com.idrsolutions.image.jpeg.JpegScanner 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 1997-2015 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
*
* ---------------
* JpegScanner.java
* ---------------
*/
package com.idrsolutions.image.jpeg;
import java.util.List;
/**
*
*/
public class JpegScanner {
private static final int DCFirst = 0;
private static final int DCSuccessive = 1;
private static final int ACFirst = 2;
private static final int ACSuccessive = 3;
private static final int Baseline = 4;
private final byte[] data;
private int bitPos;
private int bitBuffer;
private int eobrun;
private int mcusX;
private int offset;
private int successive, sStart, sEnd;
private int stateAC, stateNextAC;
public JpegScanner(byte[] data) {
this.data = data;
}
public int decodeScan(int off, Frame frame, List components, int resetInterval, int sStart, int sEnd, int sPrev, int successive) {
mcusX = frame.mcusX;
this.offset = off;
this.successive = successive;
this.sStart = sStart;
this.sEnd = sEnd;
int componentsLength = components.size();
Component component;
int i, j, k, n;
int decodeFn;
if (frame.progressive) {
if (sStart == 0) {
decodeFn = sPrev == 0 ? DCFirst : DCSuccessive;
} else {
decodeFn = sPrev == 0 ? ACFirst : ACSuccessive;
}
} else {
decodeFn = Baseline;
}
int mcu = 0, marker;
int mcuExpected;
if (componentsLength == 1) {
mcuExpected = components.get(0).blocksX * components.get(0).blocksY;
} else {
mcuExpected = mcusX * frame.mcusY;
}
int nc = resetInterval==0? mcuExpected : resetInterval;
int h, v;
while (mcu < mcuExpected) {
// reset interval stuff
for (i = 0; i < componentsLength; i++) {
components.get(i).pred = 0;
}
eobrun = 0;
if (componentsLength == 1) {
component = components.get(0);
for (n = 0; n < nc; n++) {
decodeBlock(component, decodeFn, mcu);
mcu++;
}
} else {
for (n = 0; n < nc; n++) {
for (i = 0; i < componentsLength; i++) {
component = components.get(i);
h = component.h;
v = component.v;
for (j = 0; j < v; j++) {
for (k = 0; k < h; k++) {
decodeMcu(component, decodeFn, mcu, j, k);
}
}
}
mcu++;
}
}
bitPos = 0;
marker = ((data[offset] & 0xff) << 8) | (data[offset + 1] & 0xff);
if (marker <= 0xFF00) {
}
if (marker >= 0xFFD0 && marker <= 0xFFD7) { // RSTx
offset += 2;
} else {
break;
}
}
return offset - off;
}
private int findHuffmanValue(Object tree) {
Object node = tree;
while (true) {
node = ((Object[]) node)[readBit()];
if (node instanceof Integer) {
return (Integer) node;
}
}
}
private int readBit() {
if (bitPos > 0) {
bitPos--;
return (bitBuffer >> bitPos) & 1;
}
bitBuffer = data[offset++] & 0xff;
if (bitBuffer == 0xFF) {
int nextByte = data[offset++] & 0xff;
if (nextByte != 0) {
System.err.println("invalid marker found");
}
}
bitPos = 7;
return bitBuffer >>> 7;
}
private int getNext(int length) {
int n = 0;
while (length > 0) {
n = (n << 1) | readBit();
length--;
}
return n;
}
private int getNextFull(int length) {
if (length == 1) {
return readBit() == 1 ? 1 : -1;
}
int n = getNext(length);
if (n >= 1 << (length - 1)) {
return n;
}
return n + (-1 << length) + 1;
}
private void decodeMcu(Component component, int decodeFn, int mcu, int row, int col) {
int mcuRow = mcu / mcusX;
int mcuCol = mcu % mcusX;
int blockRow = mcuRow * component.v + row;
int blockCol = mcuCol * component.h + col;
int offsetD = getCodeBlockOffset(component, blockRow, blockCol);
decodeOrdering(component, offsetD, decodeFn);
}
private void decodeBlock(Component component, int decodeFn, int mcu) {
int blockRow = mcu / component.blocksX;
int blockCol = mcu % component.blocksX;
int offsetD = getCodeBlockOffset(component, blockRow, blockCol);
decodeOrdering(component, offsetD, decodeFn);
}
private void decodeOrdering(Component component, int offset, int decodeFn) {
int a, b, c, d, e, f, diff, z;
switch (decodeFn) {
case DCFirst:
e = findHuffmanValue(component.huffmanTableDC);
diff = e == 0 ? 0 : (getNextFull(e) << successive);
component.codeBlock[offset] = (component.pred += diff);
break;
case DCSuccessive:
component.codeBlock[offset] |= (readBit() << successive);
break;
case ACFirst:
if (eobrun > 0) {
eobrun--;
return;
}
a = sStart;
b = sEnd;
while (a <= b) {
f = findHuffmanValue(component.huffmanTableAC);
d = f & 15;
c = f >> 4;
if (d == 0) {
if (c < 15) {
eobrun = getNext(c) + (1 << c) - 1;
break;
}
a += 16;
continue;
}
a += c;
z = JpegLUT.ZIGZAGORDER[a];
component.codeBlock[offset + z]
= getNextFull(d) * (1 << successive);
a++;
}
break;
case ACSuccessive:
a = sStart;
b = sEnd;
c = 0;
while (a <= b) {
z = JpegLUT.ZIGZAGORDER[a];
switch (stateAC) {
case 0: // initial state
f = findHuffmanValue(component.huffmanTableAC);
d = f & 15;
c = f >> 4;
if (d == 0) {
if (c < 15) {
eobrun = getNext(c) + (1 << c);
stateAC = 4;
} else {
c = 16;
stateAC = 1;
}
} else {
if (d != 1) {
}
stateNextAC = getNextFull(d);
stateAC = c != 0 ? 2 : 3;
}
continue;
case 1: // skipping r zero items
case 2:
if (component.codeBlock[offset + z] != 0) {
component.codeBlock[offset + z] += (readBit() << successive);
} else {
c--;
if (c == 0) {
stateAC = stateAC == 2 ? 3 : 0;
}
}
break;
case 3: // set value for a zero item
if (component.codeBlock[offset + z] != 0) {
component.codeBlock[offset + z] += (readBit() << successive);
} else {
component.codeBlock[offset + z]
= stateNextAC << successive;
stateAC = 0;
}
break;
case 4: // eob
if (component.codeBlock[offset + z] != 0) {
component.codeBlock[offset + z] += (readBit() << successive);
}
break;
}
a++;
}
if (stateAC == 4) {
eobrun--;
if (eobrun == 0) {
stateAC = 0;
}
}
break;
case Baseline:
e = findHuffmanValue(component.huffmanTableDC);
diff = e == 0 ? 0 : getNextFull(e);
component.codeBlock[offset] = (component.pred += diff);
a = 1;
while (a < 64) {
f = findHuffmanValue(component.huffmanTableAC);
d = f & 15;
c = f >> 4;
if (d == 0) {
if (c < 15) {
break;
}
a += 16;
continue;
}
a += c;
z = JpegLUT.ZIGZAGORDER[a];
component.codeBlock[offset + z] = getNextFull(d);
a++;
}
break;
}
}
public static int getCodeBlockOffset(Component component, int row, int col) {
return 64 * ((component.blocksX + 1) * row + col);
}
}
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