| /* |
| * Copyright (c) 2001, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package com.sun.imageio.plugins.jpeg; |
| |
| import javax.imageio.stream.ImageInputStream; |
| import javax.imageio.IIOException; |
| |
| import java.io.IOException; |
| |
| /** |
| * A class wrapping a buffer and its state. For efficiency, |
| * the members are made visible to other classes in this package. |
| */ |
| class JPEGBuffer { |
| |
| private boolean debug = false; |
| |
| /** |
| * The size of the buffer. This is large enough to hold all |
| * known marker segments (other than thumbnails and icc profiles) |
| */ |
| final int BUFFER_SIZE = 4096; |
| |
| /** |
| * The actual buffer. |
| */ |
| byte [] buf; |
| |
| /** |
| * The number of bytes available for reading from the buffer. |
| * Anytime data is read from the buffer, this should be updated. |
| */ |
| int bufAvail; |
| |
| /** |
| * A pointer to the next available byte in the buffer. This is |
| * used to read data from the buffer and must be updated to |
| * move through the buffer. |
| */ |
| int bufPtr; |
| |
| /** |
| * The ImageInputStream buffered. |
| */ |
| ImageInputStream iis; |
| |
| JPEGBuffer (ImageInputStream iis) { |
| buf = new byte[BUFFER_SIZE]; |
| bufAvail = 0; |
| bufPtr = 0; |
| this.iis = iis; |
| } |
| |
| /** |
| * Ensures that there are at least <code>count</code> bytes available |
| * in the buffer, loading more data and moving any remaining |
| * bytes to the front. A count of 0 means to just fill the buffer. |
| * If the count is larger than the buffer size, just fills the buffer. |
| * If the end of the stream is encountered before a non-0 count can |
| * be satisfied, an <code>IIOException</code> is thrown with the |
| * message "Image Format Error". |
| */ |
| void loadBuf(int count) throws IOException { |
| if (debug) { |
| System.out.print("loadbuf called with "); |
| System.out.print("count " + count + ", "); |
| System.out.println("bufAvail " + bufAvail + ", "); |
| } |
| if (count != 0) { |
| if (bufAvail >= count) { // have enough |
| return; |
| } |
| } else { |
| if (bufAvail == BUFFER_SIZE) { // already full |
| return; |
| } |
| } |
| // First copy any remaining bytes down to the beginning |
| if ((bufAvail > 0) && (bufAvail < BUFFER_SIZE)) { |
| System.arraycopy(buf, bufPtr, buf, 0, bufAvail); |
| } |
| // Now fill the rest of the buffer |
| int ret = iis.read(buf, bufAvail, buf.length - bufAvail); |
| if (debug) { |
| System.out.println("iis.read returned " + ret); |
| } |
| if (ret != -1) { |
| bufAvail += ret; |
| } |
| bufPtr = 0; |
| int minimum = Math.min(BUFFER_SIZE, count); |
| if (bufAvail < minimum) { |
| throw new IIOException ("Image Format Error"); |
| } |
| } |
| |
| /** |
| * Fills the data array from the stream, starting with |
| * the buffer and then reading directly from the stream |
| * if necessary. The buffer is left in an appropriate |
| * state. If the end of the stream is encountered, an |
| * <code>IIOException</code> is thrown with the |
| * message "Image Format Error". |
| */ |
| void readData(byte [] data) throws IOException { |
| int count = data.length; |
| // First see what's left in the buffer. |
| if (bufAvail >= count) { // It's enough |
| System.arraycopy(buf, bufPtr, data, 0, count); |
| bufAvail -= count; |
| bufPtr += count; |
| return; |
| } |
| int offset = 0; |
| if (bufAvail > 0) { // Some there, but not enough |
| System.arraycopy(buf, bufPtr, data, 0, bufAvail); |
| offset = bufAvail; |
| count -= bufAvail; |
| bufAvail = 0; |
| bufPtr = 0; |
| } |
| // Now read the rest directly from the stream |
| if (iis.read(data, offset, count) != count) { |
| throw new IIOException ("Image format Error"); |
| } |
| } |
| |
| /** |
| * Skips <code>count</code> bytes, leaving the buffer |
| * in an appropriate state. If the end of the stream is |
| * encountered, an <code>IIOException</code> is thrown with the |
| * message "Image Format Error". |
| */ |
| void skipData(int count) throws IOException { |
| // First see what's left in the buffer. |
| if (bufAvail >= count) { // It's enough |
| bufAvail -= count; |
| bufPtr += count; |
| return; |
| } |
| if (bufAvail > 0) { // Some there, but not enough |
| count -= bufAvail; |
| bufAvail = 0; |
| bufPtr = 0; |
| } |
| // Now read the rest directly from the stream |
| if (iis.skipBytes(count) != count) { |
| throw new IIOException ("Image format Error"); |
| } |
| } |
| |
| /** |
| * Push back the remaining contents of the buffer by |
| * repositioning the input stream. |
| */ |
| void pushBack() throws IOException { |
| iis.seek(iis.getStreamPosition()-bufAvail); |
| bufAvail = 0; |
| bufPtr = 0; |
| } |
| |
| /** |
| * Return the stream position corresponding to the next |
| * available byte in the buffer. |
| */ |
| long getStreamPosition() throws IOException { |
| return (iis.getStreamPosition()-bufAvail); |
| } |
| |
| /** |
| * Scan the buffer until the next 0xff byte, reloading |
| * the buffer as necessary. The buffer position is left |
| * pointing to the first non-0xff byte after a run of |
| * 0xff bytes. If the end of the stream is encountered, |
| * an EOI marker is inserted into the buffer and <code>true</code> |
| * is returned. Otherwise returns <code>false</code>. |
| */ |
| boolean scanForFF(JPEGImageReader reader) throws IOException { |
| boolean retval = false; |
| boolean foundFF = false; |
| while (foundFF == false) { |
| while (bufAvail > 0) { |
| if ((buf[bufPtr++] & 0xff) == 0xff) { |
| bufAvail--; |
| foundFF = true; |
| break; // out of inner while |
| } |
| bufAvail--; |
| } |
| // Reload the buffer and keep going |
| loadBuf(0); |
| // Skip any remaining pad bytes |
| if (foundFF == true) { |
| while ((bufAvail > 0) && (buf[bufPtr] & 0xff) == 0xff) { |
| bufPtr++; // Only if it still is 0xff |
| bufAvail--; |
| } |
| } |
| if (bufAvail == 0) { // Premature EOF |
| // send out a warning, but treat it as EOI |
| //reader.warningOccurred(JPEGImageReader.WARNING_NO_EOI); |
| retval = true; |
| buf[0] = (byte)JPEG.EOI; |
| bufAvail = 1; |
| bufPtr = 0; |
| foundFF = true; |
| } |
| } |
| return retval; |
| } |
| |
| /** |
| * Prints the contents of the buffer, in hex. |
| * @param count the number of bytes to print, |
| * starting at the current available byte. |
| */ |
| void print(int count) { |
| System.out.print("buffer has "); |
| System.out.print(bufAvail); |
| System.out.println(" bytes available"); |
| if (bufAvail < count) { |
| count = bufAvail; |
| } |
| for (int ptr = bufPtr; count > 0; count--) { |
| int val = (int)buf[ptr++] & 0xff; |
| System.out.print(" " + Integer.toHexString(val)); |
| } |
| System.out.println(); |
| } |
| |
| } |