Add pie chart visualization template

[skaphan]

Summary

• Add embedded pie chart web component with templates and static assets
• Add pie chart tab icon and nonblocking template for async loading
• Build pie chart data from processed Graph (respects config filters)
• Add hidePie setting following hideSankey/hideTabular pattern
• Pass config options (textForWinner, excludeFinalWinnerAndEliminatedCandidate) to component
• Initialize pie chart to final round on load
• Add 32 tests for graphToRCtab converter
• Fix tooltip positioning (position:fixed + operator precedence fix)

Response to feedback

Matching the candidate colors with the rest of the visualizations

Done.

The data doesn't seem to match the rest of the visualization. I suspect this is because you're reading directly from the JSON without viewing other config options.

Done. The pie chart now reads from the processed Graph (via a new graphToRCtab converter) instead of raw JSON, so it respects all config filters including excludeFinalWinnerAndEliminatedCandidate.

The other visualizations show Undeclared Write-Ins eliminated first but the pie chart hides UWI altogether.

We haven't been doing anything special about this. Not sure what the issue is.

The pie chart doesn't seem to respect any of the configuration options on the upload page (like "How to refer to the winner", "Hide winner because results are preliminary")

Done. textForWinner and excludeFinalWinnerAndEliminatedCandidate are now passed through from the config.

"Use first-round totals for all percentage calculations"

We do this by default. Do you need it to work from active votes if you don't have it this way?

The pie chart shows the first round on page load instead of the last round

Done.

We should have a setting that allows you to hide the Pie chart

Done. Added hidePie model field, config JS variable, settings checkbox, and tab hiding — following the exact hideSankey/hideTabular pattern. Not heavily tested but it's a mechanical copy of the existing pattern.

We should remove the extraneous buttons that don't match the rest of RCVis, like the "one small step" and the description at the bottom

Got rid of the description at the bottom (now behind a showCaptions prop, default false).

I'm going to push back a little on the "one small step" button. It is a useful feature when you're really trying to see what's going on. The animation is a three-phase thing:

1. Show the transfers that are going to be made
2. Move them to the candidates those votes are going to be transferred to
3. Merge them in with those candidates

We can rename or restyle the button, no problem, but I don't think it's helpful to remove it entirely. But for rcvis, it's really up to you. I will say though that without that, for my purposes I'd rather stick with a version that has it.

I'd like at least cursory tests that step through the visualization to ensure it doesn't break in the future

Added 32 tests for the graphToRCtab converter covering: structure validation, tally correctness, eliminations, multi-winner surplus, inactive ballots, no-threshold elections, the excludeFinalWinnerAndEliminatedCandidate flag, and the _stringify helper.

I'd like to run a PageSpeed Insights test to ensure no degradation in loading times

Please do, but be aware that all we're doing is downloading a piece of code that will be cached for the lifetime of the browser instance, so it only has to happen once per browser instance. The only downloading after that will be the parameters (the color map and JSON file) to be visualized.

[artoonie]

I haven't looked at the code, but the interface looks great, only a few small things remain:

1. Matching the candidate colors with the rest of the visualizations
2. The data doesn't seem to match the rest of the visualization. I suspect this is because you're reading directly from the JSON without viewing other config options. For example, in this JSON, the other visualizations show Undeclared Write-Ins eliminated first but the pie chart hides UWI altogether.
3. Similarly, the pie chart doesn't seem to respect any of the configuration options on the upload page (like "How to refer to the winner", " Hide winner because results are preliminary", "Use first-round totals for all percentage calculations"
4. The pie chart shows the first round on page load instead of the last round
5. We should have a setting that allows you to hide the Pie chart, just like we can hide the tabular and sankey formats. Some jurisdictions want control over which visualizations are visible.
6. We should remove the extraneous buttons that don't match the rest of RCVis, like the "one small step" and the description at the bottom
7. I'd like at least cursory tests that step through the visualization to ensure it doesn't break in the future
8. I'd like to run a PageSpeed Insights test to ensure no degradation in loading times

[skaphan]

Added 7 new tests for the pie chart feature:

testSimple.py (3 new + 1 updated):

• test_pie_vistype_renders — ?vistype=pie embedded URL returns 200
• test_pie_embedly_redirect — /vo/{slug}/pie redirects to /ve/{slug}?vistype=pie
• test_hide_pie_config — hidePie toggle propagates to JavaScript config
• test_cloudflare_purge — expected URLs updated to include pie paths (/vo/{slug}/pie and ?vistype=pie)

testGraphToRCtab.py (4 new in SpecialCharacterTests class):

• Tests that candidate names with HTML tags, quotes, commas, and other special characters survive the graph-to-RCTab JSON conversion without corruption