Stage (libgdx API)

java.lang.Object
- com.badlogic.gdx.InputAdapter
- - com.badlogic.gdx.scenes.scene2d.Stage

All Implemented Interfaces:

InputProcessor, Disposable
```
public class Stage
extends InputAdapter
implements Disposable
```
A 2D scene graph containing hierarchies of actors. Stage handles the viewport and distributes input events.
A stage fills the whole screen. setViewport(float, float, boolean) controls the coordinates used within the stage and sets up the camera used to convert between stage coordinates and screen coordinates.
A stage must receive input events so it can distribute them to actors. This is typically done by passing the stage to Gdx.input.setInputProcessor. An InputMultiplexer may be used to handle input events before or after the stage does. If an actor handles an event by returning true from the input method, then the stage's input method will also return true, causing subsequent InputProcessors to not receive the event.
The Stage and its constituents (like Actors and Listeners) are not thread-safe and should only be updated and queried from a single thread (presumably the main render thread). Methods should be reentrant, so you can update Actors and Stages from within callbacks and handlers.

Author:

mzechner, Nathan Sweet

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Stage.TouchFocus
Internal class for managing touch focus.

Nested Classes
Modifier and Type	Class and Description
`static class`	`Stage.TouchFocus` Internal class for managing touch focus.

Constructor Summary

Constructors
Constructor and Description
`Stage()` Creates a stage with a `viewport` equal to the device screen resolution.
`Stage(float width, float height, boolean keepAspectRatio)` Creates a stage with the specified `viewport`.
`Stage(float width, float height, boolean keepAspectRatio, SpriteBatch batch)` Creates a stage with the specified `viewport` and `SpriteBatch`.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`act()` Calls `act(float)` with `Graphics.getDeltaTime()`.
`void`	`act(float delta)` Calls the `Actor.act(float)` method on each actor in the stage.
`void`	`addAction(Action action)` Adds an action to the root of the stage.
`void`	`addActor(Actor actor)` Adds an actor to the root of the stage.
`boolean`	`addCaptureListener(EventListener listener)` Adds a capture listener to the root.
`boolean`	`addListener(EventListener listener)` Adds a listener to the root.
`void`	`addTouchFocus(EventListener listener, Actor listenerActor, Actor target, int pointer, int button)` Adds the listener to be notified for all touchDragged and touchUp events for the specified pointer and button.
`void`	`cancelTouchFocus()` Sends a touchUp event to all listeners that are registered to receive touchDragged and touchUp events and removes their touch focus.
`void`	`cancelTouchFocus(EventListener listener, Actor actor)` Cancels touch focus for all listeners except the specified listener.
`void`	`clear()` Removes the root's children, actions, and listeners.
`void`	`dispose()` Releases all resources of this object.
`void`	`draw()`
`Array<Actor>`	`getActors()` Returns the root's child actors.
`Camera`	`getCamera()`
`float`	`getGutterHeight()` Half the amount in the y direction that the stage's viewport was lengthened to fill the screen.
`float`	`getGutterWidth()` Half the amount in the x direction that the stage's viewport was lengthened to fill the screen.
`float`	`getHeight()` The height of the stage's viewport.
`Actor`	`getKeyboardFocus()` Gets the actor that will receive key events.
`Group`	`getRoot()` Returns the root group which holds all actors in the stage.
`Actor`	`getScrollFocus()` Gets the actor that will receive scroll events.
`SpriteBatch`	`getSpriteBatch()`
`float`	`getWidth()` The width of the stage's viewport.
`Actor`	`hit(float stageX, float stageY, boolean touchable)` Returns the `Actor` at the specified location in stage coordinates.
`boolean`	`keyDown(int keyCode)` Applies a key down event to the actor that has `keyboard focus`, if any, and returns true if the event was `handled`.
`boolean`	`keyTyped(char character)` Applies a key typed event to the actor that has `keyboard focus`, if any, and returns true if the event was `handled`.
`boolean`	`keyUp(int keyCode)` Applies a key up event to the actor that has `keyboard focus`, if any, and returns true if the event was `handled`.
`boolean`	`mouseMoved(int screenX, int screenY)` Applies a mouse moved event to the stage and returns true if an actor in the scene `handled` the event.
`boolean`	`removeCaptureListener(EventListener listener)` Removes a listener from the root.
`boolean`	`removeListener(EventListener listener)` Removes a listener from the root.
`void`	`removeTouchFocus(EventListener listener, Actor listenerActor, Actor target, int pointer, int button)` Removes the listener from being notified for all touchDragged and touchUp events for the specified pointer and button.
`Vector2`	`screenToStageCoordinates(Vector2 screenCoords)` Transforms the screen coordinates to stage coordinates.
`boolean`	`scrolled(int amount)` Applies a mouse scroll event to the stage and returns true if an actor in the scene `handled` the event.
`void`	`setCamera(Camera camera)` Sets the stage's camera.
`void`	`setKeyboardFocus(Actor actor)` Sets the actor that will receive key events.
`void`	`setScrollFocus(Actor actor)` Sets the actor that will receive scroll events.
`void`	`setViewport(float width, float height, boolean keepAspectRatio)` Sets the dimensions of the stage's viewport.
`Vector2`	`stageToScreenCoordinates(Vector2 stageCoords)` Transforms the stage coordinates to screen coordinates.
`Vector2`	`toScreenCoordinates(Vector2 coords, Matrix4 transformMatrix)` Transforms the coordinates to screen coordinates.
`boolean`	`touchDown(int screenX, int screenY, int pointer, int button)` Applies a touch down event to the stage and returns true if an actor in the scene `handled` the event.
`boolean`	`touchDragged(int screenX, int screenY, int pointer)` Applies a touch moved event to the stage and returns true if an actor in the scene `handled` the event.
`boolean`	`touchUp(int screenX, int screenY, int pointer, int button)` Applies a touch up event to the stage and returns true if an actor in the scene `handled` the event.
`void`	`unfocus(Actor actor)` Removes the touch, keyboard, and scroll focus for the specified actor and any descendants.
`void`	`unfocusAll()` Removes the touch, keyboard, and scroll focused actors.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Stage
```
public Stage()
```
    Creates a stage with a viewport equal to the device screen resolution. The stage will use its own SpriteBatch.
  - Stage
```
public Stage(float width,
     float height,
     boolean keepAspectRatio)
```
    Creates a stage with the specified viewport. The stage will use its own SpriteBatch, which will be disposed when the stage is disposed.
  - Stage
```
public Stage(float width,
     float height,
     boolean keepAspectRatio,
     SpriteBatch batch)
```
    Creates a stage with the specified viewport and SpriteBatch. This can be used to avoid creating a new SpriteBatch (which can be somewhat slow) if multiple stages are used during an applications life time.
    
    Parameters:
    batch - Will not be disposed if dispose() is called. Handle disposal yourself.
- Method Detail
  - setViewport
```
public void setViewport(float width,
               float height,
               boolean keepAspectRatio)
```
    Sets the dimensions of the stage's viewport. The viewport covers the entire screen. If keepAspectRatio is false, the viewport is simply stretched to the screen resolution, which may distort the aspect ratio. If keepAspectRatio is true, the viewport is first scaled to fit then the shorter dimension is lengthened to fill the screen, which keeps the aspect ratio from changing. The getGutterWidth() and getGutterHeight() provide access to the amount that was lengthened.
  - draw
```
public void draw()
```
  - act
```
public void act()
```
    Calls act(float) with Graphics.getDeltaTime().
  - act
```
public void act(float delta)
```
    Calls the Actor.act(float) method on each actor in the stage. Typically called each frame. This method also fires enter and exit events.
    
    Parameters:
    delta - Time in seconds since the last frame.
  - touchDown
```
public boolean touchDown(int screenX,
                int screenY,
                int pointer,
                int button)
```
    Applies a touch down event to the stage and returns true if an actor in the scene handled the event.
    
    Specified by:
    
    touchDown in interface InputProcessor
    
    Overrides:
    
    touchDown in class InputAdapter
    
    Parameters:
    screenX - The x coordinate, origin is in the upper left corner
    screenY - The y coordinate, origin is in the upper left corner
    pointer - the pointer for the event.
    button - the button
    
    Returns:
    whether the input was processed
  - touchDragged
```
public boolean touchDragged(int screenX,
                   int screenY,
                   int pointer)
```
    Applies a touch moved event to the stage and returns true if an actor in the scene handled the event. Only listeners that returned true for touchDown will receive this event.
    
    Specified by:
    
    touchDragged in interface InputProcessor
    
    Overrides:
    
    touchDragged in class InputAdapter
    
    pointer - the pointer for the event.
    
    Returns:
    whether the input was processed
  - touchUp
```
public boolean touchUp(int screenX,
              int screenY,
              int pointer,
              int button)
```
    Applies a touch up event to the stage and returns true if an actor in the scene handled the event. Only listeners that returned true for touchDown will receive this event.
    
    Specified by:
    
    touchUp in interface InputProcessor
    
    Overrides:
    
    touchUp in class InputAdapter
    
    pointer - the pointer for the event.
    button - the button
    
    Returns:
    whether the input was processed
  - mouseMoved
```
public boolean mouseMoved(int screenX,
                 int screenY)
```
    Applies a mouse moved event to the stage and returns true if an actor in the scene handled the event. This event only occurs on the desktop.
    
    Specified by:
    
    mouseMoved in interface InputProcessor
    
    Overrides:
    
    mouseMoved in class InputAdapter
    
    Returns:
    whether the input was processed
  - scrolled
```
public boolean scrolled(int amount)
```
    Applies a mouse scroll event to the stage and returns true if an actor in the scene handled the event. This event only occurs on the desktop.
    
    Specified by:
    
    scrolled in interface InputProcessor
    
    Overrides:
    
    scrolled in class InputAdapter
    
    Parameters:
    amount - the scroll amount, -1 or 1 depending on the direction the wheel was scrolled.
    
    Returns:
    whether the input was processed.
  - keyDown
```
public boolean keyDown(int keyCode)
```
    Applies a key down event to the actor that has keyboard focus, if any, and returns true if the event was handled.
    
    Specified by:
    
    keyDown in interface InputProcessor
    
    Overrides:
    
    keyDown in class InputAdapter
    
    Parameters:
    keyCode - one of the constants in Input.Keys
    
    Returns:
    whether the input was processed
  - keyUp
```
public boolean keyUp(int keyCode)
```
    Applies a key up event to the actor that has keyboard focus, if any, and returns true if the event was handled.
    
    Specified by:
    
    keyUp in interface InputProcessor
    
    Overrides:
    
    keyUp in class InputAdapter
    
    Parameters:
    keyCode - one of the constants in Input.Keys
    
    Returns:
    whether the input was processed
  - keyTyped
```
public boolean keyTyped(char character)
```
    Applies a key typed event to the actor that has keyboard focus, if any, and returns true if the event was handled.
    
    Specified by:
    
    keyTyped in interface InputProcessor
    
    Overrides:
    
    keyTyped in class InputAdapter
    
    Parameters:
    character - The character
    
    Returns:
    whether the input was processed
  - addTouchFocus
```
public void addTouchFocus(EventListener listener,
                 Actor listenerActor,
                 Actor target,
                 int pointer,
                 int button)
```
    Adds the listener to be notified for all touchDragged and touchUp events for the specified pointer and button. The actor will be used as the listener actor and target.
  - removeTouchFocus
```
public void removeTouchFocus(EventListener listener,
                    Actor listenerActor,
                    Actor target,
                    int pointer,
                    int button)
```
    Removes the listener from being notified for all touchDragged and touchUp events for the specified pointer and button. Note the listener may never receive a touchUp event if this method is used.
  - cancelTouchFocus
```
public void cancelTouchFocus()
```
    Sends a touchUp event to all listeners that are registered to receive touchDragged and touchUp events and removes their touch focus. The location of the touchUp is Integer.MIN_VALUE. This method removes all touch focus listeners, but sends a touchUp event so that the state of the listeners remains consistent (listeners typically expect to receive touchUp eventually).
  - cancelTouchFocus
```
public void cancelTouchFocus(EventListener listener,
                    Actor actor)
```
    Cancels touch focus for all listeners except the specified listener.
    
    See Also:
    cancelTouchFocus()
  - addActor
```
public void addActor(Actor actor)
```
    Adds an actor to the root of the stage.
    
    See Also:
    Group.addActor(Actor), Actor.remove()
  - addAction
```
public void addAction(Action action)
```
    Adds an action to the root of the stage.
    
    See Also:
    Actor.addAction(Action)
  - getActors
```
public Array<Actor> getActors()
```
    Returns the root's child actors.
    
    See Also:
    Group.getChildren()
  - addListener
```
public boolean addListener(EventListener listener)
```
    Adds a listener to the root.
    
    See Also:
    Actor.addListener(EventListener)
  - removeListener
```
public boolean removeListener(EventListener listener)
```
    Removes a listener from the root.
    
    See Also:
    Actor.removeListener(EventListener)
  - addCaptureListener
```
public boolean addCaptureListener(EventListener listener)
```
    Adds a capture listener to the root.
    
    See Also:
    Actor.addCaptureListener(EventListener)
  - removeCaptureListener
```
public boolean removeCaptureListener(EventListener listener)
```
    Removes a listener from the root.
    
    See Also:
    Actor.removeCaptureListener(EventListener)
  - clear
```
public void clear()
```
    Removes the root's children, actions, and listeners.
  - unfocusAll
```
public void unfocusAll()
```
    Removes the touch, keyboard, and scroll focused actors.
  - unfocus
```
public void unfocus(Actor actor)
```
    Removes the touch, keyboard, and scroll focus for the specified actor and any descendants.
  - setKeyboardFocus
```
public void setKeyboardFocus(Actor actor)
```
    Sets the actor that will receive key events.
    
    Parameters:
    actor - May be null.
  - getKeyboardFocus
```
public Actor getKeyboardFocus()
```
    Gets the actor that will receive key events.
    
    Returns:
    May be null.
  - setScrollFocus
```
public void setScrollFocus(Actor actor)
```
    Sets the actor that will receive scroll events.
    
    Parameters:
    actor - May be null.
  - getScrollFocus
```
public Actor getScrollFocus()
```
    Gets the actor that will receive scroll events.
    
    Returns:
    May be null.
  - getWidth
```
public float getWidth()
```
    The width of the stage's viewport.
    
    See Also:
    setViewport(float, float, boolean)
  - getHeight
```
public float getHeight()
```
    The height of the stage's viewport.
    
    See Also:
    setViewport(float, float, boolean)
  - getGutterWidth
```
public float getGutterWidth()
```
    Half the amount in the x direction that the stage's viewport was lengthened to fill the screen.
    
    See Also:
    setViewport(float, float, boolean)
  - getGutterHeight
```
public float getGutterHeight()
```
    Half the amount in the y direction that the stage's viewport was lengthened to fill the screen.
    
    See Also:
    setViewport(float, float, boolean)
  - getSpriteBatch
```
public SpriteBatch getSpriteBatch()
```
  - getCamera
```
public Camera getCamera()
```
  - setCamera
```
public void setCamera(Camera camera)
```
    Sets the stage's camera. The camera must be configured properly or setViewport(float, float, boolean) can be called after the camera is set. draw() will call Camera.update() and use the Camera.combined matrix for the SpriteBatch projection matrix.
  - getRoot
```
public Group getRoot()
```
    Returns the root group which holds all actors in the stage.
  - hit
```
public Actor hit(float stageX,
        float stageY,
        boolean touchable)
```
    Returns the Actor at the specified location in stage coordinates. Hit testing is performed in the order the actors were inserted into the stage, last inserted actors being tested first. To get stage coordinates from screen coordinates, use screenToStageCoordinates(Vector2).
    
    Parameters:
    touchable - If true, the hit detection will respect the touchability.
    
    Returns:
    May be null if no actor was hit.
  - screenToStageCoordinates
```
public Vector2 screenToStageCoordinates(Vector2 screenCoords)
```
    Transforms the screen coordinates to stage coordinates.
    
    Parameters:
    screenCoords - Input screen coordinates and output for resulting stage coordinates.
  - stageToScreenCoordinates
```
public Vector2 stageToScreenCoordinates(Vector2 stageCoords)
```
    Transforms the stage coordinates to screen coordinates.
    
    Parameters:
    stageCoords - Input stage coordinates and output for resulting screen coordinates.
  - toScreenCoordinates
```
public Vector2 toScreenCoordinates(Vector2 coords,
                          Matrix4 transformMatrix)
```
    Transforms the coordinates to screen coordinates. The coordinates can be anywhere in the stage since the transform matrix describes how to convert them. The transform matrix is typically obtained from SpriteBatch.getTransformMatrix() during Actor.draw(SpriteBatch, float).
    
    See Also:
    Actor.localToStageCoordinates(Vector2)
  - dispose
```
public void dispose()
```
    Description copied from interface: Disposable
    
    Releases all resources of this object.
    
    Specified by:
    
    dispose in interface Disposable

Class Stage

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Stage

Stage

Stage

Method Detail

setViewport

draw

act

act

touchDown

touchDragged

touchUp

mouseMoved

scrolled

keyDown

keyUp

keyTyped

addTouchFocus

removeTouchFocus

cancelTouchFocus

cancelTouchFocus

addActor

addAction

getActors

addListener

removeListener

addCaptureListener

removeCaptureListener

clear

unfocusAll

unfocus

setKeyboardFocus

getKeyboardFocus

setScrollFocus

getScrollFocus

getWidth

getHeight

getGutterWidth

getGutterHeight

getSpriteBatch

getCamera

setCamera

getRoot

hit

screenToStageCoordinates

stageToScreenCoordinates

toScreenCoordinates

dispose