如何使用 HTML5 <canvas> clip()

Question

我是 HTML5 <canvas> 的新手，正在尝试制作一些东西，实际上是绘制 PORTAL2 徽标:)。

到现在为止

但是你可以看到腿从墙上伸出来，我想知道如何去除多余的油漆。

我想这可以通过clip() 函数完成，但我不知道如何使用它。

这就是我想要的

这是我正在尝试的代码，也可在此处的 JS Bin http://jsbin.com/exado5/edit 获得

//function to convert deg to radian
function acDegToRad(deg)
{
     return deg* (-(Math.PI / 180.0));    
}

//set fill color to gray
ctx.fillStyle = "rgb(120,120,120)";
//save the current state with fillcolor
ctx.save();

//draw 2's base rectangle
ctx.fillRect(20,200,120,35);
//bring origin to 2's base
ctx.translate(20,200);
//rotate the canvas 35 deg anti-clockwise
ctx.rotate(acDegToRad(35));
//draw 2's slant rectangle
ctx.fillRect(0,0,100,35);
//restore the canvas to reset transforms
ctx.restore();
//set stroke color width and draw the 2's top semi circle
ctx.strokeStyle = "rgb(120,120,120)";
ctx.lineWidth = 35;
ctx.beginPath();
ctx.arc(77,135,40,acDegToRad(-40),acDegToRad(180),true);
ctx.stroke();

//reset canvas transforms
ctx.restore();

//change color to blue
ctx.fillStyle = "rgb(0,160,212)";
//save current state of canvas
ctx.save();
//draw long dividing rectangle 
ctx.fillRect(162,20,8,300);
//draw player head circle
ctx.beginPath();
ctx.arc(225,80,35,acDegToRad(0),acDegToRad(360));
ctx.fill();

//start new path for tummy :)
ctx.beginPath();
ctx.moveTo(170,90);
ctx.lineTo(230,140);
ctx.lineTo(170,210);
ctx.fill();

//start new path for hand
//set lineCap and lineJoin to "round", blue color 
//for stroke, and width of 25px
ctx.lineWidth = 25;
ctx.lineCap = "round";
ctx.strokeStyle = "rgb(0,160,212)";
ctx.lineJoin = "round";
ctx.beginPath();
ctx.moveTo(222,150);
ctx.lineTo(230,190);
ctx.lineTo(270,220);
ctx.stroke();

//begin new path for drawing leg
ctx.beginPath();
ctx.moveTo(160,210);
ctx.lineTo(195,260);
ctx.lineTo(160,290);
ctx.stroke();

请帮忙。

Answer 1

添加这个：

...
//reset canvas transforms
ctx.restore();

ctx.beginPath();
ctx.moveTo(162, 20);
ctx.lineTo(162, 320);
ctx.lineTo(300, 320);
ctx.lineTo(300, 20);
ctx.clip();

//change color to blue
ctx.fillStyle = "rgb(0,160,212)";
//save current state of canvas
...

Answer 2

更改代码并检查它

//change color to blue
ctx.fillStyle = "rgb(0,160,212)";
//save current state of canvas
ctx.save();
//draw long dividing rectangle
ctx.fillRect(157,20,15,300);
//draw player head circle
ctx.beginPath();
ctx.arc(225,80,35,acDegToRad(0),acDegToRad(360));
ctx.fill();

//start new path for tummy :)
ctx.beginPath();
ctx.moveTo(170,90);
ctx.lineTo(230,140);
ctx.lineTo(170,210);
ctx.fill();

//start new path for hand
//set lineCap and lineJoin to "round", blue color
//for stroke, and width of 25px
ctx.lineWidth = 25;
ctx.lineCap = "round";
ctx.strokeStyle = "rgb(0,160,212)";
ctx.lineJoin = "round";
ctx.beginPath();
ctx.moveTo(222,150);
ctx.lineTo(230,190);
ctx.lineTo(270,220);
ctx.stroke();

//begin new path for drawing leg
ctx.beginPath();
ctx.moveTo(170,210);
ctx.lineTo(200,260);
ctx.lineTo(170,290);
ctx.stroke();