Documentation
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Overview ¶
Package selection defines the canonical structured selection event emitted by every Prism rendering context (Go-native, WASM/browser, Twirp /prism/scene). The same Event shape travels the wire in every environment so a single consumer handler works against any binding.
Mark-type uniformity: every selection — point, interval, lasso — and every mark type (bar, line, point, rule + text combos, …) emits the same Event struct. The selection kind, populated fields, and extent pointers tell consumers what kind of gesture produced the event; the structure itself is invariant.
Data-space coordinates are the canonical form. Pixel-space extent is optional and exists for UI overlays (brushes, tooltips) — for any downstream protocol the data-space extent is what matters because it survives re-renders at different sizes.
Stable instance keys: InstanceKey is derived from the (layer_id, row_id) pair, not from render-time ordering. Re-rendering the same spec with the same data produces identical instance keys.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
func InstanceKey ¶
InstanceKey returns the canonical instance-key string for a (layer, row) pair. Exposed for callers building events manually.
Types ¶
type AxisExtent ¶
type AxisExtent struct {
Min *float64 `json:"min,omitempty"`
Max *float64 `json:"max,omitempty"`
Categories []string `json:"categories,omitempty"`
}
AxisExtent is one axis's worth of selection bounds. Numeric ranges use Min/Max; categorical brushes populate Categories.
type BuildInput ¶
type BuildInput struct {
SceneID string
SelectionID string
Kind Kind
Timestamp int64 // 0 → now (ms since epoch)
// Point gestures populate Points; interval / lasso gestures
// populate Range / Categories + optional Pixel*.
Points []PointHit
// Range is the value-space brush extent for interval gestures.
Range *DataExtent
// PixelExtent is optional UI-overlay info.
PixelExtent *PixelExtent
}
BuildInput is the raw selection state from a gesture (DOM hit-test, brush release, server selection apply). Build resolves it against a SceneDoc to produce a structured Event.
type DataExtent ¶
type DataExtent struct {
X *AxisExtent `json:"x,omitempty"`
Y *AxisExtent `json:"y,omitempty"`
}
DataExtent carries the value-space bounds of an interval / lasso selection. For non-numeric (categorical) brushes, X/Y carry the stringified domain values via the optional Categories list.
type DataRowRef ¶
type DataRowRef struct {
DatasetName string `json:"dataset_name"`
RowIndex int `json:"row_index"`
RowID string `json:"row_id,omitempty"`
}
DataRowRef points back into a named dataset. DatasetName is the scene-layer Source (the spec's data.source / dataset name). RowIndex is the table position; RowID is the dataset's id-column value when present.
type Event ¶
type Event struct {
SceneID string `json:"scene_id"`
SelectionID string `json:"selection_id"`
Kind Kind `json:"kind"`
Timestamp int64 `json:"timestamp"`
Marks []SelectedMark `json:"marks"`
DataRows []DataRowRef `json:"data_rows"`
DataExtent *DataExtent `json:"data_extent,omitempty"`
PixelExtent *PixelExtent `json:"pixel_extent,omitempty"`
SpecPath string `json:"spec_path"`
}
Event is the structured selection emission. It is the contract between Prism and downstream consumers (UI handlers, Twirp clients, MCP agents). JSON shape uses snake_case keys per Prism's wire conventions; field ordering in the struct mirrors the upgrade spec.
func Build ¶
Build resolves the raw input against the SceneDoc + Spec to produce the canonical Event. doc is the scene the gesture happened on; sp is the spec the scene was compiled from (used to map selection IDs to their JSON Pointer in the spec). doc must be non-nil; sp may be nil — when nil, SpecPath is computed structurally as "/selection/<id>".
type PixelExtent ¶
type PixelExtent struct {
X *PixelRange `json:"x,omitempty"`
Y *PixelRange `json:"y,omitempty"`
}
PixelExtent carries pixel-space bounds of an interval / lasso brush. Optional — populated when the renderer has pixel info to share; consumers should not assume presence.
type PixelRange ¶
PixelRange is one axis's pixel bounds.
type SelectedMark ¶
type SelectedMark struct {
MarkIndex int `json:"mark_index"`
InstanceKey string `json:"instance_key"`
}
SelectedMark identifies one selected mark instance. MarkIndex is the layer index in the spec (Prism has one mark per layer; for an unlayered single-mark spec, MarkIndex is 0). InstanceKey is stable across re-renders.
Source Files