function m(d){f=d.pageX-c.offsetLeft-n||f;e=d.pageY-c.offsetTop-n||e;d=s(e,f),t=f*f+e*e;t>w&&(f=g*l.cos(d),e=g*l.sin(d),d=s(e,f),t=f*f+e*e);z.textContent=b.style.background=A((d+u)/B,C(t)/g,j.value/D)[3];a.putImageData(E,0,0);a.font="1em arial";a.fillText("\u2665",f+n-4,e+n+4)}function A(d,e,h){var d=6*d,f=~~d,g=d-f,d=h*(1-e),i=h*(1-g*e),e=h*(1-(1-g)*e),j=f%6,f=[h,i,d,d,e,h][j]*o,g=[e,h,h,i,d,d][j]*o,h=[d,d,e,h,h,i][j]*o;return[f,g,h,"rgb("+~~f+","+~~g+","+~~h+")"]}k=document;
k.c=k.createElement;b.a=b.appendChild;p=c.width=c.height=400,z=b.a(k.c("p")),j=b.a(k.c("input")),E=a.createImageData(p,p),q=E.data,D=j.value=j.max=100,g=190,n=200,w=g*g,o=255,e=D,f=-e,r=16040,l=Math,u=l.PI,B=2*u,C=l.sqrt,s=l.atan2;b.style.textAlign="center";z.style.font="2em courier";j.type="range";for(y=j.min=0;y<p;y++)for(x=0;x<p;x++){i=x-g,v=y-g,F=i*i+v*v,i=A((s(v,i)+u)/B,C(F)/g,1);q[r++]=i[0];q[r++]=i[1];q[r++]=i[2];q[r++]=F>w?0:o}j.onchange=m;c.onmousedown=k.onmouseup=function(d){k.onmousemove=
/p/.test(d.type)?0:(m(d),m)};m(0)
(function() {
// Declare constants and variables to help with minification
// Some of these are inlined (with comments to the side with the actual equation)
b.a = b.appendChild;
var width = c.width = c.height = 400,
doc = document,
label = b.a(doc.createElement("p")),
input = b.a(doc.createElement("input")),
imageData = a.createImageData(width, width),
pixels = imageData.data,
oneHundred = input.value = input.max = 100,
circleOffset = 10,
diameter = 380, //width-circleOffset*2,
radius = 190, //diameter / 2,
radiusPlusOffset = 200, //radius + circleOffset
radiusSquared = radius * radius,
two55 = 255,
currentY = oneHundred,
currentX = -currentY,
wheelPixel = 16040; // circleOffset*4*width+circleOffset*4;
// Math helpers
var math = Math,
PI = math.PI,
PI2 = PI * 2,
sqrt = math.sqrt,
atan2 = math.atan2;
// Setup DOM properties
b.style.textAlign="center";
label.style.font = "2em courier";
input.type = "range";
// Load color wheel data into memory.
for (y = input.min = 0; y < width; y++) {
for (x = 0; x < width; x++) {
var rx = x - radius,
ry = y - radius,
d = rx * rx + ry * ry,
rgb = hsvToRgb(
(atan2(ry, rx) + PI) / PI2, // Hue
sqrt(d) / radius, // Saturation
1 // Value
);
// Print current color, but hide if outside the area of the circle
pixels[wheelPixel++] = rgb[0];
pixels[wheelPixel++] = rgb[1];
pixels[wheelPixel++] = rgb[2];
pixels[wheelPixel++] = d > radiusSquared ? 0 : two55;
}
}
// Bind Event Handlers
input.onchange = redraw;
c.onmousedown = doc.onmouseup = function(e) {
// Unbind mousemove if this is a mouseup event, or bind mousemove if this a mousedown event
doc.onmousemove = /p/.test(e.type) ? 0 : (redraw(e), redraw);
}
// Handle manual calls + mousemove event handler + input change event handler all in one place.
function redraw(e) {
// Only process an actual change if it is triggered by the mousemove or mousedown event.
// Otherwise e.pageX will be undefined, which will cause the result to be NaN, so it will fallback to the current value
currentX = e.pageX - c.offsetLeft - radiusPlusOffset || currentX;
currentY = e.pageY - c.offsetTop - radiusPlusOffset || currentY;
// Scope these locally so the compiler will minify the names. Will manually remove the 'var' keyword in the minified version.
var theta = atan2(currentY, currentX),
d = currentX * currentX + currentY * currentY;
// If the x/y is not in the circle, find angle between center and mouse point:
// Draw a line at that angle from center with the distance of radius
// Use that point on the circumference as the draggable location
if (d > radiusSquared) {
currentX = radius * math.cos(theta);
currentY = radius * math.sin(theta);
theta = atan2(currentY, currentX);
d = currentX * currentX + currentY * currentY;
}
label.textContent = b.style.background = hsvToRgb(
(theta + PI) / PI2, // Current hue (how many degrees along the circle)
sqrt(d) / radius, // Current saturation (how close to the middle)
input.value / oneHundred // Current value (input type="range" slider value)
)[3];
// Reset to color wheel and draw a spot on the current location.
a.putImageData(imageData, 0, 0);
// Draw the current spot.
// I have tried a rectangle, circle, and heart shape.
/*
// Rectangle:
a.fillStyle = '#000';
a.fillRect(currentX+radiusPlusOffset,currentY+radiusPlusOffset, 6, 6);
*/
/*
// Circle:
a.beginPath();
a.strokeStyle = '#000';
a.arc(~~currentX+radiusPlusOffset,~~currentY+radiusPlusOffset, 4, 0, PI2);
a.stroke();
*/
// Heart:
a.font = "1em arial";
a.fillText("♥", currentX+radiusPlusOffset-4,currentY+radiusPlusOffset+4);
}
// Created a shorter version of the HSV to RGB conversion function in TinyColor
// https://github.com/bgrins/TinyColor/blob/master/tinycolor.js
function hsvToRgb(h, s, v) {
h*=6;
var i = ~~h,
f = h - i,
p = v * (1 - s),
q = v * (1 - f * s),
t = v * (1 - (1 - f) * s),
mod = i % 6,
r = [v, q, p, p, t, v][mod] * two55,
g = [t, v, v, q, p, p][mod] * two55,
b = [p, p, t, v, v, q][mod] * two55;
return [r, g, b, "rgb("+ ~~r + "," + ~~g + "," + ~~b + ")"];
}
// Kick everything off
redraw(0);
/*
// Just an idea I had to kick everything off with some changing colors…
// Probably no way to squeeze this into 1k, but it could probably be a lot smaller than this:
currentX = currentY = 1;
var interval = setInterval(function() {
currentX--;
currentY*=1.05;
redraw(0)
}, 7);
setTimeout(function() {
clearInterval(interval)
}, 700)
*/
})();
