属性
shadowOffsetX = float           阴影向右偏移量
shadowOffsetY = float           阴影向下偏移量
shadowBlur = float              阴影模糊效果
shadowColor = color             阴影颜色设置阴影
const canvas = document.getElementById(‘canvas‘);
const ctx = canvas.getContext(‘2d‘);
ctx.shadowOffsetX = 10;
ctx.shadowOffsetY = 10;
ctx.shadowBlur = 10;
ctx.shadowColor = ‘rgba(0, 0, 0, 0.5)‘;
ctx.fillRect(25, 25, 100, 100);原文:https://www.cnblogs.com/ye-hcj/p/10357475.html