Tabindex for new Objects in Canvas?

Creating a new object on mouseclick as a way for users to create reference points (which I call 'crumbs') when reading large web documents. I've got this working with a new Image() function, however, that won't let me assign a tabindex to each new image creat开发者_如何转开发ed by mouseclick (posX, posY). 'crumbtoggle' simply acknowledges that the crumb dropping tool has been selected.

working new Image() function:

function draw_crumb() 
{
var b_canvas = document.getElementById("b");
var b_context = b_canvas.getContext("2d");
var crumb = new Image();
crumb.src = "crumb.gif";
if(crumbtoggle.className == "on")
{
b_context.drawImage(crumb, posX-20, posY-20, 50, 75);
}
}

non-working new Object () function:

function draw_crumb() 
{
var b_canvas = document.getElementById("b");
var b_context = b_canvas.getContext("2d");
var crumb = new Object();
crumb.type = "button";
crumb.src = "crumb.gif";
crumb.tabindex = 1;
if(crumbtoggle.className == "on")
{
b_context.drawObject(crumb, posX-20, posY-20, 50, 75);
}
}

I've looked in to applying focus to the new Image objects, but that doesn't seem to be a good alternative to tabindex attributes. Any ideas would be greatly appreciated.

An HTML5 Canvas is like a real-world canvas with instantly-drying paint. When you paint a rectangle or line or image on the canvas, it becomes part of the canvas. You cannot later re-order the items, or move them relative to each other. It is not a separate entity that can get focus.

Any sort of focus management integrated with the browser's handling of focus will have to be done through form inputs or anchors recognized by the browser.

It's not clear to me why you need a canvas, or if you need one at all.