canvas rounded rectangle

canvas_round_rect.js

var roundRect = function(ctx,o) {
    if(!ctx || !o.x || !o.y || !o.w || !o.h || !o.r) {
        return;            
    }

    var x = o.x,
        y = o.y,
        w = o.w,
        h = o.h,
        r = o.r,
        s = o.stroke,
        f = o.fill;
        
    ctx.save();
    r = (r*2<w && r*2<h) ? r : (w<h) ? w/2 : h/2;    

    ctx.beginPath();
    ctx.moveTo(x+r,y);
    // top and top right
    ctx.arcTo(x+w,y,x+w,y+h-r,r);   
    // bottom right and bottom
    ctx.arcTo(x+w,y+h,x+r,y+h,r);
    // bottom left corner and left
    ctx.arcTo(x,y+h,x,y+r,r);
    // top left corner
    ctx.arcTo(x,y,x+r,y,r);
    
    if(s) { 
        if(o.strokeStyle){ctx.strokeStyle = o.strokeStyle;}
        ctx.stroke(); 
    }
    if(f) { 
        if(o.fillStyle){ctx.fillStyle = o.fillStyle;} 
        ctx.fill(); 
    }
    
    ctx.restore();
};