Javascript and Canvas Draw Circle with Hole in Middle - Stack Overflow

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I want to draw something like a donut, so a circle with a hole in the middle. I tried using ctx.clip(), but I realized it limits the path to inside, and I want it to limit the path to the outside.

Things to note:
this.lineWidth is how thick the "rim" or the outside portion is

    ctx.beginPath();
    // this should be the hole
    ctx.arc(this.x,this.y,this.r,0,Math.PI*2,false);
    ctx.clip();
    // this should be the outside part
    ctx.arc(this.x,this.y,this.r+this.lineWidth,0,Math.PI*2,false);
    ctx.fillStyle = "#00ff00";
    ctx.fill();

Instead I'm getting a filled-in circle because it's limiting the path to inside the smaller arc instead of outside it. Is there another method that does the opposite of clip()?

I want to draw something like a donut, so a circle with a hole in the middle. I tried using ctx.clip(), but I realized it limits the path to inside, and I want it to limit the path to the outside.

Things to note:
this.lineWidth is how thick the "rim" or the outside portion is

    ctx.beginPath();
    // this should be the hole
    ctx.arc(this.x,this.y,this.r,0,Math.PI*2,false);
    ctx.clip();
    // this should be the outside part
    ctx.arc(this.x,this.y,this.r+this.lineWidth,0,Math.PI*2,false);
    ctx.fillStyle = "#00ff00";
    ctx.fill();

Instead I'm getting a filled-in circle because it's limiting the path to inside the smaller arc instead of outside it. Is there another method that does the opposite of clip()?

• javascript
• canvas

Share Improve this question Follow asked May 4, 2016 at 22:10 Tyler DaltonTyler Dalton 6911 silver badge66 bronze badges

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2 Answers 2

Sorted by: Reset to default 6

I found this solution http://jsfiddle/Hnw6a/:

var can = document.getElementById('canvas1');
var ctx = can.getContext('2d');

//ctx.arc(x,y,radius,startAngle,endAngle, anticlockwise);  

ctx.beginPath()
ctx.arc(100,100,100,0,Math.PI*2, false); // outer (filled)
ctx.arc(100,100,55,0,Math.PI*2, true); // outer (unfills it)
ctx.fill();

With following canvas node:

<canvas id="canvas1" width="500" height="500"></canvas>

Set the linewidth to the desired width, draw your circle, and use "ctx.stroke();". Note that this doesn't allow you to fill the inner circle with a color.

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