How to draw a path with a variable stroke width

My code is mainly from this example ( http://corner.squareup.com/2010/07/smooth-signatures.html ) and the Google API (FingerPaint), but now I want to use a class VelocityTrackerto change the stroke width depending on speed of my finger.

I thought I could split the path into smaller parts, but I did not find any examples. There is also this second post ( http://corner.squareup.com/2012/07/smoother-signatures.html ), but I don’t have a specific Bezier curve class, and I don’t collect all the points in ArrayListso their example is to adjust the stroke width not very helpful.

Does anyone have an idea how to handle this? I started learning the code two weeks ago, so I'm pretty new to all of this.

Edit: I tried to implement the speed of my MotionEvents, and I used LogCat to track the current speed during application launch. This worked, but when I tried to use speed as part of the parameter for mPaint.setStrokeWidth, I did not get what I really wanted. The width of the path that I draw on my canvas has been changing all the time since the moment I started to draw a line until I moved my finger. Therefore, I want to break the path into smaller parts, because, as now, only the last tracked speed affects strokeWidth.

public class SignatureView extends View {

    private static final String TAG = SignatureView.class.getSimpleName();
    private static final float STROKE_WIDTH = 10;
    private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
    private final double TOUCH_TOLERANCE = 5;
    private int h = getResources().getDisplayMetrics().heightPixels;
    private int w = getResources().getDisplayMetrics().widthPixels;

    private Path mPath = new Path();
    private Paint mPaint = new Paint();
    private Paint mBitmapPaint = new Paint(Paint.DITHER_FLAG);
    private Bitmap mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
    private Canvas mCanvas = new Canvas(mBitmap);

    private float mX, mY;
    private float lastTouchX, lastTouchY;
    private final RectF dirtyRect = new RectF();

public SignatureView(Context context, AttributeSet attrs) {
    super(context, attrs);

    mPaint.setAntiAlias(true);
    mPaint.setColor(Color.BLACK);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeWidth(INITIAL_STROKE_WIDTH);

    Log.d(TAG, "TOUCH_TOLERANCE = " +TOUCH_TOLERANCE);
}

@Override
protected void onDraw(Canvas canvas) {
    canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);            
    canvas.drawPath(mPath, mPaint);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    float eventX = event.getX();
    float eventY = event.getY();
    int historySize = event.getHistorySize();

    switch (event.getAction()) {

        case MotionEvent.ACTION_DOWN:

            resetDirtyRect(eventX, eventY);
            mPath.reset();
            mPath.moveTo(eventX, eventY);
            mX = eventX;
            mY = eventY;
            break;

        case MotionEvent.ACTION_MOVE:

            float dx = Math.abs(eventX - mX);
            float dy = Math.abs(eventY - mY);

            if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {

                mPath.quadTo(mX, mY, (eventX + mX)/2, (eventY + mY)/2);
                mX = eventX;
                mY = eventY;
            }

            for (int i = 0; i < historySize; i++) {
                float historicalX = event.getHistoricalX(i);
                float historicalY = event.getHistoricalY(i);
                expandDirtyRect(historicalX, historicalY);
            }
            break;

        case MotionEvent.ACTION_UP:

            for (int i = 0; i < historySize; i++) {
                float historicalX = event.getHistoricalX(i);
                float historicalY = event.getHistoricalY(i);
                expandDirtyRect(historicalX, historicalY);
            }

            mPath.lineTo(mX, mY);
            mCanvas.drawPath(mPath, mPaint);
            mPath.reset();
            break;

        default:
            Log.d(TAG, "Ignored touch event: " + event.toString());
        return false;
    }

    // Include half the stroke width to avoid clipping.
        invalidate(     (int) (dirtyRect.left - HALF_STROKE_WIDTH),
                        (int) (dirtyRect.top - HALF_STROKE_WIDTH),
                        (int) (dirtyRect.right + HALF_STROKE_WIDTH),
                        (int) (dirtyRect.bottom + HALF_STROKE_WIDTH));

    lastTouchX = eventX;
    lastTouchY = eventY;
    return true;
}

private void expandDirtyRect(float historicalX, float historicalY) {
    if (historicalX < dirtyRect.left) {
        dirtyRect.left = historicalX;
    } else if (historicalX > dirtyRect.right) {
        dirtyRect.right = historicalX;
    }
    if (historicalY < dirtyRect.top) {
        dirtyRect.top = historicalY;
    } else if (historicalY > dirtyRect.bottom) {
        dirtyRect.bottom = historicalY;
    }
}

private void resetDirtyRect(float eventX, float eventY) {

    dirtyRect.left = Math.min(lastTouchX, eventX);
    dirtyRect.right = Math.max(lastTouchX, eventX);
    dirtyRect.top = Math.min(lastTouchY, eventY);
    dirtyRect.bottom = Math.max(lastTouchY, eventY);
}
}