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发信人: henrywang (海盗), 信区: Java, 读者数: 10 标 题: Re: 我想将canvas里头的图画保存成为gif或jpg图象,how 发信站: BBS 水木清华站 (Sun Jan 10 09:00:22 1999) 【 在 weffen (John) 的大作中提到: 】 : 有没有这样的库？ : 或者怎样实现？ 给你一个存成bmp的类,至于jpg和gif照此琢磨着玩吧 package testPrint; import java.awt.*; import java.io.*; import java.awt.image.*; public class BMPFile extends Component { //--- Private constants private final static int BITMAPFILEHEADER_SIZE = 14; private final static int BITMAPINFOHEADER_SIZE = 40; //--- Private variable declaration //--- Bitmap file header private byte bitmapFileHeader [] = new byte [14]; private byte bfType [] = {'B', 'M'}; private int bfSize = 0; private int bfReserved1 = 0; private int bfReserved2 = 0; private int bfOffBits = BITMAPFILEHEADER_SIZE + BITMAPINFOHEADER_SIZE; //--- Bitmap info header private byte bitmapInfoHeader [] = new byte [40]; private int biSize = BITMAPINFOHEADER_SIZE; private int biWidth = 0; private int biHeight = 0; private int biPlanes = 1; private int biBitCount = 24; private int biCompression = 0; private int biSizeImage = 0x030000; private int biXPelsPerMeter = 0x0; private int biYPelsPerMeter = 0x0; private int biClrUsed = 0; private int biClrImportant = 0; //--- Bitmap raw data private int bitmap []; //--- File section private FileOutputStream fo; //--- Default constructor public BMPFile() { } public void saveBitmap (String parFilename, Image parImage, int parWidth, int parHeight) { try { fo = new FileOutputStream (parFilename); save (parImage, parWidth, parHeight); fo.close (); } catch (Exception saveEx) { saveEx.printStackTrace (); } } } /* * The saveMethod is the main method of the process. This method * will call the convertImage method to convert the memory image to * a byte array; method writeBitmapFileHeader creates and writes * the bitmap file header; writeBitmapInfoHeader creates the * information header; and writeBitmap writes the image. * */ private void save (Image parImage, int parWidth, int parHeight) { try { convertImage (parImage, parWidth, parHeight); writeBitmapFileHeader (); writeBitmapInfoHeader (); writeBitmap (); } catch (Exception saveEx) { saveEx.printStackTrace (); } } } /* * convertImage converts the memory image to the bitmap format (BRG). * It also computes some information for the bitmap info header. * */ private boolean convertImage (Image parImage, int parWidth, int parHeight) { int pad; bitmap = new int [parWidth * parHeight]; PixelGrabber pg = new PixelGrabber (parImage, 0, 0, parWidth, parHeight, bitmap, 0, parWidth); try { pg.grabPixels (); } catch (InterruptedException e) { e.printStackTrace (); return (false); } } pad = (parWidth * 3) % 4; if (pad != 0) pad = (4 - pad) * parHeight; biSizeImage = ((parWidth * parHeight) * 3) + pad; bfSize = biSizeImage + BITMAPFILEHEADER_SIZE + BITMAPINFOHEADER_SIZE; biWidth = parWidth; biHeight = parHeight; return (true); } /* * writeBitmap converts the image returned from the pixel grabber to * the format required. Remember: scan lines are inverted in * a bitmap file! * * Each scan line must be padded to an even 4-byte boundary. */ private void writeBitmap () { int size; int size; int value; int j; int i; int rowCount; int rowIndex; int lastRowIndex; int pad; int padCount; byte rgb [] = new byte [3]; // if a scanline is not time of 4, add some bytes size = (biWidth * biHeight) - 1; pad = ((biWidth * 3) % 4); if (pad != 0) pad = 4 - pad; rowCount = 1; padCount = 0; rowIndex = size - biWidth; lastRowIndex = rowIndex; try { for (j = 0; j < size; j++) { value = bitmap [rowIndex]; rgb [0] = (byte) (value & 0xFF); rgb [1] = (byte) ((value >> 8) & 0xFF); rgb [2] = (byte) ((value >> 16) & 0xFF); fo.write (rgb); if (rowCount == biWidth) { padCount += pad; for (i = 1; i <= pad; i++) fo.write (0x00); rowCount = 1; rowIndex = lastRowIndex - biWidth; lastRowIndex = rowIndex; } else rowCount++; rowIndex++; } //--- Update the size of the file bfSize += padCount - pad; biSizeImage += padCount - pad; } catch (Exception wb) { wb.printStackTrace (); } } /* * writeBitmapFileHeader writes the bitmap file header to the file. * */ private void writeBitmapFileHeader () { try { fo.write (bfType); fo.write (intToDWord (bfSize)); fo.write (intToWord (bfReserved1)); fo.write (intToWord (bfReserved2)); fo.write (intToDWord (bfOffBits)); } catch (Exception wbfh) { wbfh.printStackTrace (); } } } /* * * writeBitmapInfoHeader writes the bitmap information header * to the file. * */ private void writeBitmapInfoHeader () { try { fo.write (intToDWord (biSize)); fo.write (intToDWord (biWidth)); fo.write (intToDWord (biHeight)); fo.write (intToWord (biPlanes)); fo.write (intToWord (biBitCount)); fo.write (intToDWord (biCompression)); fo.write (intToDWord (biSizeImage)); fo.write (intToDWord (biXPelsPerMeter)); fo.write (intToDWord (biYPelsPerMeter)); fo.write (intToDWord (biClrUsed)); fo.write (intToDWord (biClrImportant)); } catch (Exception wbih) { wbih.printStackTrace (); } } /* * * intToWord converts an int to a word, where the return * value is stored in a 2-byte array. * */ private byte [] intToWord (int parvalue) { byte retvalue [] = new byte [2]; retvalue [0] = (byte) (parvalue & 0x00FF); retvalue [1] = (byte) ((parvalue >> 8) & 0x00FF); return (retvalue); } /* * * intToDWord converts an int to a double word, where the return * value is stored in a 4-byte array. * */ private byte [] intToDWord (int parvalue) { byte retvalue [] = new byte [4]; retvalue [0] = (byte) (parvalue & 0x00FF); retvalue [1] = (byte) ((parvalue >> 8) & 0x000000FF); retvalue [2] = (byte) ((parvalue >> 16) & 0x000000FF); retvalue [3] = (byte) ((parvalue >> 24) & 0x000000FF); return (retvalue); } } (海盗) |