maxWidth设置文字的最大宽度，如果低于文字宽度会被压缩，运用较少
fillText()是填充，strokeText()是描边
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
* {
margin: 0;
padding: 0;
}
</style>
</head>
<body>
<canvas width="600" height="600" id="canvas"></canvas>
<script>
let canvas = document.querySelector("#canvas");
let context = canvas.getContext("2d");
context.filter = "blur(10px)";
// 添加滤镜
let image = new Image();
image.src = "./bj.jpg";
image.onload = () => {
context.drawImage(image, 0, 0, 500, 500, 100, 100, 500, 500);
};
</script>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
* {
margin: 0;
padding: 0;
}
</style>
</head>
<body>
<canvas width="600" height="600" id="canvas"></canvas>
<script>
let canvas = document.querySelector("#canvas");
let context = canvas.getContext("2d");
context.translate(100, 100);
// 位移(基于原点位置)
context.rotate((45 * Math.PI) / 180);
// 旋转(基于原点位置)
context.scale(1, 1);
// 缩放(x方向,y方向)
context.fillRect(0, 0, 100, 100);
</script>
</body>
</html>
transform相当于一个集合的api，可进行位移旋转缩放
