Hi, I have implemented a tool (which inherits from GestureTool) where user drags a line. User can then click on the line later to select it and edit it be dragging it around or moving its ends.

It looks like this:

In order to calculate if the user has clicked on a line, I have implemented the following function which works well:

```
ptOnLine(
pt_x: number,
pt_y: number,
ln_x1: number,
ln_y1: number,
ln_x2: number,
ln_y2: number,
slack: number = LINE_HIT_SLACK
) {
const d1 = Math.sqrt(Math.pow(pt_x - ln_x1, 2) + Math.pow(pt_y - ln_y1, 2));
const d2 = Math.sqrt(Math.pow(pt_x - ln_x2, 2) + Math.pow(pt_y - ln_y2, 2));
const d3 = Math.sqrt(
Math.pow(ln_x1 - ln_x2, 2) + Math.pow(ln_y1 - ln_y2, 2)
);
return d1 + d2 >= d3 - slack && d1 + d2 <= d3 + slack;
}
```

In order to calculate if the user has clicked on a knob (circle - approximated as a square), I have implemented the following function which works well:

```
ptInBB(
pt_x: number,
pt_y: number,
bbc_x: number,
bbc_y: number,
radius: number
): boolean {
return (
pt_x <= bbc_x + radius &&
pt_x >= bbc_x - radius &&
pt_y <= bbc_y + radius &&
pt_y >= bbc_y - radius
);
}
```

The problem is that this is currently calculated in screen coordinates which does not take zoom level into account. I would like to have this implemented in data coordinates instead to make it more usable for the user. But that would require me to somehow access the axis ranges from within the plugin. How do I do that?