3.org/TR/png/#11pHYs|Source}
*/
var PhysChunk = Png.PhysChunk = (function() {
function PhysChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
PhysChunk.prototype._read = function() {
this.pixelsPerUnitX = this._io.readU4be();
this.pixelsPerUnitY = this._io.readU4be();
this.unit = this._io.readU1();
if (!Object.prototype.hasOwnProperty.call(Png.PhysUnit, this.unit)) {
throw new KaitaiStream.ValidationNotInEnumError(this.unit, this._io, "/types/phys_chunk/seq/2");
}
}
/**
* Horizontal resolution (DPI)
*/
Object.defineProperty(PhysChunk.prototype, 'dotsPerInchX', {
get: function() {
if (this._m_dotsPerInchX !== undefined)
return this._m_dotsPerInchX;
if (this.unit == Png.PhysUnit.METER) {
this._m_dotsPerInchX = this.pixelsPerUnitX * 0.0254;
}
return this._m_dotsPerInchX;
}
});
/**
* Vertical resolution (DPI)
*/
Object.defineProperty(PhysChunk.prototype, 'dotsPerInchY', {
get: function() {
if (this._m_dotsPerInchY !== undefined)
return this._m_dotsPerInchY;
if (this.unit == Png.PhysUnit.METER) {
this._m_dotsPerInchY = this.pixelsPerUnitY * 0.0254;
}
return this._m_dotsPerInchY;
}
});
/**
* Number of pixels per physical unit (typically, 1 meter) by X
* axis.
*/
/**
* Number of pixels per physical unit (typically, 1 meter) by Y
* axis.
*/
return PhysChunk;
})();
/**
* @see {@link https://www.w3.org/TR/png/#11PLTE|Source}
*/
var PlteChunk = Png.PlteChunk = (function() {
function PlteChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
PlteChunk.prototype._read = function() {
this.entries = [];
var i = 0;
while (!this._io.isEof()) {
this.entries.push(new Rgb(this._io, this, this._root));
i++;
}
}
return PlteChunk;
})();
var Rgb = Png.Rgb = (function() {
function Rgb(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
Rgb.prototype._read = function() {
this.r = this._io.readU1();
this.g = this._io.readU1();
this.b = this._io.readU1();
}
return Rgb;
})();
/**
* @see {@link https://www.w3.org/TR/png/#11sRGB|Source}
*/
var SrgbChunk = Png.SrgbChunk = (function() {
SrgbChunk.Intent = Object.freeze({
PERCEPTUAL: 0,
RELATIVE_COLORIMETRIC: 1,
SATURATION: 2,
ABSOLUTE_COLORIMETRIC: 3,
0: "PERCEPTUAL",
1: "RELATIVE_COLORIMETRIC",
2: "SATURATION",
3: "ABSOLUTE_COLORIMETRIC",
});
function SrgbChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
SrgbChunk.prototype._read = function() {
this.renderIntent = this._io.readU1();
if (!Object.prototype.hasOwnProperty.call(Png.SrgbChunk.Intent, this.renderIntent)) {
throw new KaitaiStream.ValidationNotInEnumError(this.renderIntent, this._io, "/types/srgb_chunk/seq/0");
}
}
return SrgbChunk;
})();
/**
* Textual data (`tEXt`) chunk effectively allows you to store key-value
* string pairs in the PNG container.
*
* Both the "key" (`keyword`) and "value" (`text`) parts are restricted to
* printable ISO-8859-1 (Latin-1) characters and ASCII spaces, with the
* exception that `text` can also contain newlines (U+000A LINE FEED (LF)
* characters) and U+00A0 NON-BREAKING SPACE characters.
* @see {@link https://www.w3.org/TR/png/#11tEXt|Source}
*/
var TextChunk = Png.TextChunk = (function() {
function TextChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
TextChunk.prototype._read = function() {
this.keyword = KaitaiStream.bytesToStr(this._io.readBytesTerm(0, false, true, true), "ISO-8859-1");
this.text = KaitaiStream.bytesToStr(this._io.readBytesFull(), "ISO-8859-1");
}
/**
* Indicates the type of information represented by the text string.
*
* Keywords must consist exclusively of printable ISO-8859-1 (Latin-1)
* characters and spaces; that is, only code points 0x20-0x7E and
* 0xA1-0xFF are allowed. To reduce the chances for human misreading of a
* keyword, leading spaces, trailing spaces, and consecutive spaces are
* not permitted.
* @see {@link https://www.w3.org/TR/2025/REC-png-3-20250624/#11keywords|Source}
*/
/**
* Text string (the "value" of this key-value pair).
*
* Although it is not null-terminated (unlike the keyword), it must not
* contain a zero byte (U+0000 NULL character). A newline should be
* represented by a single U+000A LINE FEED (LF) character (aka `\n`).
* The remaining control characters (U+0001..U+0009, U+000B..0+001F,
* U+007F..U+009F) are discouraged.
*/
return TextChunk;
})();
/**
* Time chunk stores time stamp of last modification of this image,
* up to 1 second precision in UTC timezone.
* @see {@link https://www.w3.org/TR/png/#11tIME|Source}
*/
var TimeChunk = Png.TimeChunk = (function() {
function TimeChunk(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
TimeChunk.prototype._read = function() {
this.year = this._io.readU2be();
this.month = this._io.readU1();
this.day = this._io.readU1();
this.hour = this._io.readU1();
this.minute = this._io.readU1();
this.second = this._io.readU1();
}
return TimeChunk;
})();
return Png;
})();
Png_.Png = Png;
});