pixelbutler/build/core/color.js

Low-res bitmap render engine for big screens

'use strict';
var RGBA = require('./RGBA');
var HSV = require('./HSV');
function useAlpha(col) {
    return (typeof col.a === 'number' && col.a < 255);
}
exports.useAlpha = useAlpha;
function hsv2rgb(hsv) {
    var r, g, b;
    var i;
    var f, p, q, t;
    var h = hsv.h;
    var s = hsv.s;
    var v = hsv.v;
    h = Math.max(0, Math.min(360, h));
    s = Math.max(0, Math.min(100, s));
    v = Math.max(0, Math.min(100, v));
    s /= 100;
    v /= 100;
    if (s === 0) {
        r = g = b = v;
        return new RGBA(Math.round(r * 255), Math.round(g * 255), Math.round(b * 255));
    }
    h /= 60;
    i = Math.floor(h);
    f = h - i;
    p = v * (1 - s);
    q = v * (1 - s * f);
    t = v * (1 - s * (1 - f));
    switch (i) {
        case 0:
            r = v;
            g = t;
            b = p;
            break;
        case 1:
            r = q;
            g = v;
            b = p;
            break;
        case 2:
            r = p;
            g = v;
            b = t;
            break;
        case 3:
            r = p;
            g = q;
            b = v;
            break;
        case 4:
            r = t;
            g = p;
            b = v;
            break;
        default:
            r = v;
            g = p;
            b = q;
    }
    return new RGBA(Math.round(r * 255), Math.round(g * 255), Math.round(b * 255));
}
exports.hsv2rgb = hsv2rgb;
function rgb2hsv(rgb) {
    var rr, gg, bb, r = rgb.r / 255, g = rgb.g / 255, b = rgb.b / 255, h, s, v = Math.max(r, g, b), diff = v - Math.min(r, g, b), diffc = function (c) {
        return (v - c) / 6 / diff + 1 / 2;
    };
    if (diff === 0) {
        h = s = 0;
    } else {
        s = diff / v;
        rr = diffc(r);
        gg = diffc(g);
        bb = diffc(b);
        if (r === v) {
            h = bb - gg;
        } else if (g === v) {
            h = (1 / 3) + rr - bb;
        } else if (b === v) {
            h = (2 / 3) + gg - rr;
        }
        if (h < 0) {
            h += 1;
        } else if (h > 1) {
            h -= 1;
        }
    }
    return new HSV(Math.round(h * 360), Math.round(s * 100), Math.round(v * 100));
}
exports.rgb2hsv = rgb2hsv;