Java tutorial
/* * Copyright 2003 by Paulo Soares. * * The contents of this file are subject to the Mozilla Public License Version 1.1 * (the "License"); you may not use this file except in compliance with the License. * You may obtain a copy of the License at http://www.mozilla.org/MPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the License. * * The Original Code is 'iText, a free JAVA-PDF library'. * * The Initial Developer of the Original Code is Bruno Lowagie. Portions created by * the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie. * All Rights Reserved. * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer * are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved. * * Contributor(s): all the names of the contributors are added in the source code * where applicable. * * Alternatively, the contents of this file may be used under the terms of the * LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the * provisions of LGPL are applicable instead of those above. If you wish to * allow use of your version of this file only under the terms of the LGPL * License and not to allow others to use your version of this file under * the MPL, indicate your decision by deleting the provisions above and * replace them with the notice and other provisions required by the LGPL. * If you do not delete the provisions above, a recipient may use your version * of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE. * * This library is free software; you can redistribute it and/or modify it * under the terms of the MPL as stated above or under the terms of the GNU * Library General Public License as published by the Free Software Foundation; * either version 2 of the License, or any later version. * * This library is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU Library general Public License for more * details. * * If you didn't download this code from the following link, you should check if * you aren't using an obsolete version: * http://www.lowagie.com/iText/ */ package com.lowagie.text.pdf.codec; import java.io.BufferedInputStream; import java.io.ByteArrayInputStream; import java.io.DataInputStream; import java.io.IOException; import java.io.InputStream; import java.net.URL; import java.util.ArrayList; import com.lowagie.text.ExceptionConverter; import com.lowagie.text.Image; import com.lowagie.text.ImgRaw; import com.lowagie.text.Utilities; import com.lowagie.text.pdf.PdfArray; import com.lowagie.text.pdf.PdfDictionary; import com.lowagie.text.pdf.PdfName; import com.lowagie.text.pdf.PdfNumber; import com.lowagie.text.pdf.PdfString; /** Reads gif images of all types. All the images in a gif are read in the constructors * and can be retrieved with other methods. * @author Paulo Soares (psoares@consiste.pt) */ public class GifImage { protected DataInputStream in; protected int width; // full image width protected int height; // full image height protected boolean gctFlag; // global color table used protected int bgIndex; // background color index protected int bgColor; // background color protected int pixelAspect; // pixel aspect ratio protected boolean lctFlag; // local color table flag protected boolean interlace; // interlace flag protected int lctSize; // local color table size protected int ix, iy, iw, ih; // current image rectangle protected byte[] block = new byte[256]; // current data block protected int blockSize = 0; // block size // last graphic control extension info protected int dispose = 0; // 0=no action; 1=leave in place; 2=restore to bg; 3=restore to prev protected boolean transparency = false; // use transparent color protected int delay = 0; // delay in milliseconds protected int transIndex; // transparent color index protected static final int MaxStackSize = 4096; // max decoder pixel stack size // LZW decoder working arrays protected short[] prefix; protected byte[] suffix; protected byte[] pixelStack; protected byte[] pixels; protected byte m_out[]; protected int m_bpc; protected int m_gbpc; protected byte m_global_table[]; protected byte m_local_table[]; protected byte m_curr_table[]; protected int m_line_stride; protected byte fromData[]; protected URL fromUrl; protected ArrayList frames = new ArrayList(); // frames read from current file /** Reads gif images from an URL. * @param url the URL * @throws IOException on error */ public GifImage(URL url) throws IOException { fromUrl = url; InputStream is = null; try { is = url.openStream(); process(is); } finally { if (is != null) { is.close(); } } } /** Reads gif images from a file. * @param file the file * @throws IOException on error */ public GifImage(String file) throws IOException { this(Utilities.toURL(file)); } /** Reads gif images from a byte array. * @param data the byte array * @throws IOException on error */ public GifImage(byte data[]) throws IOException { fromData = data; InputStream is = null; try { is = new ByteArrayInputStream(data); process(is); } finally { if (is != null) { is.close(); } } } /** Reads gif images from a stream. The stream is not closed. * @param is the stream * @throws IOException on error */ public GifImage(InputStream is) throws IOException { process(is); } /** Gets the number of frames the gif has. * @return the number of frames the gif has */ public int getFrameCount() { return frames.size(); } /** Gets the image from a frame. The first frame is 1. * @param frame the frame to get the image from * @return the image */ public Image getImage(int frame) { GifFrame gf = (GifFrame) frames.get(frame - 1); return gf.image; } /** Gets the [x,y] position of the frame in reference to the * logical screen. * @param frame the frame * @return the [x,y] position of the frame */ public int[] getFramePosition(int frame) { GifFrame gf = (GifFrame) frames.get(frame - 1); return new int[] { gf.ix, gf.iy }; } /** Gets the logical screen. The images may be smaller and placed * in some position in this screen to playback some animation. * No image will be be bigger that this. * @return the logical screen dimensions as [x,y] */ public int[] getLogicalScreen() { return new int[] { width, height }; } void process(InputStream is) throws IOException { in = new DataInputStream(new BufferedInputStream(is)); readHeader(); readContents(); if (frames.isEmpty()) throw new IOException("The file does not contain any valid image."); } /** * Reads GIF file header information. */ protected void readHeader() throws IOException { String id = ""; for (int i = 0; i < 6; i++) id += (char) in.read(); if (!id.startsWith("GIF8")) { throw new IOException("Gif signature nor found."); } readLSD(); if (gctFlag) { m_global_table = readColorTable(m_gbpc); } } /** * Reads Logical Screen Descriptor */ protected void readLSD() throws IOException { // logical screen size width = readShort(); height = readShort(); // packed fields int packed = in.read(); gctFlag = (packed & 0x80) != 0; // 1 : global color table flag m_gbpc = (packed & 7) + 1; bgIndex = in.read(); // background color index pixelAspect = in.read(); // pixel aspect ratio } /** * Reads next 16-bit value, LSB first */ protected int readShort() throws IOException { // read 16-bit value, LSB first return in.read() | (in.read() << 8); } /** * Reads next variable length block from input. * * @return number of bytes stored in "buffer" */ protected int readBlock() throws IOException { blockSize = in.read(); if (blockSize <= 0) return blockSize = 0; for (int k = 0; k < blockSize; ++k) { int v = in.read(); if (v < 0) { return blockSize = k; } block[k] = (byte) v; } return blockSize; } protected byte[] readColorTable(int bpc) throws IOException { int ncolors = 1 << bpc; int nbytes = 3 * ncolors; bpc = newBpc(bpc); byte table[] = new byte[(1 << bpc) * 3]; in.readFully(table, 0, nbytes); return table; } static protected int newBpc(int bpc) { switch (bpc) { case 1: case 2: case 4: break; case 3: return 4; default: return 8; } return bpc; } protected void readContents() throws IOException { // read GIF file content blocks boolean done = false; while (!done) { int code = in.read(); switch (code) { case 0x2C: // image separator readImage(); break; case 0x21: // extension code = in.read(); switch (code) { case 0xf9: // graphics control extension readGraphicControlExt(); break; case 0xff: // application extension readBlock(); skip(); // don't care break; default: // uninteresting extension skip(); } break; default: done = true; break; } } } /** * Reads next frame image */ protected void readImage() throws IOException { ix = readShort(); // (sub)image position & size iy = readShort(); iw = readShort(); ih = readShort(); int packed = in.read(); lctFlag = (packed & 0x80) != 0; // 1 - local color table flag interlace = (packed & 0x40) != 0; // 2 - interlace flag // 3 - sort flag // 4-5 - reserved lctSize = 2 << (packed & 7); // 6-8 - local color table size m_bpc = newBpc(m_gbpc); if (lctFlag) { m_curr_table = readColorTable((packed & 7) + 1); // read table m_bpc = newBpc((packed & 7) + 1); } else { m_curr_table = m_global_table; } if (transparency && transIndex >= m_curr_table.length / 3) transparency = false; if (transparency && m_bpc == 1) { // Acrobat 5.05 doesn't like this combination byte tp[] = new byte[12]; System.arraycopy(m_curr_table, 0, tp, 0, 6); m_curr_table = tp; m_bpc = 2; } boolean skipZero = decodeImageData(); // decode pixel data if (!skipZero) skip(); Image img = null; try { img = new ImgRaw(iw, ih, 1, m_bpc, m_out); PdfArray colorspace = new PdfArray(); colorspace.add(PdfName.INDEXED); colorspace.add(PdfName.DEVICERGB); int len = m_curr_table.length; colorspace.add(new PdfNumber(len / 3 - 1)); colorspace.add(new PdfString(m_curr_table)); PdfDictionary ad = new PdfDictionary(); ad.put(PdfName.COLORSPACE, colorspace); img.setAdditional(ad); if (transparency) { img.setTransparency(new int[] { transIndex, transIndex }); } } catch (Exception e) { throw new ExceptionConverter(e); } img.setOriginalType(Image.ORIGINAL_GIF); img.setOriginalData(fromData); img.setUrl(fromUrl); GifFrame gf = new GifFrame(); gf.image = img; gf.ix = ix; gf.iy = iy; frames.add(gf); // add image to frame list //resetFrame(); } protected boolean decodeImageData() throws IOException { int NullCode = -1; int npix = iw * ih; int available, clear, code_mask, code_size, end_of_information, in_code, old_code, bits, code, count, i, datum, data_size, first, top, bi; boolean skipZero = false; if (prefix == null) prefix = new short[MaxStackSize]; if (suffix == null) suffix = new byte[MaxStackSize]; if (pixelStack == null) pixelStack = new byte[MaxStackSize + 1]; m_line_stride = (iw * m_bpc + 7) / 8; m_out = new byte[m_line_stride * ih]; int pass = 1; int inc = interlace ? 8 : 1; int line = 0; int xpos = 0; // Initialize GIF data stream decoder. data_size = in.read(); clear = 1 << data_size; end_of_information = clear + 1; available = clear + 2; old_code = NullCode; code_size = data_size + 1; code_mask = (1 << code_size) - 1; for (code = 0; code < clear; code++) { prefix[code] = 0; suffix[code] = (byte) code; } // Decode GIF pixel stream. datum = bits = count = first = top = bi = 0; for (i = 0; i < npix;) { if (top == 0) { if (bits < code_size) { // Load bytes until there are enough bits for a code. if (count == 0) { // Read a new data block. count = readBlock(); if (count <= 0) { skipZero = true; break; } bi = 0; } datum += (block[bi] & 0xff) << bits; bits += 8; bi++; count--; continue; } // Get the next code. code = datum & code_mask; datum >>= code_size; bits -= code_size; // Interpret the code if ((code > available) || (code == end_of_information)) break; if (code == clear) { // Reset decoder. code_size = data_size + 1; code_mask = (1 << code_size) - 1; available = clear + 2; old_code = NullCode; continue; } if (old_code == NullCode) { pixelStack[top++] = suffix[code]; old_code = code; first = code; continue; } in_code = code; if (code == available) { pixelStack[top++] = (byte) first; code = old_code; } while (code > clear) { pixelStack[top++] = suffix[code]; code = prefix[code]; } first = suffix[code] & 0xff; // Add a new string to the string table, if (available >= MaxStackSize) break; pixelStack[top++] = (byte) first; prefix[available] = (short) old_code; suffix[available] = (byte) first; available++; if (((available & code_mask) == 0) && (available < MaxStackSize)) { code_size++; code_mask += available; } old_code = in_code; } // Pop a pixel off the pixel stack. top--; i++; setPixel(xpos, line, pixelStack[top]); ++xpos; if (xpos >= iw) { xpos = 0; line += inc; if (line >= ih) { if (interlace) { do { pass++; switch (pass) { case 2: line = 4; break; case 3: line = 2; inc = 4; break; case 4: line = 1; inc = 2; break; default: // this shouldn't happen line = ih - 1; inc = 0; } } while (line >= ih); } else { line = ih - 1; // this shouldn't happen inc = 0; } } } } return skipZero; } protected void setPixel(int x, int y, int v) { if (m_bpc == 8) { int pos = x + iw * y; m_out[pos] = (byte) v; } else { int pos = m_line_stride * y + x / (8 / m_bpc); int vout = v << (8 - m_bpc * (x % (8 / m_bpc)) - m_bpc); m_out[pos] |= vout; } } /** * Resets frame state for reading next image. */ protected void resetFrame() { // it does nothing in the pdf context //boolean transparency = false; //int delay = 0; } /** * Reads Graphics Control Extension values */ protected void readGraphicControlExt() throws IOException { in.read(); // block size int packed = in.read(); // packed fields dispose = (packed & 0x1c) >> 2; // disposal method if (dispose == 0) dispose = 1; // elect to keep old image if discretionary transparency = (packed & 1) != 0; delay = readShort() * 10; // delay in milliseconds transIndex = in.read(); // transparent color index in.read(); // block terminator } /** * Skips variable length blocks up to and including * next zero length block. */ protected void skip() throws IOException { do { readBlock(); } while (blockSize > 0); } static class GifFrame { Image image; int ix; int iy; } }