Skip non-numeric values in image trace plot

[archmoj]

Fix in respect to @emmanuelle 's comment
#4301 (comment)
i.e. by drawing those pixels with full transparency.

before vs after demo

@alexcjohnson

cc: @nicolaskruchten
cc: @plotly/plotly_js

[alexcjohnson]

Beautiful, love the new mock! 💃

[etpinard]

Nice PR @archmoj - can I why you made some of the colorscale attributes editType: 'calc' now? I suspect this was to make the plot step faster, but I'd like to confirm with you.

[archmoj]

@etpinard Yes. That was for speed and ( if I recall ) not for calling isNumeric during the plot.

[etpinard]

Yes. That was for speed and ( if I recall ) not for calling isNumeric during the plot.

Yeah, that's very nice. Most colorscale computations for other traces are done during the calc step, so this is fantastic 👍