關於陰影有如下的幾個屬性
context.shadowOffsetX
context.shadowOffsetY
context.shadowBlur
其中blur的英文解釋爲模糊不清的，在canvas中填寫一個數值即可
如下例子
程序運行截圖如下：
源碼如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<canvas id="canvas" style="border: 1px solid #aaa; display: block; margin: 50px auto;">
當前瀏覽器不支持canvas
</canvas>
<script>
window.onload = function(){
let canvas = document.getElementById("canvas");
canvas.width = 800;
canvas.height = 800;
let context = canvas.getContext("2d");
context.shadowColor = "gray";
context.shadowOffsetX = 20;
context.shadowOffsetY = 20;
context.shadowBlur = 5;
context.fillRect(200, 200, 400, 400);
}
</script>
</body>
</html>
把參數換成這樣的：
<script>
window.onload = function(){
let canvas = document.getElementById("canvas");
canvas.width = 800;
canvas.height = 800;
let context = canvas.getContext("2d");
context.shadowColor = "gray";
context.shadowOffsetX = -50;
context.shadowOffsetY = -50;
context.shadowBlur = 50;
context.fillRect(200, 200, 400, 400);
}
</script>
運行截圖如下：
