android - ライブ壁紙 - キャンバスフリッカー

Question

シンプルなライブ壁紙を作ろうと思っています。ランダムな色、直径、位置の円を描くことになっています。そして、スクリーンがタッチされると、タッチ位置でランダムな円を描く必要があります。現在は動作しますが、唯一の問題は、円が表示されたり消えたりすることです。私はビットマップに描くべきだと思いますか？これが私の情報源です。これを機能させる方法を知っている人はいますか?

package com.my.livewallpaper;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Random;

import android.content.SharedPreferences;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.preference.PreferenceManager;
import android.service.wallpaper.WallpaperService;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;

public class MyWallpaperService extends WallpaperService {

    @Override
    public Engine onCreateEngine() {
        return new MyWallpaperEngine();
    }

    private class MyWallpaperEngine extends Engine {
        private final Handler handler = new Handler();
        private final Runnable drawRunner = new Runnable() {
            @Override
            public void run() {
                draw();
            }

        };
        private List<MyPoint> circles;
        private Paint paint = new Paint();
        private int width;
        int height;
        public Canvas canvas = null;
        private boolean visible = true;
        private int maxNumber;
        private int timestamp=0;
        private boolean touchEnabled;
        public MyWallpaperEngine() {
            circles = new ArrayList<MyPoint>();
            paint.setAntiAlias(true);
            paint.setStyle(Paint.Style.FILL);
            paint.setStrokeJoin(Paint.Join.ROUND);
            handler.post(drawRunner);
        }

        @Override
        public void onVisibilityChanged(boolean visible) {
            this.visible = visible;
            if (visible) {
                handler.post(drawRunner);
            } else {
                handler.removeCallbacks(drawRunner);
            }
        }

        @Override
        public void onSurfaceDestroyed(SurfaceHolder holder) {
            super.onSurfaceDestroyed(holder);
            this.visible = false;
            handler.removeCallbacks(drawRunner);
        }

        @Override
        public void onSurfaceChanged(SurfaceHolder holder, int format,
                int width, int height) {
            this.width = width;
            this.height = height;
            super.onSurfaceChanged(holder, format, width, height);
        }

        @Override
        public void onTouchEvent(MotionEvent event) {
            float x = event.getX();
            float y = event.getY();
            SurfaceHolder holder = getSurfaceHolder();
            //Canvas canvas = null;
            try {
                canvas = holder.lockCanvas();
                if (canvas != null) {
                    drawCircles(canvas, x, y);
                }
            } finally {
                if (canvas != null)
                {holder.unlockCanvasAndPost(canvas);}
            }
            super.onTouchEvent(event);
        }

        private void draw() {
            SurfaceHolder holder = getSurfaceHolder();
            //Log.e("Msg","What you have to print");
            try {
                canvas = holder.lockCanvas();
                if (canvas != null) {
                    drawCircles(canvas,-1f,-1f);
                }
            } finally {
                if (canvas != null) 
                {
                    holder.unlockCanvasAndPost(canvas);
                }
            }
            handler.removeCallbacks(drawRunner);
            if (visible) {
                handler.postDelayed(drawRunner, 400);
            }
        }

        // Surface view requires that all elements are drawn completely
        private void drawCircles(Canvas canvas, float xx, float yy) {
            float minX = 10.0f;
            float maxX = 60.0f;
            Random rand = new Random();
            float diameter = rand.nextFloat() * (maxX - minX) + minX;
            float x = xx;
            float y = yy;

            if (xx==-1) {
                x = (float) (width * Math.random());
                y = (float) (height * Math.random());
            }
            paint.setARGB(rand.nextInt(200), rand.nextInt(256), rand.nextInt(256), rand.nextInt(256));
            canvas.drawCircle(x, y, diameter, paint);
        }
    }

}