mirror of
https://github.com/danbulant/pngjs
synced 2026-06-15 04:21:10 +00:00
348 lines
9.6 KiB
JavaScript
348 lines
9.6 KiB
JavaScript
// Copyright (c) 2012 Kuba Niegowski
|
|
//
|
|
// Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
// of this software and associated documentation files (the "Software"), to deal
|
|
// in the Software without restriction, including without limitation the rights
|
|
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
// copies of the Software, and to permit persons to whom the Software is
|
|
// furnished to do so, subject to the following conditions:
|
|
//
|
|
// The above copyright notice and this permission notice shall be included in
|
|
// all copies or substantial portions of the Software.
|
|
//
|
|
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
// THE SOFTWARE.
|
|
|
|
'use strict';
|
|
|
|
|
|
var util = require('util'),
|
|
Stream = require('stream'),
|
|
zlib = require('zlib'),
|
|
helpers = require('./helpers'),
|
|
constants = require('./constants'),
|
|
Filter = require('./filter');
|
|
|
|
|
|
var Parser = module.exports = function(options) {
|
|
Stream.call(this);
|
|
|
|
this._options = options;
|
|
options.checkCRC = options.checkCRC !== false;
|
|
|
|
this._hasIHDR = false;
|
|
this._hasIEND = false;
|
|
|
|
this._stream = new ReadStream();
|
|
this._inflate = null;
|
|
|
|
// input flags/metadata
|
|
this._palette = [];
|
|
this._colorType = 0;
|
|
this._width = 0;
|
|
this._height = 0;
|
|
|
|
this._chunks = {};
|
|
this._chunks[constants.TYPE_IHDR] = this._handleIHDR.bind(this);
|
|
this._chunks[constants.TYPE_IEND] = this._handleIEND.bind(this);
|
|
this._chunks[constants.TYPE_IDAT] = this._handleIDAT.bind(this);
|
|
this._chunks[constants.TYPE_PLTE] = this._handlePLTE.bind(this);
|
|
this._chunks[constants.TYPE_tRNS] = this._handleTRNS.bind(this);
|
|
this._chunks[constants.TYPE_gAMA] = this._handleGAMA.bind(this);
|
|
|
|
this.writable = true;
|
|
|
|
this.on('error', this._handleError.bind(this));
|
|
|
|
this._handleSignature();
|
|
};
|
|
util.inherits(Parser, Stream);
|
|
|
|
|
|
Parser.prototype.write = function(data) {
|
|
this._stream.write(data);
|
|
};
|
|
|
|
Parser.prototype.end = function(data) {
|
|
this._stream.end(data);
|
|
};
|
|
|
|
Parser.prototype._handleError = function() {
|
|
|
|
this.writable = false;
|
|
this._stream.destroy();
|
|
|
|
if (this._inflate)
|
|
this._inflate.destroy();
|
|
};
|
|
|
|
Parser.prototype._handleSignature = function() {
|
|
this._stream.read(constants.PNG_SIGNATURE.length,
|
|
this._parseSignature.bind(this)
|
|
);
|
|
};
|
|
|
|
Parser.prototype._parseSignature = function(data) {
|
|
|
|
var signature = constants.PNG_SIGNATURE;
|
|
|
|
for (var i = 0; i < signature.length; i++)
|
|
if (data[i] != signature[i]) {
|
|
this.emit('error', new Error('Invalid file signature'));
|
|
return;
|
|
}
|
|
}
|
|
this._stream.read(8, this._parseChunkBegin.bind(this));
|
|
};
|
|
|
|
Parser.prototype._parseChunkBegin = function(data) {
|
|
|
|
// chunk content length
|
|
var length = data.readUInt32BE(0);
|
|
|
|
// chunk type
|
|
var type = data.readUInt32BE(4),
|
|
name = '';
|
|
for (var i = 4; i < 8; i++)
|
|
name += String.fromCharCode(data[i]);
|
|
|
|
// chunk flags
|
|
var ancillary = !!(data[4] & 0x20), // or critical
|
|
priv = !!(data[5] & 0x20), // or public
|
|
safeToCopy = !!(data[7] & 0x20); // or unsafe
|
|
|
|
if (!this._hasIHDR && type != constants.TYPE_IHDR) {
|
|
this.emit('error', new Error('Expected IHDR on beggining'));
|
|
return;
|
|
}
|
|
|
|
if (this._chunks[type]) {
|
|
return this._chunks[type](length);
|
|
|
|
} else if (!ancillary) {
|
|
this.emit('error', new Error('Unsupported critical chunk type ' + name));
|
|
return;
|
|
}
|
|
};
|
|
|
|
Parser.prototype._handleChunkEnd = function() {
|
|
this._stream.read(4, this._parseChunkEnd.bind(this));
|
|
};
|
|
|
|
Parser.prototype._parseChunkEnd = function(data) {
|
|
|
|
var fileCrc = data.readInt32BE(0);
|
|
|
|
// // calc CRC (of chunk type and content)
|
|
// var calcCrc = helpers.crc32(data.slice(idx - 4, idx + length)),
|
|
// content = data.slice(idx, idx + length);
|
|
// idx += length;
|
|
|
|
// // read CRC
|
|
// var fileCrc = data.readInt32BE(idx);
|
|
// idx += 4;
|
|
|
|
// // and check CRC
|
|
// if (this._options.checkCRC && calcCrc != fileCrc)
|
|
// throw new Error('Crc error');
|
|
|
|
// TODO: calc crc on stream
|
|
|
|
if (this._hasIEND) {
|
|
this._stream.destroy();
|
|
|
|
} else {
|
|
this._stream.read(8, this._parseChunkBegin.bind(this));
|
|
}
|
|
};
|
|
|
|
|
|
Parser.prototype._handleIHDR = function(length) {
|
|
this._stream.read(length, this._parseIHDR.bind(this));
|
|
};
|
|
Parser.prototype._parseIHDR = function(data) {
|
|
|
|
var width = data.readUInt32BE(0),
|
|
height = data.readUInt32BE(4),
|
|
depth = data[8],
|
|
colorType = data[9], // bits: 1 palette, 2 color, 4 alpha
|
|
compr = data[10],
|
|
filter = data[11],
|
|
interlace = data[12];
|
|
|
|
console.log(' width', width, 'height', height,
|
|
'depth', depth, 'colorType', colorType,
|
|
'compr', compr, 'filter', filter, 'interlace', interlace
|
|
);
|
|
|
|
if (depth != 8) {
|
|
this.emit('error', new Error('Unsupported bit depth ' + depth));
|
|
return;
|
|
}
|
|
if (compr != 0) {
|
|
this.emit('error', new Error('Unsupported compression method'));
|
|
return;
|
|
}
|
|
if (filter != 0) {
|
|
this.emit('error', new Error('Unsupported filter method'));
|
|
return;
|
|
}
|
|
if (interlace != 0) {
|
|
this.emit('error', new Error('Unsupported interlace method'));
|
|
return;
|
|
}
|
|
|
|
this._colorType = colorType;
|
|
this._width = width;
|
|
this._height = height;
|
|
this._hasIHDR = true;
|
|
|
|
this.emit('metadata', {
|
|
width: width,
|
|
height: height,
|
|
palette: !!(colorType & constants.COLOR_PALETTE),
|
|
color: !!(colorType & constants.COLOR_COLOR),
|
|
alpha: !!(colorType & constants.COLOR_ALPHA)
|
|
});
|
|
|
|
this._handleChunkEnd();
|
|
};
|
|
|
|
|
|
Parser.prototype._handlePLTE = function(length) {
|
|
this._stream.read(length, this._parsePLTE.bind(this));
|
|
};
|
|
Parser.prototype._parsePLTE = function(data) {
|
|
|
|
var entries = Math.floor(data.length / 3);
|
|
console.log('Palette:', entries);
|
|
|
|
for (var i = 0; i < entries; i++) {
|
|
this._palette.push([
|
|
data.readUInt8(i * 3),
|
|
data.readUInt8(i * 3 + 1),
|
|
data.readUInt8(i * 3 + 2 ),
|
|
0xff
|
|
]);
|
|
}
|
|
|
|
this._handleChunkEnd();
|
|
};
|
|
|
|
Parser.prototype._handleTRNS = function(length) {
|
|
this._stream.read(length, this._parseTRNS.bind(this));
|
|
};
|
|
Parser.prototype._parseTRNS = function(data) {
|
|
|
|
// palette
|
|
if (this._colorType == 3) {
|
|
if (this._palette.length == 0) {
|
|
this.emit('error', new Error('Transparency chunk must be after palette'));
|
|
return;
|
|
}
|
|
if (data.length > this._palette.length) {
|
|
this.emit('error', new Error('More transparent colors than palette size'));
|
|
return;
|
|
}
|
|
for (var i = 0; i < this._palette.length; i++) {
|
|
this._palette[i][3] = i < data.length ? data.readUInt8(i) : 0xff;
|
|
}
|
|
}
|
|
|
|
// for colorType 0 (grayscale) and 2 (rgb)
|
|
// there might be one gray/color defined as transparent
|
|
|
|
this._handleChunkEnd();
|
|
};
|
|
|
|
Parser.prototype._handleGAMA = function(length) {
|
|
this._stream.read(length, this._parseGAMA.bind(this));
|
|
};
|
|
Parser.prototype._parseGAMA = function(data) {
|
|
|
|
this.emit('gamma', data.readUInt32BE(0) / 100000);
|
|
|
|
this._handleChunkEnd();
|
|
};
|
|
|
|
Parser.prototype._handleIDAT = function(length) {
|
|
this._stream.read(-length, this._parseIDAT.bind(this, length));
|
|
};
|
|
Parser.prototype._parseIDAT = function(lenght, data) {
|
|
|
|
if (this._colorType == 3 && this._palette.length == 0)
|
|
throw new Error('Expected palette not found');
|
|
|
|
if (!this._inflate) {
|
|
this._inflate = zlib.createInflate();
|
|
|
|
this._inflate.on('error', this.emit.bind(this, 'error'));
|
|
//this._inflate.pipe(filter);
|
|
}
|
|
|
|
this._inflate.write(data);
|
|
length -= data.length;
|
|
|
|
if (length > 0)
|
|
this._handleIDAT(length);
|
|
else
|
|
this._handleChunkEnd();
|
|
};
|
|
|
|
|
|
Parser.prototype._handleIEND = function(length) {
|
|
this._stream.read(length, this._parseIEND.bind(this));
|
|
};
|
|
Parser.prototype._parseIEND = function(data) {
|
|
|
|
// no more data to inflate
|
|
this._inflate.end();
|
|
|
|
this._hasIEND = true;
|
|
this._handleChunkEnd();
|
|
};
|
|
|
|
|
|
|
|
Parser.prototype._unfilter = function(data) {
|
|
|
|
// expand data to 32 bit depending on colorType
|
|
if (this._colorType == 0) { // L
|
|
data = this._filter.unfilter(data, 1); // 1 Bpp
|
|
|
|
} else if (this._colorType == 2) { // RGB
|
|
data = this._filter.unfilter(data, 3); // 3 Bpp
|
|
|
|
} else if (this._colorType == 3) { // I
|
|
data = this._filter.unfilter(data, 1); // 1 Bpp
|
|
|
|
// use values fom palette
|
|
var pxLineLength = this.width << 2;
|
|
|
|
for (var y = 0; y < this.height; y++) {
|
|
var pxRowPos = y * pxLineLength;
|
|
|
|
for (var x = 0; x < this.width; x++) {
|
|
var pxPos = pxRowPos + (x << 2),
|
|
color = this._palette[data[pxPos]];
|
|
|
|
for (var i = 0; i < 4; i++)
|
|
data[pxPos + i] = color[i];
|
|
}
|
|
}
|
|
|
|
} else if (this._colorType == 4) { // LA
|
|
data = this._filter.unfilter(data, 2); // 2 Bpp
|
|
|
|
} else if (this._colorType == 6) { // RGBA
|
|
data = this._filter.unfilter(data, 4); // 4 Bpp
|
|
|
|
} else throw new Error('Unsupported color type');
|
|
|
|
this.emit('parsed', data);
|
|
};
|