J2me中實現淡進淡出成果

飄飄白雲([email protected])

    在J2ME中實現淡進淡出後果，據我所知至少有三種方法。
第一種是取得需要變換圖片的像素，依次設置每個象素的alpha通道值,讓它在0~100之間變更。
    第二種是修正圖片的調色板數據，讓其在調色板原始數據到255之間變更。
    第三種，實在也是利用上面的措施，先描畫圖片，然後在圖片上籠罩一個玄色矩形，轉變這個玄色矩形透明度就可以實現淡進淡出的後果。
    前兩種方法相比擬的話，第一種方法運算量是比擬大的，而且第一種方法由於midp1.0不支撐alpha通道，在一些手機上無法實現。

    下面給出第二種方法的示例，在我們開端之前，應當熟悉png文件格局，假如還不是很明白的話，可以google一下，或者查看前面的帖子中的相干連接。
    代碼很明白，下面是源代碼：

------------CODE__START-----------------------
import Java.io.DataInputStream;
import Java.util.Timer;
import Java.util.TimerTask;

import Javax.microedition.lcdui.Canvas;
import Javax.microedition.lcdui.Display;
import Javax.microedition.lcdui.Graphics;
import Javax.microedition.lcdui.Image;
import Javax.microedition.midlet.MIDlet;
import Javax.microedition.midlet.MIDletStateChangeException;

/**
 * Discription : 修正調色板數據實現淡進淡出後果 Author : 飄飄白雲([email protected]) Created date :
 * 2006/07/13 18:06:39 ModifIEd history :
 */

public class PngFadeInOut extends MIDlet
{
 GameCanvas canvas;

 Display display;

 public PngFadeInOut()
 {
  super();
  try
  {
   display = Display.getDisplay(this);
   canvas = new GameCanvas(this);
  } catch (Exception e)
  {
  }
 }

 protected void startApp() throws MIDletStateChangeException
 {
  if (canvas != null)
  {
   display.setCurrent(canvas);
   canvas.start();
  }
 }

 protected void pauseApp()
 {
  canvas.isExit = true;
 }

 protected void destroyApp(boolean arg0) throws MIDletStateChangeException
 {
 }
}

class GameCanvas extends Canvas
{
 static String imageName = "/fadeInOut.png";

 public static final int MAX_TARDINESS = 30;

 // ---------------------------------------------------
 PngFadeInOut app;

 boolean isInited = false;

 public boolean isExit = false;

 Image offImage = null;

 public Graphics g = null;

 int scrW;

 int scrH;

 // ---------------------------------------------------
 int gameMode;

 int subMode;

 static final int smInit = 0;

 static final int smProc = 1;

 static final int smEnd = 2;

 static final int gmStart = 0;

 // ---------------------------------------------------
 Image testImage = null;

 byte[] oldRGBData = null;

 byte[] imgData = null;

 static final int FADE_IN = 0;

 static final int FADE_OUT = 1;

 static final int FADE_STEP = 1;

 static int fadeType = FADE_IN;

 // ---------------------------------------------------
 // ---Timer process
 // ---------------------------------------------------
 TimerTask task;

 Timer timer;

 int timerDelayTime;

 public boolean isTimerRunning;

 void startTimer(int delayTime)
 {
  timerDelayTime = delayTime;
  isTimerRunning = true;

  timer = new Timer();
  task = new ProcessingRunner();
  timer.scheduleAtFixedRate(task, 0, delayTime);
 }

 public void stopTimer()
 {
  if (task != null)
   task.cancel();

  isTimerRunning = false;
  timer = null;
  task = null;
 }

 // -----------------------------------------------------
 class ProcessingRunner extends TimerTask
 {
  public void run()
  {
   if (isExit)
   {
    stopTimer();
    app.notifyDestroyed();
   }

   if (!isTimerRunning
     || System.currentTimeMillis() - scheduledExecutionTime() >= timerDelayTime)
   {
    return;
   }

   gameMain();
   gameDraw();

   repaint();
   serviceRepaints();
   System.gc();
  }
 }

 // -------------------------------------------------

 public GameCanvas(MIDlet midlet)
 {
  app = (PngFadeInOut) midlet;
 }

 public void start()
 {
  setFullScreenMode(true);
  while (!isShown())
   ;

  if (!isInited)
  {
   gameInit();
   isInited = true;
  }

  startTimer(MAX_TARDINESS);
 }

 void gameInit()
 {
  scrW = getWidth();
  scrH = getHeight();

  if (g == null || offImage == null)
  {
   offImage = Image.createImage(scrW, scrH);

  g = offImage.getGraphics();
  }

  changeGameMode(gmStart);
 }

 public void changeGameMode(int gm)
 {
  gameMode = gm;
  subMode = smInit;
 }

 // ---------------------------------------------------
 // 游戲主邏輯處理
 // ---------------------------------------------------
 void gameMain()
 {
  if (gameMode == gmStart)
  {
   if (subMode == smInit)
   {
    // 取得圖片的二進制數據
    imgData = loadFile(imageName);

    // 保留原始圖片的調色板rgb數據
    oldRGBData = getPlteRGBData(imgData);

    if (fadeType == FADE_IN)
    {
     // 設置調色板色彩為白色，淡進後果
     for (int i = rgbDataStartPos; i < rgbDataStartPos
     + rgbDataLength; i++)
     {
      imgData = (byte) 255;
     }
    }
   }
  }
 }
}