isometric-compose/io.github.jayteealao.isometric.compose.runtime/CustomRenderNode

CustomRenderNode

class CustomRenderNode(var renderFunction: (context: RenderContext, nodeId: String) -> List<RenderCommand>) : IsometricNode

Node that delegates rendering to a user-provided function.

This is the escape hatch for users who need geometry beyond the built-in shapes. The renderFunction receives the accumulated RenderContext and the node's nodeId (for use in RenderCommand.ownerNodeId), and returns render commands that will be included in the scene's depth sorting and drawing.

Constructors

CustomRenderNode

constructor(renderFunction: (context: RenderContext, nodeId: String) -> List<RenderCommand>)

Properties

childrenSnapshot

@Volatile

var childrenSnapshot: List<IsometricNode>

Thread-safe snapshot of children for rendering and traversal. Updated atomically after Applier mutations complete (copy-on-write).

isDirty

@Volatile

var isDirty: Boolean

Dirty tracking for efficient rendering. Volatile to ensure visibility across threads (Applier vs Canvas draw).

isVisible

var isVisible: Boolean

Visibility flag

nodeId

val nodeId: String

Unique identifier for this node. Uses a monotonically increasing atomic counter to guarantee collision-free IDs across the lifetime of the process, even under concurrent creation.

onDirty

var onDirty: () -> Unit?

Callback invoked when dirty propagation reaches a root node (parent == null). Used by IsometricScene to trigger Canvas invalidation via Compose state.

parent

var parent: IsometricNode?

Parent node in the tree

position

var position: Point

Local transform properties

renderFunction

var renderFunction: (context: RenderContext, nodeId: String) -> List<RenderCommand>

renderOptions

var renderOptions: RenderOptions?

Optional per-node render options override. When non-null, overrides the inherited render options for this node and its subtree. When null (default), inherits from the parent context.

rotation

var rotation: Double

rotationOrigin

var rotationOrigin: Point?

scale

var scale: Double

scaleOrigin

var scaleOrigin: Point?

Functions

markClean

fun markClean()

Clear dirty flag (called after rendering)

markDirty

fun markDirty()

Mark this node and all ancestors as dirty. When propagation reaches the root (no parent), invokes onDirty to trigger a Canvas redraw via Compose's snapshot system.

renderTo

open override fun renderTo(output: MutableList<RenderCommand>, context: RenderContext)

Render this node and its children into the given accumulator list. Eliminates intermediate list allocations compared to a returning render() method.

updateChildrenSnapshot

fun updateChildrenSnapshot()

Update the snapshot from the current mutable children list. Called by the Applier after structural mutations.