[AddComponentMenu("UI (Canvas)/Slider", 34)]
[ExecuteAlways]
[RequireComponent(typeof(RectTransform))]
public class Slider : Selectable, IMoveHandler, IPointerDownHandler, IPointerUpHandler, IPointerEnterHandler, IPointerExitHandler, ISelectHandler, IDeselectHandler, IDragHandler, IInitializePotentialDragHandler, IEventSystemHandler, ICanvasElement

Remarks

The slider component is a Selectable that controls a fill, a handle, or both. The fill, when used, spans from the minimum value to the current value while the handle, when used, follow the current value. The anchors of the fill and handle RectTransforms are driven by the Slider. The fill and handle can be direct children of the GameObject with the Slider, or intermediary RectTransforms can be placed in between for additional control. When a change to the slider value occurs, a callback is sent to any registered listeners of UI.Slider.onValueChanged.

Constructors

Slider()

Protected default constructor. Use UnityEngine.GameObject.AddComponent<T>() to add a Slider to a GameObject.

Declaration

protected Slider()

Fields

m_Value

Serialized backing field for value.

Declaration

[SerializeField]
protected float m_Value

Field Value

Type	Description
float

Properties

direction

The direction of the slider, from minimum to maximum value.

Declaration

public Slider.Direction direction { get; set; }

Property Value

Type	Description
Slider.Direction

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;

    public void Start()
    {
        //Changes the direction of the slider.
        if (mainSlider.direction == Slider.Direction.BottomToTop)
        {
            mainSlider.direction = Slider.Direction.TopToBottom;
        }
    }
}

fillRect

Optional RectTransform to use as fill for the slider.

Declaration

public RectTransform fillRect { get; set; }

Property Value

Type	Description
RectTransform

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI;  // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;
    //Reference to new "RectTransform"(Child of FillArea).
    public RectTransform newFillRect;

    //Deactivates the old FillRect and assigns a new one.
    void Start()
    {
        mainSlider.fillRect.gameObject.SetActive(false);
        mainSlider.fillRect = newFillRect;
    }
}

handleRect

Optional RectTransform to use as a handle for the slider.

Declaration

public RectTransform handleRect { get; set; }

Property Value

Type	Description
RectTransform

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;
    //Reference to new "RectTransform" (Child of "Handle Slide Area").
    public RectTransform handleHighlighted;

    //Deactivates the old Handle, then assigns and enables the new one.
    void Start()
    {
        mainSlider.handleRect.gameObject.SetActive(false);
        mainSlider.handleRect = handleHighlighted;
        mainSlider.handleRect.gameObject.SetActive(true);
    }
}

maxValue

The maximum allowed value of the slider.

Declaration

public float maxValue { get; set; }

Property Value

Type	Description
float

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;

    void Start()
    {
        // Changes the max value of the slider to 20;
        mainSlider.maxValue = 20;
    }
}

minValue

The minimum allowed value of the slider.

Declaration

public float minValue { get; set; }

Property Value

Type	Description
float

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;

    void Start()
    {
        // Changes the minimum value of the slider to 10;
        mainSlider.minValue = 10;
    }
}

normalizedValue

The current value of the slider normalized into a value between 0 and 1.

Declaration

public float normalizedValue { get; set; }

Property Value

Type	Description
float

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;

    //Set to invoke when "OnValueChanged" method is called.
    void CheckNormalisedValue()
    {
        //Displays the normalised value of the slider everytime the value changes.
        Debug.Log(mainSlider.normalizedValue);
    }
}

onValueChanged

Callback executed when the value of the slider is changed.

Declaration

public Slider.SliderEvent onValueChanged { get; set; }

Property Value

Type	Description
Slider.SliderEvent

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;

    public void Start()
    {
        //Adds a listener to the main slider and invokes a method when the value changes.
        mainSlider.onValueChanged.AddListener(delegate {ValueChangeCheck(); });
    }

    // Invoked when the value of the slider changes.
    public void ValueChangeCheck()
    {
        Debug.Log(mainSlider.value);
    }
}

value

The current value of the slider.

Declaration

public virtual float value { get; set; }

Property Value

Type	Description
float

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;

    //Invoked when a submit button is clicked.
    public void SubmitSliderSetting()
    {
        //Displays the value of the slider in the console.
        Debug.Log(mainSlider.value);
    }
}

wholeNumbers

Should the value only be allowed to be whole numbers?

Declaration

public bool wholeNumbers { get; set; }

Property Value

Type	Description
bool

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;

    public void Start()
    {
        //sets the slider's value to accept whole numbers only.
        mainSlider.wholeNumbers = true;
    }
}

Methods

FindSelectableOnDown()

Find the selectable object below this one.

Declaration

public override Selectable FindSelectableOnDown()

Returns

Type	Description
Selectable	The nearest Selectable below, or null.

Overrides

Selectable.FindSelectableOnDown()

Examples

  using UnityEngine;
                        using System.Collections;
                        using UnityEngine.UI; // required when using UI elements in scripts

                        public class Example : MonoBehaviour
                        {
                            public Button startButton;

                            // Disables the selectable UI element directly below the Start Button
                            public void IgnoreSelectables()
                            {
                                //Finds the selectable UI element below the start button and assigns it to a variable of type "Selectable"
                                Selectable secondButton = startButton.FindSelectableOnDown();
                                //Disables interaction with the selectable UI element
                                secondButton.interactable = false;
                            }
                        }

FindSelectableOnLeft()

Find the selectable object to the left of this one.

Declaration

public override Selectable FindSelectableOnLeft()

Returns

Type	Description
Selectable	The nearest Selectable to the left, or null.

Overrides

Selectable.FindSelectableOnLeft()

Examples

  using UnityEngine;
                        using System.Collections;
                        using UnityEngine.UI; // required when using UI elements in scripts

                        public class ExampleClass : MonoBehaviour
                        {
                            public Button btnMain;

                            // Disables the selectable UI element directly to the left of the Start Button
                            public void IgnoreSelectables()
                            {
                                //Finds the selectable UI element to the left the start button and assigns it to a variable of type "Selectable"
                                Selectable secondButton = startButton.FindSelectableOnLeft();
                                //Disables interaction with the selectable UI element
                                secondButton.interactable = false;
                            }
                        }

FindSelectableOnRight()

Find the selectable object to the right of this one.

Declaration

public override Selectable FindSelectableOnRight()

Returns

Type	Description
Selectable	The nearest Selectable to the right, or null.

Overrides

Selectable.FindSelectableOnRight()

Examples

  using UnityEngine;
                        using System.Collections;
                        using UnityEngine.UI; // required when using UI elements in scripts

                        public class ExampleClass : MonoBehaviour
                        {
                            public Button btnMain;

                            // Disables the selectable UI element directly to the right the Start Button
                            public void IgnoreSelectables()
                            {
                                //Finds the selectable UI element to the right the start button and assigns it to a variable of type "Selectable"
                                Selectable secondButton = startButton.FindSelectableOnRight();
                                //Disables interaction with the selectable UI element
                                secondButton.interactable = false;
                            }
                        }

FindSelectableOnUp()

The Selectable object above current

Declaration

public override Selectable FindSelectableOnUp()

Returns

Type	Description
Selectable	The nearest Selectable above, or null.

Overrides

Selectable.FindSelectableOnUp()

Examples

  using UnityEngine;
                        using System.Collections;
                        using UnityEngine.UI; // required when using UI elements in scripts

                        public class ExampleClass : MonoBehaviour
                        {
                            public Button btnMain;

                            // Disables the selectable UI element directly above the Start Button
                            public void IgnoreSelectables()
                            {
                                //Finds the selectable UI element above the start button and assigns it to a variable of type "Selectable"
                                Selectable secondButton = startButton.FindSelectableOnUp();
                                //Disables interaction with the selectable UI element
                                secondButton.interactable = false;
                            }
                        }

GraphicUpdateComplete()

See ICanvasElement.GraphicUpdateComplete

Declaration

public virtual void GraphicUpdateComplete()

LayoutComplete()

See ICanvasElement.LayoutComplete

Declaration

public virtual void LayoutComplete()

OnDidApplyAnimationProperties()

Called when animation properties are applied. Updates the slider visual state.

Declaration

protected override void OnDidApplyAnimationProperties()

Overrides

Selectable.OnDidApplyAnimationProperties()

OnDisable()

Called when it becomes disabled. Unregisters from canvas rebuilding.

Declaration

protected override void OnDisable()

Overrides

Selectable.OnDisable()

OnDrag(PointerEventData)

Called while dragging the slider. Updates the value based on the drag position.

Declaration

public virtual void OnDrag(PointerEventData eventData)

Parameters

Type	Name	Description
PointerEventData	eventData	The pointer event data for the drag.

OnEnable()

Called when it becomes enabled. Registers for canvas rebuilding and updates visuals.

Declaration

protected override void OnEnable()

Overrides

Selectable.OnEnable()

OnInitializePotentialDrag(PointerEventData)

Called when a potential drag is detected. Disables inertia for immediate response.

Declaration

public virtual void OnInitializePotentialDrag(PointerEventData eventData)

Parameters

Type	Name	Description
PointerEventData	eventData	The pointer event data.

OnMove(AxisEventData)

Called when a move event occurs. Adjusts the value by one step in the specified direction.

Declaration

public override void OnMove(AxisEventData eventData)

Parameters

Type	Name	Description
AxisEventData	eventData	The axis event data containing the move direction.

Overrides

Selectable.OnMove(AxisEventData)

OnPointerDown(PointerEventData)

Called when the pointer is pressed on the slider. Sets the value based on the press position.

Declaration

public override void OnPointerDown(PointerEventData eventData)

Parameters

Type	Name	Description
PointerEventData	eventData	The pointer event data for the press.

Overrides

Selectable.OnPointerDown(PointerEventData)

OnRectTransformDimensionsChange()

Called when the RectTransform dimensions change. Updates the slider visual state.

Declaration

protected override void OnRectTransformDimensionsChange()

Overrides

UIBehaviour.OnRectTransformDimensionsChange()

OnValidate()

Declaration

protected override void OnValidate()

Overrides

Selectable.OnValidate()

Rebuild(CanvasUpdate)

Called by the canvas update system to rebuild the slider fill and handle visuals.

Declaration

public virtual void Rebuild(CanvasUpdate executing)

Parameters

Type	Name	Description
CanvasUpdate	executing	The current canvas update stage.

Set(float, bool)

Set the value of the slider.

Declaration

protected virtual void Set(float input, bool sendCallback = true)

Parameters

Type	Name	Description
float	input	The new value for the slider.
bool	sendCallback	If the OnValueChanged callback should be invoked.

Remarks

Process the input to ensure the value is between min and max value. If the input is different set the value and send the callback is required.

SetDirection(Direction, bool)

Sets the direction of this slider, optionally changing the layout as well.

Declaration

public void SetDirection(Slider.Direction direction, bool includeRectLayouts)

Parameters

Type	Name	Description
Slider.Direction	direction	The direction of the slider
bool	includeRectLayouts	Should the layout be flipped together with the slider direction

Examples

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour
{
    public Slider mainSlider;

    public void Start()
    {
        mainSlider.SetDirection(Slider.Direction.LeftToRight, false);
    }
}

SetValueWithoutNotify(float)

Set the value of the slider without invoking onValueChanged callback.

Declaration

public virtual void SetValueWithoutNotify(float input)

Parameters

Type	Name	Description
float	input	The new value for the slider.

Update()

Update the rect based on the delayed update visuals. Got around issue of calling sendMessage from onValidate.

Declaration

protected virtual void Update()

Implements

IMoveHandler

IPointerDownHandler

IPointerUpHandler

IPointerEnterHandler

IPointerExitHandler

ISelectHandler

IDeselectHandler

IDragHandler

IInitializePotentialDragHandler

IEventSystemHandler

ICanvasElement