mightyscape-1.2/extensions/fablabchemnitz/imagetracerjs/imagetracerjs-master/nodecli/PNG.js

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2022-10-03 02:49:07 +02:00
"use strict";
var PNG = function(){
// initialize all members to keep the same hidden class
this.width = 0;
this.height = 0;
this.bitDepth = 0;
this.colorType = 0;
this.compressionMethod = 0;
this.filterMethod = 0;
this.interlaceMethod = 0;
this.colors = 0;
this.alpha = false;
this.pixelBits = 0;
this.palette = null;
this.pixels = null;
};
PNG.prototype.getWidth = function(){
return this.width;
};
PNG.prototype.setWidth = function(width){
this.width = width;
};
PNG.prototype.getHeight = function(){
return this.height;
};
PNG.prototype.setHeight = function(height){
this.height = height;
};
PNG.prototype.getBitDepth = function(){
return this.bitDepth;
};
PNG.prototype.setBitDepth = function(bitDepth){
if ([2, 4, 8, 16].indexOf(bitDepth) === -1){
throw new Error("invalid bith depth " + bitDepth);
}
this.bitDepth = bitDepth;
};
PNG.prototype.getColorType = function(){
return this.colorType;
};
PNG.prototype.setColorType = function(colorType){
// Color Allowed Interpretation
// Type Bit Depths
//
// 0 1,2,4,8,16 Each pixel is a grayscale sample.
//
// 2 8,16 Each pixel is an R,G,B triple.
//
// 3 1,2,4,8 Each pixel is a palette index;
// a PLTE chunk must appear.
//
// 4 8,16 Each pixel is a grayscale sample,
// followed by an alpha sample.
//
// 6 8,16 Each pixel is an R,G,B triple,
// followed by an alpha sample.
var colors = 0, alpha = false;
switch (colorType){
case 0: colors = 1; break;
case 2: colors = 3; break;
case 3: colors = 1; break;
case 4: colors = 2; alpha = true; break;
case 6: colors = 4; alpha = true; break;
default: throw new Error("invalid color type");
}
this.colors = colors;
this.alpha = alpha;
this.colorType = colorType;
};
PNG.prototype.getCompressionMethod = function(){
return this.compressionMethod;
};
PNG.prototype.setCompressionMethod = function(compressionMethod){
if (compressionMethod !== 0){
throw new Error("invalid compression method " + compressionMethod);
}
this.compressionMethod = compressionMethod;
};
PNG.prototype.getFilterMethod = function(){
return this.filterMethod;
};
PNG.prototype.setFilterMethod = function(filterMethod){
if (filterMethod !== 0){
throw new Error("invalid filter method " + filterMethod);
}
this.filterMethod = filterMethod;
};
PNG.prototype.getInterlaceMethod = function(){
return this.interlaceMethod;
};
PNG.prototype.setInterlaceMethod = function(interlaceMethod){
if (interlaceMethod !== 0 && interlaceMethod !== 1){
throw new Error("invalid interlace method " + interlaceMethod);
}
this.interlaceMethod = interlaceMethod;
};
PNG.prototype.setPalette = function(palette){
if (palette.length % 3 !== 0){
throw new Error("incorrect PLTE chunk length");
}
if (palette.length > (Math.pow(2, this.bitDepth) * 3)){
throw new Error("palette has more colors than 2^bitdepth");
}
this.palette = palette;
};
PNG.prototype.getPalette = function(){
return this.palette;
};
/**
* get the pixel color on a certain location in a normalized way
* result is an array: [red, green, blue, alpha]
*/
PNG.prototype.getPixel = function(x, y){
if (!this.pixels) throw new Error("pixel data is empty");
if (x >= this.width || y >= this.height){
throw new Error("x,y position out of bound");
}
var i = this.colors * this.bitDepth / 8 * (y * this.width + x);
var pixels = this.pixels;
switch (this.colorType){
case 0: return [pixels[i], pixels[i], pixels[i], 255];
case 2: return [pixels[i], pixels[i + 1], pixels[i + 2], 255];
case 3: return [
this.palette[pixels[i] * 3 + 0],
this.palette[pixels[i] * 3 + 1],
this.palette[pixels[i] * 3 + 2],
255];
case 4: return [pixels[i], pixels[i], pixels[i], pixels[i + 1]];
case 6: return [pixels[i], pixels[i + 1], pixels[i + 2], pixels[i + 3]];
}
};
module.exports = PNG;