PixelParserBitFields.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.imaging.formats.bmp;
import static org.apache.commons.imaging.common.BinaryFunctions.read2Bytes;
import static org.apache.commons.imaging.common.BinaryFunctions.read3Bytes;
import static org.apache.commons.imaging.common.BinaryFunctions.read4Bytes;
import static org.apache.commons.imaging.common.BinaryFunctions.readByte;
import java.io.IOException;
import java.nio.ByteOrder;
import org.apache.commons.imaging.ImagingException;
final class PixelParserBitFields extends AbstractPixelParserSimple {
private final int redShift;
private final int greenShift;
private final int blueShift;
private final int alphaShift;
private final int redMask;
private final int greenMask;
private final int blueMask;
private final int alphaMask;
private int byteCount;
PixelParserBitFields(final BmpHeaderInfo bhi, final byte[] colorTable, final byte[] imageData) {
super(bhi, colorTable, imageData);
redMask = bhi.redMask;
greenMask = bhi.greenMask;
blueMask = bhi.blueMask;
alphaMask = bhi.alphaMask;
redShift = getMaskShift(redMask);
greenShift = getMaskShift(greenMask);
blueShift = getMaskShift(blueMask);
alphaShift = alphaMask != 0 ? getMaskShift(alphaMask) : 0;
}
private int getMaskShift(int mask) {
if (mask == 0) {
return 0;
}
int trailingZeroes = 0;
while ((0x1 & mask) == 0) {
mask = 0x7fffffff & mask >> 1;
trailingZeroes++;
}
int maskLength = 0;
while ((0x1 & mask) == 1) {
mask = 0x7fffffff & mask >> 1;
maskLength++;
}
return trailingZeroes - (8 - maskLength);
}
@Override
public int getNextRgb() throws ImagingException, IOException {
int data;
switch (bhi.bitsPerPixel) {
case 8:
data = 0xff & imageData[byteCount + 0];
byteCount += 1;
break;
case 24:
data = read3Bytes("Pixel", is, "BMP Image Data", ByteOrder.LITTLE_ENDIAN);
byteCount += 3;
break;
case 32:
data = read4Bytes("Pixel", is, "BMP Image Data", ByteOrder.LITTLE_ENDIAN);
byteCount += 4;
break;
case 16:
data = read2Bytes("Pixel", is, "BMP Image Data", ByteOrder.LITTLE_ENDIAN);
byteCount += 2;
break;
default:
throw new ImagingException("Unknown BitsPerPixel: " + bhi.bitsPerPixel);
}
int red = redMask & data;
int green = greenMask & data;
int blue = blueMask & data;
int alpha = alphaMask != 0 ? alphaMask & data : 0xff;
red = redShift >= 0 ? red >> redShift : red << -redShift;
green = greenShift >= 0 ? green >> greenShift : green << -greenShift;
blue = blueShift >= 0 ? blue >> blueShift : blue << -blueShift;
alpha = alphaShift >= 0 ? alpha >> alphaShift : alpha << -alphaShift;
return alpha << 24 | red << 16 | green << 8 | blue << 0;
}
@Override
public void newline() throws ImagingException, IOException {
while (byteCount % 4 != 0) {
readByte("Pixel", is, "BMP Image Data");
byteCount++;
}
}
}