effectutils.java

来自「Mobile 应用程序使用 Java Micro Edition (Java M」· Java 代码 · 共 410 行 · 第 1/2 页

        }

        for (int i = 0; i < data.length; i++) {
            data[i] /= total;
        }

        return data;
    }

    // =================================================================================================================
    // Get/Set Pixels helper methods

    /**
     * <p>Returns an array of pixels, stored as integers, from a <code>BufferedImage</code>. The pixels are grabbed from
     * a rectangular area defined by a location and two dimensions. Calling this method on an image of type different
     * from <code>BufferedImage.TYPE_INT_ARGB</code> and <code>BufferedImage.TYPE_INT_RGB</code> will unmanage the
     * image.</p>
     *
     * @param img    the source image
     * @param x      the x location at which to start grabbing pixels
     * @param y      the y location at which to start grabbing pixels
     * @param w      the width of the rectangle of pixels to grab
     * @param h      the height of the rectangle of pixels to grab
     * @param pixels a pre-allocated array of pixels of size w*h; can be null
     * @return <code>pixels</code> if non-null, a new array of integers otherwise
     * @throws IllegalArgumentException is <code>pixels</code> is non-null and of length &lt; w*h
     */
    static byte[] getPixels(BufferedImage img,
                                   int x, int y, int w, int h, byte[] pixels) {
        if (w == 0 || h == 0) {
            return new byte[0];
        }

        if (pixels == null) {
            pixels = new byte[w * h];
        } else if (pixels.length < w * h) {
            throw new IllegalArgumentException("pixels array must have a length >= w*h");
        }

        int imageType = img.getType();
        if (imageType == BufferedImage.TYPE_BYTE_GRAY) {
            Raster raster = img.getRaster();
            return (byte[]) raster.getDataElements(x, y, w, h, pixels);
        } else {
            throw new IllegalArgumentException("Only type BYTE_GRAY is supported");
        }
    }

    /**
     * <p>Writes a rectangular area of pixels in the destination <code>BufferedImage</code>. Calling this method on an
     * image of type different from <code>BufferedImage.TYPE_INT_ARGB</code> and <code>BufferedImage.TYPE_INT_RGB</code>
     * will unmanage the image.</p>
     *
     * @param img    the destination image
     * @param x      the x location at which to start storing pixels
     * @param y      the y location at which to start storing pixels
     * @param w      the width of the rectangle of pixels to store
     * @param h      the height of the rectangle of pixels to store
     * @param pixels an array of pixels, stored as integers
     * @throws IllegalArgumentException is <code>pixels</code> is non-null and of length &lt; w*h
     */
    static void setPixels(BufferedImage img,
                                 int x, int y, int w, int h, byte[] pixels) {
        if (pixels == null || w == 0 || h == 0) {
            return;
        } else if (pixels.length < w * h) {
            throw new IllegalArgumentException("pixels array must have a length >= w*h");
        }
        int imageType = img.getType();
        if (imageType == BufferedImage.TYPE_BYTE_GRAY) {
            WritableRaster raster = img.getRaster();
            raster.setDataElements(x, y, w, h, pixels);
        } else {
            throw new IllegalArgumentException("Only type BYTE_GRAY is supported");
        }
    }

    /**
     * <p>Returns an array of pixels, stored as integers, from a
     * <code>BufferedImage</code>. The pixels are grabbed from a rectangular
     * area defined by a location and two dimensions. Calling this method on
     * an image of type different from <code>BufferedImage.TYPE_INT_ARGB</code>
     * and <code>BufferedImage.TYPE_INT_RGB</code> will unmanage the image.</p>
     *
     * @param img the source image
     * @param x the x location at which to start grabbing pixels
     * @param y the y location at which to start grabbing pixels
     * @param w the width of the rectangle of pixels to grab
     * @param h the height of the rectangle of pixels to grab
     * @param pixels a pre-allocated array of pixels of size w*h; can be null
     * @return <code>pixels</code> if non-null, a new array of integers
     *   otherwise
     * @throws IllegalArgumentException is <code>pixels</code> is non-null and
     *   of length &lt; w*h
     */
    public static int[] getPixels(BufferedImage img,
                                  int x, int y, int w, int h, int[] pixels) {
        if (w == 0 || h == 0) {
            return new int[0];
        }

        if (pixels == null) {
            pixels = new int[w * h];
        } else if (pixels.length < w * h) {
            throw new IllegalArgumentException("pixels array must have a length" +
                                               " >= w*h");
        }

        int imageType = img.getType();
        if (imageType == BufferedImage.TYPE_INT_ARGB ||
            imageType == BufferedImage.TYPE_INT_RGB) {
            Raster raster = img.getRaster();
            return (int[]) raster.getDataElements(x, y, w, h, pixels);
        }

        // Unmanages the image
        return img.getRGB(x, y, w, h, pixels, 0, w);
    }

    /**
     * <p>Writes a rectangular area of pixels in the destination
     * <code>BufferedImage</code>. Calling this method on
     * an image of type different from <code>BufferedImage.TYPE_INT_ARGB</code>
     * and <code>BufferedImage.TYPE_INT_RGB</code> will unmanage the image.</p>
     *
     * @param img the destination image
     * @param x the x location at which to start storing pixels
     * @param y the y location at which to start storing pixels
     * @param w the width of the rectangle of pixels to store
     * @param h the height of the rectangle of pixels to store
     * @param pixels an array of pixels, stored as integers
     * @throws IllegalArgumentException is <code>pixels</code> is non-null and
     *   of length &lt; w*h
     */
    public static void setPixels(BufferedImage img,
                                 int x, int y, int w, int h, int[] pixels) {
        if (pixels == null || w == 0 || h == 0) {
            return;
        } else if (pixels.length < w * h) {
            throw new IllegalArgumentException("pixels array must have a length" +
                                               " >= w*h");
        }

        int imageType = img.getType();
        if (imageType == BufferedImage.TYPE_INT_ARGB ||
            imageType == BufferedImage.TYPE_INT_RGB) {
            WritableRaster raster = img.getRaster();
            raster.setDataElements(x, y, w, h, pixels);
        } else {
            // Unmanages the image
            img.setRGB(x, y, w, h, pixels, 0, w);
        }
    }

    /**
     * <p>Returns a new <code>BufferedImage</code> using the same color model
     * as the image passed as a parameter. The returned image is only compatible
     * with the image passed as a parameter. This does not mean the returned
     * image is compatible with the hardware.</p>
     *
     * @param image the reference image from which the color model of the new
     *   image is obtained
     * @return a new <code>BufferedImage</code>, compatible with the color model
     *   of <code>image</code>
     */
    public static BufferedImage createColorModelCompatibleImage(BufferedImage image) {
        ColorModel cm = image.getColorModel();
        return new BufferedImage(cm,
            cm.createCompatibleWritableRaster(image.getWidth(),
                                              image.getHeight()),
            cm.isAlphaPremultiplied(), null);
    }

    /**
     * <p>Returns a new translucent compatible image of the specified width and
     * height. That is, the returned <code>BufferedImage</code> is compatible with
     * the graphics hardware. If the method is called in a headless
     * environment, then the returned BufferedImage will be compatible with
     * the source image.</p>
     *
     * @param width the width of the new image
     * @param height the height of the new image
     * @return a new translucent compatible <code>BufferedImage</code> of the
     *   specified width and height
     */
    public static BufferedImage createCompatibleTranslucentImage(int width,
                                                                 int height) {
        return isHeadless() ?
                new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB) :
                getGraphicsConfiguration().createCompatibleImage(width, height,
                                                   Transparency.TRANSLUCENT);
    }

    private static boolean isHeadless() {
        return GraphicsEnvironment.isHeadless();
    }

    // Returns the graphics configuration for the primary screen
    private static GraphicsConfiguration getGraphicsConfiguration() {
        return GraphicsEnvironment.getLocalGraphicsEnvironment().
                    getDefaultScreenDevice().getDefaultConfiguration();
    }

}