關於MIDP 1.0 圖片翻轉換色的討論

最近工作有點空，所以想研究研究關於 MIDP1.0圖片翻轉的問題，可能有人會問 midp2 裡不是有翻轉函數位，但是我可以說國內絕大多數的公司都是使用1.0在開發，因為中國有太多使用者使用的手機不支援2.0,而且2.0的 GameAPI 也是差強人意。

好了，接下來看看我現在找到的一點關於 1.0 翻轉已經換色的資料

import javax.microedition.lcdui.*;

class Png
{
  static int[]  crc_table;
  static int  dataptr;
  static int  crcfrom;
  static int  pngsize;
  static byte[]  data;
  static byte[]  PNG_header={-119,80,78,71,13,10,26,10,0,0,0,13,73,72,68,82,0,0,0,0,0,0,0,0,8,3,0,0,0};
  static byte[]  PNG_End={0,0,0,0,73,69,78,68,-82,66,96,-126};

  static
  {
      crc_table = new int[256];
    
      for (int n = 0; n < 256; n++)
      {
        int c = n;
        for (int k = 8;  --k >= 0; )
        {
            if ((c & 1) != 0)
              c = 0xedb88320 ^ (c >>> 1);
            else
              c = c >>> 1;
        }      
        crc_table[n] = c;
      }
  }

  static Image create(int width, int height, int palette, byte[] idata, byte[] pal, int trans, int flips, int imgStart, int palStart)
  {
      int i,j;
      Image temp;
    
      if(flips>3)            // If rotating swap width and height around
      {
        int t=width;
        width=height;
        height=t;
      }    
    
      pngsize = palette*3 + (width+1)*height + 80;
    
      if(trans>-1) pngsize += 13 + trans;
    
      data = new byte[pngsize];
    
      // Create PNG Header    
      for(i=0;i<PNG_header.length;i++)
        data[i] = PNG_header[i];

      data[19] = (byte)width;
      data[23] = (byte)height;

      dataptr=29;
    
      writeInt(calc_crc(data, 12, 17));

      writeInt(palette*3);
    
      crcfrom=dataptr;
    
      writeInt(0x504c5445);      // PLTE Header
    
      for(i=0;i<palette*3;i++)
        data[dataptr++]=pal[i+palStart*3];
    
      writeInt(calc_crc(data, crcfrom, dataptr - crcfrom));
    
      if(trans>-1)
      {
        writeInt(trans+1);

        crcfrom=dataptr;    

        writeInt(0x74524e53);      // tRNS Header
      
        for(i=0;i<trans;i++)
            data[dataptr++]=(byte)0xff;
      
        data[dataptr++]=0;
      
        writeInt(calc_crc(data, crcfrom, dataptr - crcfrom));
      }
    
      int compsize = (width+1) * height;
    
      writeInt(compsize+11);        // Write IDAT Length
    
      crcfrom=dataptr;    
    
      writeInt(0x49444154);        // IDAT Header
    
      data[dataptr++]=(byte)0x78;      // PNG compression flags
      data[dataptr++]=(byte)0xda;      // PNG compression flags
      data[dataptr++]=(byte)0x01;      // PNG final block / No compression

      data[dataptr++]=(byte)(compsize & 0xff);      // Write data length (little endian)
      data[dataptr++]=(byte)((compsize>>>8) & 0xff);
    
      data[dataptr]=(byte)(~data[dataptr-2]);        // Write inverse length
      dataptr++;
      data[dataptr]=(byte)(~data[dataptr-2]);
      dataptr++;
    
      int adlerstart = dataptr;

      switch(flips)
      {
        case 0:      // No Flip

            i=imgStart;          
            for(int y=0;y<height;y++)
            {
              data[dataptr++]=0;
              for(int x=0;x<width;x++)
                  data[dataptr++]=idata[i++];
            }
            break;
          
        case 1:      // X Flip
          
            for(int y=0;y<height;y++)
            {
              i=(y+1)*width-1+imgStart;
              data[dataptr++]=0;
              for(int x=0;x<width;x++)
                  data[dataptr++]=idata[i--];
            }
            break;
          
        case 2:      // Y Flip
          
            for(int y=0;y<height;y++)
            {
              i=(height-y-1)*width+imgStart;
              data[dataptr++]=0;      // No Filter flag for each line
              for(int x=0;x<width;x++)
                  data[dataptr++]=idata[i++];
            }
            break;
          
        case 3:      // XY Flip
          
            for(int y=0;y<height;y++)
            {
              i=(height-y)*width-1+imgStart;
              data[dataptr++]=0;      // No Filter flag for each line
              for(int x=0;x<width;x++)
                  data[dataptr++]=idata[i--];
            }
            break;
          
        case 4:  // Rotated 90 CW
          
            j=(width-1)*height+imgStart;
            for(int y=0;y<height;y++)
            {
              i=j+y;
              data[dataptr++]=0;
              for(int x=0;x<width;x++)
              {
                  data[dataptr++]=idata[i];
                  i-=height;
              }
            }
            break;
          
        case 5:  // Rotated 90 CCW
          
            j=height+imgStart-1;
            for(int y=0;y<height;y++)
            {
              i=j-y;
              data[dataptr++]=0;
              for(int x=0;x<width;x++)
              {
                  data[dataptr++]=idata[i];
                  i+=height;
              }
            }
            break;            
      }
    
      int adler1=1;
      int adler2=0;

      for(i=0;i<compsize;i++)
      {
        adler1=adler1+((int)data[adlerstart+i]&0xff);
        adler2=adler1+adler2;
        adler1%=65521;
        adler2%=65521;
      }    
      writeInt((adler2<<16) | adler1 );    
      writeInt(calc_crc(data, crcfrom, dataptr - crcfrom));
    
      for(i=0;i<PNG_End.length;i++)
        data[dataptr++] = PNG_End[i];
    
      temp = Image.createImage (data,0, dataptr);
      data = null;    
      return temp;
  }

  static void writeInt(long crc)
  {
      data[dataptr++]=(byte)((crc>>>24)&255);
      data[dataptr++]=(byte)((crc>>>16)&255);    
      data[dataptr++]=(byte)((crc>>>8)&255);    
      data[dataptr++]=(byte)(crc&255);
  }

  static long calc_crc (byte[] buf, int off, int len)
  {
      int c = ~0;
      while (--len >= 0)
      c = crc_table[(c ^ buf[off++]) & 0xff] ^ (c >>> 8);    
      return (long) ~c & 0xffffffffL;
  }
}

這是國外的程式寫的一段代碼，在1.0中實現了圖片的翻轉和換色，而且在遊戲中進行了應用，取得了不錯的效果，但是關鍵他用的圖片格式是RAW的一種格式，是未壓縮的格式，也就是說是連續的格式，但是我不清楚這種格式是如何轉成的。我說這些只是想起一個頭，大家有興趣的可以討論一下這個話題。測試程式見附件