Add hoverongaps to heatmap and contour for suppressing hovers on missing data

[archmoj]

Resolves #4226.

A new attribute titled hovergaps is added to contour and heatmap for disabling hover when the z is missing.

@plotly/plotly_js

[etpinard]

A few questions:

• What about histogram2d and histogram2dcontour - do they currently show hover labels for out-sample (x,y) coordinates?
• What about surface - do hover labels ever show NaN values?

[archmoj]

• What about surface - do hover labels ever show NaN values?

surface plot won't be visible true with missing data.

[etpinard]

So this mean when hovergaps:false, zLabel and zLabelVal remain undefined, but we still pass pointData back to Fx.hover?

Does this mean that the hover label is suppressed, but the plotly_hover event is still getting triggered?

[archmoj]

Here is a codepen displaying the current behaviour with hoverongaps disabled.
Please let me know if you prefer not to have hover effects at all.
cc: @emmanuelle

[etpinard]

I think the behaviour in @archmoj above codepen is incorrect. Under hoverongaps: false, there should be no hover labels shown and no plotly_hover event triggered.

[archmoj]

Now fixed in 9269352.
new demo

[etpinard]

Fantastic!!

[etpinard]

surface plot won't be visible true with missing data.

What wait. What about -> https://codepen.io/etpinard/pen/LYYxRVO ?

[archmoj]

• What about histogram2d and histogram2dcontour - do they currently show hover labels for out-sample (x,y) coordinates?

histogram2d and histogram2dcontour apply null values as zeros.
So the hover on those areas display the zero and not any NaN.
demo.

[etpinard]

Very nicely done @archmoj

💃 for me!

[janosh]

Great feature! Thanks for implementing!