ContextActionService
Allows an experience to bind user input to contextual actions, or actions that are only enabled under some condition or period of time. For example, allowing a player to open a door only while close by. In code, an action is simply a string (the name of the action) used by the service to differentiate between unique actions. The action string is provided to BindAction and UnbindAction, among other member functions. If two actions are bound to the same input, the most recently bound will take priority. When the most recent action is unbound, the one bound before that takes control again. Since this service deals with user input, you can only use it in client-side LocalScripts.
Context and Action
A context is simply a condition during which a player may perform some action. Some examples include holding a Tool, being seated in a car or standing near a door. Whatever the case may be, it is up to your LocalScripts to call BindAction when the context is entered and UnbindAction when the context is left.
An action is simply some input that can be performed by the player while in that context. Such an action could open/close some menu, trigger a secondary tool action or send a request to the server using RemoteFunction:InvokeServer(). An action is identified by a unique string as the first parameter of both BindAction and UnbindAction. The string can be anything, but it should reflect the action being performed, not the input being used. For example, don't use "KeyH" as an action name - use "CarHorn" instead. It is best to define your actions as a constant at the top of your script since you will use it in at least three different places in your code.
Binding Actions Contextually
It's better to use ContextActionService's BindAction than UserInputService.InputBegan for most cases. For UserInputService.InputBegan, your connected function would have to check if the player is in the context of the action being performed. In most cases, this is harder than just calling a function when a context is entered/ left. For example, if you want to have the H key trigger a car horn sound while the player is sitting in it, the player might type "hello" in chat or otherwise use the H key for something else. It is harder to determine if something else is using the H key (like chat) - the car might honk when the player didn't mean to. If you instead use BindAction and UnbindAction when the player enters/leaves the car, ContextActionService will make sure that H key presses trigger the honk action only when it is the most recently bound action. If something else (like chat) takes control, you won't have to worry about checking that.
Inspecting Bound Actions
To see a list of actions and their bound inputs, you can inspect the "Action Bindings" tab in the Developer Console (F9 while in game). This shows all bindings, including those bound by Roblox core scripts and default camera/control scripts too. This is useful for debugging if your actions are being bound/unbound at the correct times, or if some other action is stealing input from your actions. For example, if you are attempting to bind WASD, it may be the case that default character movement scripts are binding over those same keys. Similarly, the camera control script can steal right-click input if the script runs after yours.
Keyboardless Input
This service is especially useful for supporting gamepad and touch input. For gamepad input, you might choose to bind the B button to an action that returns the user to the previous menu when they enter another menu. For touch, on-screen touch buttons can be used in place of key presses: these buttons display only while the action is bound, and the position, text and/or images of these buttons can be configured through this service. They're somewhat limited in the amount of customization provided by this service; it's usually a better idea to make your own on-screen buttons using ImageButton or TextButton.
Code Samples
This example properly shows how to use ContextActionService in binding user input to a contextual action. The context is the tool being equipped; the action is reloading some weapon. Test this code sample by placing it in a LocalScript parented to a Tool. When the Tool is equipped, a "Reload" action is bound, and when the Tool is unequipped the "Reload" action is unbound. When the player presses R with the Tool equipped, the message "Reloading!" will appear.
local ContextActionService = game:GetService("ContextActionService")
local ACTION_RELOAD = "Reload"
local tool = script.Parent
local function handleAction(actionName, inputState, _inputObject)
if actionName == ACTION_RELOAD and inputState == Enum.UserInputState.Begin then
print("Reloading!")
end
end
tool.Equipped:Connect(function()
ContextActionService:BindAction(ACTION_RELOAD, handleAction, true, Enum.KeyCode.R)
end)
tool.Unequipped:Connect(function()
ContextActionService:UnbindAction(ACTION_RELOAD)
end)Summary
Methods
- BindAction(actionName : string,functionToBind : function,createTouchButton : boolean,inputTypes : Tuple):()
Bind user input to an action given an action handling function.
Behaves like BindAction but also allows a priority to be assigned to the bound action for overlapping input types (higher before lower).
Bind a Enum.KeyCode with a specific Enum.UserInputType to trigger Tool.Activation and ClickDetector events.
Get a table of information about all bound actions (key is the name passed to BindAction, value is a table from GetBoundActionInfo when called with the key).
Get a table of information about a bound action given its name originally passed to BindAction.
Retrieves a ImageButton of a bound action that had a touch input button created.
Return the BackpackItem.TextureId of a Tool currently equipped by the Player.
Given the name of a bound action with a touch button, sets the description of the action.
If actionName key contains a bound action, then image is set as the image of the touch button.
Given the name of a bound action with a touch button, sets the position of the button within the ContextButtonFrame.
Given the name of a bound action with a touch button, sets the text shown on the button.
Unbind an action from input given its name.
- UnbindActivate(userInputTypeForActivation : Enum.UserInputType,keyCodeForActivation : Enum.KeyCode):()
Unbind a Enum.KeyCode with a specific Enum.UserInputType from triggering Tool.Activation when bound with ContextActionService:BindActivate().
Removes all functions bound. No actionNames will remain. All touch buttons will be removed.
Events
Properties
Methods
BindAction
Parameters
Returns
Code Samples
local ContextActionService = game:GetService("ContextActionService")
local ACTION_RELOAD = "Reload"
local tool = script.Parent
local function handleAction(actionName, inputState, _inputObject)
if actionName == ACTION_RELOAD and inputState == Enum.UserInputState.Begin then
print("Reloading!")
end
end
tool.Equipped:Connect(function()
ContextActionService:BindAction(ACTION_RELOAD, handleAction, true, Enum.KeyCode.R)
end)
tool.Unequipped:Connect(function()
ContextActionService:UnbindAction(ACTION_RELOAD)
end)local ContextActionService = game:GetService("ContextActionService")
local function handleAction(actionName, inputState, inputObj)
if inputState == Enum.UserInputState.Begin then
print("Handling action: " .. actionName)
print(inputObj.UserInputType)
end
-- Since this function does not return anything, this handler will
-- "sink" the input and no other action handlers will be called after
-- this one.
end
ContextActionService:BindAction("BoundAction", handleAction, false, Enum.KeyCode.F)local ContextActionService = game:GetService("ContextActionService")
-- Define an action handler for FirstAction
local function actionHandlerOne(actionName, inputState, _inputObj)
if inputState == Enum.UserInputState.Begin then
print("Action Handler One: " .. actionName)
end
-- This action handler returns nil, so it is assumed that
-- it properly handles the action.
end
-- Binding the action FirstAction (it's on the bottom of the stack)
ContextActionService:BindAction("FirstAction", actionHandlerOne, false, Enum.KeyCode.Z, Enum.KeyCode.X, Enum.KeyCode.C)
-- Define an action handler for SecondAction
local function actionHandlerTwo(actionName, inputState, inputObj)
if inputState == Enum.UserInputState.Begin then
print("Action Handler Two: " .. actionName)
end
if inputObj.KeyCode == Enum.KeyCode.X then
return Enum.ContextActionResult.Pass
else
-- Returning nil implicitly Sinks inputs
return Enum.ContextActionResult.Sink
end
end
-- Binding SecondAction over the first action (since it bound more recently, it is on the top of the stack)
-- Note that SecondAction uses the same keys as
ContextActionService:BindAction("SecondAction", actionHandlerTwo, false, Enum.KeyCode.Z, Enum.KeyCode.X)BindActionAtPriority
Parameters
Returns
Code Samples
local ContextActionService = game:GetService("ContextActionService")
local INPUT_KEY1 = Enum.KeyCode.Q
local INPUT_KEY2 = Enum.KeyCode.E
local function handleThrow(actionName: string, inputState: Enum.UserInputState, inputObject: InputObject)
if inputState ~= Enum.UserInputState.Begin then
return Enum.ContextActionResult.Pass
end
print(`Action [{actionName}] occurred. KeyCode [{inputObject.KeyCode}] pressed.`)
return Enum.ContextActionResult.Sink
end
local function handlePunch(actionName: string, inputState: Enum.UserInputState, inputObject: InputObject)
if inputState ~= Enum.UserInputState.Begin then
return Enum.ContextActionResult.Pass
end
print(`Action [{actionName}] occurred. KeyCode [{inputObject.KeyCode}] pressed.`)
return Enum.ContextActionResult.Sink
end
-- Without specifying priority, the most recently bound action is called first,
-- so pressing INPUT_KEY1 prints "Punch" and then sinks the input.
ContextActionService:BindAction("DefaultThrow", handleThrow, false, INPUT_KEY1)
ContextActionService:BindAction("DefaultPunch", handlePunch, false, INPUT_KEY1)
-- Here we bind both functions in the same order as above, but with explicitly swapped priorities.
-- That is, we give "Throw" a higher priority of 2 so it will be called first,
-- despite "Punch" still being bound more recently.
-- Pressing INPUT_KEY2 prints "Throw" and then sinks the input.
ContextActionService:BindActionAtPriority("PriorityThrow", handleThrow, false, 2, INPUT_KEY2)
ContextActionService:BindActionAtPriority("PriorityPunch", handlePunch, false, 1, INPUT_KEY2)BindActivate
Parameters
Returns
SetDescription
Parameters
Returns
Code Samples
local ContextActionService = game:GetService("ContextActionService")
local ACTION_INSPECT = "Inspect"
local INPUT_INSPECT = Enum.KeyCode.E
local IMAGE_INSPECT = "rbxassetid://1826746856" -- Image of a speech bubble with ? in it
local function handleAction(actionName, inputState, _inputObject)
if actionName == ACTION_INSPECT and inputState == Enum.UserInputState.End then
print("Inspecting")
end
end
-- For touch devices, a button is created on-screen automatically via the 3rd parameter
ContextActionService:BindAction(ACTION_INSPECT, handleAction, true, INPUT_INSPECT)
-- We can use these functions to customize the button:
ContextActionService:SetImage(ACTION_INSPECT, IMAGE_INSPECT)
ContextActionService:SetTitle(ACTION_INSPECT, "Look")
ContextActionService:SetDescription(ACTION_INSPECT, "Inspect something.")
ContextActionService:SetPosition(ACTION_INSPECT, UDim2.new(0, 0, 0, 0))
-- We can manipulate the button directly using ContextActionService:GetButton
local imgButton = ContextActionService:GetButton(ACTION_INSPECT)
if imgButton then -- Remember: non-touch devices won't return anything!
imgButton.ImageColor3 = Color3.new(0.5, 1, 0.5) -- Tint the ImageButton green
endSetImage
Parameters
Returns
Code Samples
local ContextActionService = game:GetService("ContextActionService")
local ACTION_INSPECT = "Inspect"
local INPUT_INSPECT = Enum.KeyCode.E
local IMAGE_INSPECT = "rbxassetid://1826746856" -- Image of a speech bubble with ? in it
local function handleAction(actionName, inputState, _inputObject)
if actionName == ACTION_INSPECT and inputState == Enum.UserInputState.End then
print("Inspecting")
end
end
-- For touch devices, a button is created on-screen automatically via the 3rd parameter
ContextActionService:BindAction(ACTION_INSPECT, handleAction, true, INPUT_INSPECT)
-- We can use these functions to customize the button:
ContextActionService:SetImage(ACTION_INSPECT, IMAGE_INSPECT)
ContextActionService:SetTitle(ACTION_INSPECT, "Look")
ContextActionService:SetDescription(ACTION_INSPECT, "Inspect something.")
ContextActionService:SetPosition(ACTION_INSPECT, UDim2.new(0, 0, 0, 0))
-- We can manipulate the button directly using ContextActionService:GetButton
local imgButton = ContextActionService:GetButton(ACTION_INSPECT)
if imgButton then -- Remember: non-touch devices won't return anything!
imgButton.ImageColor3 = Color3.new(0.5, 1, 0.5) -- Tint the ImageButton green
endSetPosition
Parameters
Returns
Code Samples
local ContextActionService = game:GetService("ContextActionService")
local ACTION_INSPECT = "Inspect"
local INPUT_INSPECT = Enum.KeyCode.E
local IMAGE_INSPECT = "rbxassetid://1826746856" -- Image of a speech bubble with ? in it
local function handleAction(actionName, inputState, _inputObject)
if actionName == ACTION_INSPECT and inputState == Enum.UserInputState.End then
print("Inspecting")
end
end
-- For touch devices, a button is created on-screen automatically via the 3rd parameter
ContextActionService:BindAction(ACTION_INSPECT, handleAction, true, INPUT_INSPECT)
-- We can use these functions to customize the button:
ContextActionService:SetImage(ACTION_INSPECT, IMAGE_INSPECT)
ContextActionService:SetTitle(ACTION_INSPECT, "Look")
ContextActionService:SetDescription(ACTION_INSPECT, "Inspect something.")
ContextActionService:SetPosition(ACTION_INSPECT, UDim2.new(0, 0, 0, 0))
-- We can manipulate the button directly using ContextActionService:GetButton
local imgButton = ContextActionService:GetButton(ACTION_INSPECT)
if imgButton then -- Remember: non-touch devices won't return anything!
imgButton.ImageColor3 = Color3.new(0.5, 1, 0.5) -- Tint the ImageButton green
endSetTitle
Parameters
Returns
Code Samples
local ContextActionService = game:GetService("ContextActionService")
local ACTION_INSPECT = "Inspect"
local INPUT_INSPECT = Enum.KeyCode.E
local IMAGE_INSPECT = "rbxassetid://1826746856" -- Image of a speech bubble with ? in it
local function handleAction(actionName, inputState, _inputObject)
if actionName == ACTION_INSPECT and inputState == Enum.UserInputState.End then
print("Inspecting")
end
end
-- For touch devices, a button is created on-screen automatically via the 3rd parameter
ContextActionService:BindAction(ACTION_INSPECT, handleAction, true, INPUT_INSPECT)
-- We can use these functions to customize the button:
ContextActionService:SetImage(ACTION_INSPECT, IMAGE_INSPECT)
ContextActionService:SetTitle(ACTION_INSPECT, "Look")
ContextActionService:SetDescription(ACTION_INSPECT, "Inspect something.")
ContextActionService:SetPosition(ACTION_INSPECT, UDim2.new(0, 0, 0, 0))
-- We can manipulate the button directly using ContextActionService:GetButton
local imgButton = ContextActionService:GetButton(ACTION_INSPECT)
if imgButton then -- Remember: non-touch devices won't return anything!
imgButton.ImageColor3 = Color3.new(0.5, 1, 0.5) -- Tint the ImageButton green
endUnbindAction
Parameters
Returns
Code Samples
local ContextActionService = game:GetService("ContextActionService")
local ACTION_RELOAD = "Reload"
local tool = script.Parent
local function handleAction(actionName, inputState, _inputObject)
if actionName == ACTION_RELOAD and inputState == Enum.UserInputState.Begin then
print("Reloading!")
end
end
tool.Equipped:Connect(function()
ContextActionService:BindAction(ACTION_RELOAD, handleAction, true, Enum.KeyCode.R)
end)
tool.Unequipped:Connect(function()
ContextActionService:UnbindAction(ACTION_RELOAD)
end)