Scrolling credits text in Android

Question

I need to make a credits screen (Activity) in my game. It would be just a vertically scrolling text lines without any images. Scrolling is to be performed automatically and no user interaction is allowed. Just like movie credits that goes from bottom to top. After the last text line has disappeared above top of the screen, it should restart.

How do I do it? It is sufficient to just use TextView and animate it somehow? Or should I put that TextView into ScrollView? What would you suggest?

Answer 1

I am using this :-

    /**
 * A TextView that scrolls it contents across the screen, in a similar fashion as movie credits roll
 * across the theater screen.
 *
 * @author Matthias Kaeppler
 */
public class ScrollingTextView extends TextView implements Runnable {

    private static final float DEFAULT_SPEED = 15.0f;

    private Scroller scroller;
    private float speed = DEFAULT_SPEED;
    private boolean continuousScrolling = true;

    public ScrollingTextView(Context context) {
        super(context);
        setup(context);
    }

    public ScrollingTextView(Context context, AttributeSet attributes) {
        super(context, attributes);
        setup(context);
    }

    private void setup(Context context) {
        scroller = new Scroller(context, new LinearInterpolator());
        setScroller(scroller);
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        if (scroller.isFinished()) {
            scroll();
        }
    }

    private void scroll() {
        int viewHeight = getHeight();
        int visibleHeight = viewHeight - getPaddingBottom() - getPaddingTop();
        int lineHeight = getLineHeight();

        int offset = -1 * visibleHeight;
        int totallineHeight = getLineCount() * lineHeight;
        int distance = totallineHeight + visibleHeight;
        int duration = (int) (distance * speed);

        if (totallineHeight > visibleHeight) {
            scroller.startScroll(0, offset, 0, distance, duration);

            if (continuousScrolling) {
                post(this);
            }
        }
    }

    @Override
    public void run() {
        if (scroller.isFinished()) {
            scroll();
        } else {
            post(this);
        }
    }

    public void setSpeed(float speed) {
        this.speed = speed;
    }

    public float getSpeed() {
        return speed;
    }

    public void setContinuousScrolling(boolean continuousScrolling) {
        this.continuousScrolling = continuousScrolling;
    }

    public boolean isContinuousScrolling() {
        return continuousScrolling;
    }
}