JLayeredPane的，背景图像+“图标”层(JLayeredPane, background

我需要的顶部2个独立JPanels（或任何轻质组分）的每其他最终嵌入一个JPanel内，直接或通过类似一个的JLayeredPane。因此，没有重量组分或玻璃板。底部JPanel（名为BackgroundPanel）描绘了一个背景图像或播放视频，同时保持纵横比和使用α。上面板（称为CompassPanel）上有图标，并允许用户添加图标，删除它们，移动它们（如图表库，这个功能是不是这个职位直接相关的，虽然）。我不能因为我的JNLP应用和部署环境的带宽限制很多外部依赖性增加。但是，如果有人知道一个轻量级的图表库，可以处理的α和纵横比维持的背景图像和视频，我的比赛。否则，我不能为我的生命弄清楚为什么这个空间正在调整大小后分配：

我已阅读JAVA教程上没有布局管理器去（不是我所想要做的，你在哪里！？GBL），但这些缩放需求，并具有图标大小调整期间留在图像的相同部分，等等。我想不出另一种方式来做到这一点。

下面是代码，我使用的Java 1.7。此外，这是我的第一个计算器，不温柔;-)

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Composite;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Insets;
import java.awt.Rectangle;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.border.BevelBorder;

public class Panel extends JPanel {

    private static final Logger logger = Logger.getLogger(Panel.class.getName());

    public Panel() throws IOException {

        final BufferedImage backgroundImage = ImageIO.read(new URL(
                "http://www.windpoweringamerica.gov/images/windmaps/us_windmap_80meters_820w.jpg"));
        final Dimension backgroundImageSize = new Dimension(backgroundImage.getWidth(), backgroundImage.getHeight());
        logger.log(Level.INFO, "Image dimensions: {0}", backgroundImageSize);
        setToolTipText("This is the panel");

        final JLayeredPane layeredPane = new JLayeredPane();
        layeredPane.setBorder(BorderFactory.createLineBorder(Color.RED, 10));
        layeredPane.setToolTipText("This is the layered pane!");
        layeredPane.getInsets().set(0, 0, 0, 0);

        final BackgroundPanel backgroundImagePanel = new BackgroundPanel(backgroundImage);
        final CompassPanel compassPanel = new CompassPanel();
        backgroundImagePanel.setToolTipText("You'll probably never see me, I'm in the background, forever beneath the compass panel");
        compassPanel.setToolTipText("I'm the compass panel");

        // Per http://docs.oracle.com/javase/tutorial/uiswing/layout/none.html, for every container w/o a layout manager, I must:
        // 1) Set the container's layout manager to null by calling setLayout(null). -- I do this here
        // 2) Call the Component class's setbounds method for each of the container's children. --- I do this when resizing
        // 3) Call the Component class's repaint method. --- I do this when resizing

        setLayout(null);
        add(layeredPane);
        layeredPane.add(backgroundImagePanel, JLayeredPane.DEFAULT_LAYER);
        layeredPane.add(compassPanel, JLayeredPane.PALETTE_LAYER);

        // Whenever this panel gets resized, make sure the layered pane gets resized to preserve the aspect ratio of the background image
        addComponentListener(new ComponentAdapter() {
            @Override
            public void componentResized(ComponentEvent evt) {
                Dimension availableSize = calculateAvailableSize(Panel.this);
                Rectangle contentBounds = calculateBoundsToFitImage(availableSize, backgroundImageSize);
                // Ok, this is a big deal. Now I know how big everything has to be, lets force it all to be the right size & repaint.
                layeredPane.setBounds(contentBounds);
                backgroundImagePanel.setBounds(contentBounds);
                compassPanel.setBounds(contentBounds);

                Panel.this.repaint();
                logger.info(String.format("Panel size: %s. Available size: %s. Content Bounds: %s", getSize(), availableSize, contentBounds));
            }
        });
    }

    /**
     * Paints the constant fitted aspect-ratio background image with an alpha of 0.5
     */
    private static class BackgroundPanel extends JPanel {

        private static final Logger logger = Logger.getLogger(BackgroundPanel.class.getName());
        private final AlphaComposite ac = AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, 0.5f);
        private final BufferedImage backgroundImage;

        BackgroundPanel(BufferedImage backgroundImage) {
            setLayout(null);
            this.backgroundImage = backgroundImage;
        }
        private Dimension lastPaintedDimensions = null;

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            final Dimension size = getSize();
            if (lastPaintedDimensions == null || !size.equals(lastPaintedDimensions)) {
                logger.log(Level.INFO, String.format("Painting background on %d x %d", size.width, size.height));
            }
            final Image paintMe = backgroundImage.getScaledInstance(size.width, size.height, Image.SCALE_SMOOTH);
            final Graphics2D g2 = (Graphics2D) g.create();
            g2.drawImage(paintMe, 0, 0, this);
            g2.setColor(Color.BLUE);
            g2.dispose();
            lastPaintedDimensions = size;
        }
    };

    private static class CompassPanel extends JPanel {

        final List<Compass> compassLabels = new ArrayList<>();

        CompassPanel() {
            setLayout(null);
            setOpaque(false);
            setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
        }
    }

    private static class Compass extends JLabel {

        private static final BufferedImage compassImage;

        static {
            try {
                compassImage = ImageIO.read(new URL("http://cdn1.iconfinder.com/data/icons/gur-project-1/32/1_7.png"));
            } catch (IOException ex) {
                throw new RuntimeException("Failed to read compass image", ex);
            }
        }
        final float xPercent, yPercent;

        public Compass(float xPercent, float yPercent) {
            this.xPercent = xPercent;
            this.yPercent = yPercent;
            setIcon(new ImageIcon(compassImage));
            setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));
            setOpaque(true);
            setCursor(Cursor.getDefaultCursor());
        }
    }

    public static void main(String[] args) throws IOException {
        final JFrame frame = new JFrame("Hello Stackoverflowwwwwww! Here is a Dynamic Layered Pane Question.");
        frame.setLayout(null);
        frame.setContentPane(new Panel());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(800, 600);
        frame.setVisible(true);
    }

    private static Dimension calculateAvailableSize(final JComponent component) {

        int availableHeight = component.getSize().height;
        int availableWidth = component.getSize().width;

        final Insets insets = component.getInsets();

        availableHeight -= insets.top;
        availableHeight -= insets.bottom;

        availableWidth -= insets.left;
        availableWidth -= insets.right;

        if (component.getBorder() != null) {
            Insets borderInsets = component.getBorder().getBorderInsets(component);
            if (borderInsets != null) {
                availableHeight -= borderInsets.top;
                availableHeight -= borderInsets.bottom;

                availableWidth -= borderInsets.left;
                availableWidth -= borderInsets.right;
            }
        }

        return new Dimension(availableWidth, availableHeight);
    }

    private static Rectangle calculateBoundsToFitImage(Dimension parentSize, Dimension imageSize) {
        final double scaleFactor;
        final int xOffset, yOffset, scaledHeight, scaledWidth;
        {
            final double xScaleFactor = (double) parentSize.width / imageSize.width;
            final double yScaleFactor = (double) parentSize.height / imageSize.height;
            scaleFactor = xScaleFactor > yScaleFactor ? yScaleFactor : xScaleFactor;
            scaledHeight = (int) Math.round(scaleFactor * imageSize.height);
            scaledWidth = (int) Math.round(scaleFactor * imageSize.width);
        }

        xOffset = (int) ((parentSize.width - scaledWidth) / 2.0);
        yOffset = (int) ((parentSize.height - scaledHeight) / 2.0);
        return new Rectangle(xOffset, yOffset, scaledWidth, scaledHeight);
    }
}

卫生署。我刚才已经回答我的问题。调用#setBounds是相对于你的父容器，所以X和Y偏移量需要适当说明，所以这修正了：

backgroundImagePanel.setBounds(0, 0, contentBounds.width, contentBounds.height);
compassPanel.setBounds(0, 0, contentBounds.width, contentBounds.height);