Allow label-transform to place labels out of a chart's boundary with padding: 'Infinity' or Infinity

[chanwutk]

Add an option to label-transform.
Allow padding: 'inf'.

[domoritz]

Hmm, can someone not already use Infinity? I think we could support your new use case with the existing API of numbers.

[chanwutk]

@domoritz Do you mean we should let users pass in the value Infinity instead?
I thought that JSON does not support Infinity like JavaScript.

[domoritz]

Ahh, right. We should still support it for people who don't use Vega via json, I think.

[chanwutk]

So, should we make the behavior for padding: Infinity to be the same as padding: 'inf'?

[domoritz]

So, should we make the behavior for padding: Infinity to be the same as padding: 'inf'?

I would expect that to be the case.

[chanwutk]

Should the string value be 'inf' or 'infinity'?

[jheer]

The nice part about 'inf' is that it is fairly readable, though I do think 'Infinity' is clearer and more consistent with JS numbers. However, that also changes the type signature of the parameter... One alternative might include using null to indicate no bounds, but I think that might be confusing for a parameter named "padding" -- I'd associate that with having no padding (or at least a default value). Another option might be to use negative numbers to indicate Infinite padding -- that is not as clear as text but seems reasonable as a way of saying "no limits" and keeps the types tidier (unless we already support negative numbers as a way of forcing an inset margin). Any thoughts on this, @chanwutk or @domoritz? I'm OK moving ahead with the text string 'Infinity' unless someone strongly prefers another option.

I also agree with Dominik that numeric Infinity should be supported for specs that are defined in JS directly (not JSON text).

[chanwutk]

Thank you for the comment.
We already support negative padding value (this will tighten the space allowed for labels to be placed).
I am also OK with the text string 'Infinity'.

[jheer]

OK, so let's go with 'Infinity' and then I think we can merge.

[jheer]

I see that that the typings have been updated, but the metadata for Vega's JSON schema has not been updated:

vega/packages/vega-label/src/Label.js

Line 62 in cc7733f

{ name: 'padding', type: 'number', default: 0 },

The parsing for JSON schema types is here: https://github.com/vega/vega/blob/master/packages/vega-schema/src/transform.js#L44

Unfortunately, I don't think we support union types at the moment, only the "flat" types listed in the switch statement in the linked method in vega-schema above. This design was intentional, to avoid having overloaded parameter types. Unfortunately, I think that prevents the design decided upon here. Sorry I didn't realize/remember this sooner.

[chanwutk]

I see.
How about if we omit padding, the padding is default to 0.
But, if we set padding to null, then the padding can be Infinity?

[jheer]

Yes, null would work. We just need to include null: true as part of the parameter metadata.