我有一个可视化器设置,它每7.5秒更改一次颜色,问题是,它立即完成了,您可以在fillStyle上使用.animate()吗?如果没有,是否有任何方法可以添加到fillStyle的过渡?
最佳答案
fillStyle
没有自动为其过渡设置动画的方法。
但是,创建动画循环以动画化过渡相当容易。
您要做的是在2.50秒内发生的动画循环中,每帧绘制两次疯狂的内容:
使用不透明度会在您的2.50秒内降低的起始颜色进行绘制。
绘制时,结束色的不透明度会在您的2.50秒内增加。
这是带注释的示例代码和演示:
// canvas related variables
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;
var duration=2.50;
// starting and ending colors
var rgbStart='#BC49FF';
var rgbEnd='#574FFF';
// calculate the # of frames that requestAnimationFrame can
// draw during the duration
var opacitySteps=parseInt(60*duration);
// set the current opacity step at its starting number (0)
var opacityStep=0;
// start the 2.5 second animation
requestAnimationFrame(animate);
function animate(time){
// calculate the current opacity as a percentage
// of opacityStep/opacitySteps
var opacity=100*(opacityStep/opacitySteps);
if(opacityStep>=opacitySteps-1){ opacity=100; }
// clear the canvas
ctx.clearRect(0,0,cw,ch);
// draw with the starting color using a lessening opacity
ctx.globalAlpha=(100-opacity)/100;
ctx.fillStyle=rgbStart;
ctx.fillRect(20,20,100,75);
ctx.strokeRect(20,20,100,75);
// draw with the ending color using a increasing opacity
ctx.globalAlpha=(opacity)/100;
ctx.fillStyle=rgbEnd;
ctx.fillRect(20,20,100,75);
ctx.strokeRect(20,20,100,75);
// clean up, reset globalAlpha to it's default of 1.00
ctx.globalAlpha=1.00;
// return if all steps have been played
if(++opacityStep>=opacitySteps){return;}
// otherwise request another frame
requestAnimationFrame(animate);
}
$('#again').click(function(){
opacityStep=0;
requestAnimationFrame(animate);
})
body{ background-color: ivory; }
#canvas{border:1px solid red;}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<h4>Transitioning a fillStyle over 2.50 seconds</h4>
<br><button id=again>Again</button>
<br><canvas id="canvas" width=300 height=300></canvas>
关于jquery - fillStyle颜色上的过渡,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/29447306/