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 * 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
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 *
 * 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).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.awt.image;

import java.awt.color.ColorSpace;
import java.awt.geom.Rectangle2D;
import java.awt.AlphaComposite;
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 Also:
/**
 * 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.
 * <p>
 * The pseudo code for the rescaling operation is as follows:
 * <pre>
 *for each pixel from Source object {
 *    for each band/component of the pixel {
 *        dstElement = (srcElement*scaleFactor) + offset
 *    }
 *}
 * </pre>
 * <p>
 * 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.
 * <p>
 * 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.
 * <p>
 * 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.
 * <p>
 * Images with an IndexColorModel cannot be rescaled.
 * <p>
 * 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.
 * <p>
 * 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.

Params:
  • scaleFactors – the specified scale factors
  • offsets – the specified offsets
  • hints – the specified RenderingHints, or null
/**
     * 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.

Params:
  • scaleFactor – the specified scale factor
  • offset – the specified offset
  • hints – the specified RenderingHints, or null
/**
     * 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.

Params:
  • scaleFactors – the array to contain the scale factors of this RescaleOp
Returns:the scale factors of this RescaleOp.
/**
     * 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.

Params:
  • offsets – the array to contain the offsets of this RescaleOp
Returns:the offsets of this RescaleOp.
/**
     * 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.

Returns:the number of scaling factors and offsets of this RescaleOp.
/**
     * 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.

Params:
  • nElems –    Number of elements the table is to have.
                 This will generally be 256 for byte and
                 65536 for short.
/**
     * 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<scale.length; band++) {
            float  bandScale   = scale[band];
            float  bandOff     = off[band];
            byte[] bandLutData = lutData[band];
            for (int i=0; i<nElems; i++) {
                int val = (int)(i*bandScale + bandOff);
                if ((val & 0xffffff00) != 0) {
                    if (val < 0) {
                        val = 0;
                    } else {
                        val = 255;
                    }
                }
                bandLutData[i] = (byte)val;
            }

        }
        int maxToCopy = (nBands == 4 && scale.length == 4) ? 4 : 3;
        while (band < lutData.length && band < maxToCopy) {
           System.arraycopy(lutData[band-1], 0, lutData[band], 0, nElems);
           band++;
        }
        if (nBands == 4 && band < nBands) {
           byte[] bandLutData = lutData[band];
           for (int i=0; i<nElems; i++) {
              bandLutData[i] = (byte)i;
           }
        }

        return new ByteLookupTable(0, lutData);
    }

    
Creates a ShortLookupTable to implement the rescale.
The table may have either a SHORT or BYTE input.

Params:
  • nElems –    Number of elements the table is to have.
                 This will generally be 256 for byte and
                 65536 for short.
/**
     * Creates a ShortLookupTable 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 ShortLookupTable createShortLut(float[] scale,
                                            float[] off,
                                            int   nBands,
                                            int   nElems) {

        short[][]        lutData = new short[nBands][nElems];
        int band = 0;

        for (band=0; band<scale.length; band++) {
            float   bandScale   = scale[band];
            float   bandOff     = off[band];
            short[] bandLutData = lutData[band];
            for (int i=0; i<nElems; i++) {
                int val = (int)(i*bandScale + bandOff);
                if ((val & 0xffff0000) != 0) {
                    if (val < 0) {
                        val = 0;
                    } else {
                        val = 65535;
                    }
                }
                bandLutData[i] = (short)val;
            }
        }
        int maxToCopy = (nBands == 4 && scale.length == 4) ? 4 : 3;
        while (band < lutData.length && band < maxToCopy) {
           System.arraycopy(lutData[band-1], 0, lutData[band], 0, nElems);
           band++;
        }
        if (nBands == 4 && band < nBands) {
           short[] bandLutData = lutData[band];
           for (int i=0; i<nElems; i++) {
              bandLutData[i] = (short)i;
           }
        }

        return new ShortLookupTable(0, lutData);
    }


    
Determines if the rescale can be performed as a lookup.
The dst must be a byte or short type.
The src must be less than 16 bits.
All source band sizes must be the same and all dst band sizes
must be the same.

/**
     * Determines if the rescale can be performed as a lookup.
     * The dst must be a byte or short type.
     * The src must be less than 16 bits.
     * All source band sizes must be the same and all dst band sizes
     * must be the same.
     */
    private boolean canUseLookup(Raster src, Raster dst) {

        //
        // Check that the src datatype is either a BYTE or SHORT
        //
        int datatype = src.getDataBuffer().getDataType();
        if(datatype != DataBuffer.TYPE_BYTE &&
           datatype != DataBuffer.TYPE_USHORT) {
            return false;
        }

        //
        // Check dst sample sizes. All must be 8 or 16 bits.
        //
        SampleModel dstSM = dst.getSampleModel();
        dstNbits = dstSM.getSampleSize(0);

        if (!(dstNbits == 8 || dstNbits == 16)) {
            return false;
        }
        for (int i=1; i<src.getNumBands(); i++) {
            int bandSize = dstSM.getSampleSize(i);
            if (bandSize != dstNbits) {
                return false;
            }
        }

        //
        // Check src sample sizes. All must be the same size
        //
        SampleModel srcSM = src.getSampleModel();
        srcNbits = srcSM.getSampleSize(0);
        if (srcNbits > 16) {
            return false;
        }
        for (int i=1; i<src.getNumBands(); i++) {
            int bandSize = srcSM.getSampleSize(i);
            if (bandSize != srcNbits) {
                return false;
            }
        }

      if (dstSM instanceof ComponentSampleModel) {
           ComponentSampleModel dsm = (ComponentSampleModel)dstSM;
           if (dsm.getPixelStride() != dst.getNumBands()) {
               return false;
           }
        }
        if (srcSM instanceof ComponentSampleModel) {
           ComponentSampleModel csm = (ComponentSampleModel)srcSM;
           if (csm.getPixelStride() != src.getNumBands()) {
               return false;
           }
        }

        return true;
    }

    
Rescales the source BufferedImage.
If the color model in the source image is not the same as that
in the destination image, the pixels will be converted
in the destination.  If the destination image is null,
a BufferedImage will be created with the source ColorModel.
An IllegalArgumentException may be thrown if the number of
scaling factors/offsets in this object does not meet the
restrictions stated in the class comments above, or if the
source image has an IndexColorModel.

Params:
  • src – the BufferedImage to be filtered
  • dst – the destination for the filtering operation or null
Throws:
  • IllegalArgumentException – if the ColorModel of src is an IndexColorModel, or if the number of scaling factors and offsets in this RescaleOp do not meet the requirements stated in the class comments, or if the source and destination images differ in size.
Returns:the filtered BufferedImage.
/**
     * Rescales the source BufferedImage.
     * If the color model in the source image is not the same as that
     * in the destination image, the pixels will be converted
     * in the destination.  If the destination image is null,
     * a BufferedImage will be created with the source ColorModel.
     * An IllegalArgumentException may be thrown if the number of
     * scaling factors/offsets in this object does not meet the
     * restrictions stated in the class comments above, or if the
     * source image has an IndexColorModel.
     * @param src the {@code BufferedImage} to be filtered
     * @param dst the destination for the filtering operation
     *            or {@code null}
     * @return the filtered {@code BufferedImage}.
     * @throws IllegalArgumentException if the {@code ColorModel}
     *         of {@code src} is an {@code IndexColorModel},
     *         or if the number of scaling factors and offsets in this
     *         {@code RescaleOp} do not meet the requirements
     *         stated in the class comments, or if the source and
     *         destination images differ in size.
     */
    public final BufferedImage filter (BufferedImage src, BufferedImage dst) {
        ColorModel srcCM = src.getColorModel();
        ColorModel dstCM;
        int numSrcColorComp = srcCM.getNumColorComponents();
        int scaleConst = length;

        if (srcCM instanceof IndexColorModel) {
            throw new
                IllegalArgumentException("Rescaling cannot be "+
                                         "performed on an indexed image");
        }
        if (scaleConst != 1 && scaleConst != numSrcColorComp &&
            scaleConst != srcCM.getNumComponents())
        {
            throw new IllegalArgumentException("Number of scaling constants "+
                                               "does not equal the number of"+
                                               " of color or color/alpha "+
                                               " components");
        }

        boolean needToConvert = false;
        boolean needToDraw = false;

        // Include alpha
        if (scaleConst > numSrcColorComp && srcCM.hasAlpha()) {
            scaleConst = numSrcColorComp+1;
        }

        int width = src.getWidth();
        int height = src.getHeight();

        BufferedImage origDst = dst;
        if (dst == null) {
            dst = createCompatibleDestImage(src, null);
            dstCM = srcCM;
        }
        else {
            if (width != dst.getWidth()) {
                throw new
                    IllegalArgumentException("Src width ("+width+
                                             ") not equal to dst width ("+
                                             dst.getWidth()+")");
            }
            if (height != dst.getHeight()) {
                throw new
                    IllegalArgumentException("Src height ("+height+
                                             ") not equal to dst height ("+
                                             dst.getHeight()+")");
            }

            dstCM = dst.getColorModel();
            if(srcCM.getColorSpace().getType() !=
                 dstCM.getColorSpace().getType()) {
                needToConvert = true;
                dst = createCompatibleDestImage(src, null);
            }

        }

        //
        // Try to use a native BI rescale operation first
        //
        if (ImagingLib.filter(this, src, dst) == null) {
            if (src.getRaster().getNumBands() !=
                dst.getRaster().getNumBands()) {
                needToDraw = true;
                dst = createCompatibleDestImage(src, null);
            }

            //
            // Native BI rescale failed - convert to rasters
            //
            WritableRaster srcRaster = src.getRaster();
            WritableRaster dstRaster = dst.getRaster();

            //
            // Call the raster filter method
            //
            filterRasterImpl(srcRaster, dstRaster, scaleConst, false);
        }

        if (needToDraw) {
             Graphics2D g = origDst.createGraphics();
             g.setComposite(AlphaComposite.Src);
             g.drawImage(dst, 0, 0, width, height, null);
             g.dispose();
        }
        if (needToConvert) {
            // ColorModels are not the same
            ColorConvertOp ccop = new ColorConvertOp(hints);
            dst = ccop.filter(dst, origDst);
        }
        return dst;
    }

    
Rescales the pixel data in the source Raster.
If the destination Raster is null, a new Raster will be created.
The source and destination must have the same number of bands.
Otherwise, an IllegalArgumentException is thrown.
Note that the number of scaling factors/offsets in this object must
meet the restrictions stated in the class comments above.
Otherwise, an IllegalArgumentException is thrown.

Params:
  • src – the Raster to be filtered
  • dst – the destination for the filtering operation or null
Throws:
  • IllegalArgumentException – if src and dst do not have the same number of bands, or if the number of scaling factors and offsets in this RescaleOp do not meet the requirements stated in the class comments, or if the source and destination rasters differ in size.
Returns:the filtered WritableRaster.
/**
     * Rescales the pixel data in the source Raster.
     * If the destination Raster is null, a new Raster will be created.
     * The source and destination must have the same number of bands.
     * Otherwise, an IllegalArgumentException is thrown.
     * Note that the number of scaling factors/offsets in this object must
     * meet the restrictions stated in the class comments above.
     * Otherwise, an IllegalArgumentException is thrown.
     * @param src the {@code Raster} to be filtered
     * @param dst the destination for the filtering operation
     *            or {@code null}
     * @return the filtered {@code WritableRaster}.
     * @throws IllegalArgumentException if {@code src} and
     *         {@code dst} do not have the same number of bands,
     *         or if the number of scaling factors and offsets in this
     *         {@code RescaleOp} do not meet the requirements
     *         stated in the class comments, or if the source and
     *         destination rasters differ in size.
     */
    public final WritableRaster filter (Raster src, WritableRaster dst)  {
        return filterRasterImpl(src, dst, length, true);
    }

    private WritableRaster filterRasterImpl(Raster src, WritableRaster dst,
                                            int scaleConst, boolean sCheck) {
        int numBands = src.getNumBands();
        int width  = src.getWidth();
        int height = src.getHeight();
        int[] srcPix = null;
        int step = 0;
        int tidx = 0;

        // Create a new destination Raster, if needed
        if (dst == null) {
            dst = createCompatibleDestRaster(src);
        }
        else if (height != dst.getHeight() || width != dst.getWidth()) {
            throw new
               IllegalArgumentException("Width or height of Rasters do not "+
                                        "match");
        }
        else if (numBands != dst.getNumBands()) {
            // Make sure that the number of bands are equal
            throw new IllegalArgumentException("Number of bands in src "
                            + numBands
                            + " does not equal number of bands in dest "
                            + dst.getNumBands());
        }

        // Make sure that the arrays match
        // Make sure that the low/high/constant arrays match
        if (sCheck && scaleConst != 1 && scaleConst != src.getNumBands()) {
            throw new IllegalArgumentException("Number of scaling constants "+
                                               "does not equal the number of"+
                                               " of bands in the src raster");
        }

        //
        // Try for a native raster rescale first
        //
        if (ImagingLib.filter(this, src, dst) != null) {
            return dst;
        }

        //
        // Native raster rescale failed.
        // Try to see if a lookup operation can be used
        //
        if (canUseLookup(src, dst)) {
            int srcNgray = (1 << srcNbits);
            int dstNgray = (1 << dstNbits);

            if (dstNgray == 256) {
                ByteLookupTable lut = createByteLut(scaleFactors, offsets,
                                                    numBands, srcNgray);
                LookupOp op = new LookupOp(lut, hints);
                op.filter(src, dst);
            } else {
                ShortLookupTable lut = createShortLut(scaleFactors, offsets,
                                                      numBands, srcNgray);
                LookupOp op = new LookupOp(lut, hints);
                op.filter(src, dst);
            }
        } else {
            //
            // Fall back to the slow code
            //
            if (scaleConst > 1) {
                step = 1;
            }

            int sminX = src.getMinX();
            int sY = src.getMinY();
            int dminX = dst.getMinX();
            int dY = dst.getMinY();
            int sX;
            int dX;

            //
            //  Determine bits per band to determine maxval for clamps.
            //  The min is assumed to be zero.
            //  REMIND: This must change if we ever support signed data types.
            //
            int nbits;
            int[] dstMax = new int[numBands];
            int[] dstMask = new int[numBands];
            SampleModel dstSM = dst.getSampleModel();
            for (int z=0; z<numBands; z++) {
                nbits = dstSM.getSampleSize(z);
                dstMax[z] = (1 << nbits) - 1;
                dstMask[z] = ~(dstMax[z]);
            }

            int val;
            for (int y=0; y < height; y++, sY++, dY++) {
                dX = dminX;
                sX = sminX;
                for (int x = 0; x < width; x++, sX++, dX++) {
                    // Get data for all bands at this x,y position
                    srcPix = src.getPixel(sX, sY, srcPix);
                    tidx = 0;
                    for (int z=0; z<numBands; z++, tidx += step) {
                        if ((scaleConst == 1 || scaleConst == 3) &&
                            (z == 3) && (numBands == 4)) {
                           val = srcPix[z];
                        } else {
                            val = (int)(srcPix[z]*scaleFactors[tidx]
                                              + offsets[tidx]);

                        }
                        // Clamp
                        if ((val & dstMask[z]) != 0) {
                            if (val < 0) {
                                val = 0;
                            } else {
                                val = dstMax[z];
                            }
                        }
                        srcPix[z] = val;

                    }

                    // Put it back for all bands
                    dst.setPixel(dX, dY, srcPix);
                }
            }
        }
        return dst;
    }

    
Returns the bounding box of the rescaled destination image.  Since
this is not a geometric operation, the bounding box does not
change.

/**
     * Returns the bounding box of the rescaled destination image.  Since
     * this is not a geometric operation, the bounding box does not
     * change.
     */
    public final Rectangle2D getBounds2D (BufferedImage src) {
         return getBounds2D(src.getRaster());
    }

    
Returns the bounding box of the rescaled destination Raster.  Since
this is not a geometric operation, the bounding box does not
change.

Params:
  • src – the rescaled destination Raster
Returns:the bounds of the specified Raster.
/**
     * Returns the bounding box of the rescaled destination Raster.  Since
     * this is not a geometric operation, the bounding box does not
     * change.
     * @param src the rescaled destination {@code Raster}
     * @return the bounds of the specified {@code Raster}.
     */
    public final Rectangle2D getBounds2D (Raster src) {
        return src.getBounds();
    }

    
Creates a zeroed destination image with the correct size and number of
bands.

Params:
  • src –       Source image for the filter operation.
  • destCM –    ColorModel of the destination.  If null, the
                 ColorModel of the source will be used.
Returns:the zeroed-destination image.
/**
     * Creates a zeroed destination image with the correct size and number of
     * bands.
     * @param src       Source image for the filter operation.
     * @param destCM    ColorModel of the destination.  If null, the
     *                  ColorModel of the source will be used.
     * @return the zeroed-destination image.
     */
    public BufferedImage createCompatibleDestImage (BufferedImage src,
                                                    ColorModel destCM) {
        BufferedImage image;
        if (destCM == null) {
            ColorModel cm = src.getColorModel();
            image = new BufferedImage(cm,
                                      src.getRaster().createCompatibleWritableRaster(),
                                      cm.isAlphaPremultiplied(),
                                      null);
        }
        else {
            int w = src.getWidth();
            int h = src.getHeight();
            image = new BufferedImage (destCM,
                                   destCM.createCompatibleWritableRaster(w, h),
                                   destCM.isAlphaPremultiplied(), null);
        }

        return image;
    }

    
Creates a zeroed-destination Raster with the correct size and number of bands, given this source. 
Params:
  • src –  the source Raster
Returns:the zeroed-destination Raster.
/**
     * Creates a zeroed-destination {@code Raster} with the correct
     * size and number of bands, given this source.
     * @param src       the source {@code Raster}
     * @return the zeroed-destination {@code Raster}.
     */
    public WritableRaster createCompatibleDestRaster (Raster src) {
        return src.createCompatibleWritableRaster(src.getWidth(), src.getHeight());
    }

    
Returns the location of the destination point given a
point in the source.  If dstPt is non-null, it will
be used to hold the return value.  Since this is not a geometric
operation, the srcPt will equal the dstPt.

Params:
  • srcPt – a point in the source image
  • dstPt – the destination point or null
Returns:the location of the destination point.
/**
     * Returns the location of the destination point given a
     * point in the source.  If dstPt is non-null, it will
     * be used to hold the return value.  Since this is not a geometric
     * operation, the srcPt will equal the dstPt.
     * @param srcPt a point in the source image
     * @param dstPt the destination point or {@code null}
     * @return the location of the destination point.
     */
    public final Point2D getPoint2D (Point2D srcPt, Point2D dstPt) {
        if (dstPt == null) {
            dstPt = new Point2D.Float();
        }
        dstPt.setLocation(srcPt.getX(), srcPt.getY());
        return dstPt;
    }

    
Returns the rendering hints for this op.

Returns:the rendering hints of this RescaleOp.
/**
     * Returns the rendering hints for this op.
     * @return the rendering hints of this {@code RescaleOp}.
     */
    public final RenderingHints getRenderingHints() {
        return hints;
    }
}