Fill HTML5 arc with a picture - HTML5 Canvas

问题:

I have a HTML5 Canvas (JSFiddle) that looks like:

I am creating the balls by the following method:

function createball(x,y,r,color){
    context.beginPath();
    context.arc(x,y,r,0,Math.PI*2,true);
    context.fillStyle = color;
    context.fill();

}

How can I fill the ball with image? I mean a image that might have patters or some natural color?

回答1:

You could create a pattern and set the ball's fillStyle to that pattern

Here's example code and a Demo:

var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;


var img=new Image();
img.onload=start;
img.src="https://dl.dropboxusercontent.com/u/139992952/multple/checkerboard.jpg";
function start(){
  var pattern=ctx.createPattern(img,'repeat');
  ctx.beginPath();
  ctx.arc(50,50,15,0,Math.PI*2);
  ctx.closePath();
  ctx.fillStyle=pattern;
  ctx.fill();
  ctx.stroke();
}

body{ background-color: ivory; }
#canvas{border:1px solid red;}

<h4>Source Image:</h4>
<img src='https://dl.dropboxusercontent.com/u/139992952/multple/checkerboard.jpg'>
<h4>Fill Circle with pattern made from source image</h4>
<canvas id="canvas" width=100 height=100></canvas>