有没有办法给jQuery添加角度渐变knob插件,以便它从一种颜色开始,沿着弧线,变成另一种颜色?
最佳答案
我在互联网上寻找解决方案,但没有人尝试过或发布解决方案。最后我发布一个问答。如果有人有更好的解决方案,请与我们分享。
在初始化期间,我重写了绘制方法并检查了属性shaded=“true”。如果存在,就会形成一个渐变,从白色开始向 fgColor 移动。要选择白色以外的起始颜色,请设置属性 shadeColor="#(颜色十六进制代码)"。
<input class="knob" value="95" autocomplete="off" data-readOnly=true data-fgColor="#FF0000" data-bgColor="transparent" shaded="1" shadeColor="#00FF00"/>
<script>
$(function(){
$('.knob').knob({
draw : function () {
var a = this.angle(this.cv) // Angle
, sa = this.startAngle // Previous start angle
, sat = this.startAngle // Start angle
, ea // Previous end angle
, eat = sat + a // End angle
, r = 1;
this.g.lineWidth = this.lineWidth;
if(this.$.attr('shaded')){
var color1 = r ? this.o.fgColor : this.fgColor;
var color2 = this.$.attr('shadeColor') ? this.$.attr('shadeColor') : '#ffffff';
var grad = getGradient(color2, color1);
var saDeg = parseInt((sa * 180 / Math.PI) % 360);
var eatDeg = parseInt((eat * 180 / Math.PI) % 360);
for(var angle = saDeg;(angle % 360) != eatDeg;angle++){
sat = angle * (Math.PI / 180);
eat = (angle + 2) * (Math.PI / 180);
if(grad.color2[0] != grad.color1[0] && (angle + 1) % grad.steps[0] == 0){
grad.color1[0] += grad.adder[0];
}
if(grad.color2[1] != grad.color1[1] && (angle + 1) % grad.steps[1] == 0){
grad.color1[1] += grad.adder[1];
}
if(grad.color2[2] != grad.color1[2] && (angle + 1) % grad.steps[2] == 0){
grad.color1[2] += grad.adder[2];
}
color = '#' + toHex(grad.color1[0]) + toHex(grad.color1[1]) + toHex(grad.color1[2]);
this.g.beginPath();
this.g.strokeStyle = color;
this.g.arc(this.xy, this.xy, this.radius, sat, eat, false);
this.g.stroke();
}
} else {
this.g.beginPath();
this.g.strokeStyle = r ? this.o.fgColor : this.fgColor ;
this.g.arc(this.xy, this.xy, this.radius, sat, eat, false);
this.g.stroke();
}
return false;
}
});
});
function getGradient(color1, color2){
var ret = new Object();
ret.color1 = new Array();
ret.color2 = new Array();
ret.steps = new Array();
ret.adder = new Array();
color1 = color1.replace('#','');
ret.color1[0] = parseInt(color1.slice(0,2), 16),
ret.color1[1] = parseInt(color1.slice(2,4), 16),
ret.color1[2] = parseInt(color1.slice(4,6), 16);
color2 = color2.replace('#','');
ret.color2[0] = parseInt(color2.slice(0,2), 16),
ret.color2[1] = parseInt(color2.slice(2,4), 16),
ret.color2[2] = parseInt(color2.slice(4,6), 16);
ret.steps[0] = (ret.color1[0] == ret.color2[0])? 0 : parseInt(360 / Math.abs(ret.color1[0] - ret.color2[0])),
ret.steps[1] = (ret.color1[1] == ret.color2[1])? 0 : parseInt(360 / Math.abs(ret.color1[1] - ret.color2[1])),
ret.steps[2] = (ret.color1[2] == ret.color2[2])? 0 : parseInt(360 / Math.abs(ret.color1[2] - ret.color2[2])),
ret.adder[0] = (ret.color1[0] > ret.color2[0])? -1 : 1;
ret.adder[1] = (ret.color1[1] > ret.color2[1])? -1 : 1;
ret.adder[2] = (ret.color1[2] > ret.color2[2])? -1 : 1;
return ret;
}
function toHex(number){
number = number.toString(16);
if(number.length < 2){
number = '0' + number;
}
return number;
}
</script>
它为每一度绘制一个单独的圆弧(为了平滑起见,圆弧角度为 2 度而不是 1 度)。弧线的颜色经历从fgColor到shadeColor的过渡。
颜色混合效果就像油漆混合而不是光混合,所以如果你从绿色开始走向红色,你将不会在中心得到黄色阴影。具有光混合效果看起来很酷,但不知道到底如何做到这一点。而且它不是一个优化良好的代码,它只是一个解决方案。巨大的改进空间..
关于canvas - jquery旋钮角度渐变,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/14731054/