Vertical AutoScrolling TextView in Android

In android by default we can scroll the text in horizontal using marquee in layout, but if we want to scroll the text in vertical its not possible by default.
So here we will learn to create a custom TextView which will auto-scroll in vertical direction.
Source Code: VerticalScrollingTextView-Android

Create a AutoScrollingTextView.class which extends TextView:

@SuppressLint("AppCompatCustomView")
public class AutoScrollingTextView extends TextView {

    private static final float DEFAULT_SPEED = 65.0f;
    public Scroller scroller;    
    public float speed = DEFAULT_SPEED;    
    public boolean continuousScrolling = true;
    public AutoScrollingTextView(Context context) {
        super(context);        
        init(null, 0);        
        scrollerInstance(context);    
    }

    public AutoScrollingTextView(Context context, AttributeSet attrs) {
        super(context, attrs);        
        init(attrs, 0);        
        scrollerInstance(context);    
    }

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    public AutoScrollingTextView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, 
                                                              int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);        
        init(attrs, defStyleAttr);        
        scrollerInstance(context);    
    }

    private void init(AttributeSet attrs, int defStyleAttr) {
        TypedArray attrArray = getContext().obtainStyledAttributes(attrs, R.styleable.MyTextView, 
                                                               defStyleAttr, 0);        
        initAttributes(attrArray);    
    }

    protected void initAttributes(TypedArray attrArray) {
        String textStyle = attrArray.getString(R.styleable.MyTextView_myTextStyle);
        if (textStyle == null || textStyle.equals(null) || textStyle.equals("")) {

        } else {
            Typeface tf = Typeface.createFromAsset(getContext().getAssets(), textStyle);            
            setTypeface(tf);        
        }

    }

    public void scrollerInstance(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();
        }
    }

    public void scroll() {
        int viewHeight = getHeight();
        int visibleHeight = viewHeight - getPaddingBottom() - getPaddingTop();        
        int lineHeight = getLineHeight();
        int offset = -1 * visibleHeight;
        int distance = visibleHeight + getLineCount() * lineHeight;        
        int duration = (int) (distance * speed);
        scroller.startScroll(0, offset, 0, distance, duration);
    }

    @Override    
    public void computeScroll() {
        super.computeScroll();
        if (null == scroller)
            return;
        if (scroller.isFinished() && continuousScrolling) {
            scroll();        
        }
    }

    @Override    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (null == scroller)
            return;
        if (scroller.isFinished() && continuousScrolling) {
            scroll();        
        }
    }

    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;
    }
}

For detail on how to add attrs which is used in above class follow this link Custom FontTextView in Android.

Now add the AutoScrollingTextView in layout:

<com.AutoScrollingTextView    
    android:id="@+id/tvContent"    
    android:layout_width="match_parent"    
    android:layout_height="wrap_content"    
    android:ellipsize="marquee"
    android:marqueeRepeatLimit="marquee_forever"    
    android:maxLines="3"    
    android:scrollHorizontally="false"
    android:scrollbars="vertical"    
    android:text="@string/lipsum"    
    android:textAlignment="inherit"    
    android:textColor="@android:color/white"    
    android:textSize="@dimen/twenty" />

In MyActivity.class:

AutoScrollingTextView tvContent = (AutoScrollingTextView) findViewById(R.id.tvContent);
tvContent.setMovementMethod(new ScrollingMovementMethod());
tvContent.scroll();

Happy coding!!!