ChangeHistoryService
Plugin developers must use ChangeHistoryService to tell Studio how to undo and redo changes that their plugins make to experiences by recording. Before making changes, a plugin calls ChangeHistoryService:TryBeginRecording(), remembering the identifier it assigns, then after making changes, the Plugin calls ChangeHistoryService:FinishRecording() to complete the recording.
Plugins may also programmatically invoke an undo or redo through ChangeHistoryService:Undo() or ChangeHistoryService:Redo().
ChangeHistoryService is not enabled at runtime, so calling its methods in a running experience has no effect.
Summary
Methods
- FinishRecording(identifier : string,operation : Enum.FinishRecordingOperation,finalOptions : Dictionary?):void
Communicates to Studio that the identified recording is finished and to take the final operation to complete the recording.
Returns whether there are actions that can be redone, and, if there are, returns the last of them.
Returns whether there are actions that can be undone, and, if there are, returns the last of them.
Executes the last action that was undone.
Clears the history, causing all undo/redo waypoints to be removed.
Sets whether or not the ChangeHistoryService is enabled.
Sets a new waypoint which can be used as an undo or redo point.
Begins tracking changes made to the data model into a recording.
Undos the last action taken, for which there exists a waypoint.
Events
- OnRecordingFinished(name : string,displayName : string?,identifier : string?,operationn : Enum.FinishRecordingOperation,finalOptions : Dictionary?):RBXScriptSignal
Fired when the user completes an action. Parameters come from TryBeginRecording() and FinishRecording().
Fired when the user begins an action. Parameters come from TryBeginRecording().
Fired when the user reverses the undo command. Waypoint describes the type action that has been redone.
Fired when the user undoes an action in studio. Waypoint describes the type action that has been undone.
Properties
Methods
FinishRecording
Parameters
Identifies the recording from the previous call to TryBeginRecording(). If the operation is Enum.ChangeHistoryService.FinishRecordingOperation.Cancel, this value is ignored, and the recording is determined by context.
Specifies the operation to take.
Optional table of values to pass to OnFinishRecording.
Returns
Code Samples
local ChangeHistoryService = game:GetService("ChangeHistoryService")
local Selection = game:GetService("Selection")
local toolbar = plugin:CreateToolbar("Example Plugin")
local button = toolbar:CreateButton("Neon it up", "", "")
button.Click:Connect(function()
local parts = {}
for _, part in pairs(Selection:Get()) do
if part:IsA("BasePart") then
parts[#parts + 1] = part
end
end
if #parts < 1 then
-- Nothing to do.
return
end
local recording = ChangeHistoryService:TryBeginRecording("Set selection to neon")
if not recording then
-- Handle error here. This indidcates that your plugin began a previous
-- recording and never completed it. You may only have one recording
-- per plugin active at a time.
return
end
for _, part in pairs(parts) do
part.Material = Enum.Material.Neon
end
ChangeHistoryService:FinishRecording(recording, Enum.FinishRecordingOperation.Commit)
end)GetCanRedo
Returns whether there are actions that can be redone, and, if there are, returns the last of them.
Returns
GetCanUndo
Returns whether there are actions that can be undone, and, if there are, returns the last of them.
Returns
Redo
Executes the last action that was undone.
Returns
ResetWaypoints
Clears the history, causing all undo/redo waypoints to be removed.
Returns
SetEnabled
Sets whether or not the ChangeHistoryService is enabled. When set to false, the undo/redo list is cleared, and does not repopulate. When set to true again, the original list is not restored, but further operations append to the list once more
Parameters
Returns
SetWaypoint
This method will be deprecated soon in favor of TryBeginRecording().
ChangeHistoryService tracks plugin history as a stream of property changes. SetWaypoint() creates a cut in that stream of property changes so that the undo and redo actions know where to stop.
By convention, user-invoked actions in Studio must call SetWaypoint() after completing their set of changes to the experience. Calling it before a set of changes may clean up another misbehaving plugin which failed to set a waypoint, but it's a poor reason to justify such usage in your own plugin.
Parameters
Returns
Code Samples
local ChangeHistoryService = game:GetService("ChangeHistoryService")
local Selection = game:GetService("Selection")
local toolbar = plugin:CreateToolbar("Example Plugin")
local button = toolbar:CreateButton("Neon it up", "", "")
button.Click:Connect(function()
local parts = {}
for _, part in pairs(Selection:Get()) do
if part:IsA("BasePart") then
parts[#parts + 1] = part
end
end
if #parts > 0 then
-- Calling SetWaypoint before the work will not cause any issues, however
-- it is redundant, only the call AFTER the work is needed.
--ChangeHistoryService:SetWaypoint("Setting selection to neon")
for _, part in pairs(parts) do
part.Material = Enum.Material.Neon
end
-- Call SetWaypoint AFTER completing the work
ChangeHistoryService:SetWaypoint("Set selection to neon")
else
-- Nothing to do. You do not need to call SetWaypoint in the case where
-- the action did not end up making any changes to the experience.
end
end)TryBeginRecording
This method begins a recording to track changes to the data model. You must call it prior to making changes to avoid future warnings or errors.
When the recording is completed, you call FinishRecording() with the returned recording identifier to complete the recording and update the undo/redo stack.
This method will return nil if it fails to begin a recording. Recordings fail if the plugin already has a recording in progress, or if the user is in Run or Play mode.
You may use IsRecordingInProgress() to check the recording status of the plugin.
Parameters
Name of the action being performed suitable for logging and coding purposes.
Name of the action being performed to display to the user.
Returns
Code Samples
local ChangeHistoryService = game:GetService("ChangeHistoryService")
local Selection = game:GetService("Selection")
local toolbar = plugin:CreateToolbar("Example Plugin")
local button = toolbar:CreateButton("Neon it up", "", "")
button.Click:Connect(function()
local parts = {}
for _, part in pairs(Selection:Get()) do
if part:IsA("BasePart") then
parts[#parts + 1] = part
end
end
if #parts < 1 then
-- Nothing to do.
return
end
local recording = ChangeHistoryService:TryBeginRecording("Set selection to neon")
if not recording then
-- Handle error here. This indidcates that your plugin began a previous
-- recording and never completed it. You may only have one recording
-- per plugin active at a time.
return
end
for _, part in pairs(parts) do
part.Material = Enum.Material.Neon
end
ChangeHistoryService:FinishRecording(recording, Enum.FinishRecordingOperation.Commit)
end)Undo
Undos the last action taken, for which there exists a waypoint.
Returns
Events
OnRecordingFinished
Parameters
Name of the action being performed suitable for logging and coding purposes.
Name of the action being performed to display to the user.
The identifier for the recording.
Optional table from FinishOperation().
OnRecordingStarted
Parameters
Name of the action being performed suitable for logging and coding purposes.
Name of the action being performed to display to the user.
OnRedo
Fired when the user reverses the undo command. Waypoint describes the type action that has been redone.
Parameters
OnUndo
Fired when the user undoes an action in studio. Waypoint describes the type action that has been undone.