[Traits](https://oods-foundry.com/traits) / MarkPoint

# MarkPoint

Canonical point mark for scatterplots and overlays.

Generated from @oods/foundry 0.10.1

- Group

  viz.mark

- Maturity

  alpha

- Contexts

  detail, form, list

Encodes each datum as a discrete glyph with configurable shape, size, and fill semantics.

## Fields it adds

| Field | Type | Required | Description |
| - | - | - | - |
| `viz_mark_type` | `string` (point) | yes | Normalized mark identifier consumed by renderer adapters. |
| `viz_point_shape` | `string` (circle, square, diamond, triangle) | no | Glyph shape applied to all rendered points by default. |
| `viz_point_size` | `number` | no | Default glyph area in square pixels. |
| `viz_point_fill` | `string` (solid, hollow) | no | Fill strategy for glyph interior. |
| `viz_point_stroke_width` | `number` | no | Outline stroke width for hollow glyphs. |
| `viz_point_opacity` | `number` | no | Default opacity used for overplotting mitigation. |
| `viz_mark_role` | `string` | yes | Semantic role for heuristics and docs. |
| `viz_mark_a11y_label` | `string` | yes | Accessible description fragment for describing point marks. |

## What it shows in each context

- [detail](https://oods-foundry.com/contexts/detail)

  `VizPointPreview`

- [form](https://oods-foundry.com/contexts/form)

  `VizPointControls`

- [list](https://oods-foundry.com/contexts/list)

  `VizRoleBadge`

## Parameters

- `chart` `object`

  Optional read-only chart declaration binding existing domain fields; projects into supported detail and dashboard views.

- `title` `string`

  Title for the bound chart and its accessible figure.

- `description` `string`

  Description of the bound chart measurements and units.

- `renderIntent` `string`

  JSON-encoded Cartesian viz.render input fragment for the governed authoring recipes. Data rows remain a consumer operand.

- `previewSvg` `string`

  Static SVG returned by viz.render for the authored sample; omitted until a chart is rendered.

- `shape` `string`

  Glyph shape rendered for each data point.

- `size` `number`

  Default glyph area in square pixels.

- `fill` `string`

  Fill strategy for glyph interior.

- `strokeWidth` `number`

  Outline stroke width for hollow glyphs.

- `opacity` `number`

  Default opacity applied to each point for overplotting.

## Objects that use it

No shipped object uses this trait.

## The trait file

`traits/viz/mark-point.trait.yaml`

```
trait:
  name: MarkPoint
  version: 0.2.0
  description: |
    Canonical point mark for scatterplots and overlays. Encodes each datum as a
    discrete glyph with configurable shape, size, and fill semantics.
  category: viz.mark
  tags:
    - viz
    - mark
    - point
    - distribution

parameters:
  - {"name": "chart", "type": "object", "required": false, "description": "Optional read-only chart declaration binding existing domain fields; projects into supported detail and dashboard views."}
  - {"name": "title", "type": "string", "required": false, "description": "Title for the bound chart and its accessible figure."}
  - {"name": "description", "type": "string", "required": false, "description": "Description of the bound chart measurements and units."}
  - {"name": "renderIntent", "type": "string", "required": false, "default": "{}", "description": "JSON-encoded Cartesian viz.render input fragment for the governed authoring recipes. Data rows remain a consumer operand."}
  - {"name": "previewSvg", "type": "string", "required": false, "description": "Static SVG returned by viz.render for the authored sample; omitted until a chart is rendered."}
  - name: shape
    type: string
    required: false
    description: Glyph shape rendered for each data point.
    default: circle
    validation:
      enum:
        - circle
        - square
        - diamond
        - triangle
  - name: size
    type: number
    required: false
    description: Default glyph area in square pixels.
    default: 48
    validation:
      minimum: 4
      maximum: 196
  - name: fill
    type: string
    required: false
    description: Fill strategy for glyph interior.
    default: solid
    validation:
      enum:
        - solid
        - hollow
  - name: strokeWidth
    type: number
    required: false
    description: Outline stroke width for hollow glyphs.
    default: 1
    validation:
      minimum: 0
      maximum: 6
  - name: opacity
    type: number
    required: false
    description: Default opacity applied to each point for overplotting.
    default: 0.85
    validation:
      minimum: 0.1
      maximum: 1

schema:
  viz_mark_type:
    type: string
    required: true
    description: Normalized mark identifier consumed by renderer adapters.
    default: point
    validation:
      enum:
        - point
  viz_point_shape:
    type: string
    required: false
    description: Glyph shape applied to all rendered points by default.
    defaultFromParameter: shape
    validation:
      enum:
        - circle
        - square
        - diamond
        - triangle
  viz_point_size:
    type: number
    required: false
    description: Default glyph area in square pixels.
    defaultFromParameter: size
    validation:
      minimum: 4
      maximum: 196
  viz_point_fill:
    type: string
    required: false
    description: Fill strategy for glyph interior.
    defaultFromParameter: fill
    validation:
      enum:
        - solid
        - hollow
  viz_point_stroke_width:
    type: number
    required: false
    description: Outline stroke width for hollow glyphs.
    defaultFromParameter: strokeWidth
    validation:
      minimum: 0
      maximum: 6
  viz_point_opacity:
    type: number
    required: false
    description: Default opacity used for overplotting mitigation.
    defaultFromParameter: opacity
    validation:
      minimum: 0.1
      maximum: 1
  viz_mark_role:
    type: string
    required: true
    description: Semantic role for heuristics and docs.
    default: distribution
  viz_mark_a11y_label:
    type: string
    required: true
    description: Accessible description fragment for describing point marks.
    default: Point mark representing discrete values or observations.

semantics:
  viz_mark_type:
    semantic_type: viz.mark.type
    token_mapping: tokenMap(viz.mark.type)
    ui_hints:
      component: VizMarkSummary
  viz_point_shape:
    semantic_type: viz.mark.shape
    token_mapping: tokenMap(viz.mark.shape)
    ui_hints:
      component: VizShapeHint
  viz_point_size:
    semantic_type: viz.mark.size
    token_mapping: tokenMap(viz.mark.size)
    ui_hints:
      component: NumericPreview
      unit: px^2
  viz_point_fill:
    semantic_type: viz.mark.fill
    token_mapping: tokenMap(viz.mark.fill)
    ui_hints:
      component: TextBadge
  viz_point_opacity:
    semantic_type: viz.mark.opacity
    token_mapping: tokenMap(viz.mark.opacity)
    ui_hints:
      component: NumericPreview
      unit: opacity
  viz_mark_a11y_label:
    semantic_type: a11y.description
    token_mapping: tokenMap(a11y.chart.description)
    ui_hints:
      component: ScreenReaderHint

view_extensions:
  detail:
    - component: VizPointPreview
      position: top
      priority: 55
      props:
        svgParameter: previewSvg
        shapeField: viz_point_shape
        sizeField: viz_point_size
        fillField: viz_point_fill
  form:
    - component: VizPointControls
      position: top
      props:
        intentParameter: renderIntent
        shapeField: viz_point_shape
        sizeField: viz_point_size
        opacityField: viz_point_opacity
        strokeField: viz_point_stroke_width
  list:
    - component: VizRoleBadge
      props:
        intentParameter: renderIntent
        labelField: viz_mark_role

tokens:
  # Default fill color for point glyphs — varies by palette assignment
  viz.mark.point.fill.default: "var(--cmp-viz-mark-point-fill)"
  # Stroke outline for hollow or outlined glyphs
  viz.mark.point.stroke.default: "var(--cmp-viz-mark-point-stroke)"
  # Default opacity for overplotting mitigation in dense scatterplots
  viz.mark.point.opacity.default: "var(--cmp-viz-mark-point-opacity)"

events:
  mark.hovered:
    description: Fired when a point glyph is hovered. Payload includes the datum and glyph coordinates.
    payload: [datum, index, x, y]
  mark.selected:
    description: Fired when a point is clicked/tapped. Used by InteractionHighlight.
    payload: [datum, index]
  mark.focused:
    description: Fired when a point receives keyboard focus for scatter navigation.
    payload: [datum, index]

dependencies:
  - EncodingPositionX
  - EncodingPositionY

metadata:
  created: "2025-11-15"
  updated: "2026-02-28"
  owners:
    - viz@oods.systems
    - design@oods.systems
  maturity: alpha
  conflicts_with:
    - MarkBar
    - MarkLine
    - MarkArea
  accessibility:
    rule_reference: A11Y-R-01
    notes: Provide redundant encoding (color, shape, or texture) per RDV.4.
  regionsUsed:
    - detail
    - form
    - list
  examples:
    - ProfitVsRevenue
    - SLAHeatScatter
  references:
    - RDS.7 Trait-Driven Visualization System Specification (v0.1)
```