awt/image/ReplicateScaleFilter.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * particular file as subject to the "Classpath" exception as provided
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 * accompanied this code).
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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.
 * <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.
     */
    protected int srcWidth;

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

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

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

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

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

    /**
     * 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.
     * @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 {@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.
     * <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.
     * <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.
     * <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);
            }
        }
    }
}