Feature: Add StackedPieChart

[jay-k98]

As described in #2003 a "Stacked Pie Chart" was requested. This Pull Request aims to add this feature.

Solution

The Implementation of [StackedPieChart] is very similar to [PieChart]. The biggest difference is drawing a Section with multiple Segments.

The radius of a segment is calculated like this:

SegmentRadius = SectionRadius * SegmentValue / TotalSectionValues

The sweep angles are then calculated like in [PieChart]

Todo's and Improvements

• Add drawing strokes
• Extend the Demo (add icon and more examples)
• Add tests
• Extract duplicate logic from [PieChart] and [StackedPieChart]

[codecov]

Codecov Report

❌ Patch coverage is 0% with 479 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.97%. Comparing base (32e75f5) to head (b88f01f).

Files with missing lines	Patch %	Lines
...t/stacked_pie_chart/stacked_pie_chart_painter.dart	0.00%	262 Missing ⚠️
...hart/stacked_pie_chart/stacked_pie_chart_data.dart	0.00%	111 Missing ⚠️
.../stacked_pie_chart/stacked_pie_chart_renderer.dart	0.00%	74 Missing ⚠️
...src/chart/stacked_pie_chart/stacked_pie_chart.dart	0.00%	20 Missing ⚠️
...rt/stacked_pie_chart/stacked_pie_chart_helper.dart	0.00%	8 Missing ⚠️
lib/src/utils/lerp.dart	0.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2004       +/-   ##
===========================================
- Coverage   92.49%   81.97%   -10.53%     
===========================================
  Files          50       55        +5     
  Lines        3731     4210      +479     
===========================================
  Hits         3451     3451               
- Misses        280      759      +479     

Flag	Coverage Δ
flutter	81.97% <0.00%> (-10.53%)	⬇️

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[imaNNeo]

Hi, thanks for your contribution.
I think we can use the current implementation of the PieChart to just add the stacked logic into it.
This way, we reuse a lot of code that we already wrote.

Just like what I did for the stacked bar chart here: #112

Please let me know your thoughts on it.

[jay-k98]

Hi, yeah thank you for responding! I wanted to hear your opinion about that. I'll implement analogous to #112 and add tests :)

[imaNNeo]

I appreciate it!
Thanks in advance.

[jay-k98]

Hi @imaNNeo i was on vacation but now I'm back and implemented the stacked logic for PieChart. I also updated tests and added a new sample for the example app. Looking forward to your feedback :)

[Bazni]

Hey 👋,
I think I commented at the wrong place the first time, sorry about that.

Thx for the work. I'm looking to do something like this:

Do you think I will be able to do it with your StackedPieChart?

[imaNNeo]

Hi @imaNNeo i was on vacation but now I'm back and implemented the stacked logic for PieChart. I also updated tests and added a new sample for the example app. Looking forward to your feedback :)

Can you please update your branch with the latest changes? Then I can check it again.
(You don't need to update the CHANGELOG.md)

[jay-k98]

Can you please update your branch with the latest changes? Then I can check it again. (You don't need to update the CHANGELOG.md)

Hey, I updated the branch and removed CHANGELOG.md changes.

[jay-k98]

Hey 👋, I think I commented at the wrong place the first time, sorry about that.

Thx for the work. I'm looking to do something like this:

Do you think I will be able to do it with your StackedPieChart?

Yes, the green and red part will definetly be possible. You can checkout the branch of this PR and run the example. Pie Chart Sample 4 is pretty close to the screenshot you provided.

About the grid you might need to get creative.. :D But I guess you could put two PieCharts in a Stack and use the "lower" PieChart to create the grid with section and segment outlines as well as labels. Hope this helps :)