/* * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.awt.image; import java.awt.color.ColorSpace; import java.awt.geom.Rectangle2D; import java.awt.Graphics2D; import java.awt.Rectangle; import java.awt.geom.Point2D; import java.awt.RenderingHints; import sun.awt.image.ImagingLib; /** * This class performs a pixel-by-pixel rescaling of the data in the * source image by multiplying the sample values for each pixel by a scale * factor and then adding an offset. The scaled sample values are clipped * to the minimum/maximum representable in the destination image. *
* The pseudo code for the rescaling operation is as follows: *
*for each pixel from Source object { * for each band/component of the pixel { * dstElement = (srcElement*scaleFactor) + offset * } *} **
* For Rasters, rescaling operates on bands. The number of * sets of scaling constants may be one, in which case the same constants * are applied to all bands, or it must equal the number of Source * Raster bands. *
* For BufferedImages, rescaling operates on color and alpha components. * The number of sets of scaling constants may be one, in which case the * same constants are applied to all color (but not alpha) components. * Otherwise, the number of sets of scaling constants may * equal the number of Source color components, in which case no * rescaling of the alpha component (if present) is performed. * If neither of these cases apply, the number of sets of scaling constants * must equal the number of Source color components plus alpha components, * in which case all color and alpha components are rescaled. *
* BufferedImage sources with premultiplied alpha data are treated in the same * manner as non-premultiplied images for purposes of rescaling. That is, * the rescaling is done per band on the raw data of the BufferedImage source * without regard to whether the data is premultiplied. If a color conversion * is required to the destination ColorModel, the premultiplied state of * both source and destination will be taken into account for this step. *
* Images with an IndexColorModel cannot be rescaled. *
* If a RenderingHints object is specified in the constructor, the * color rendering hint and the dithering hint may be used when color * conversion is required. *
* Note that in-place operation is allowed (i.e. the source and destination can
* be the same object).
* @see java.awt.RenderingHints#KEY_COLOR_RENDERING
* @see java.awt.RenderingHints#KEY_DITHERING
*/
public class RescaleOp implements BufferedImageOp, RasterOp {
float[] scaleFactors;
float[] offsets;
int length = 0;
RenderingHints hints;
private int srcNbits;
private int dstNbits;
/**
* Constructs a new RescaleOp with the desired scale factors
* and offsets. The length of the scaleFactor and offset arrays
* must meet the restrictions stated in the class comments above.
* The RenderingHints argument may be null.
* @param scaleFactors the specified scale factors
* @param offsets the specified offsets
* @param hints the specified {@code RenderingHints}, or
* {@code null}
*/
public RescaleOp (float[] scaleFactors, float[] offsets,
RenderingHints hints) {
length = scaleFactors.length;
if (length > offsets.length) length = offsets.length;
this.scaleFactors = new float[length];
this.offsets = new float[length];
for (int i=0; i < length; i++) {
this.scaleFactors[i] = scaleFactors[i];
this.offsets[i] = offsets[i];
}
this.hints = hints;
}
/**
* Constructs a new RescaleOp with the desired scale factor
* and offset. The scaleFactor and offset will be applied to
* all bands in a source Raster and to all color (but not alpha)
* components in a BufferedImage.
* The RenderingHints argument may be null.
* @param scaleFactor the specified scale factor
* @param offset the specified offset
* @param hints the specified {@code RenderingHints}, or
* {@code null}
*/
public RescaleOp (float scaleFactor, float offset, RenderingHints hints) {
length = 1;
this.scaleFactors = new float[1];
this.offsets = new float[1];
this.scaleFactors[0] = scaleFactor;
this.offsets[0] = offset;
this.hints = hints;
}
/**
* Returns the scale factors in the given array. The array is also
* returned for convenience. If scaleFactors is null, a new array
* will be allocated.
* @param scaleFactors the array to contain the scale factors of
* this {@code RescaleOp}
* @return the scale factors of this {@code RescaleOp}.
*/
public final float[] getScaleFactors (float scaleFactors[]) {
if (scaleFactors == null) {
return this.scaleFactors.clone();
}
System.arraycopy (this.scaleFactors, 0, scaleFactors, 0,
Math.min(this.scaleFactors.length,
scaleFactors.length));
return scaleFactors;
}
/**
* Returns the offsets in the given array. The array is also returned
* for convenience. If offsets is null, a new array
* will be allocated.
* @param offsets the array to contain the offsets of
* this {@code RescaleOp}
* @return the offsets of this {@code RescaleOp}.
*/
public final float[] getOffsets(float offsets[]) {
if (offsets == null) {
return this.offsets.clone();
}
System.arraycopy (this.offsets, 0, offsets, 0,
Math.min(this.offsets.length, offsets.length));
return offsets;
}
/**
* Returns the number of scaling factors and offsets used in this
* RescaleOp.
* @return the number of scaling factors and offsets of this
* {@code RescaleOp}.
*/
public final int getNumFactors() {
return length;
}
/**
* Creates a ByteLookupTable to implement the rescale.
* The table may have either a SHORT or BYTE input.
* @param nElems Number of elements the table is to have.
* This will generally be 256 for byte and
* 65536 for short.
*/
private ByteLookupTable createByteLut(float scale[],
float off[],
int nBands,
int nElems) {
byte[][] lutData = new byte[nBands][nElems];
int band;
for (band=0; band