Changed rendering of baseline and area series when using scaleMargins

[markeasting]

Type of PR:
Enhancement

PR checklist:

• Addresses an existing issue: fixes Baseline series should use min/max price range in visible range to calculate gradient stops #1005
• Includes tests
• Documentation update

Overview of change:
This change will make the rendering of color stops in the baseline and area series gradients more consistent when using scaleMargins.

The gradient will now always reach the full color whether it is scaled to the top or bottom of the view (as I'd expect from setting its color options).

Is there anything you'd like reviewers to focus on?
The gradient is only changed when using a custom price scale, since it seems that these cannot be moved manually. Is this correct? Otherwise, the gradient will go into negative values, giving unwanted results.

Furthermore, I'm using the code below to check whether or not we are on a custom price scale:

const isCustomScale = priceScale.id() !== 'right' && priceScale.id() !== 'left';

Not sure if this is the best method, open for suggestions. Maybe use the DefaultPriceScaleId enum?

[timocov]

See comments. Also, could you add tests for this feature please? Let me know if you need any help or additional information.

[timocov]

If you don't mind let's revert this. This folder should in your global gitignore since it has no in common with the project itself.

[timocov]

well, I don't think that it should be like that. Instead, we need to get min/max coordinates for a visible range of this series. If we'll do this we won't need to check whether it is a "custom" scale or not because it will work automatically for any series. See my comment here #1005 (comment)

[timocov]

we have this._items where we can get all coordinates for each item, but please make sure that you use this._itemsVisibleRange to iterate over that array properly.

[timocov]

also, you could take a look at _convertToCoordinates method, which is used to update coordinates, probably we could change override it here and calculate the data only once and save it somewhere.

[SlicedSilver]

Updates:

• This change of behavior should be an option.
• Need to perform an investigation on the desired behavior when margins are negative.