Vertical SeekBar for Android

Simple customized VerticalSeekBar which extends SeekBar also shows how to customize a view class in java.

/**
* @author hafsalrahman
*
*/
public class VerticalSeekBar extends SeekBar {
    public VerticalSeekBar(Context context) {
        super(context);
    }
    public VerticalSeekBar(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }
    public VerticalSeekBar(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(h, w, oldh, oldw);
    }
    @Override
    protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(heightMeasureSpec, widthMeasureSpec);
        setMeasuredDimension(getMeasuredHeight(), getMeasuredWidth());
    }
    protected void onDraw(Canvas c) {
        c.rotate(-90);
        c.translate(-getHeight(), 0);
        super.onDraw(c);
    }
    private OnSeekBarChangeListener onChangeListener;
    @Override
    public void setOnSeekBarChangeListener(OnSeekBarChangeListener onChangeListener){
        this.onChangeListener = onChangeListener;
    }
    private int lastProgress = 0;
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (!isEnabled()) {
            return false;
        }
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            onChangeListener.onStartTrackingTouch(this);
            setPressed(true);
            setSelected(true);
            break;
        case MotionEvent.ACTION_MOVE:
            super.onTouchEvent(event);
            int progress = getMax() - (int) (getMax() * event.getY() / getHeight());
             
            // Ensure progress stays within boundaries
            if(progress < 0) {progress = 0;}
            if(progress > getMax()) {progress = getMax();}
            setProgress(progress);  // Draw progress
            if(progress != lastProgress) {
                // Only enact listener if the progress has actually changed
                lastProgress = progress;
                onChangeListener.onProgressChanged(this, progress, true);
            }
             
            onSizeChanged(getWidth(), getHeight() , 0, 0);
            setPressed(true);
            setSelected(true);
            break;
        case MotionEvent.ACTION_UP:
            onChangeListener.onStopTrackingTouch(this);
            setPressed(false);
            setSelected(false);
            break;
        case MotionEvent.ACTION_CANCEL:
            super.onTouchEvent(event);
            setPressed(false);
            setSelected(false);
            break;
        }
        return true;
    }
    public synchronized void setProgressAndThumb(int progress) {
        setProgress(progress);
        onSizeChanged(getWidth(), getHeight() , 0, 0);
        if(progress != lastProgress) {
            // Only enact listener if the progress has actually changed
            lastProgress = progress;
            onChangeListener.onProgressChanged(this, progress, true);
        }
    }
    public synchronized void setMaximum(int maximum) {
        setMax(maximum);
    }
    public synchronized int getMaximum() {
        return getMax();
    }
}

It can be used from XML as below

<com.hafsal.flag.VerticalSeekBar
        android:id="@+id/calculatorVerticalSeekBar"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_gravity="bottom"
        android:max="20"
        android:progress="0" />