Android : onTouch event and ragged track of finger movement (it is not smooth issue)

I made simple application for drawing via finger on a tablet.

When I touch and move the finger fast then I get a ragged line.

When I turn on the OS pointer tracking (Android 4.2.2: Settings->Developer options->(Input) Pointer location) the track of the OS pointer location is not ragged. Moreover, when I open application and drawing, the track from OS pointer location is not covered with track from application!

onTouch event and OS pointer location is not the same event?

When I look on ragged curve I saw additional points according to OS pointer location. These additional points are corrupted? How I can filtered it? I use only MotionEvent.ACTION_MOVE event.

Please look (bottom left curves):

Source code: TouchDrawExamples-src.tar.gz

Ready to install and run: TouchDrawExamples.apk

Another screen shots: nocovered2.png nocovered3.png

package pl.edu.pk.iti.examples.touch;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;

public class FingerPaintActivity extends Activity {

    DrawingView dv;
    private Paint mPaint;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        dv = new DrawingView(this);
        setContentView(dv);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(Color.GREEN);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(2);
    }

    public class DrawingView extends View {

        public int width;
        public int height;
        private Bitmap mBitmap;
        private Canvas mCanvas;
        private Path mPath;
        private Paint mBitmapPaint;
        Context context;
        private Paint circlePaint;
        private Path circlePath;

        public DrawingView(Context c) {
            super(c);
            context = c;
            mPath = new Path();
            mBitmapPaint = new Paint(Paint.DITHER_FLAG);
            circlePaint = new Paint();
            circlePath = new Path();
            circlePaint.setAntiAlias(true);
            circlePaint.setColor(Color.BLUE);
            circlePaint.setStyle(Paint.Style.STROKE);
            circlePaint.setStrokeJoin(Paint.Join.MITER);
            circlePaint.setStrokeWidth(4f);

        }

        @Override
        protected void onSizeChanged(int w, int h, int oldw, int oldh) {
            super.onSizeChanged(w, h, oldw, oldh);

            mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
            mCanvas = new Canvas(mBitmap);

        }

        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);

            canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);

            canvas.drawPath(mPath, mPaint);

            canvas.drawPath(circlePath, circlePaint);
        }

        private void touch_start(float x, float y) {
            mPath.reset();
            mPath.moveTo(x, y);
        }

        private void touch_move(float x, float y) {
            mPath.lineTo(x, y);
        }

        private void touch_up() {
            circlePath.reset();
            // commit the path to our offscreen
            mCanvas.drawPath(mPath, mPaint);
            // kill this so we don't double draw
            mPath.reset();
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            if (event.getAction() != MotionEvent.ACTION_DOWN && 
                    event.getAction() != MotionEvent.ACTION_UP && 
                    event.getAction() != MotionEvent.ACTION_MOVE) {
                return false;
            }

            boolean first = false;
            boolean last = false;

            if (event.getAction() == MotionEvent.ACTION_DOWN) {
                first = true;
            }

            if (event.getAction() == MotionEvent.ACTION_UP) {
                last = true;
            }

            for (int i = 0; i < event.getHistorySize(); i++) {
                drawPoint(event.getHistoricalX(i), event.getHistoricalY(i), first, false);
                first = false;
            }

            drawPoint(event.getX(), event.getY(), first, last);

            invalidate();
            return true;
        }

        private void drawPoint(float x, float y, boolean first, boolean last) {
            if (first) {
                touch_start(x, y);
            } else if (last) {
                touch_move(x, y);
                touch_up();
            } else {
                touch_move(x, y);
            }
        }
    }
}