admin管理员组

文章数量:1350027

I am trying to generate rainbow colors based on the numeric value.

var max = 10000;
var min = 0;
var val = 8890;

function getcolor(min,max,val) {
     // return red - black;
 }

colors Red Yellow Green Blue Black (value == 0)

Like in the url .jpg

From the above values how to generate color between red - black. High value is red and low value is black.

I am trying to generate rainbow colors based on the numeric value.

var max = 10000;
var min = 0;
var val = 8890;

function getcolor(min,max,val) {
     // return red - black;
 }

colors Red Yellow Green Blue Black (value == 0)

Like in the url https://i.sstatic/MRevs.jpg

From the above values how to generate color between red - black. High value is red and low value is black.

  • javascript
  • html
  • css
  • colors
Share Improve this question edited Apr 18, 2016 at 7:08 user6217823 asked Apr 18, 2016 at 7:01 user6217823user6217823 881 silver badge6 bronze badges 2
  • convert them to hexadecimal? try this.stackoverflow./questions/57803/… – Giri Commented Apr 18, 2016 at 7:05
  • No, I want to generate color code based on the value, max, min. – user6217823 Commented Apr 18, 2016 at 7:06
Add a ment  | 

3 Answers 3

Reset to default 6

There's just a couple things you need to do and understand in order to acplish this task. The first is realizing that the RGB colourspace is not the one you want for this task - the HSV or HSL ones are far better. Since the browsers are happy to work with HSL, we'll use that one.

Next, if you look at the H channel of the HSL colourspace, you can see that the exact band of colours you want is present there. The blue has a hue of about 240° and the red has one of 0­°.

This means that we want to map the range of [min..max] to the Hues of [240..0] (yes, the mapping is 'backwards') With this in mind, we can set about creating a function that will do the mapping for us and return a valid colour string.

function calcColor(min, max, val)
{
    var minHue = 240, maxHue=0;
    var curPercent = (val - min) / (max-min);
    var colString = "hsl(" + ((curPercent * (maxHue-minHue) ) + minHue) + ",100%,50%)";
    return colString;
}

First, we setup the two end-points of the Hues that we wish to use. Next, we work out where abouts in the current range the current value is. Finally, we put ourselves in the same position relatively speaking, in the Hue range instead of the user-input range.

A simple, example of its use is shown.

<!DOCTYPE html>
<html>
<head>
<script>
"use strict";
function newEl(tag){return document.createElement(tag);}

window.addEventListener('load', onDocLoaded, false);

function onDocLoaded()
{
    for (var i=0; i<10; i++)
    {
        var elem = newEl('div');
        elem.style.backgroundColor = calcColor(0, 9, i);
        elem.className = "rgb";
        document.body.appendChild(elem);
    }
}

function calcColor(min, max, val)
{
    var minHue = 240, maxHue=0;
    var curPercent = (val - min) / (max-min);
    var colString = "hsl(" + ((curPercent * (maxHue-minHue) ) + minHue) + ",100%,50%)";
    return colString;
}

</script>
<style>
.rgb
{
    width: 16px;
    height: 16px;
    display: inline-block;
}
</style>
</head>
<body>
</body>
</html>

make some proportions:

if you got max - min range, and you want to vary colors from black to red as u described, just divide your range in 6 phases:

first 1/4: R G B values are (0, 0, 0) at lower value and (0, 0, 255) at higher, so you'll have graduation from black to blue..

second 1/4: from (0, 0, 255) to (0, 255, 0) so you'll have graduation from blue to green

third 1/4: from (0, 255, 0) to (255, 255, 0) and that's the yellow

last 1/4: from (255, 255, 0) to (255, 0, 0) and here's red.

use proportion to determine intermediate values.

Enjoy :), here's a little explanation in terms of code...

https://jsfiddle/4cq8fqjg/10/

Try this.

use this library. https://github./bgrins/TinyColor

calculate the percentage of your value based on you max value.

run the script with that value.

tinycolor("hsv (_CALCULATED PERCENTAGE_ 100% 100%)");

本文标签： javascriptGenerate rainbow colors based on valueStack Overflow

版权声明：本文标题：javascript - Generate rainbow colors based on value - Stack Overflow 内容由网友自发贡献，该文观点仅代表作者本人， 转载请联系作者并注明出处：http://www.betaflare.com/web/1743871686a2553584.html， 本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌抄袭侵权/违法违规的内容，一经查实，本站将立刻删除。