我正在使用this color wheel，我想以编程方式更改色轮的颜色。所以如果我有一个颜色值（rgb，hsv等）我想将色轮改成那个特定的颜色？
例如，如果我有rgb(255, 255, 80)，如何更改色轮以显示？
自定义代码：
function changeColor() {
var redColor = 255;
var greenColor = 255;
var blueColor = 80;
//currentX =
//currentY =
redraw(0);
// The following line is redundent if I'm calling 'redraw`, but it's there just to show what I mean.
label.textContent = b.style.background = 'rgb(' + redColor + ', ' + greenColor + ', ' + blueColor + ')';
}
redraw() function 的实际代码
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.
a.stroke();
a.font = "1em arial";
a.fillText("♥", currentX+radiusPlusOffset-4,currentY+radiusPlusOffset+4);
}
(function() {
document.getElementById('button').onclick = changeColor;
function changeColor() {
var redColor = 255;
var greenColor = 255;
var blueColor = 80;
//currentX =
//currentY =
redraw(0);
// The following line is redundent if I'm calling 'redraw`, but it's there just to show what I mean.
label.textContent = b.style.background = 'rgb(' + redColor + ', ' + greenColor + ', ' + blueColor + ')';
}
// Declare constants and variables to help with minification
// Some of these are inlined (with comments to the side with the actual equation)
var doc = document;
doc.c = doc.createElement;
b.a = b.appendChild;
var width = c.width = c.height = 400,
label = b.a(doc.c("p")),
input = b.a(doc.c("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)
*/
})();<button id="button">Click Me To Change Color</button>
<br />
<canvas id="c"></canvas>
<script>
var b = document.body;
var c = document.getElementsByTagName('canvas')[0];
var a = c.getContext('2d');
document.body.clientWidth; // fix bug in webkit: http://qfox.nl/weblog/218
</script>
答案 0 :(得分：0)
色轮仅使用var mx = cx - s * radius * Math.cos(2 * Math.PI * h);
var my = cy - s * radius * Math.sin(2 * Math.PI * h);
值1，因此假设您可以使用现有库从RGB等转换回HSV，您需要做的就是提取H和S并转换它们回到像素坐标。
在此车轮上，从负X轴顺时针测量色调，＆＃34; S＆＃34;中心是0，外面是1，所以：
cx, cy其中[(]?\d{3}[)]?[(\s)?.-]\d{3}[\s.-]\d{4}
是色轮的中心。
答案 1 :(得分：0)
这是一个取自TinyColor的函数（已在此色轮源中引用）并添加到某些代码中，以将HSV转换回x，y和滑块值。
// Created a modified version of the HSV to RGB conversion function in TinyColor
// https://github.com/bgrins/TinyColor/blob/master/tinycolor.js
function rgbToHsv(r, g, b) {
r = r / two55;
g = g / two55;
b = b / two55;
var max = math.max(r, g, b), min = math.min(r, g, b);
var h, s, v = max;
var d = max - min;
s = max === 0 ? 0 : d / max;
if(max == min) {
h = 0; // achromatic
}
else {
switch(max) {
case r: h = (g - b) / d + (g < b ? 6 : 0); break;
case g: h = (b - r) / d + 2; break;
case b: h = (r - g) / d + 4; break;
}
h /= 6;
}
return { h: h, s: s, v: v };
}
// This function converts the RGB to HSV and uses the HSV to set the
// currentX, currentY, and input.value (saturation) values.
function update(r,g,b){
var hsv = rgbToHsv(r,g,b);
var newD = math.round(math.pow(radius * hsv.s, 2));
var newTheta = (hsv.h * PI2) - PI;
currentX = math.round(math.sqrt(newD) * math.cos(newTheta));
currentY = math.round(math.sqrt(newD) * math.sin(newTheta));
input.value = hsv.v * 100;
redraw(0);
}
update(158,255,151);
除非您更改..函数中的~~ NOT按位运算符以消除掉小数的舍入问题，否则最终显示的RGB值与传入的值略有不同。
这是整个修改过的库的要点。 https://gist.github.com/tonypatton/bf4e13cabf03fc4a1777