Hylograph.Interaction.Pointer

attachPointerDrag :: forall datum. Element -> PointerDragConfig datum -> Effect (Effect Unit)

Attach drag behavior using native Pointer Events

Returns a cleanup function that removes all event listeners.

Features:

• Uses setPointerCapture for smooth dragging even outside element
• Sets touch-action: none to prevent browser gestures
• Sets cursor to 'grab' / 'grabbing'
• Prevents native drag for images

cleanup <- attachPointerDrag circleElement
  { onStart: \node _ _ -> log $ "Dragging node " <> show node.id
  , onDrag: \node x y _ _ -> do
      node.fx = x
      node.fy = y
  , onEnd: \node _ _ -> do
      node.fx = null
      node.fy = null
  }

-- Later, to remove:
cleanup

attachSimulationDrag :: Element -> Effect Unit -> Effect (Effect Unit)

Attach simulation-aware drag using Pointer Events

Simplified version for force simulation nodes:

• Calls reheat function on drag start
• Sets fx/fy during drag
• Releases fx/fy on drag end

The element's __data__ must be the simulation node directly.

cleanup <- attachSimulationDrag circleElement reheatSimulation

attachSimulationDragNested :: Element -> Effect Unit -> Effect (Effect Unit)

Attach simulation-aware drag for nested datum structure

Like attachSimulationDrag but for when the element's datum has a .node field containing the actual simulation node.

-- Datum is { node :: SimNode, label :: String, ... }
cleanup <- attachSimulationDragNested groupElement reheatSimulation

type PointerDragConfig datum = { onDrag :: datum -> Number -> Number -> Number -> Number -> Effect Unit, onEnd :: datum -> Number -> Number -> Effect Unit, onStart :: datum -> Number -> Number -> Effect Unit }

Configuration for pointer drag behavior

All callbacks receive the datum bound to the element via __data__.

attachSimpleDrag :: Element -> Unit -> Effect Element

Attach simple drag behavior using Pointer Events

Moves element via SVG transform attribute. No simulation awareness - just basic drag.

registerSimulationForPointer :: String -> Effect Unit -> Effect Unit

Register a simulation with the Pointer module's registry

This enables attachSimulationDragById to look up simulations by ID. Called automatically when using TreeAPI with SimulationDrag behavior.

unregisterSimulationForPointer :: String -> Effect Unit

Unregister a simulation from the Pointer module's registry

attachSimulationDragById :: Element -> String -> Effect Element

Attach simulation drag by looking up simulation ID in registry

Used by TreeAPI's SimulationDrag simId behavior. Element's __data__ must be the simulation node directly.

attachSimulationDragNestedById :: Element -> String -> Effect Element

Attach simulation drag for nested datum by looking up simulation ID

Used by TreeAPI's SimulationDragNested simId behavior. Element's __data__ must have a .node field with the simulation node.

pointerPosition :: PointerEvent -> Element -> Effect Point

Get pointer position relative to a container element

Handles SVG coordinate transformation via CTM (Current Transform Matrix). Replacement for d3-selection's pointer() function.

handlePointerMove event = do
  { x, y } <- pointerPosition event svgElement
  log $ "SVG coords: " <> show x <> ", " <> show y

type Point = { x :: Number, y :: Number }

2D point