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var CanvasLoader = (function(){
var loader = new Loader (function(){})
function CanvasLoader (opt){
this.opt = defaults(opt, {
rotate: true,
})
this.canvas = document.createElement("canvas")
this.ctx = this.canvas.getContext('2d')
}
CanvasLoader.prototype.load_image = function(url, cb){
loader.preloadImage(url, function(img){
var w = this.w = img.naturalWidth
var h = this.h = img.naturalHeight
this.img = img
cb(img, w, h)
}.bind(this))
}
CanvasLoader.prototype.scale_image_data = function(opt){
var w, h
if (opt.scale) {
w = this.w * opt.scale
h = this.h * opt.scale
}
if (opt.w) {
w = opt.w
h = opt.w * this.h / this.w
}
else if (opt.h) {
w = opt.h * this.w / this.h
h = opt.h
}
this.canvas.width = w
this.canvas.height = h
this.ctx.save()
if (this.opt.rotate) {
this.ctx.translate(w/2, h/2)
this.ctx.rotate( Math.PI )
this.ctx.translate(-w/2, -h/2)
}
this.ctx.drawImage(this.img, 0, 0, w, h)
this.ctx.restore()
return this.ctx.getImageData(0, 0, w, h)
}
CanvasLoader.prototype.gray_image_data = function(opt){
var data = this.scale_image_data(opt)
var pixels = data.data
var len = data.width * data.height
var gray_data = new Uint8Array( len )
var invert = this.opt.invert
var gray, ii
for (var i = 0; i < len; i++) {
ii = i * 4
gray = (255 - (pixels[ii] + pixels[ii+1] + pixels[ii+2]) / 3 ) * (pixels[ii+3]/255)
gray_data[i] = (invert) ? 255 - gray : gray
}
return {
width: data.width,
height: data.height,
data: gray_data,
}
}
// in: imagedata [r,g,b,a] and a palette
// out: an array strided as [ palette offset, alpha ]
CanvasLoader.prototype.palette_image_data = function(opt){
var data = this.scale_image_data(opt)
var pixels = data.data
var len = data.width * data.height
var palette_data = new Uint8Array( len*2 )
var invert = this.opt.invert
var palette = this.paletteToNumbers(opt.palette)
var color, index, ii
for (var i = 0; i < len; i++) {
ii = i * 2
jj = i * 4
index = closest_to( palette, pixels.slice(jj, jj+3) )
palette_data[ii] = index
palette_data[ii+1] = pixels[jj+3]
}
return {
width: data.width,
height: data.height,
data: palette_data,
}
}
CanvasLoader.prototype.paletteToStrings = function (palette){
if (typeof palette[0] === "string") return palette
return palette.map(function(rgb){
return "rgb(" + rgb.join(",") + ")"
})
}
CanvasLoader.prototype.paletteToNumbers = function (palette){
if (typeof palette[0] !== "string") return palette
var colors = palette.map(function(color){
if (color[0] == "#") return hexToRgb(color)
return rgbStringToRgb(color)
}).filter(function(color){ return !! color }).map(function(rgb){
return [rgb.r, rgb.g, rgb.b]
})
return colors
}
function hexToRgb(hex) {
// Expand shorthand form (e.g. "03F") to full form (e.g. "0033FF")
var shorthandRegex = /^#?([a-f\d])([a-f\d])([a-f\d])$/i;
hex = hex.replace(shorthandRegex, function(m, r, g, b) {
return r + r + g + g + b + b;
});
var result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
return result ? {
r: parseInt(result[1], 16),
g: parseInt(result[2], 16),
b: parseInt(result[3], 16)
} : null;
}
function rgbStringToRgb(rgb) {
var nums = rgb.replace(/rgba?\(/,"").replace(/\)/,"").split(",")
return { r: nums[0], g: nums[1], b: nums[2] }
}
function closest_to(palette, pixel){
return palette.reduce(function(prev, curr, index) {
var d = distance(pixel, curr)
if (prev[0] > d) {
prev[0] = d
prev[1] = index
}
return prev
}, [Infinity, -1])[1]
}
function distance(u, v){
if (! v) return Math.Infinity
var r = u[0] - v[0]
var g = u[1] - v[1]
var b = u[2] - v[2]
return Math.sqrt(r*r+g*g+b*b)
}
return CanvasLoader
})()
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