JDK8/Java8源码在线阅读

/*
 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
 * 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
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package sun.awt.image;

import java.awt.Dimension;
import java.awt.Image;
import java.awt.geom.Dimension2D;
import java.awt.image.ImageObserver;
import java.util.Arrays;
import java.util.List;
import java.util.function.Function;
import java.util.function.BiFunction;
import java.util.stream.Collectors;

public class MultiResolutionCachedImage extends AbstractMultiResolutionImage {

    private final int baseImageWidth;
    private final int baseImageHeight;
    private final Dimension2D[] sizes;
    private final BiFunction<Integer, Integer, Image> mapper;
    private int availableInfo;

    public MultiResolutionCachedImage(int baseImageWidth, int baseImageHeight,
            BiFunction<Integer, Integer, Image> mapper) {
        this(baseImageWidth, baseImageHeight, new Dimension[]{new Dimension(
            baseImageWidth, baseImageHeight)
        }, mapper);
    }

    public MultiResolutionCachedImage(int baseImageWidth, int baseImageHeight,
            Dimension2D[] sizes, BiFunction<Integer, Integer, Image> mapper) {
        this.baseImageWidth = baseImageWidth;
        this.baseImageHeight = baseImageHeight;
        this.sizes = (sizes == null) ? null : Arrays.copyOf(sizes, sizes.length);
        this.mapper = mapper;
    }

    @Override
    public Image getResolutionVariant(int width, int height) {
        ImageCache cache = ImageCache.getInstance();
        ImageCacheKey key = new ImageCacheKey(this, width, height);
        Image resolutionVariant = cache.getImage(key);
        if (resolutionVariant == null) {
            resolutionVariant = mapper.apply(width, height);
            cache.setImage(key, resolutionVariant);
        }
        preload(resolutionVariant, availableInfo);
        return resolutionVariant;
    }

    @Override
    public List<Image> getResolutionVariants() {
        return Arrays.stream(sizes).map((Function<Dimension2D, Image>) size
                -> getResolutionVariant((int) size.getWidth(),
                        (int) size.getHeight())).collect(Collectors.toList());
    }

    public MultiResolutionCachedImage map(Function<Image, Image> mapper) {
        return new MultiResolutionCachedImage(baseImageWidth, baseImageHeight,
                sizes, (width, height) ->
                        mapper.apply(getResolutionVariant(width, height)));
    }

    @Override
    public int getWidth(ImageObserver observer) {
        updateInfo(observer, ImageObserver.WIDTH);
        return super.getWidth(observer);
    }

    @Override
    public int getHeight(ImageObserver observer) {
        updateInfo(observer, ImageObserver.HEIGHT);
        return super.getHeight(observer);
    }

    @Override
    public Object getProperty(String name, ImageObserver observer) {
        updateInfo(observer, ImageObserver.PROPERTIES);
        return super.getProperty(name, observer);
    }

    @Override
    protected Image getBaseImage() {
        return getResolutionVariant(baseImageWidth, baseImageHeight);
    }

    private void updateInfo(ImageObserver observer, int info) {
        availableInfo |= (observer == null) ? ImageObserver.ALLBITS : info;
    }

    private static int getInfo(Image image) {
        if (image instanceof ToolkitImage) {
            return ((ToolkitImage) image).getImageRep().check(
                    (img, infoflags, x, y, w, h) -> false);
        }
        return 0;
    }

    private static void preload(Image image, int availableInfo) {
        if (availableInfo != 0 && image instanceof ToolkitImage) {
            ((ToolkitImage) image).preload(new ImageObserver() {
                int flags = availableInfo;

                @Override
                public boolean imageUpdate(Image img, int infoflags,
                        int x, int y, int width, int height) {
                    flags &= ~infoflags;
                    return (flags != 0) && ((infoflags
                            & (ImageObserver.ERROR | ImageObserver.ABORT)) == 0);
                }
            });
        }
    }

    private static class ImageCacheKey implements ImageCache.PixelsKey {

        private final int pixelCount;
        private final int hash;

        private final int w;
        private final int h;
        private final Image baseImage;

        ImageCacheKey(final Image baseImage,
                final int w, final int h) {
            this.baseImage = baseImage;
            this.w = w;
            this.h = h;
            this.pixelCount = w * h;
            hash = hash();
        }

        @Override

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