HTML canvas shadowOffsetY 属性

示例

绘制一个矩形，其阴影放置在矩形顶部位置下方 20 像素处：

<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
您的浏览器不支持 HTML5 canvas 标签。</canvas>

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.shadowBlur = 10;
ctx.shadowOffsetY = 20;
ctx.shadowColor = "black";
ctx.fillStyle = "red";
ctx.fillRect(20, 20, 100, 80);
</script>

JavaScript:

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.shadowBlur = 10;
ctx.shadowOffsetY = 20;
ctx.shadowColor = "black";
ctx.fillStyle = "red";
ctx.fillRect(20, 20, 100, 80);