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Apache Commons Imaging (previously Sanselan) is a pure-Java image library.
/*
* 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.common;
import java.awt.color.ColorSpace;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.DataBuffer;
import java.awt.image.DataBufferInt;
import java.awt.image.DirectColorModel;
import java.awt.image.Raster;
import java.awt.image.RasterFormatException;
import java.awt.image.WritableRaster;
import java.util.Properties;
/*
* Development notes:
* This class was introduced to the Apache Commons Imaging library in
* order to improve performance in building images. The setRGB method
* provided by this class represents a substantial improvement in speed
* compared to that of the BufferedImage class that was originally used
* in Apache Sanselan.
* This increase is attained because ImageBuilder is a highly specialized
* class that does not need to perform the general-purpose logic required
* for BufferedImage. If you need to modify this class to add new
* image formats or functionality, keep in mind that some of its methods
* are invoked literally millions of times when building an image.
* Since even the introduction of something as small as a single conditional
* inside of setRGB could result in a noticeable increase in the
* time to read a file, changes should be made with care.
* During development, I experimented with inlining the setRGB logic
* in some of the code that uses it. This approach did not significantly
* improve performance, leading me to speculate that the Java JIT compiler
* might have inlined the method at run time. Further investigation
* is required.
*
*/
/**
* A utility class primary intended for storing data obtained by reading
* image files.
*/
public class ImageBuilder {
private final int[] data;
private final int width;
private final int height;
private final boolean hasAlpha;
private final boolean isAlphaPremultiplied;
/**
* Construct an ImageBuilder instance
* @param width the width of the image to be built
* @param height the height of the image to be built
* @param hasAlpha indicates whether the image has an alpha channel
* (the selection of alpha channel does not change the memory
* requirements for the ImageBuilder or resulting BufferedImage.
*/
public ImageBuilder(final int width, final int height, final boolean hasAlpha) {
checkDimensions(width, height);
data = new int[width * height];
this.width = width;
this.height = height;
this.hasAlpha = hasAlpha;
this.isAlphaPremultiplied = false;
}
/**
* Construct an ImageBuilder instance
* @param width the width of the image to be built
* @param height the height of the image to be built
* @param hasAlpha indicates whether the image has an alpha channel
* (the selection of alpha channel does not change the memory
* requirements for the ImageBuilder or resulting BufferedImage.
* @param isAlphaPremultiplied indicates whether alpha values are
* pre-multiplied; this setting is relevant only if alpha is true.
*
*/
public ImageBuilder(final int width, final int height,
final boolean hasAlpha, final boolean isAlphaPremultiplied) {
checkDimensions(width, height);
data = new int[width * height];
this.width = width;
this.height = height;
this.hasAlpha = hasAlpha;
this.isAlphaPremultiplied = isAlphaPremultiplied;
}
/**
* @param width image width (must be greater than zero)
* @param height image height (must be greater than zero)
* @throws RasterFormatException if {@code width} or {@code height} are equal or less than zero
*/
private void checkDimensions(final int width, final int height) {
if (width <= 0) {
throw new RasterFormatException("zero or negative width value");
}
if (height <= 0) {
throw new RasterFormatException("zero or negative height value");
}
}
/**
* Get the width of the ImageBuilder pixel field
* @return a positive integer
*/
public int getWidth() {
return width;
}
/**
* Get the height of the ImageBuilder pixel field
* @return a positive integer
*/
public int getHeight() {
return height;
}
/**
* Get the RGB or ARGB value for the pixel at the position (x,y)
* within the image builder pixel field. For performance reasons
* no bounds checking is applied.
* @param x the X coordinate of the pixel to be read
* @param y the Y coordinate of the pixel to be read
* @return the RGB or ARGB pixel value
*/
public int getRGB(final int x, final int y) {
final int rowOffset = y * width;
return data[rowOffset + x];
}
/**
* Set the RGB or ARGB value for the pixel at position (x,y)
* within the image builder pixel field. For performance reasons,
* no bounds checking is applied.
* @param x the X coordinate of the pixel to be set
* @param y the Y coordinate of the pixel to be set
* @param argb the RGB or ARGB value to be stored.
*/
public void setRGB(final int x, final int y, final int argb) {
final int rowOffset = y * width;
data[rowOffset + x] = argb;
}
/**
* Create a BufferedImage using the data stored in the ImageBuilder.
* @return a valid BufferedImage.
*/
public BufferedImage getBufferedImage() {
return makeBufferedImage(data, width, height, hasAlpha);
}
/**
* Performs a check on the specified sub-region to verify
* that it is within the constraints of the ImageBuilder bounds.
*
* @param x the X coordinate of the upper-left corner of the
* specified rectangular region
* @param y the Y coordinate of the upper-left corner of the
* specified rectangular region
* @param w the width of the specified rectangular region
* @param h the height of the specified rectangular region
* @throws RasterFormatException if width or height are equal or less than zero, or if the subimage is outside raster (on x or y axis)
*/
private void checkBounds(final int x, final int y, final int w, final int h) {
if (w <= 0) {
throw new RasterFormatException("negative or zero subimage width");
}
if (h <= 0) {
throw new RasterFormatException("negative or zero subimage height");
}
if (x < 0 || x >= width) {
throw new RasterFormatException("subimage x is outside raster");
}
if (x + w > width) {
throw new RasterFormatException(
"subimage (x+width) is outside raster");
}
if (y < 0 || y >= height) {
throw new RasterFormatException("subimage y is outside raster");
}
if (y + h > height) {
throw new RasterFormatException(
"subimage (y+height) is outside raster");
}
}
/**
* Gets a subset of the ImageBuilder content using the specified parameters
* to indicate an area of interest. If the parameters specify a rectangular
* region that is not entirely contained within the bounds defined
* by the ImageBuilder, this method will throw a RasterFormatException.
* This run- time exception is consistent with the behavior of the
* getSubimage method provided by BufferedImage.
* @param x the X coordinate of the upper-left corner of the
* specified rectangular region
* @param y the Y coordinate of the upper-left corner of the
* specified rectangular region
* @param w the width of the specified rectangular region
* @param h the height of the specified rectangular region
* @return a valid instance of the specified width and height.
* @throws RasterFormatException if the specified area is not contained
* within this ImageBuilder
*/
public ImageBuilder getSubset(final int x, final int y, final int w, final int h) {
checkBounds(x, y, w, h);
final ImageBuilder b = new ImageBuilder(w, h, hasAlpha, isAlphaPremultiplied);
for(int i=0; i