将Image对像转换为png格式的byte数组.doc

将Image对像转换为png格式的byte数组 作者：lupenglo文章来源：本站原创点击数：4629更新时间：2008-5-18 由于J2me中没有ImageIO 导致一些功能无法在J2me上实现.导致大家无法实现一些功能.如绘图软件.大头贴.截屏等.貌私新版的jsr什么什么实现了将Image 输出为png or jpg但估计等到这种手机上市的时候以是几年后的事情了.其实在j2me上将Image 对象转成png格式的数组并不是不可能的任务.原理上说1 获取Image 的ARGB数据2将ARGB转换成PNG存储用的的RGBA格式3RGBA格式的数据还要做些小的处理每行后面加一个byte 04用LZ77方法将RGBA格式的数组压缩5附加正确格式PNG24文件头输出即可包括IHEAD IHDR IEND IDAT外壳但是使用LZ77压缩手机上无论时间或空间都是不太能接受的还好LZ77 存在一钟无压缩的压缩方法本文的方法就是使用无压缩的方式搞定数据压缩的参阅了jzlib 代码使用300行左右的代码搞定了将Image对象转pngimport javax.microedition.lcdui.*;import java.io.*;import javax.microedition.io.file.FileConnection;import javax.microedition.io.Connector;public class CGame extends Canvas /Image2Bytes by AnderLu /生成的byte数组可直接用于外部存储为.png格式的图片文件看图软件可直接打开 public static int IDATPOS; public static byte HEADChunk = (byte) 0x89, (byte) 0x50, (byte) 0x4E, (byte) 0x47, (byte) 0x0D, (byte) 0x0A, (byte) 0x1A, (byte) 0x0A, ; public static byte tRNSChunk = (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x01, (byte) 0x74, (byte) 0x52, (byte) 0x4E, (byte) 0x53, (byte) 0x00, (byte) 0x40, (byte) 0xE6, (byte) 0xD8, (byte) 0x66, ; public static byte IENDChunk = /PNGIEND (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x49, (byte) 0x45, (byte) 0x4E, (byte) 0x44, (byte) 0xAE, (byte) 0x42, (byte) 0x60, (byte) 0x82 ; Image img; public CGame() Image img = null; try img = Image.createImage(/cap.png); catch (IOException ex) ex.printStackTrace(); byte data = Image2Bytes(img); this.img = Image.createImage(data, 0, data.length); saveFile(file:/e:/a.png, data); protected void paint(Graphics g) g.setColor(0xffffff); g.fillRect(0, 0, 240, 320); g.drawImage(img, 0, 0, 0); /*保存文件 * path:路径 * fileData:文件数据 * return: 0:出现异常,1:保存成功 */ public int saveFile(String path, byte fileData) FileConnection fc = null; try fc = (FileConnection) Connector.open(path, Connector.READ_WRITE); if (!fc.exists() fc.create(); OutputStream os = fc.openOutputStream(); os.write(fileData); os.flush(); os.close(); fc.close(); return 1; catch (IOException ex) ex.printStackTrace(); return 0; public byte Image2Bytes(Image img) try int w = img.getWidth(); int h = img.getHeight(); int offset = 0; byte buffer = new byte(w * 4 + 1) * h + offset; getImageBufferForImageARGB8888(img, buffer, w, h, offset); System.gc(); ByteArrayOutputStream baos = new ByteArrayOutputStream(); DataOutputStream dout = new DataOutputStream(baos); WritePng(dout, w, h, buffer, null, false, offset); byte data = baos.toByteArray(); writeCRC(data, 8); /更新IHDR CRC writeCRC(data, 33); /更新PLTE CRC writeCRC(data, IDATPOS); /更新IDAT CRC buffer = null; System.gc(); return data; catch (IOException ex) ex.printStackTrace(); return null; public static void writeCRC(byte data, int chunkpos) int chunklen = (datachunkpos & 0xFF) 24) | (datachunkpos + 1 & 0xFF) 16) | (datachunkpos + 2 & 0xFF) 24); datapos + 1 = (byte) (val & 0xFF0000) 16); datapos + 2 = (byte) (val & 0xFF00) 8); datapos + 3 = (byte) (val & 0xFF); public static int crc_table; /CRC 表 public static int CRCChecksum(byte buf, int off, int len) int c = 0xffffffff; int n; if (crc_table = null) int mkc; int mkn, mkk; crc_table = new int256; for (mkn = 0; mkn 256; mkn+) mkc = mkn; for (mkk = 0; mkk 1); else mkc = mkc 1; crc_tablemkn = mkc; for (n = off; n 8); return c; public static long adler32(long adler, byte buf, int index, int len) int BASE = 65521; int NMAX = 5552; /TODO remove this function at all if (buf = null) return 1L; long s1 = adler & 0xffff; long s2 = (adler 16) & 0xffff; int k; while (len 0) k = len = 16) s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; s1 += bufindex+ & 0xff; s2 += s1; k -= 16; if (k != 0) do s1 += bufindex+ & 0xff; s2 += s1; while (-k != 0); s1 %= BASE; s2 %= BASE; return (s2 16) | s1; public static void WritePng(DataOutputStream output, int width, int height, byte buffer, byte colors, boolean Transparent, int offset) throws IOException int adler = (int) adler32(1l, buffer, offset, buffer.length - offset); byte lenNlen = /压缩块的LEN和NLEN信息 (byte) 0, (byte) 0xfa, (byte) 0x7e, (byte) 0x05, (byte) 0x81 ; IDATPOS = 0; output.write(HEADChunk); IDATPOS += HEADChunk.length; /写IHDR output.writeInt(13); /len output.writeInt(1229472850); /IHDR type code output.writeInt(width); /写宽度 output.writeInt(height); /写高度 output.writeByte(8); /1Bitdepth if (colors = null) output.writeByte(6); /2ColorType else output.writeByte(3); /2ColorType output.writeByte(0); /3CompressionMethod output.writeByte(0); /4Filter method output.writeByte(0); /5Interlace method output.writeInt(0); /写crc IDATPOS += 25; /写PLTE if (colors != null) output.writeInt(colors.length); /len output.writeInt(1347179589); /type code output.write(colors); /data output.writeInt(0); /crc IDATPOS += colors.length + 12; /写TRNS if (Transparent) output.write(tRNSChunk); IDATPOS += tRNSChunk.length; /写IDAT byte dpixels = buffer; int bufferlen = dpixels.length - offset; int blocklen = 32506; int blocknum = 1; if (dpixels.length % blocklen) = 0) blocknum = bufferlen / blocklen; else blocknum = (bufferlen / blocklen) + 1; int IDATChunkLen = (bufferlen + 6 + blocknum * 5); output.writeInt(IDATChunkLen); /len output.writeInt(1229209940); /idat type code output.writeShort(short) 0x78da); /78da for (int i = 0; i = blocklen) len = blocklen; lenNlen0 = (byte) 0; else lenNlen0 = (byte) 1; int msb = (len & 0xff); int lsb = (len 8); lenNlen1 = (byte) msb; lenNlen2 = (byte) lsb; lenNlen3 = (byte) (msb 0xff); lenNlen4 = (byte) (lsb 0xff); output.write(lenNlen); output.write(dpixels, off + offset, len); output.writeIn