Working Vertical SeekBar for Android

So! More than likely you’ve come here wanting source code for a fully working Vertical SeekBar, or you’re a friend who knows little about programming but happened to click on my Facebook or Twitter post. I’ve made this quick explanation/tutorial in frustration over the lack of working solutions found on Google and StackOverflow – They mostly worked, but there was always something wrong with each implementation; the progress didn’t update correctly, the bar didn’t draw correctly, the thumb didn’t unhighlight, or maybe it just didn’t look right. This solution seems to solve all of this.

It’s not the best code in the world, but it works.

Here is the important parts of the VerticalSeekBar class. I merged a few solutions I found to make this. The goal was to make VerticalSeekBar behave exactly like a normal horizontal SeekBar.

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();
	}
}

I then inserted the VerticalSeekBar inside a LinearLayout like so:

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <com.safetyculture.jsadroidtablet.VerticalSeekBar
        android:id="@+id/calculatorVerticalSeekBar"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_gravity="bottom"
        android:max="4"
        android:progress="2" />

</LinearLayout>

NOTE: In this implementation you must set an OnSeekBarChangeListener for the VerticalSeekBar before using it in the app, otherwise interacting with the VerticalSeekBar will produce NullPointerException.

NOTE2: If you wish to change the progress manually/programmatically rather than through the UI Motion Events, you will need to call setProgressAndThumb(progress), otherwise the thumb doesn’t update correctly.

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