Add Table<GradientStops> gradient rendering

[YohYamasaki]

Part of #2779

This PR fixes the renderer of Table<GradientStops> and allows using the gradient tool for the gradient position control.

Demo

Screen.Recording.2026-04-03.at.13.52.06.mp4

Notes

• Use Table's transform for the control geometry instead of the current Gradient struct's start/end. The initial transform, created upon node insertion, places the gradient from (0, 0) to (100, 0).
• Add support for thumbnail rendering. To not break the semantics of BoundingBox::bounding_box for infinite footprint layers yet correctly render the contents in a thumbnail, added BoundingBox::thumbnail_bounding_box, which virtually applies the boundary based on the stops of a gradient.
• The gradient tool converts between Table<GradientStops> and Gradient internally to reuse existing logic. This should be refactored when it becomes ready to use Table<GradientStops> for all gradient use cases.
• No support for Radial gradient currently. This should be implemented after adding a custom columns feature to the Table.

[gemini-code-assist]

Code Review

This pull request introduces support for GradientTable (a table of GradientStops) throughout the editor and rendering pipeline. Key changes include the addition of the GradientTableSet message, updates to the gradient tool to support table-based gradients, and the implementation of Vello rendering for these tables using manual encoding. Furthermore, a thumbnail_bounding_box method has been added to the BoundingBox trait to refine bounding box calculations for thumbnails. Review feedback highlights an inconsistency in default transform scales and potential numeric stability issues in SVG rendering for infinite fills.

[cubic-dev-ai]

5 issues found across 19 files

Confidence score: 3/5

• There is concrete user-facing regression risk: in node-graph/libraries/graphic-types/src/artboard.rs, Artboard::thumbnail_bounding_box currently mirrors bounding_box, which can miss child thumbnail-specific finite bounds (such as gradients) and produce incorrect thumbnails.
• In node-graph/libraries/rendering/src/renderer.rs, skipping gradient layers in Outline mode can make content disappear in that view, which is a noticeable behavior break even if normal rendering still works.
• The fallback transform mismatch in editor/src/messages/portfolio/document/node_graph/node_properties.rs versus the canonical default in value.rs (identity vs 100x scale) adds inconsistency risk for empty gradient tables; maintainability drift is also signaled by duplicated thumbnail-bound logic in node-graph/libraries/core-types/src/table.rs.
• Pay close attention to node-graph/libraries/graphic-types/src/artboard.rs, node-graph/libraries/rendering/src/renderer.rs, editor/src/messages/portfolio/document/node_graph/node_properties.rs, node-graph/libraries/core-types/src/table.rs, and editor/src/messages/tool/tool_messages/gradient_tool.rs - thumbnail bounds, outline visibility, default transform consistency, and stale gradient tool UI state are the key risk areas.

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="node-graph/libraries/rendering/src/renderer.rs">

<violation number="1" location="node-graph/libraries/rendering/src/renderer.rs:1698">
P2: Gradient layers are fully skipped in Outline mode, causing them to disappear instead of rendering any outline/preview representation.</violation>
</file>

<file name="node-graph/libraries/core-types/src/table.rs">

<violation number="1" location="node-graph/libraries/core-types/src/table.rs:150">
P2: `thumbnail_bounding_box` duplicates `bounding_box` aggregation logic, increasing risk of future behavioral drift between normal and thumbnail bounds.</violation>
</file>

<file name="node-graph/libraries/graphic-types/src/artboard.rs">

<violation number="1" location="node-graph/libraries/graphic-types/src/artboard.rs:59">
P1: `Artboard::thumbnail_bounding_box` is a no-op wrapper around `bounding_box`, bypassing child thumbnail-specific finite bounds (e.g., gradients).</violation>
</file>

<file name="editor/src/messages/portfolio/document/node_graph/node_properties.rs">

<violation number="1" location="editor/src/messages/portfolio/document/node_graph/node_properties.rs:1156">
P2: The default fallback transform here is `DAffine2::IDENTITY` (scale 1), but the canonical default for a `GradientTable` in `value.rs` uses `DAffine2::from_scale(DVec2::splat(100.))`. If the table is empty when this runs, the `on_update` closure will reconstruct it with a scale-1 transform, causing the gradient to render 100× smaller than expected.</violation>
</file>

<file name="editor/src/messages/tool/tool_messages/gradient_tool.rs">

<violation number="1" location="editor/src/messages/tool/tool_messages/gradient_tool.rs:140">
P2: Gradient-table mode can still show radial-only controls from stale global state, and those actions do not apply to table-backed gradients.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}