[SIP] Add Palette Type Control to Treemap Chart

[hassaansaleem28]

[SIP] Add Palette Type Control to Treemap Chart

Motivation

Currently, Treemap charts in Superset always rely on categorical palettes.
There is no support for automatically switching to sequential palettes when metric values vary, and users have no explicit way to choose between sequential and categorical palettes.

This SIP proposes to improve the user experience by:

1. Introducing automatic palette logic (via PR #36847, pending review).
2. Exposing a new form control so users can override the behavior and explicitly select their preferred palette type.

Proposed Change

Add a new form control in Treemap chart settings:

• Palette Type (SelectControl)
  • Options: auto (default), sequential, categorical.
  • Default: auto (preserves current behavior once PR fix(treemap): restore sequential coloring + remove label box, 1px gap (fixes #36807) #36847 is merged)

Implementation details:

• Add control in controlPanel.ts.
• Update transformProps.ts to respect formData.paletteType.
• Extend Jest tests in transformProps.test.ts to cover all three modes.
• Default remains auto to avoid breaking existing dashboards.

Screenshots/mocks:

• Dropdown in chart settings showing palette type options.
• Example Treemap with sequential palette vs categorical palette.

New or Changed Public Interfaces

• Chart Controls: New paletteType option in Treemap chart control panel.
• Visualization Behavior: Treemap rendering logic updated to respect user choice.
• No changes to REST endpoints, CLI, or deployment.

New dependencies

• None. Uses existing getSequentialSchemeRegistry and getCategoricalSchemeRegistry utilities already in Superset.

Migration Plan and Compatibility

• No database migrations required.
• Default remains auto, so existing dashboards continue to render identically.
• Users can opt into sequential/categorical explicitly if desired.

Documentation

• Update Superset user documentation to include the new Palette Type option in Treemap chart settings.
• Add screenshots showing how to select sequential vs categorical palettes.
• Clarify that auto is the default and preserves existing behavior.
• Update the Charts → Treemap section in Superset docs to reflect this new control.

Rejected Alternatives

• Keep only auto logic: Would improve defaults but still leave users without control.
• Expose only sequential palettes: Too restrictive; categorical palettes are still useful for discrete metrics.
• Custom palette editor: Out of scope for this SIP; more complex and requires separate discussion.

[hassaansaleem28]

Happy to provide mocks or start drafting the implementation once there’s consensus.
Looking forward to feedback from the community and committers.

[dosubot]

Thanks for offering to provide mocks and help with implementation. Your SIP is well-aligned with ongoing theming and customization efforts in Superset, and the need for a Palette Type control in Treemap charts is clear—currently, only categorical palettes are supported, and there’s no user-facing way to select or switch palette types. The proposed approach fits existing UI patterns and would require new code in the control panel, type definitions, and transform logic, but no breaking changes or new dependencies. Recent theming groundwork (like passing vizType for theme overrides) doesn’t yet address palette selection, so your proposal fills a real gap source.

Encouraging community and committer feedback here will help drive consensus. If anyone has thoughts, suggestions, or concerns, now’s a great time to share them so the proposal can move forward! If you need more technical details or want help surfacing related code or prior art, let me know.

To reply, just mention @dosu.

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