com.keypoint.PngEncoderB Maven / Gradle / Ivy
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package com.keypoint;
/**
* PngEncoderB takes a Java BufferedImage object and creates a byte string which can be saved as a PNG file.
* The encoder will accept BufferedImages with eight-bit samples
* or 4-byte ARGB samples.
*
* There is also code to handle 4-byte samples returned as
* one int per pixel, but that has not been tested.
*
* Thanks to Jay Denny at KeyPoint Software
* http://www.keypoint.com/
* who let me develop this code on company time.
*
* You may contact me with (probably very-much-needed) improvements,
* comments, and bug fixes at:
*
* [email protected]
*
* 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
* A copy of the GNU LGPL may be found at
* http://www.gnu.org/copyleft/lesser.html,
*
* @author J. David Eisenberg
* @version 1.4, 31 March 2000
*/
import java.awt.image.BufferedImage;
import java.awt.image.DataBuffer;
import java.awt.image.IndexColorModel;
import java.awt.image.WritableRaster;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
public class PngEncoderB extends PngEncoder {
protected BufferedImage image;
protected WritableRaster wRaster;
protected int tType;
/**
* Class constructor
*/
public PngEncoderB() {
this(null, false, FILTER_NONE, 0);
}
/**
* Class constructor specifying BufferedImage to encode, with no alpha channel encoding.
*
* @param image A Java BufferedImage object
*/
public PngEncoderB(BufferedImage image) {
this(image, false, FILTER_NONE, 0);
}
/**
* Class constructor specifying BufferedImage to encode, and whether to encode alpha.
*
* @param image A Java BufferedImage object
* @param encodeAlpha Encode the alpha channel? false=no; true=yes
*/
public PngEncoderB(BufferedImage image, boolean encodeAlpha) {
this(image, encodeAlpha, FILTER_NONE, 0);
}
/**
* Class constructor specifying BufferedImage to encode, whether to encode alpha, and filter to use.
*
* @param image A Java BufferedImage object
* @param encodeAlpha Encode the alpha channel? false=no; true=yes
* @param whichFilter 0=none, 1=sub, 2=up
*/
public PngEncoderB(BufferedImage image, boolean encodeAlpha,
int whichFilter) {
this(image, encodeAlpha, whichFilter, 0);
}
/**
* Class constructor specifying BufferedImage source to encode, whether to encode alpha, filter to use, and compression level
*
* @param image A Java BufferedImage object
* @param encodeAlpha Encode the alpha channel? false=no; true=yes
* @param whichFilter 0=none, 1=sub, 2=up
* @param compLevel 0..9
*/
public PngEncoderB(BufferedImage image, boolean encodeAlpha,
int whichFilter, int compLevel) {
this.image = image;
this.encodeAlpha = encodeAlpha;
setFilter(whichFilter);
if (compLevel >= 0 && compLevel <= 9) {
this.compressionLevel = compLevel;
}
}
/**
* Set the BufferedImage to be encoded
*
* @param image A Java BufferedImage object
*/
public void setImage(BufferedImage image) {
this.image = image;
pngBytes = null;
}
/**
* Creates an array of bytes that is the PNG equivalent of the current image, specifying whether to encode alpha or not.
*
* @param encodeAlpha boolean false=no alpha, true=encode alpha
* @return an array of bytes, or null if there was a problem
*/
@Override
public byte[] pngEncode(boolean encodeAlpha) {
byte[] pngIdBytes = {-119, 80, 78, 71, 13, 10, 26, 10};
int i;
if (image == null) {
return null;
}
width = image.getWidth(null);
height = image.getHeight(null);
// this.image = image;
if (!establishStorageInfo()) {
return null;
}
/*
* start with an array that is big enough to hold all the pixels
* (plus filter bytes), and an extra 200 bytes for header info
*/
pngBytes = new byte[((width + 1) * height * 3) + 200];
/*
* keep track of largest byte written to the array
*/
maxPos = 0;
bytePos = writeBytes(pngIdBytes, 0);
hdrPos = bytePos;
writeHeader();
dataPos = bytePos;
if (writeImageData()) {
writeEnd();
pngBytes = resizeByteArray(pngBytes, maxPos);
} else {
pngBytes = null;
}
return pngBytes;
}
/**
* Creates an array of bytes that is the PNG equivalent of the current image.
* Alpha encoding is determined by its setting in the constructor.
*
* @return an array of bytes, or null if there was a problem
*/
@Override
public byte[] pngEncode() {
return pngEncode(encodeAlpha);
}
/**
* Get and set variables that determine how picture is stored.
*
* Retrieves the writable raster of the buffered image,
* as well its transfer type.
*
* Sets number of output bytes per pixel, and, if only
* eight-bit bytes, turns off alpha encoding.
*
* @return true if 1-byte or 4-byte data, false otherwise
*/
protected boolean establishStorageInfo() {
wRaster = image.getRaster();
int dataBytes = wRaster.getNumDataElements();
tType = wRaster.getTransferType();
if (((tType == DataBuffer.TYPE_BYTE) && (dataBytes == 4)) ||
((tType == DataBuffer.TYPE_INT) && (dataBytes == 1))) {
bytesPerPixel = (encodeAlpha) ? 4 : 3;
} else if ((tType == DataBuffer.TYPE_BYTE) && (dataBytes == 1)) {
bytesPerPixel = 1;
encodeAlpha = false; // one-byte samples
} else {
return false;
}
return true;
}
/**
* Write a PNG "IHDR" chunk into the pngBytes array.
*/
@Override
protected void writeHeader() {
int startPos = bytePos = writeInt4(13, bytePos);
bytePos = writeString("IHDR", bytePos);
width = image.getWidth(null);
height = image.getHeight(null);
bytePos = writeInt4(width, bytePos);
bytePos = writeInt4(height, bytePos);
bytePos = writeByte(8, bytePos); // bit depth
if (bytesPerPixel != 1) {
bytePos = writeByte((encodeAlpha) ? 6 : 2, bytePos); // direct model
} else {
bytePos = writeByte(3, bytePos); // indexed
}
bytePos = writeByte(0, bytePos); // compression method
bytePos = writeByte(0, bytePos); // filter method
bytePos = writeByte(0, bytePos); // no interlace
crc.reset();
crc.update(pngBytes, startPos, bytePos - startPos);
crcValue = crc.getValue();
bytePos = writeInt4((int) crcValue, bytePos);
}
protected void writePalette(IndexColorModel icm) {
byte[] redPal = new byte[256];
icm.getReds(redPal);
byte[] greenPal = new byte[256];
icm.getGreens(greenPal);
byte[] bluePal = new byte[256];
icm.getBlues(bluePal);
byte[] allPal = new byte[768];
for (int i = 0; i < 256; i++) {
allPal[i * 3] = redPal[i];
allPal[i * 3 + 1] = greenPal[i];
allPal[i * 3 + 2] = bluePal[i];
}
bytePos = writeInt4(768, bytePos);
bytePos = writeString("PLTE", bytePos);
crc.reset();
crc.update("PLTE".getBytes());
bytePos = writeBytes(allPal, bytePos);
crc.update(allPal);
crcValue = crc.getValue();
bytePos = writeInt4((int) crcValue, bytePos);
}
/**
* Write the image data into the pngBytes array.
* This will write one or more PNG "IDAT" chunks. In order
* to conserve memory, this method grabs as many rows as will
* fit into 32K bytes, or the whole image; whichever is less.
*
* @return true if no errors; false if error grabbing pixels
*/
@Override
protected boolean writeImageData() {
int rowsLeft = height; // number of rows remaining to write
Deflater scrunch = new Deflater(compressionLevel);
ByteArrayOutputStream outBytes =
new ByteArrayOutputStream(1024);
if (bytesPerPixel == 1) {
writePalette((IndexColorModel) image.getColorModel());
}
try {
DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes, scrunch);
int startRow = 0; // starting row to process this time through
while (rowsLeft > 0) {
int nRows = Math.min(32767 / (width * (bytesPerPixel + 1)), rowsLeft); // how many rows to grab at a time
// nRows = rowsLeft;
/*
* Create a data chunk. scanLines adds "nRows" for
* the filter bytes.
*/
byte[] scanLines = new byte[width * nRows * bytesPerPixel + nRows]; // the scan lines to be compressed
if (filter == FILTER_SUB) {
leftBytes = new byte[16];
}
if (filter == FILTER_UP) {
priorRow = new byte[width * bytesPerPixel];
}
int[] iPixels; // storage area for int-sized pixels
byte[] pixels; // storage area for byte-sized pixels
if (tType == DataBuffer.TYPE_BYTE) {
pixels = (byte[]) wRaster.getDataElements(0, startRow, width, nRows, null);
iPixels = null;
} else {
iPixels = (int[]) wRaster.getDataElements(0, startRow, width, nRows, null);
pixels = null;
}
int scanPos = 0; // where we are in the scan lines
int readPos = 0; // position from which source pixels are read
int startPos = 1; // where this line's actual pixels start (used for filtering)
for (int i = 0; i < width * nRows; i++) {
if (i % width == 0) {
scanLines[scanPos++] = (byte) filter;
startPos = scanPos;
}
if (bytesPerPixel == 1) {
scanLines[scanPos++] = pixels[readPos++];
} else if (tType == DataBuffer.TYPE_BYTE) {
scanLines[scanPos++] = pixels[readPos++];
scanLines[scanPos++] = pixels[readPos++];
scanLines[scanPos++] = pixels[readPos++];
if (encodeAlpha) {
scanLines[scanPos++] = pixels[readPos++];
} else {
readPos++;
}
} else {
scanLines[scanPos++] = (byte) ((iPixels[readPos] >> 16) & 0xff);
scanLines[scanPos++] = (byte) ((iPixels[readPos] >> 8) & 0xff);
scanLines[scanPos++] = (byte) ((iPixels[readPos]) & 0xff);
if (encodeAlpha) {
scanLines[scanPos++] = (byte) ((iPixels[readPos] >> 24) & 0xff);
}
readPos++;
}
if ((i % width == width - 1) && (filter != FILTER_NONE)) {
if (filter == FILTER_SUB) {
filterSub(scanLines, startPos, width);
}
if (filter == FILTER_UP) {
filterUp(scanLines, startPos, width);
}
}
}
/*
* Write these lines to the output area
*/
compBytes.write(scanLines, 0, scanPos);
startRow += nRows;
rowsLeft -= nRows;
}
compBytes.close();
/*
* Write the compressed bytes
*/
byte[] compressedLines = outBytes.toByteArray(); // the resultant compressed lines
int nCompressed = compressedLines.length; // how big is the compressed area?
crc.reset();
bytePos = writeInt4(nCompressed, bytePos);
bytePos = writeString("IDAT", bytePos);
crc.update("IDAT".getBytes());
bytePos = writeBytes(compressedLines, nCompressed, bytePos);
crc.update(compressedLines, 0, nCompressed);
crcValue = crc.getValue();
bytePos = writeInt4((int) crcValue, bytePos);
scrunch.finish();
return true;
} catch (IOException e) {
System.err.println(e.toString());
return false;
}
}
}