我的问题与以下第二个(外部)矩形中使用的shadowBlur功能有关。在此矩形之后,这个shadowBlur功能适用于每个形状。(如果您注释掉第21和22行的shadowColor和shadowBlur行,并取消注释14和15行的shadowColor和shadowBlur行,则应该看到我所说的内容。)我的问题是,如何将shadowBlur应用于Canvas绘图的特定部分,而不是将其应用于每个后续的Canvas绘图部分。在这个例子中,我尝试为每个画布和上下文创建单独的变量,但问题仍然存在。
归属:这些例子基于来自html5canvastutorials.com的示例。
归属:这些例子基于来自html5canvastutorials.com的示例。
<!DOCTYPE html>
<html lang="en"
<head>
<script type="text/javascript">
function addRect(){
var canvas1=document.getElementById("myCanvas");
var ctx=canvas1.getContext("2d");
var canvas3=document.getElementById("myCanvas");
var ctx3=canvas3.getContext("2d");
ctx.rect(60,60,180,80);
ctx.fillStyle="green";
//ctx.shadowColor="black";
//ctx.shadowBlur = 10;
ctx.fill();
ctx3.lineWidth = 3;
ctx3.strokeStyle='red';
ctx3.shadowColor="black";
ctx3.shadowBlur = 10;
ctx3.strokeRect(45,45,210,110);
}
function addOval(){
var canvas2=document.getElementById("myCanvas");
var context=canvas2.getContext("2d");
// define center of oval
var centerX = 288;
var centerY = 250;
// define size of oval
var height = 100;
var width = 250;
var controlRectWidth = width * 1.33;
context.beginPath();
context.moveTo(centerX,centerY - height/2);
// draw left side of oval
context.bezierCurveTo(centerX-controlRectWidth/2,centerY-height/2,
centerX-controlRectWidth/2,centerY+height/2,
centerX,centerY+height/2);
// draw right side of oval
context.bezierCurveTo(centerX+controlRectWidth/2,centerY+height/2,
centerX+controlRectWidth/2,centerY-height/2,
centerX,centerY-height/2);
context.fillStyle="red";
context.fill();
context.lineWidth=5;
context.strokeStyle="blue";
context.stroke();
context.closePath();
}
</script>
</head>
<body onload="addRect(); addOval();">
<canvas id="myCanvas" width="700" height="400">
Your browser does not support the canvas element.
</canvas>
</body>
</html>