HistoryStack

Bounded undo/redo stack for PixelArtCanvas. Most consumers use PixelArtCanvas.undo()/redo() rather than this class directly. See PixelArtCanvas.md.

new HistoryStack(buffer: DefaultPixelBuffer, uvMap: UVMap, options?: HistoryStackOptions)

interface HistoryStackOptions {
  /** @default 10 */
  limit?: number;
}

limit caps the undo stack; pushing past it drops the oldest entry.

Entry actions

Action	What it records
"stroke"	beforeColors per-position, afterColor single color
"resized" / "texture-replaced"	beforeSize / afterSize and whole-buffer beforePixels / afterPixels snapshots
"select-edit"	Per-position beforeColors / afterColors and selection metadata used by PixelArtCanvas while select mode is active
"uv-create" / "uv-delete"	Full region (undo calls the inverse UVMap method)
"uv-move"	Region id, face (null when collapsed), and oldRect / newRect
"uv-state"	Region id and full before / after snapshots

NOTE

When used through PixelArtCanvas, undo and redo emit mutation hooks. An attached sync client can propagate the resulting pixel and UV changes. See uv/UVMap.md.

API

canUndo / canRedo

get canUndo(): boolean
get canRedo(): boolean

push(entry)

push(entry: HistoryEntryInput): void

Stamps Date.now() and pushes onto the undo stack, clearing redo. Drops the oldest entry when limit is exceeded.

undo()

undo(): HistoryEntry | null

Reverts the most recent entry and moves it to the redo stack. Returns null if nothing to undo.

redo()

redo(): HistoryEntry | null

Re-applies the most recently undone entry and moves it back to the undo stack. Returns null if nothing to redo.

clear()

clear(): void

Discards both stacks. Call when the buffer is replaced from outside (e.g. remote resize or snapshot); PixelArtCanvas does this automatically.