用getRGB的方法实现淡入淡出，但是效果不太好 求解！解决方法

import javax.microedition.lcdui.game.*;import javax.microedition.lcdui.*;import javax.microedition.midlet.*;class Game extends GameCanvas implements Runnable,GameData{    MIDlet Maze;    Graphics gra;    Image logo;    Image donghua;    int GameStatus;    int w,h;    int offsetx,offsety;    int value;    long time1;        Game(MIDlet Maze)    {        super(false);         this.setFullScreenMode(true);        this.Maze=Maze;        w=this.getWidth();        h=this.getHeight();        value=0xff;                GameStatus=LOGO;        logo=createImage("/logo.png");        donghua=createImage("/donghua.png");        offsetx=(w-logo.getWidth())/2;        offsety=(h-logo.getHeight())/2;        time1=System.currentTimeMillis();        new Thread(this).start();        }            public Image createImage(String filename)    {        Image image=null;        try        {            image=Image.createImage(filename);            }        catch(java.io.IOException ex){}        return image;            }        public Image makeTransparent(Image img, int value)     {           int w = img.getWidth();        int h = img.getHeight();        int[] imgData = new int[w*h];        img.getRGB(imgData, 0, w, 0, 0, w, h);        for (int i = 0; i < imgData.length; i++)         {            imgData[i] = imgData[i] & 0x00ffffff + (value << 24);        }        return Image.createRGBImage(imgData, w, h, true);    }             public void paint(Graphics gra)    {        switch(GameStatus)        {                       case LOGO:                gra.setColor(0);                gra.fillRect(0,0,w,h);                logo=makeTransparent(logo, value);                value-=0x04;                gra.drawImage(logo,offsetx,offsety,0);        break;                            case DONGHUA:                gra.setColor(0);                gra.fillRect(0,0,w,h);                gra.drawImage(donghua,offsetx,offsety,0);                break;                    case END:                break;        }                }        public void run()    {        gra=getGraphics();        while(true)        {            input();            long st=System.currentTimeMillis();            switch(GameStatus)            {                case LOGO:                    paint(gra);                   // if(System.currentTimeMillis()-time1>3000)                    if(value<=0x00)            {                        GameStatus=DONGHUA;                        time1=System.currentTimeMillis();              gra.setColor(0);                          gra.fillRect(0,0,w,h);                    }            break;                                    case DONGHUA:                    if(System.currentTimeMillis()-time1>1000&&System.currentTimeMillis()-time1<3000)                    paint(gra);                    else if(System.currentTimeMillis()-time1>3000)                    {                        GameStatus=END;                        time1=System.currentTimeMillis();            gra.setColor(0);                    gra.fillRect(0,0,w,h);                    }            break;                            case END:                    if(System.currentTimeMillis()-time1>1000)                    Maze.notifyDestroyed();                       break;         }                flushGraphics();            long tk=System.currentTimeMillis()-st;            if(tk<100)            {                try{Thread.sleep(100-tk);}                catch(Exception e){}                }          }        }        public void input()    {        int keyState=getKeyStates();    //System.out.println(keyState);        switch(GameStatus)        {            case LOGO:                    if((keyState&FIRE_PRESSED)!=0)                    {                    GameStatus=DONGHUA;                    time1=System.currentTimeMillis();                    gra.setColor(0);                    gra.fillRect(0,0,w,h);                }                break;                            case DONGHUA:                if((keyState&FIRE_PRESSED)!=0)                    {                    GameStatus=END;                    time1=System.currentTimeMillis();                    gra.setColor(0);                    gra.fillRect(0,0,w,h);        }                break;            case END:                break;          }    }        }出现的图片渐变很不流畅 像是很卡很卡的效果 求高手指点！