Heatmap has a build-in Divide by zero bug

[Spordoz]

Steps to reproduce

1. Have plot with log axis
2. Add heatmap which can have X0 = 0
3. Plot

Platform: Windows
.NET version: 7.0
Oxyplot verion: 2.1.2

Expected behaviour

Plot heatmap in log scaling

Actual behaviour

Divide by zero and crash plot with infinite width because if axis is logarithmic: right and top are log(x1/x0)

[VisualMelon]

You can't plot zero on a log axis: what sort of output are you expecting? We should probably detect this and throw a more useful exception.

[Spordoz]

You indeed can't plot 0 on a log. but it can have 0 if the axis is not a log axes. I just expect it to handle it a little better. Because it is possible and not uncommon to be able to switch between log and non-log axes with the press of a button. For it to break the moment you switch is not desired. I would expect it to check for 0 and maybe change it slightly so the calculation does not go into infinity.

[Spordoz]

In this case I was trying to use a heatmapseries to display the density of a scatterseries. The scatterpoint can be so spread out that it sometimes needs the option to switch the axes to log axes.

[VisualMelon]

I'd have thought you'd have to recalculate the density map when changing the axis (and so compute new bounds in the log space), otherwise the alignment will necessarily be wrong. I can't really think what the correct behaviour could possibly be for this beside throwing or plotting nothing, but if you have a mock-up showing what you expect please feel free to share it.

[Spordoz]

I think you are right on that part now that I think about it some more, Ill have to figure out why my code outputs a minimum X of 0 in log space. Because the spacing and density would indeed for sure be different in log space

[Spordoz]

It also seems that just adding a color axis prevents the scatterSeries from properly showing its non selected points, which is kinda weird. The heatmapseries unfortunately needs it.

[VisualMelon]

Re. ScatterSeries, I can't remember exactly what was going on, but that sounds like it's related to #1963