issue 18 : Inverted background colors

[alixdamman]

No description provided.

[gdementen]

You shouldn't recreate the gradient object over and over for each cell! Why not storing it in self.bg_gradient?

Also, I wonder if we couldn't get rid of bgcolor_enabled: if all bg color goes through self.bg_gradient, I think self.bg_gradient is not None <=> bgcolor_enabled.

[alixdamman]

I may misunderstood the LinearGradient class. It is possible to change positions without changing colors, right?

[gdementen]

No, it is not really meant to work at the moment (*), but you can still only create the gradient object when vmin/vmax changes, not for each cell displayed.

Actually, setting the gradient .positions attribute directly should work, but I wouldn't do that unless we wrap that in a property to make sure .positions and .colors keep the same size.

If you go down that route, maybe changing the constructor to take positions and colors separately, would make it more obvious that we can change either individually.

[alixdamman]

If we drop bgcolor_enabled, it means that we need to create a new LinearGradient when vmin and vman are changed but also in bgcolor() method if state > 0?

[gdementen]

Yes, I did not realize that. Forget it then, that seems more trouble than it is worth.

[alixdamman]

In DataArrayModel.data(), what is the purpose of the following piece of code? :

    bg_value = self.bg_value
     x, y = index.row(), index.column()
     # FIXME: this is buggy on filtered data. We should change
     # bg_value when changing the filter.
     idx = y + x * bg_value.shape[-1]
     value = bg_value.data.flat[idx]
     return self.bg_gradient[value]

The background color of each cell is given by its position?

[gdementen]

the value used to compute the background color comes from another array. This is used to let compare color values depending on the difference between arrays instead of the array values themselves. This code is a hack though and (as the comment states) breaks as soon as the data is filtered.