需求：

代码：

three.beginPath();

three.moveTo(x, y);

three.lineTo((x + w) + r * 0.4, y);

three.arc((x + w) + r, y - r * 0.8, r, 0.7 * Math.PI, 0.3 * Math.PI);

three.lineTo((x + (2 * w) + (2 * r)), y);

three.lineTo((x + (2 * w) + (2 * r)), y + h);

three.arc((x + (2 * w) + (2 * r)) + (r * 0.8), y + h + r, r, 1.2 * Math.PI, 0.8 * Math.PI);

three.lineTo((x + (2 * w) + (2 * r)), y + (2 * h) + (2 * r));

three.lineTo(x, y + (2 * h) + (2 * r));

three.lineTo(x, y + h + 2 * r - r * 0.4);

three.arc(x + (r * 0.8), y + h + r, r, 0.8 * Math.PI, 1.2 * Math.PI, true);

three.lineTo(x, y);

three.clip()

three.closePath();

three.drawImage(img, 0, 0, canvas_width, canvas_height);

three.draw()

模拟器效果：

真机运行效果：

显示整张图片，怎么回事？？？？求解