Option for <canvas> padding

[silverwind]

Very minor issue here with a chart with a line width of 4 where the line and highlight dot is partially cut off on 0 values:

Maybe have a option to define a padding on the <canvas> area? I'd define a 2px padding in this case to accommodate the line width.

[leeoniya]

sounds doable.

[leeoniya]

this is now possible to do externally:

https://leeoniya.github.io/uPlot/demos/pad-scale.html

i probably won't add a built-in padding feature because the heuristics can get pretty opinionated and complex, depending on the data & requirements.

another neat thing is the elegant (imo) external impl of mousewheel zooming:

https://leeoniya.github.io/uPlot/demos/wheel-zoom.html

[silverwind]

Very nice, thanks. I will play with this soon.

It might be just me but the dot on the first example seems a bit off-centered:

I think the dot position might not yet take the line width into account. I guess I'd also increase the dot radius a bit with, is there a option for it yet?

[leeoniya]

It might be just me but the dot on the first example seems a bit off-centered: I think the dot position might not yet take the line width into account.

there were a couple rounding issues that should be fixed now. it's never gonna be perfect since all interactive elements are in the DOM while the grid + trendlines are on canvas (which follows devicePixelRatio). feel free to PR any improvements, though.

I guess I'd also increase the dot radius a bit with, is there a option for it yet?

i've moved the dot sizing logic to JS and it's now relative to series line width: Math.max(5, width * 2 - 1). additionally, series.class now exists and will get tacked onto the cursor points & legend, so you can tweak those further in css as required. at some point it might be good to add full customization like providing ready-to-go dom elements for the cursor points, but that'll likely be considered when i give more thought to #10, post 1.0.

[leeoniya]

@silverwind as of 0bbe163, the custom padding should no longer be necessary. now that the canvas goes extends outside the plotting area, it was a matter of adjusting the clipping regions for the paths and [new!] points.

if you look at https://leeoniya.github.io/uPlot/demos/pad-scale.html, there's no longer anything custom there. i'll remove this demo before 1.0, since it no longer demonstrates anything. i might re-internalize uPlot.rangeNum(), since it was first exposed specifically for this purpose.