To separate your event logic from your UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary code, use a manipulator to handle events. Manipulators are state machinesThe set of states in an Animator Controller that a character or animated GameObject can be in, along with a set of transitions between those states and a variable to remember the current state. The states available will depend on the type of gameplay, but typical states include things like idling, walking, running and jumping. More info
See in Glossary that handle user interaction with UI elements. They store, register, and unregister event callbacks. A manipulator streamlines setting up that user interaction, so you don’t have to handle each callback one by one. To handle events, use or inherit from one of the manipulators that UI Toolkit supports.
To create and use a manipulator:
The following table lists the supported manipulator classes:
Manipulator | Inherits from | Description |
---|---|---|
Manipulator |
Base class for all provided manipulators. | |
KeyboardNavigationManipulator |
Manipulator |
Handles translation of device-specific input events to higher-level navigation operations with a keyboard. |
MouseManipulator |
Manipulator |
Handles mouse input. Has a list of activation filters. |
ContextualMenuManipulator |
MouseManipulator |
Displays a contextual menu when the user clicks the right mouse button or presses the menu key on the keyboard. |
PointerManipulator |
MouseManipulator |
Handles pointer input. Has a list of activation filters. |
Clickable |
PointerManipulator |
Tracks mouse events on an element, and identifies when a click occurs, which is both a pointer press and release on the same element. |
The following examples demonstrate how to use manipulators to handle events. They do the following:
PointerManipulators
class, which handles mouse input.activators
list to specify the conditions that activate the manipulator. For example, to activate the manipulator when the user clicks the left mouse button, add
ManipulatorActivationFilter
to the activators
list with the button
field set to MouseButton.LeftMouse
.target
property to access the element that the manipulator is attached to.RegisterCallbacksOnTarget
and UnregisterCallbacksFromTarget
methods to register and unregister the event callbacks.The following example creates a manipulator that moves an element when you click and drag it:
using UnityEngine;
using UnityEngine.UIElements;
public class ExampleDragger : PointerManipulator
{
private Vector3 m_Start;
protected bool m_Active;
private int m_PointerId;
private Vector2 m_StartSize;
public ExampleDragger()
{
m_PointerId = -1;
activators.Add(new ManipulatorActivationFilter { button = MouseButton.LeftMouse });
m_Active = false;
}
protected override void RegisterCallbacksOnTarget()
{
target.RegisterCallback<PointerDownEvent>(OnPointerDown);
target.RegisterCallback<PointerMoveEvent>(OnPointerMove);
target.RegisterCallback<PointerUpEvent>(OnPointerUp);
}
protected override void UnregisterCallbacksFromTarget()
{
target.UnregisterCallback<PointerDownEvent>(OnPointerDown);
target.UnregisterCallback<PointerMoveEvent>(OnPointerMove);
target.UnregisterCallback<PointerUpEvent>(OnPointerUp);
}
protected void OnPointerDown(PointerDownEvent e)
{
if (m_Active)
{
e.StopImmediatePropagation();
return;
}
if (CanStartManipulation(e))
{
m_Start = e.localPosition;
m_PointerId = e.pointerId;
m_Active = true;
target.CapturePointer(m_PointerId);
e.StopPropagation();
}
}
protected void OnPointerMove(PointerMoveEvent e)
{
if (!m_Active || !target.HasPointerCapture(m_PointerId))
return;
Vector2 diff = e.localPosition - m_Start;
target.style.top = target.layout.y + diff.y;
target.style.left = target.layout.x + diff.x;
e.StopPropagation();
}
protected void OnPointerUp(PointerUpEvent e)
{
if (!m_Active || !target.HasPointerCapture(m_PointerId) || !CanStopManipulation(e))
return;
m_Active = false;
target.ReleaseMouse();
e.StopPropagation();
}
}
The following example creates a manipulator that resizes an element when you drag it:
using UnityEngine;
using UnityEngine.UIElements;
public class ExampleResizer : PointerManipulator
{
private Vector3 m_Start;
protected bool m_Active;
private int m_PointerId;
private Vector2 m_StartSize;
public ExampleResizer()
{
m_PointerId = -1;
activators.Add(new ManipulatorActivationFilter { button = MouseButton.LeftMouse });
m_Active = false;
}
protected override void RegisterCallbacksOnTarget()
{
target.RegisterCallback<PointerDownEvent>(OnPointerDown);
target.RegisterCallback<PointerMoveEvent>(OnPointerMove);
target.RegisterCallback<PointerUpEvent>(OnPointerUp);
}
protected override void UnregisterCallbacksFromTarget()
{
target.UnregisterCallback<PointerDownEvent>(OnPointerDown);
target.UnregisterCallback<PointerMoveEvent>(OnPointerMove);
target.UnregisterCallback<PointerUpEvent>(OnPointerUp);
}
protected void OnPointerDown(PointerDownEvent e)
{
if (m_Active)
{
e.StopImmediatePropagation();
return;
}
if (CanStartManipulation(e))
{
m_Start = e.localPosition;
m_StartSize = target.layout.size;
m_PointerId = e.pointerId;
m_Active = true;
target.CapturePointer(m_PointerId);
e.StopPropagation();
}
}
protected void OnPointerMove(PointerMoveEvent e)
{
if (!m_Active || !target.HasPointerCapture(m_PointerId))
return;
Vector2 diff = e.localPosition - m_Start;
target.style.height = m_StartSize.y + diff.y;
target.style.width = m_StartSize.x + diff.x;
e.StopPropagation();
}
protected void OnPointerUp(PointerUpEvent e)
{
if (!m_Active || !target.HasPointerCapture(m_PointerId) || !CanStopManipulation(e))
return;
m_Active = false;
target.ReleasePointer(m_PointerId);
m_PointerId = -1;
e.StopPropagation();
}
}
To add a manipulator to an element, use the AddManipulator
method. To remove a manipulator from an element, use the RemoveManipulator
method.
The following example adds and removes the ExampleDragger
to a VisualElement
:
// Create a VisualElement.
var myElement = new VisualElement();
var dragger = new ExampleDragger();
// Add manipulators to the VisualElement.
myElement.AddManipulator(dragger);
// Remove manipulators from the VisualElement.
myElement.RemoveManipulator(dragger);
The following example adds the ExampleResizer
to a VisualElement
:
var box = new VisualElement()
{
style =
{
left = 100,
top = 100,
width = 100,
height = 100,
backgroundColor = Color.red
},
pickingMode = PickingMode.Position,
};
box.AddManipulator(new ExampleResizer());
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