[Bug] `dataZoom.filterMode: 'none'` breaks sampling

[ransoing]

Version

6.0.0

Link to Minimal Reproduction

https://codepen.io/ransoing/pen/pvbOLPq

Steps to Reproduce

Uncomment the // filterMode: 'none', line in the javascript to see the data change resolution

Current Behavior

When using a high resolution dataset and turning on series-line.sampling, the chart should always show full resolution data when you zoom in a sufficient amount. However, when dataZoom.filterMode is set to none or empty, the chart no longer performs progressive disclosure, and only shows the lowest-resolution sampled data regardless of how far you zoom in.

With filterMode: 'filter' and sampling: 'lttb', zoomed in on a high-res dataset:

The same situation as above, but with filterMode: 'none':

Expected Behavior

When dataZoom.filterMode is set to none, and when zoomed in enough, the chart should look the same whether or not sampling is turned on. The chart should look like below with dataZoom.filterMode: 'none' and sampling: 'lttb':

Instead, the chart looks like the second screenshot I posted in "Current Behavior".

Environment

- OS: Mac OS 14.8.3
- Browser: Chrome 144
- Framework:

Any additional comments?

No response

[helgasoft]

Current Behavior confirmed, explanation is somewhat different however.
Setting sampling: 'lttb' means that less points should be displayed regardless of dataZoom.
When filterMode: 'filter' all points are shown - this is a bug.
When filterMode: 'none' less points are shown - correct, as expected.
Demo

[ransoing]

The documentation is unclear how dataZoom is supposed to interact with sampling. However, see the attached video showing a slow zoom out -- the plot resamples as I zoom, in order to keep a reasonable number of points drawn (not more points than there are pixels), in order to improve performance. If sampling is supposed to draw fewer points regardless of dataZoom, then this dynamic resampling would be a bug. I can't imagine that this behavior is a bug, especially since it's much more useful than always drawing fewer points. If it always drew fewer points, dataZoom would not be of much use when combined with sampling, as zooming in would not reveal additional details in the data.

sampling-zoomout.mp4

[helgasoft]

@ransoing, agree, makes perfect sense. My reasoning was wrong.
Added bug to problem list in #20392