ChangeHistoryService
Plugin developers must use ChangeHistoryService to tell Studio how to undo and redo changes which their plugins make to experiences. Plugins must call ChangeHistoryService:SetWaypoint() after making a set of changes, as failing to do so will cause unexpected undo and redo behavior. No explicit set of changes is registered by the plugin; instead, calling SetWaypoint automatically includes all of the property changes made since the last waypoint was set.
Plugins may also programmatically invoke an undo or redo through ChangeHistoryService:Undo() or ChangeHistoryService:Redo().
Note that ChangeHistoryService is not enabled at runtime, so calling its methods in a running experience has no effect.
Summary
Properties
Methods
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.
Events
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
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
Returns
SetWaypoint
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.
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)Undo
Undos the last action taken, for which there exists a waypoint.
Returns
Events
OnRedo
Fired when the user reverses the undo command. Waypoint describes the type action that has been redone.
OnUndo
Fired when the user undoes an action in studio. Waypoint describes the type action that has been undone.