javascript - 如果我有线性渐变，则更改滚动上的颜色背景

Question

如果我有线性渐变，如何使用 js 更改滚动上的颜色背景

  background: linear-gradient(115deg, #42c344 0%,#42c344 40%,#c4efc4 40%,#ffffff 40%,#ffffff 100%); background-attachment: fixed;

我已经找到了: http://jsfiddle.net/cgspicer/V4qh9/和这个: http://codepen.io/Funsella/pen/yLfAG/

Answer 1

您必须使用 RGB 值设置渐变并使用 Javascript 为它们设置动画。

您可以在下面或随附的笔中看到一个随机示例。只需连接“滚动”/“滚轮”事件即可触发 updateGradient 函数:

var colors = new Array(
  [62,35,255],
  [60,255,60],
  [255,35,98],
  [45,175,230],
  [255,0,255],
  [255,128,0]);

var step = 0;
//color table indices for: 
// current color left
// next color left
// current color right
// next color right
var colorIndices = [0,1,2,3];

//transition speed
var gradientSpeed = 0.002;

function updateGradient()
{

  if ( $===undefined ) return;

var c0_0 = colors[colorIndices[0]];
var c0_1 = colors[colorIndices[1]];
var c1_0 = colors[colorIndices[2]];
var c1_1 = colors[colorIndices[3]];

var istep = 1 - step;
var r1 = Math.round(istep * c0_0[0] + step * c0_1[0]);
var g1 = Math.round(istep * c0_0[1] + step * c0_1[1]);
var b1 = Math.round(istep * c0_0[2] + step * c0_1[2]);
var color1 = "rgb("+r1+","+g1+","+b1+")";

var r2 = Math.round(istep * c1_0[0] + step * c1_1[0]);
var g2 = Math.round(istep * c1_0[1] + step * c1_1[1]);
var b2 = Math.round(istep * c1_0[2] + step * c1_1[2]);
var color2 = "rgb("+r2+","+g2+","+b2+")";

 $('#gradient').css({
    background: "-webkit-gradient(linear, left top, right top, from("+color1+"), to("+color2+"))"}).css({
    background: "-moz-linear-gradient(left, "+color1+" 0%, "+color2+" 100%)"});

  step += gradientSpeed;
  if ( step >= 1 )
   {
    step %= 1;
    colorIndices[0] = colorIndices[1];
    colorIndices[2] = colorIndices[3];

    //pick two new target color indices
    //do not pick the same as the current one
    colorIndices[1] = ( colorIndices[1] + Math.floor( 1 + Math.random() * 
(colors.length - 1))) % colors.length;
    colorIndices[3] = ( colorIndices[3] + Math.floor( 1 + Math.random() * 
(colors.length - 1))) % colors.length;

  }
}

setInterval(updateGradient,10);

http://codepen.io/quasimondo/pen/lDdrF