html5 - drawing multiple circles - each filled with different images
Question
Alright so ive looked around and found a code that will successfulyl enable me to draw a circle on canvas and use that circle as a mask for my image.
The code looks like this: (codus to the real creater that i dont know)
var ctx = document.getElementById('your_canvas').getContext("2d");
ctx.arc(100,100, 50, 0, Math.PI*2,true); // you can use any shape
ctx.clip();
var img = new Image();
img.addEventListener('load', function(e) {
ctx.drawImage(this, 0, 0, 200, 300);
}, true);
img.src="/path/to/image.jpg";
Lets assume I want to have 5 different circles all with different images and all and each positioned differently.
Anyone got an idea on how id go about that?
2 answers
solution1
1 2013-03-15 02:15:23
Yep, pretty much what Matt said...
Here is code and a Fiddle: http://jsfiddle.net/m1erickson/Vu2Fm/
You can improve this code by using an image preloader to load all 5 of your images prior to drawing on the canvas.
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var img1=new Image();
img1.onload=function(){
var img2=new Image();
img2.onload=function(){
// draw a clipping circle and then an image to clip
ctx.save();
ctx.beginPath();
ctx.strokeStyle="blue";
ctx.arc(100, 100, 50, 0 , 2 * Math.PI, false);
ctx.stroke();
ctx.clip();
ctx.beginPath();
ctx.arc(100, 100, 50, 0 , 2 * Math.PI, false);
ctx.drawImage(img1,10,0);
ctx.restore();
// draw a second clipping circle and then an image to clip
ctx.save();
ctx.beginPath();
ctx.strokeStyle="green";
ctx.arc(275, 100, 75, 0 , 2 * Math.PI, false);
ctx.stroke();
ctx.clip();
ctx.beginPath();
ctx.drawImage(img2,150,0);
ctx.restore();
}
img2.src="http://dl.dropbox.com/u/139992952/coffee.png";
}
img1.src="http://dl.dropbox.com/u/139992952/house%20vector.png";
}); // end $(function(){});
</script>
</head>
<body>
<canvas id="canvas" width=400 height=250></canvas>
</body>
</html>
solution2
1 ACCPTED 2013-03-15 02:25:09
To keep the code short, create a function with parameters for the settings that will change from image to image.
Reusable function:
function drawImageCircle(ctx, circleX, circleY, radius,
imageX, imageY, imageWidth, imageHeight, imageUrl) {
var img = new Image();
img.onload = function(){
ctx.save();
ctx.beginPath();
ctx.arc(circleX, circleY, radius, 0, Math.PI*2, true);
ctx.clip();
ctx.drawImage(this, imageX, imageY, imageWidth, imageHeight);
ctx.restore();
};
img.src = imageUrl;
}
var ctx = document.getElementById('your_canvas').getContext("2d");
drawImageCircle(ctx, 100,100, 50, 0,0, 200,300, 'image1.jpg');
drawImageCircle(ctx, 400,400, 50, 300,300, 200,300, 'image2.jpg');
The use of save() and restore() is important when doing this more than once.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.