How to scroll ScrollPane in code?

Question

I am trying to make the Scrollwheel component as follows in LibGDX:

Im using ScrollPane as it has built-in input processing and image processing. I have an image for scrolling, which is divided into 14 sections, scrollpane itself is two sections shorter, so there will be one section on the right and left sides that it can scroll in any direction. When the scroll position reaches the end in any direction, I want the reset scroll position to return to the center. Doing this again and again should create the illusion of an infinite scroll wheel (hopefully).

Im , ScrollPane reset , . , , . Ive setScrollX() scrollTo(). Ive scrollpane ( , , ). Ive , scrollpane, , , . , updateVisualScroll() , .

, , , , Im - . scrollwheel , .

, , . act() scrollPane.getX(), "0", , ScrollPane.

, , ScrollPane , .

, , .

public class MyScrollWheel extends Container<ScrollPane> {
    private ScrollPane scrollPane;
    private Image image;
    private int scrollOffset;

    public MyScrollWheel(){
        Texture texture = new Texture(Gdx.files.internal("internal/scrollwheel.png"));
        image = new Image(texture);

        scrollOffset = (int)(image.getWidth()/14);

        scrollPane = new ScrollPane(image);
        scrollPane.setOverscroll(false, false);

        setActor(scrollPane);
        size(image.getWidth()-(scrollOffset*2), image.getHeight());

        scrollPane.setScrollX(scrollOffset); // << this doesn't scroll
        scrollPane.updateVisualScroll();
    }
}

Answer 1

, , , , . , , - , Texture.wrap SpriteBatch.draw(). , . reset , , wheel.setScroll(0);.

, Drawable, , NinePatch. , , , , . , , .

ScrollWheel:

public class ScrollWheel extends Actor {
    Texture wheelTexture;
    private int scroll = 0;

    public int getScroll() {
        return scroll;
    }
    public void setScroll(int scroll) {
        this.scroll = scroll;
    }

    public ScrollWheel(Texture texture)
    {
        wheelTexture = texture;
        wheelTexture.setWrap(Texture.TextureWrap.Repeat, Texture.TextureWrap.ClampToEdge);

        setWidth(texture.getWidth());
        setHeight(texture.getHeight());
    }

    @Override
    public void draw(Batch batch, float parentAlpha) {
        super.draw(batch, parentAlpha);

        batch.draw(wheelTexture, getX(), getY(), scroll, 0,
                wheelTexture.getWidth(), wheelTexture.getHeight());
    }
}

:

public class TestScreen implements Screen {
    Stage stage;
    ScrollWheel wheel;

    public TestScreen() {
        stage = new Stage();
        Table t = new Table();
        t.setFillParent(true);
        stage.addActor(t);

        wheel = new ScrollWheel(new Texture("hud/wheel_part.png"));
        wheel.addListener(new DragListener() {
            @Override
            public void drag(InputEvent event, float x, float y, int pointer) {
                super.drag(event, x, y, pointer);
                wheel.setScroll(wheel.getScroll() + (int)getDeltaX());
            }
        });

        t.add(wheel);
        Gdx.input.setInputProcessor(stage);
    }

    @Override
    public void render(float delta) {
        Gdx.gl.glClearColor(.3f, .36f, .42f, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        stage.act();
        stage.draw();
    }
    //...Other mandatory screen methods...
}

, , , ScrollWheel. , .

scroll , , 0 100, setScroll().

if (scroll > 100) scroll = 100; 
else if (scroll < 0) scroll = 0;

. , , scroll * 3,6f scroll * (maxScroll / maxStep)

, , : D. , : https://youtu.be/RNLk5B-VfYg

Answer 2

Menno Gouw, :

• Fling
• ScrollPane

.. Label , , , .

, , .

https://www.youtube.com/watch?v=RwVrez4BZsY&feature=youtu.be

- EDIT 1: (). ScrollPane, Drawables .

- EDIT 2: ​​ (setRightPositiveDirection()).

public class ScrollWheel extends Actor {
    private Drawable wheelDrawable, wheelShading;
    private Label label;

    private int unscaledScrollValueX=0, scrollValueX=0;
    private boolean isNotEdge;
    private int precision=40;
    private int direction=1;
    private int minValue=Integer.MIN_VALUE, maxValue=Integer.MAX_VALUE;
    // MANUAL SCROLL
    private int separator;
    private int wheelWidth;
    // FLING
    private float flingTimer, flingTime=1f;
    private float velocityX;

    public ScrollWheel(Drawable wheelDrawable, Drawable wheelShading, Label label) {
        this.wheelDrawable = wheelDrawable;
        this.wheelShading = wheelShading;
        this.label = label;

        wheelWidth = (int)wheelDrawable.getMinWidth();
        separator = wheelWidth;

        setWidth(wheelDrawable.getMinWidth());
        setHeight(wheelDrawable.getMinHeight());

        // stops ScrollPane from overriding input events
        InputListener stopTouchDown = new InputListener() {
            public boolean touchDown (InputEvent event, float x, float y, int pointer, int button) {
                event.stop();
                return false;
            }
        };
        addListener(stopTouchDown);

        ActorGestureListener flickScrollListener = new ActorGestureListener() {
            public void pan (InputEvent event, float x, float y, float deltaX, float deltaY) {
                updateScroll(deltaX);
            }
            public void fling (InputEvent event, float x, float y, int button) {
                if (Math.abs(x) > 150) {
                    flingTimer = flingTime;
                    velocityX = x;
                }
            }
            public boolean handle (Event event) {
                if (super.handle(event)) {
                    if (((InputEvent)event).getType() == InputEvent.Type.touchDown) flingTimer = 0;
                    return true;
                }
                return false;
            }
        };
        addListener(flickScrollListener);
    }

    private void updateScroll(float delta){
        unscaledScrollValueX += (delta * direction);
        scrollValueX = (int)(unscaledScrollValueX / precision);

        isNotEdge = true;
        if (scrollValueX <= minValue){
            scrollValueX = minValue;
            unscaledScrollValueX = minValue * precision;
            isNotEdge = false;          
        }
        else if (scrollValueX >= maxValue){
            scrollValueX = maxValue;
            unscaledScrollValueX = maxValue * precision;
            isNotEdge = false;          
        }
        if (isNotEdge){         
            separator += delta;
            if (separator <= 0){
                separator = wheelWidth;
            }
            else if (separator >= wheelWidth) {
                separator = 0;
            }
        }

        updateLabel();      
    }
    private void updateLabel(){
        label.setText("" + scrollValueX);   
    }

    public void setMinValue(int minValue){ this.minValue = minValue; }
    public void setMinValueToNone(){ minValue=Integer.MIN_VALUE; }
    public void setMaxValue(int maxValue){ this.maxValue = maxValue; }
    public void setMaxValueToNone(){ minValue=Integer.MAX_VALUE; }
    public void setFlingTime(float flingTime){ this.flingTime = flingTime; }
    public void setPrecision(int precision){ this.precision = precision; }
    public void setRightPositiveDirection(boolean rightPositive){ direction = (rightPositive) ? 1 : -1; }

    @Override
    public void act(float delta){
        super.act(delta);

        boolean animating = false;
        if (flingTimer > 0) {
            float alpha = flingTimer / flingTime;
            updateScroll(velocityX * alpha * delta);

            flingTimer -= delta;
            if (flingTimer <= 0) {
                velocityX = 0;
            }
            animating = true;
        }

        if (animating) {
            Stage stage = getStage();
            if (stage != null && stage.getActionsRequestRendering()){
                Gdx.graphics.requestRendering();
            }
        }
    }

    @Override
    public void draw(Batch batch, float parentAlpha){
        super.draw(batch, parentAlpha);
        batch.flush();
        if (clipBegin(getX(), getY(), getWidth(), getHeight())){
            wheelDrawable.draw(batch, getX() + separator - wheelWidth, getY(), wheelDrawable.getMinWidth(), wheelDrawable.getMinHeight());      
            wheelDrawable.draw(batch, getX() + separator, getY(), wheelDrawable.getMinWidth(), wheelDrawable.getMinHeight());
            wheelShading.draw(batch, getX(), getY(), wheelShading.getMinWidth(), wheelShading.getMinHeight());
            batch.flush();
            clipEnd();
        }
    }
}