Java RandomAccessFileOrArray.readUnsignedShort方法代码示例

import com.lowagie.text.pdf.RandomAccessFileOrArray; //导入方法依赖的package包/类
/**
 * Constructs a TIFFDirectory by reading a SeekableStream.
 * The ifd_offset parameter specifies the stream offset from which
 * to begin reading; this mechanism is sometimes used to store
 * private IFDs within a TIFF file that are not part of the normal
 * sequence of IFDs.
 *
 * @param stream a SeekableStream to read from.
 * @param ifd_offset the long byte offset of the directory.
 * @param directory the index of the directory to read beyond the
 *        one at the current stream offset; zero indicates the IFD
 *        at the current offset.
 */
public TIFFDirectory(RandomAccessFileOrArray stream, long ifd_offset, int directory)
throws IOException {
    
    long global_save_offset = stream.getFilePointer();
    stream.seek(0L);
    int endian = stream.readUnsignedShort();
    if (!isValidEndianTag(endian)) {
        throw new
        IllegalArgumentException("Bad endianness tag (not 0x4949 or 0x4d4d).");
    }
    isBigEndian = (endian == 0x4d4d);
    
    // Seek to the first IFD.
    stream.seek(ifd_offset);
    
    // Seek to desired IFD if necessary.
    int dirNum = 0;
    while(dirNum < directory) {
        // Get the number of fields in the current IFD.
        int numEntries = readUnsignedShort(stream);
        
        // Skip to the next IFD offset value field.
        stream.seek(ifd_offset + 12*numEntries);
        
        // Read the offset to the next IFD beyond this one.
        ifd_offset = readUnsignedInt(stream);
        
        // Seek to the next IFD.
        stream.seek(ifd_offset);
        
        // Increment the directory.
        dirNum++;
    }
    
    initialize(stream);
    stream.seek(global_save_offset);
}
 

import com.lowagie.text.pdf.RandomAccessFileOrArray; //导入方法依赖的package包/类
private int readUnsignedShort(RandomAccessFileOrArray stream)
throws IOException {
    if (isBigEndian) {
        return stream.readUnsignedShort();
    } else {
        return stream.readUnsignedShortLE();
    }
}
 

import com.lowagie.text.pdf.RandomAccessFileOrArray; //导入方法依赖的package包/类
/**
 * Returns the number of image directories (subimages) stored in a
 * given TIFF file, represented by a <code>SeekableStream</code>.
 */
public static int getNumDirectories(RandomAccessFileOrArray stream)
throws IOException{
    long pointer = stream.getFilePointer(); // Save stream pointer
    
    stream.seek(0L);
    int endian = stream.readUnsignedShort();
    if (!isValidEndianTag(endian)) {
        throw new
        IllegalArgumentException("Bad endianness tag (not 0x4949 or 0x4d4d).");
    }
    boolean isBigEndian = (endian == 0x4d4d);
    int magic = readUnsignedShort(stream, isBigEndian);
    if (magic != 42) {
        throw new
        IllegalArgumentException("Bad magic number, should be 42.");
    }
    
    stream.seek(4L);
    long offset = readUnsignedInt(stream, isBigEndian);
    
    int numDirectories = 0;
    while (offset != 0L) {
        ++numDirectories;
        
        // EOFException means IFD was probably not properly terminated.
        try {
            stream.seek(offset);
            int entries = readUnsignedShort(stream, isBigEndian);
            stream.skip(12*entries);
            offset = readUnsignedInt(stream, isBigEndian);
        } catch(EOFException eof) {
            //numDirectories--;
            break;
        }
    }
    
    stream.seek(pointer); // Reset stream pointer
    return numDirectories;
}
 

import com.lowagie.text.pdf.RandomAccessFileOrArray; //导入方法依赖的package包/类
private static int readUnsignedShort(RandomAccessFileOrArray stream,
boolean isBigEndian)
throws IOException {
    if (isBigEndian) {
        return stream.readUnsignedShort();
    } else {
        return stream.readUnsignedShortLE();
    }
}
 

import com.lowagie.text.pdf.RandomAccessFileOrArray; //导入方法依赖的package包/类
/**
 * Returns the number of image directories (subimages) stored in a
 * given TIFF file, represented by a <code>SeekableStream</code>.
 */
public static int getNumDirectories(RandomAccessFileOrArray stream)
throws IOException{
    long pointer = stream.getFilePointer(); // Save stream pointer
    
    stream.seek(0L);
    int endian = stream.readUnsignedShort();
    if (!isValidEndianTag(endian)) {
        throw new
        IllegalArgumentException("Bad endianness tag (not 0x4949 or 0x4d4d).");
    }
    boolean isBigEndian = (endian == 0x4d4d);
    int magic = readUnsignedShort(stream, isBigEndian);
    if (magic != 42) {
        throw new
        IllegalArgumentException("Bad magic number, should be 42.");
    }
    
    stream.seek(4L);
    long offset = readUnsignedInt(stream, isBigEndian);
    
    int numDirectories = 0;
    while (offset != 0L) {
        ++numDirectories;
        
        // EOFException means IFD was probably not properly terminated.
        try {
            stream.seek(offset);
            int entries = readUnsignedShort(stream, isBigEndian);
            stream.skip(12*entries);
            offset = readUnsignedInt(stream, isBigEndian);
        } catch(EOFException eof) {
            numDirectories--;
            break;
        }
    }
    
    stream.seek(pointer); // Reset stream pointer
    return numDirectories;
}
 

import com.lowagie.text.pdf.RandomAccessFileOrArray; //导入方法依赖的package包/类
/**
 * Constructs a TIFFDirectory from a SeekableStream.
 * The directory parameter specifies which directory to read from
 * the linked list present in the stream; directory 0 is normally
 * read but it is possible to store multiple images in a single
 * TIFF file by maintaing multiple directories.
 *
 * @param stream a SeekableStream to read from.
 * @param directory the index of the directory to read.
 */
public TIFFDirectory(RandomAccessFileOrArray stream, int directory)
throws IOException {
    
    long global_save_offset = stream.getFilePointer();
    long ifd_offset;
    
    // Read the TIFF header
    stream.seek(0L);
    int endian = stream.readUnsignedShort();
    if (!isValidEndianTag(endian)) {
        throw new
        IllegalArgumentException("Bad endianness tag (not 0x4949 or 0x4d4d).");
    }
    isBigEndian = (endian == 0x4d4d);
    
    int magic = readUnsignedShort(stream);
    if (magic != 42) {
        throw new
        IllegalArgumentException("Bad magic number, should be 42.");
    }
    
    // Get the initial ifd offset as an unsigned int (using a long)
    ifd_offset = readUnsignedInt(stream);
    
    for (int i = 0; i < directory; i++) {
        if (ifd_offset == 0L) {
            throw new
            IllegalArgumentException("Directory number too large.");
        }
        
        stream.seek(ifd_offset);
        int entries = readUnsignedShort(stream);
        stream.skip(12*entries);
        
        ifd_offset = readUnsignedInt(stream);
    }
    
    stream.seek(ifd_offset);
    initialize(stream);
    stream.seek(global_save_offset);
}