/*
Copyright 2006 Jerry Huxtable

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package org.meteoinfo.image.filter;

import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.*;

/**
 * A class containing some static utility methods for dealing with BufferedImages.
 */
public abstract class ImageUtils {
	
	private static BufferedImage backgroundImage = null;

	/**
     * Cretae a BufferedImage from an ImageProducer.
     * @param producer the ImageProducer
     * @return a new TYPE_INT_ARGB BufferedImage
     */
    public static BufferedImage createImage(ImageProducer producer) {
		PixelGrabber pg = new PixelGrabber(producer, 0, 0, -1, -1, null, 0, 0);
		try {
			pg.grabPixels();
		} catch (InterruptedException e) {
			throw new RuntimeException("Image fetch interrupted");
		}
		if ((pg.status() & ImageObserver.ABORT) != 0)
			throw new RuntimeException("Image fetch aborted");
		if ((pg.status() & ImageObserver.ERROR) != 0)
			throw new RuntimeException("Image fetch error");
		BufferedImage p = new BufferedImage(pg.getWidth(), pg.getHeight(), BufferedImage.TYPE_INT_ARGB);
		p.setRGB(0, 0, pg.getWidth(), pg.getHeight(), (int[])pg.getPixels(), 0, pg.getWidth());
		return p;
	}
	
	/**
	 * Convert an Image into a TYPE_INT_ARGB BufferedImage. If the image is already of this type, the original image is returned unchanged.
     * @param image the image to convert
     * @return the converted image
	 */
	public static BufferedImage convertImageToARGB( Image image ) {
		if ( image instanceof BufferedImage && ((BufferedImage)image).getType() == BufferedImage.TYPE_INT_ARGB )
			return (BufferedImage)image;
		BufferedImage p = new BufferedImage( image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_ARGB);
		Graphics2D g = p.createGraphics();
		g.drawImage( image, 0, 0, null );
		g.dispose();
		return p;
	}
	
	/**
	 * Returns a *copy* of a subimage of image. This avoids the performance problems associated with BufferedImage.getSubimage.
     * @param image the image
     * @param x the x position
     * @param y the y position
     * @param w the width
     * @param h the height
     * @return the subimage
	 */
	public static BufferedImage getSubimage( BufferedImage image, int x, int y, int w, int h ) {
		BufferedImage newImage = new BufferedImage( w, h, BufferedImage.TYPE_INT_ARGB );
		Graphics2D g = newImage.createGraphics();
		g.drawRenderedImage( image, AffineTransform.getTranslateInstance(-x, -y) );
		g.dispose();
		return newImage;
	}

	/**
	 * Clones a BufferedImage.
     * @param image the image to clone
     * @return the cloned image
	 */
	public static BufferedImage cloneImage( BufferedImage image ) {
		BufferedImage newImage = new BufferedImage( image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB );
		Graphics2D g = newImage.createGraphics();
		g.drawRenderedImage( image, null );
		g.dispose();
		return newImage;
	}

	/**
	 * Paint a check pattern, used for a background to indicate image transparency.
     * @param c the component to draw into
     * @param g the Graphics objects
     * @param x the x position
     * @param y the y position
     * @param width the width
     * @param height the height
	 */
	public static void paintCheckedBackground(Component c, Graphics g, int x, int y, int width, int height) {
		if ( backgroundImage == null ) {
			backgroundImage = new BufferedImage( 64, 64, BufferedImage.TYPE_INT_ARGB );
			Graphics bg = backgroundImage.createGraphics();
			for ( int by = 0; by < 64; by += 8 ) {
				for ( int bx = 0; bx < 64; bx += 8 ) {
					bg.setColor( ((bx^by) & 8) != 0 ? Color.lightGray : Color.white );
					bg.fillRect( bx, by, 8, 8 );
				}
			}
			bg.dispose();
		}

		if ( backgroundImage != null ) {
			Shape saveClip = g.getClip();
			Rectangle r = g.getClipBounds();
			if (r == null)
				r = new Rectangle(c.getSize());
			r = r.intersection(new Rectangle(x, y, width, height));
			g.setClip(r);
			int w = backgroundImage.getWidth();
			int h = backgroundImage.getHeight();
			if (w != -1 && h != -1) {
				int x1 = (r.x / w) * w;
				int y1 = (r.y / h) * h;
				int x2 = ((r.x + r.width + w - 1) / w) * w;
				int y2 = ((r.y + r.height + h - 1) / h) * h;
				for (y = y1; y < y2; y += h)
					for (x = x1; x < x2; x += w)
						g.drawImage(backgroundImage, x, y, c);
			}
			g.setClip(saveClip);
		}
	}

    /**
     * Calculates the bounds of the non-transparent parts of the given image.
     * @param p the image
     * @return the bounds of the non-transparent area
     */
	public static Rectangle getSelectedBounds(BufferedImage p) {
		int width = p.getWidth();
        int height = p.getHeight();
		int maxX = 0, maxY = 0, minX = width, minY = height;
		boolean anySelected = false;
		int y1;
		int [] pixels = null;
		
		for (y1 = height-1; y1 >= 0; y1--) {
			pixels = getRGB( p, 0, y1, width, 1, pixels );
			for (int x = 0; x < minX; x++) {
				if ((pixels[x] & 0xff000000) != 0) {
					minX = x;
					maxY = y1;
					anySelected = true;
					break;
				}
			}
			for (int x = width-1; x >= maxX; x--) {
				if ((pixels[x] & 0xff000000) != 0) {
					maxX = x;
					maxY = y1;
					anySelected = true;
					break;
				}
			}
			if ( anySelected )
				break;
		}
		pixels = null;
		for (int y = 0; y < y1; y++) {
			pixels = getRGB( p, 0, y, width, 1, pixels );
			for (int x = 0; x < minX; x++) {
				if ((pixels[x] & 0xff000000) != 0) {
					minX = x;
					if ( y < minY )
						minY = y;
					anySelected = true;
					break;
				}
			}
			for (int x = width-1; x >= maxX; x--) {
				if ((pixels[x] & 0xff000000) != 0) {
					maxX = x;
					if ( y < minY )
						minY = y;
					anySelected = true;
					break;
				}
			}
		}
		if ( anySelected )
			return new Rectangle( minX, minY, maxX-minX+1, maxY-minY+1 );
		return null;
	}

	/**
	 * Compose src onto dst using the alpha of sel to interpolate between the two.
	 * I can't think of a way to do this using AlphaComposite.
     * @param src the source raster
     * @param dst the destination raster
     * @param sel the mask raster
	 */
	public static void composeThroughMask(Raster src, WritableRaster dst, Raster sel) {
		int x = src.getMinX();
		int y = src.getMinY();
		int w = src.getWidth();
		int h = src.getHeight();

		int srcRGB[] = null;
		int selRGB[] = null;
		int dstRGB[] = null;

		for ( int i = 0; i < h; i++ ) {
			srcRGB = src.getPixels(x, y, w, 1, srcRGB);
			selRGB = sel.getPixels(x, y, w, 1, selRGB);
			dstRGB = dst.getPixels(x, y, w, 1, dstRGB);

			int k = x;
			for ( int j = 0; j < w; j++ ) {
				int sr = srcRGB[k];
				int dir = dstRGB[k];
				int sg = srcRGB[k+1];
				int dig = dstRGB[k+1];
				int sb = srcRGB[k+2];
				int dib = dstRGB[k+2];
				int sa = srcRGB[k+3];
				int dia = dstRGB[k+3];

				float a = selRGB[k+3]/255f;
				float ac = 1-a;

				dstRGB[k] = (int)(a*sr + ac*dir); 
				dstRGB[k+1] = (int)(a*sg + ac*dig); 
				dstRGB[k+2] = (int)(a*sb + ac*dib); 
				dstRGB[k+3] = (int)(a*sa + ac*dia);
				k += 4;
			}

			dst.setPixels(x, y, w, 1, dstRGB);
			y++;
		}
	}

	/**
	 * A convenience method for getting ARGB pixels from an image. This tries to avoid the performance
	 * penalty of BufferedImage.getRGB unmanaging the image.
     * @param image   a BufferedImage object
     * @param x       the left edge of the pixel block
     * @param y       the right edge of the pixel block
     * @param width   the width of the pixel arry
     * @param height  the height of the pixel arry
     * @param pixels  the array to hold the returned pixels. May be null.
     * @return the pixels
     * @see #setRGB
     */
	public static int[] getRGB( BufferedImage image, int x, int y, int width, int height, int[] pixels ) {
		int type = image.getType();
		if ( type == BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
			return (int [])image.getRaster().getDataElements( x, y, width, height, pixels );
		return image.getRGB( x, y, width, height, pixels, 0, width );
    }

	/**
	 * A convenience method for setting ARGB pixels in an image. This tries to avoid the performance
	 * penalty of BufferedImage.setRGB unmanaging the image.
     * @param image   a BufferedImage object
     * @param x       the left edge of the pixel block
     * @param y       the right edge of the pixel block
     * @param width   the width of the pixel arry
     * @param height  the height of the pixel arry
     * @param pixels  the array of pixels to set
     * @see #getRGB
	 */
	public static void setRGB( BufferedImage image, int x, int y, int width, int height, int[] pixels ) {
		int type = image.getType();
		if ( type == BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
			image.getRaster().setDataElements( x, y, width, height, pixels );
		else
			image.setRGB( x, y, width, height, pixels, 0, width );
    }
}

