com.idrsolutions.pdf.color.shading.BitReader Maven / Gradle / Ivy
/*
* ===========================================
* Java Pdf Extraction Decoding Access Library
* ===========================================
*
* Project Info: http://www.idrsolutions.com
* Help section for developers at http://www.idrsolutions.com/support/
*
* (C) Copyright 1997-2016 IDRsolutions and Contributors.
*
* This file is part of JPedal/JPDF2HTML5
*
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* ---------------
* BitReader.java
* ---------------
*/
package com.idrsolutions.pdf.color.shading;
/**
* a java class to handle bitwise reading in shading object
*/
public class BitReader {
private int p; //pointer
private int pos;
private final byte[] data;
private final boolean hasSmallBits;
private int bufferSize;
private int buffer;
private final int totalBitLen;
public BitReader(final byte[] data, final boolean hasSmallBits) {
this.hasSmallBits = hasSmallBits;
this.data = data;
this.totalBitLen = this.data.length * 8;
}
/**
* @param lenToRead
* @return this return value is not actual int and it is a data
* representation in 32 bits
*/
private int readBits(int lenToRead) {
if (hasSmallBits) {
while (bufferSize < lenToRead) {
int b = data[pos] & 0xff;
pos++;
buffer = (buffer << 8) | b;
bufferSize += 8;
}
bufferSize -= lenToRead;
p += lenToRead;
return (buffer >>> bufferSize) & ((1 << lenToRead) - 1);
} else {
int retVal = 0;
int len = lenToRead / 8;
for (int i = 0; i < len; i++) {
retVal = (retVal << 8);
retVal |= ((data[p / 8] & 0xff));
p += 8;
}
return retVal;
}
}
/**
* return positive integer only
*
* @param bitLen
* @return
*/
public int getPositive(int bitLen) {
return readBits(bitLen);
}
/**
* return floating point;
*
* @param bitLen
* @return
*/
public float getFloat(int bitLen) {
int value = readBits(bitLen);
byte[] temp = {(byte) (value >>> 24), (byte) (value >>> 16), (byte) (value >>> 8), (byte) value};
float number = 0.0f;
switch (bitLen) {
case 1:
case 2:
case 4:
number = temp[3] / 15f;
break;
case 8:
number = (temp[3] & 255) / 256f;
break;
case 16:
number = (temp[2] & 255) / 256f;
number += (temp[3] & 255) / 65536f;
break;
case 24:
number = (temp[1] & 255) / 256f;
number += (temp[2] & 255) / 65536f;
number += (temp[3] & 255) / 16777216f;
break;
case 32:
number = (temp[0] & 255) / 256f;
number += (temp[1] & 255) / 65536f;
number += (temp[2] & 255) / 16777216f;
number += (temp[3] & 255) / 4294967296f;
break;
}
return number;
}
public int getPointer() {
return p;
}
public int getTotalBitLen() {
return totalBitLen;
}
// public static void main(String[] args) {
// byte[] data = new byte[]{-128, 72, 0};
// BitSet bitset = new BitSet(data.length * 8);
// int c = 0;
// for (int i = 0; i < data.length; i++) {
// byte b = data[i];
// System.out.println(" "+Integer.toBinaryString(b));
// for (int j = 7; j >= 0; j--) {
// boolean isOn = ((b >> j) & 1) == 1;
// bitset.set(c, isOn);
// c++;//
// }
// }//
// BitReader bit = new BitReader(data);
//
// for (int i = 0; i < 24; i++) {
// System.out.println(" -- "+bit.readBits(3));
// }
// }
}