Optional round to power-of-two zooming? about d3-zoom HOT 6 CLOSED

The "wheel" event is remarkably un-configurable, including the hardcoded 500 constant. I would like to have some options here.

1. would a PR including support for dynamic configuration of this 500 value be wanted/accepted?

2. alternatively, what about a user-specified callback that converts a normalized wheel delta value to the final k value?

from d3-zoom.

@mbostock what is your opinion re. my previous comment? Would you accept a PR as described?

from d3-zoom.

Your comment is unrelated to this issue, which is about whether the dblclick event should round to the nearest power-of-two zoom level, or alternatively whether the wheel and touch gestures should round to the nearest power-of-two zoom level after the gesture ends.

If you want an immediate solution, you can remove or replace the wheel event listener registered by the zoom behavior:

selection
    .call(zoom) // Register the zoom behavior as normal.
    .on("wheel.zom", wheeled); // Replace the wheel listener with your own.

In your wheeled function, you can then programmatically drive the zoom behavior however you like using zoom.transform.

I think it’d be reasonable to have a zoom.wheelDelta function whose default implementation is:

function wheelDelta() {
  return -d3.event.deltaY * (d3.event.deltaMode ? 120 : 1) / 500);
}

This function could then be configured (optionally as a constant, which is then promoted to a function) to change the behavior.

from d3-zoom.

Your comment is unrelated to this issue, which is about whether the dblclick event should round to the nearest power-of-two zoom level, or alternatively whether the wheel and touch gestures should round to the nearest power-of-two zoom level after the gesture ends.

I am terribly sorry for using a wrong issue. I considered this one as a general question of d3-zoom's configurability (especially regarding the wheel event).

If you want an immediate solution, you can remove or replace the wheel event listener registered by the zoom behavior:

I am aware of this approach. But rather than introducing a custom solution, improving D3's sounds like a better idea to me.

I think it’d be reasonable to have a zoom.wheelDelta function whose default implementation is:

Cool, I will try to hack something together and send a PR.

Sorry again for posting in a wrong place.

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Power-of-two rounding on dblclick was removed in 31d895f.

from d3-zoom.

If we allow zoom.scaleBy to take a reference point #178, rather than using only the viewport centroid, then this will be fairly easy to do programmatically, so I don’t think we need a separate issue for this special case.

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