Interface UndoStorage

Command based undo state storage.

interface UndoStorage {
    hasUndo: boolean;
    hasRedo: boolean;
    undoIndex: number;
    undoCount: number;
    undoInProgress: boolean;
    applyOptions(options: ViewerOptions): void;
    dispose(): void;
    clear(): void;
    isCommandSupported(command: UndoCommandSupport): boolean;
    execute(command: UndoCommandSupport): Promise<void>;
    onCommandExecuted(command: UndoCommandSupport): void;
    undo(): Promise<void>;
    redo(): Promise<void>;
}

Methods

applyOptions

applyOptions(options: ViewerOptions): void
Apply undo storage options.
Parameters
- options: ViewerOptions
Returns void

dispose

dispose(): void
Dispose undo storage.

Returns void

clear

clear(): void
Clear undo storage.

Returns void

isCommandSupported

isCommandSupported(command: UndoCommandSupport): boolean
Gets a value indicating whether the command specified in the command parameter is supported.
Parameters
- command: UndoCommandSupport
  Instance of a command.
Returns boolean

execute

execute(command: UndoCommandSupport): Promise<void>
Execute a new command.
Parameters
- command: UndoCommandSupport
  Instance of a command.
Returns Promise<void>

onCommandExecuted

onCommandExecuted(command: UndoCommandSupport): void
Called after command action has been executed.
Parameters
- command: UndoCommandSupport
  Instance of a command.
Returns void

undo

undo(): Promise<void>
Undo last action.

Returns Promise<void>

redo

redo(): Promise<void>
Redo next action.

Returns Promise<void>

Properties

`Readonly`hasUndo

hasUndo: boolean

Gets a value indicating whether the undo storage can undo changes.

`Readonly`hasRedo

hasRedo: boolean

Gets a value indicating whether the undo storage can redo changes.

`Readonly`undoIndex

undoIndex: number

Gets current undo level index.

`Readonly`undoCount

undoCount: number

Gets total undo levels count.

`Readonly`undoInProgress

undoInProgress: boolean

Gets a flag indicating whether an undo/redo or execute operation is in progress.