Tick Config exports `bandSize` which seemingly has no effect; should it be `size`?

[joelostblom]

Bug Description

If you try the example in the docs, you will see that changing bandSize has no effect either for vertical or horizontal ticks. Changing the argument name to size instead will change the length of the tick as expected.

Is the wrong parameter name exported for tickConfig, so it should be size instead of bandSize? (and the docstring changed to length instead of width?

vega-lite/src/mark.ts

Lines 671 to 680 in b9f3b14

	export interface TickConfig<ES extends ExprRef | SignalRef>
	extends MarkConfig<ES>, TickThicknessMixins, RectConfig<ES> {
	/**
	* The width of the ticks.
	*
	* __Default value:__ 3/4 of step (width step for horizontal ticks and height step for vertical ticks).
	* @minimum 0
	*/
	bandSize?: number;
	}

[Adeyinka1]

Hi, I’d like to work on this issue.

I’ll reproduce the behavior and verify whether bandSize is not being applied correctly in the tick mark implementation, and whether size is the intended property. I’ll then propose a fix to align the configuration with the actual rendering behavior.

[joelostblom]

Thanks for offering to work on this @Adeyinka1. Feel free to put up a PR with the relevant fixes if you confirm the reported issue.

[Adeyinka1]

Hi @joelostblom, I dug into this a bit and was able to trace the issue further.

TickConfig exposes bandSize, but the sizing path in getBandSize() (src/channeldef.ts) appears to only check size and then fall back to timeUnitBandSize, discreteBandSize, and continuousBandSize. I couldn’t find a code path that actually reads tick.bandSize, which would explain why changing bandSize has no effect while size does.

I’m planning to put together a backward-compatible fix so bandSize is respected for tick marks, while preserving the current behavior of size.