用於畫布的裁剪區域外的Dropshadow

Question

我通過畫布將圖像裁剪成三角形，現在我想在它外面添加一個陰影。如何去做呢？

canvas1_img.src = "images/postcard.jpg"; 

var canvas_wd = 1600; 
var canvas_ht = 1000; 
var y1 = 330; 
var y2 = 682; 

canvas1.beginPath(); 
canvas1.moveTo(0, y1); 
canvas1.lineTo(0, y2); 
canvas1.lineTo(canvas_wd, canvas_ht); 
canvas1.lineTo(canvas_wd, 0); 
canvas1.closePath(); 
canvas1.clip(); 

canvas1.drawImage(canvas1_img,0,0); 

Answer 1

附近做canvas1.clip()

也是這一權利，而不是調用它canvas1，你應該CTX稱呼它，或上下文，因爲它不是一個畫布，這是一個方面，對不對？

ctx.shadowOffsetX = 2; // Sets the shadow offset x, positive number is right 
ctx.shadowOffsetY = 2; // Sets the shadow offset y, positive number is down 
ctx.shadowBlur = 4; // Sets the shadow blur size 
ctx.shadowColor = 'rgba(0, 0, 0, 0.6)'; // Sets the shadow color 
ctx.fillStyle = 'none' 
ctx.fill()