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package java.awt.image;

import java.awt.image.ImageConsumer;
import java.awt.image.ColorModel;
import java.util.Hashtable;
import java.awt.Rectangle;


An ImageFilter class for scaling images using the simplest algorithm.
This class extends the basic ImageFilter Class to scale an existing
image and provide a source for a new image containing the resampled
image.  The pixels in the source image are sampled to produce pixels
for an image of the specified size by replicating rows and columns of
pixels to scale up or omitting rows and columns of pixels to scale
down.

It is meant to be used in conjunction with a FilteredImageSource
object to produce scaled versions of existing images.  Due to
implementation dependencies, there may be differences in pixel values
of an image filtered on different platforms.

Author:     Jim Graham
See Also:
/**
 * An ImageFilter class for scaling images using the simplest algorithm.
 * This class extends the basic ImageFilter Class to scale an existing
 * image and provide a source for a new image containing the resampled
 * image.  The pixels in the source image are sampled to produce pixels
 * for an image of the specified size by replicating rows and columns of
 * pixels to scale up or omitting rows and columns of pixels to scale
 * down.
 * <p>It is meant to be used in conjunction with a FilteredImageSource
 * object to produce scaled versions of existing images.  Due to
 * implementation dependencies, there may be differences in pixel values
 * of an image filtered on different platforms.
 *
 * @see FilteredImageSource
 * @see ImageFilter
 *
 * @author      Jim Graham
 */
public class ReplicateScaleFilter extends ImageFilter {

    
The width of the source image.

/**
     * The width of the source image.
     */
    protected int srcWidth;

    
The height of the source image.

/**
     * The height of the source image.
     */
    protected int srcHeight;

    
The target width to scale the image.

/**
     * The target width to scale the image.
     */
    protected int destWidth;

    
The target height to scale the image.

/**
     * The target height to scale the image.
     */
    protected int destHeight;

    
An int array containing information about a row of pixels. 
/**
     * An {@code int} array containing information about a
     * row of pixels.
     */
    protected int srcrows[];

    
An int array containing information about a column of pixels. 
/**
     * An {@code int} array containing information about a
     * column of pixels.
     */
    protected int srccols[];

    
A byte array initialized with a size of destWidth and used to deliver a row of pixel data to the ImageConsumer. 
/**
     * A {@code byte} array initialized with a size of
     * {@link #destWidth} and used to deliver a row of pixel
     * data to the {@link ImageConsumer}.
     */
    protected Object outpixbuf;

    
Constructs a ReplicateScaleFilter that scales the pixels from
its source Image as specified by the width and height parameters.

Params:
  • width – the target width to scale the image
  • height – the target height to scale the image
Throws:
/**
     * Constructs a ReplicateScaleFilter that scales the pixels from
     * its source Image as specified by the width and height parameters.
     * @param width the target width to scale the image
     * @param height the target height to scale the image
     * @throws IllegalArgumentException if {@code width} equals
     *         zero or {@code height} equals zero
     */
    public ReplicateScaleFilter(int width, int height) {
        if (width == 0 || height == 0) {
            throw new IllegalArgumentException("Width ("+width+
                                                ") and height ("+height+
                                                ") must be non-zero");
        }
        destWidth = width;
        destHeight = height;
    }

    
Passes along the properties from the source object after adding a property indicating the scale applied. This method invokes super.setProperties, which might result in additional properties being added. 
 Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation. 
/**
     * Passes along the properties from the source object after adding a
     * property indicating the scale applied.
     * This method invokes {@code super.setProperties},
     * which might result in additional properties being added.
     * <p>
     * Note: This method is intended to be called by the
     * {@code ImageProducer} of the {@code Image} whose pixels
     * are being filtered. Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     */
    public void setProperties(Hashtable<?,?> props) {
        @SuppressWarnings("unchecked")
        Hashtable<Object,Object> p = (Hashtable<Object,Object>)props.clone();
        String key = "rescale";
        String val = destWidth + "x" + destHeight;
        Object o = p.get(key);
        if (o != null && o instanceof String) {
            val = ((String) o) + ", " + val;
        }
        p.put(key, val);
        super.setProperties(p);
    }

    
Override the dimensions of the source image and pass the dimensions
of the new scaled size to the ImageConsumer.

 Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation. 
See Also:
/**
     * Override the dimensions of the source image and pass the dimensions
     * of the new scaled size to the ImageConsumer.
     * <p>
     * Note: This method is intended to be called by the
     * {@code ImageProducer} of the {@code Image} whose pixels
     * are being filtered. Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     * @see ImageConsumer
     */
    public void setDimensions(int w, int h) {
        srcWidth = w;
        srcHeight = h;
        if (destWidth < 0) {
            if (destHeight < 0) {
                destWidth = srcWidth;
                destHeight = srcHeight;
            } else {
                destWidth = srcWidth * destHeight / srcHeight;
            }
        } else if (destHeight < 0) {
            destHeight = srcHeight * destWidth / srcWidth;
        }
        consumer.setDimensions(destWidth, destHeight);
    }

    private void calculateMaps() {
        srcrows = new int[destHeight + 1];
        for (int y = 0; y <= destHeight; y++) {
            srcrows[y] = (2 * y * srcHeight + srcHeight) / (2 * destHeight);
        }
        srccols = new int[destWidth + 1];
        for (int x = 0; x <= destWidth; x++) {
            srccols[x] = (2 * x * srcWidth + srcWidth) / (2 * destWidth);
        }
    }

    
Choose which rows and columns of the delivered byte pixels are
needed for the destination scaled image and pass through just
those rows and columns that are needed, replicated as necessary.

 Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation. 
/**
     * Choose which rows and columns of the delivered byte pixels are
     * needed for the destination scaled image and pass through just
     * those rows and columns that are needed, replicated as necessary.
     * <p>
     * Note: This method is intended to be called by the
     * {@code ImageProducer} of the {@code Image} whose pixels
     * are being filtered. Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     */
    public void setPixels(int x, int y, int w, int h,
                          ColorModel model, byte pixels[], int off,
                          int scansize) {
        if (srcrows == null || srccols == null) {
            calculateMaps();
        }
        int sx, sy;
        int dx1 = (2 * x * destWidth + srcWidth - 1) / (2 * srcWidth);
        int dy1 = (2 * y * destHeight + srcHeight - 1) / (2 * srcHeight);
        byte outpix[];
        if (outpixbuf != null && outpixbuf instanceof byte[]) {
            outpix = (byte[]) outpixbuf;
        } else {
            outpix = new byte[destWidth];
            outpixbuf = outpix;
        }
        for (int dy = dy1; (sy = srcrows[dy]) < y + h; dy++) {
            int srcoff = off + scansize * (sy - y);
            int dx;
            for (dx = dx1; (sx = srccols[dx]) < x + w; dx++) {
                outpix[dx] = pixels[srcoff + sx - x];
            }
            if (dx > dx1) {
                consumer.setPixels(dx1, dy, dx - dx1, 1,
                                   model, outpix, dx1, destWidth);
            }
        }
    }

    
Choose which rows and columns of the delivered int pixels are
needed for the destination scaled image and pass through just
those rows and columns that are needed, replicated as necessary.

 Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation. 
/**
     * Choose which rows and columns of the delivered int pixels are
     * needed for the destination scaled image and pass through just
     * those rows and columns that are needed, replicated as necessary.
     * <p>
     * Note: This method is intended to be called by the
     * {@code ImageProducer} of the {@code Image} whose pixels
     * are being filtered. Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     */
    public void setPixels(int x, int y, int w, int h,
                          ColorModel model, int pixels[], int off,
                          int scansize) {
        if (srcrows == null || srccols == null) {
            calculateMaps();
        }
        int sx, sy;
        int dx1 = (2 * x * destWidth + srcWidth - 1) / (2 * srcWidth);
        int dy1 = (2 * y * destHeight + srcHeight - 1) / (2 * srcHeight);
        int outpix[];
        if (outpixbuf != null && outpixbuf instanceof int[]) {
            outpix = (int[]) outpixbuf;
        } else {
            outpix = new int[destWidth];
            outpixbuf = outpix;
        }
        for (int dy = dy1; (sy = srcrows[dy]) < y + h; dy++) {
            int srcoff = off + scansize * (sy - y);
            int dx;
            for (dx = dx1; (sx = srccols[dx]) < x + w; dx++) {
                outpix[dx] = pixels[srcoff + sx - x];
            }
            if (dx > dx1) {
                consumer.setPixels(dx1, dy, dx - dx1, 1,
                                   model, outpix, dx1, destWidth);
            }
        }
    }
}