color.js

js基本操作

/*
	Copyright (c) 2004-2006, The Dojo Foundation
	All Rights Reserved.

	Licensed under the Academic Free License version 2.1 or above OR the
	modified BSD license. For more information on Dojo licensing, see:

		http://dojotoolkit.org/community/licensing.shtml
*/

dojo.provide("dojo.gfx.color");
dojo.require("dojo.lang.common");
dojo.require("dojo.lang.array");

// TODO: rewrite the "x2y" methods to take advantage of the parsing
//       abilities of the Color object. Also, beef up the Color
//       object (as possible) to parse most common formats

// takes an r, g, b, a(lpha) value, [r, g, b, a] array, "rgb(...)" string, hex string (#aaa, #aaaaaa, aaaaaaa)
dojo.gfx.color.Color = function(r, g, b, a) {
	// dojo.debug("r:", r[0], "g:", r[1], "b:", r[2]);
	if(dojo.lang.isArray(r)){
		this.r = r[0];
		this.g = r[1];
		this.b = r[2];
		this.a = r[3]||1.0;
	}else if(dojo.lang.isString(r)){
		var rgb = dojo.gfx.color.extractRGB(r);
		this.r = rgb[0];
		this.g = rgb[1];
		this.b = rgb[2];
		this.a = g||1.0;
	}else if(r instanceof dojo.gfx.color.Color){
		// why does this create a new instance if we were passed one?
		this.r = r.r;
		this.b = r.b;
		this.g = r.g;
		this.a = r.a;
	}else{
		this.r = r;
		this.g = g;
		this.b = b;
		this.a = a;
	}
}

dojo.gfx.color.Color.fromArray = function(arr) {
	return new dojo.gfx.color.Color(arr[0], arr[1], arr[2], arr[3]);
}

dojo.extend(dojo.gfx.color.Color, {
	toRgb: function(includeAlpha) {
		if(includeAlpha) {
			return this.toRgba();
		} else {
			return [this.r, this.g, this.b];
		}
	},
	toRgba: function() {
		return [this.r, this.g, this.b, this.a];
	},
	toHex: function() {
		return dojo.gfx.color.rgb2hex(this.toRgb());
	},
	toCss: function() {
		return "rgb(" + this.toRgb().join() + ")";
	},
	toString: function() {
		return this.toHex(); // decent default?
	},
	blend: function(color, weight){
		var rgb = null;
		if(dojo.lang.isArray(color)){
			rgb = color;
		}else if(color instanceof dojo.gfx.color.Color){
			rgb = color.toRgb();
		}else{
			rgb = new dojo.gfx.color.Color(color).toRgb();
		}
		return dojo.gfx.color.blend(this.toRgb(), rgb, weight);
	}
});

dojo.gfx.color.named = {
	white:      [255,255,255],
	black:      [0,0,0],
	red:        [255,0,0],
	green:	    [0,255,0],
	lime:	    [0,255,0],
	blue:       [0,0,255],
	navy:       [0,0,128],
	gray:       [128,128,128],
	silver:     [192,192,192]
};

dojo.gfx.color.blend = function(a, b, weight){
	// summary: 
	//		blend colors a and b (both as RGB array or hex strings) with weight
	//		from -1 to +1, 0 being a 50/50 blend
	if(typeof a == "string"){
		return dojo.gfx.color.blendHex(a, b, weight);
	}
	if(!weight){
		weight = 0;
	}
	weight = Math.min(Math.max(-1, weight), 1);

	// alex: this interface blows.
	// map -1 to 1 to the range 0 to 1
	weight = ((weight + 1)/2);
	
	var c = [];

	// var stop = (1000*weight);
	for(var x = 0; x < 3; x++){
		c[x] = parseInt( b[x] + ( (a[x] - b[x]) * weight) );
	}
	return c;
}

// very convenient blend that takes and returns hex values
// (will get called automatically by blend when blend gets strings)
dojo.gfx.color.blendHex = function(a, b, weight) {
	return dojo.gfx.color.rgb2hex(dojo.gfx.color.blend(dojo.gfx.color.hex2rgb(a), dojo.gfx.color.hex2rgb(b), weight));
}

// get RGB array from css-style color declarations
dojo.gfx.color.extractRGB = function(color) {
	var hex = "0123456789abcdef";
	color = color.toLowerCase();
	if( color.indexOf("rgb") == 0 ) {
		var matches = color.match(/rgba*\((\d+), *(\d+), *(\d+)/i);
		var ret = matches.splice(1, 3);
		return ret;
	} else {
		var colors = dojo.gfx.color.hex2rgb(color);
		if(colors) {
			return colors;
		} else {
			// named color (how many do we support?)
			return dojo.gfx.color.named[color] || [255, 255, 255];
		}
	}
}

dojo.gfx.color.hex2rgb = function(hex) {
	var hexNum = "0123456789ABCDEF";
	var rgb = new Array(3);
	if( hex.indexOf("#") == 0 ) { hex = hex.substring(1); }
	hex = hex.toUpperCase();
	if(hex.replace(new RegExp("["+hexNum+"]", "g"), "") != "") {
		return null;
	}
	if( hex.length == 3 ) {
		rgb[0] = hex.charAt(0) + hex.charAt(0)
		rgb[1] = hex.charAt(1) + hex.charAt(1)
		rgb[2] = hex.charAt(2) + hex.charAt(2);
	} else {
		rgb[0] = hex.substring(0, 2);
		rgb[1] = hex.substring(2, 4);
		rgb[2] = hex.substring(4);
	}
	for(var i = 0; i < rgb.length; i++) {
		rgb[i] = hexNum.indexOf(rgb[i].charAt(0)) * 16 + hexNum.indexOf(rgb[i].charAt(1));
	}
	return rgb;
}

dojo.gfx.color.rgb2hex = function(r, g, b) {
	if(dojo.lang.isArray(r)) {
		g = r[1] || 0;
		b = r[2] || 0;
		r = r[0] || 0;
	}
	var ret = dojo.lang.map([r, g, b], function(x) {
		x = new Number(x);
		var s = x.toString(16);
		while(s.length < 2) { s = "0" + s; }
		return s;
	});
	ret.unshift("#");
	return ret.join("");
}