HTML 5 Canvas Mouse over event on element (show tooltip) - html5-canvas

Question

I am working on a visualization project. Based on my data I am plotting hundreds of small circle on canvas. I want to add a mouse over event so that whenever a mouse is the enclosing area of a circle it will show some node property from my data as a tool tip or as text on the canvas.
My current drawCircle method
function drawCircle(canvas,x,y,r)
{
canvas.strokeStyle = "#000000";
canvas.fillStyle = "#FFFF00";
canvas.lineWidth = 2;
canvas.beginPath();
canvas.arc(x,y,r,0,Math.PI*2,true);
canvas.stroke();
canvas.fill();
canvas.closePath();
}
I have looked into kinetic.js
But can't figure it out how I can call my drawCircle [repetitively] method using their library.
Any help will be highly appreciated.

Answer 1

If you still want to use KineticJS, you would put the Kinetic shape stuff inside your drawCircle routine. This is basically pulled out of their tutorial and stripped down:
function drawCircle(stage,x,y,r) {
var circle = new Kinetic.Shape(function(){
var context = this.getContext();
// draw the circle here: strokeStyle, beginPath, arc, etc...
});
circle.addEventListener("mouseover", function(){
// do something
});
stage.add(circle);
}
If you don't want to use KineticJS after all, you will need to remember for yourself the positions and radii of every circle you drew, and then do something like this:
canvas.onmouseover = function onMouseover(e) {
var mx = e.clientX - canvas.clientLeft;
var my = e.clientY - canvas.clientTop;
// for each circle...
if ((mx-cx)*(mx-cx)+(my-cy)*(my-cy) < cr*cr)
// the mouse is over that circle
}