Bind event to shape on canvas
Question
How can I bind an event to a shape drawn on a canvas? I presumed this would work but I get an error.
<html>
<head>
<script type="application/javascript">
function draw() {
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
ctx.fillStyle = "rgb(200,0,0)";
var rec = ctx.fillRect (0, 0, 55, 50);
rec.onclick = function(){
alert('something');
}
}
</script>
</head>
<body onLoad="draw()">
<canvas id="canvas" width="300" height="300"></canvas>
</body>
</html>
3 answers
solution1
4 2012-09-29 08:54:20
Using Kineticsjs , you can handle shape events in a canvas as follows:
<script>
shape.on('mousedown mouseover' function(evt) {
// do something
});
</script>
solution2
4 ACCPTED 2010-05-09 16:50:43
Put the event handlers on the canvas element, and then use the mouse position to decide which conceptual part of the canvas the event is occurring on.
I haven't played with canvas all that much, but I wouldn't be surprised if there were already some libraries that help you manage event delegation to such imaginary elements.
solution3
3 2010-05-10 08:00:56
Sounds like you should be using svg instead since it allows you to add event listeners on shapes. I'd recommend checking out raphaeljs.com for a start.
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