java - 在 JComponent 上创建阴影的颜色不同于白色的问题

Question

我正在为 swing 开发新的外观和感觉，现在我在 JComponent 中创建阴影时遇到了问题，例如，当我创建颜色不同于白色的 JButton 时，我有一个不正确的阴影效果

这是创建阴影的代码。

protected void paintShadow(@NotNull Graphics g, @NotNull JComponent c){
        int shade = 0;
        int topOpacity = 80;
        int pixels = UIManager.getInt("Button[Default].shadowPixel");
        JButton b = (JButton) c;
        for (int i = 0; i < pixels; i++) {
            g.setColor(new Color(shade, shade, shade, ((topOpacity / pixels) * i)));
            g.drawRoundRect(i, i, b.getWidth() - ((i * 2) + 1), b.getHeight() - ((i * 2) + 1), 7, 7);
        }
    }

这是白色的正确效果

这是用其他颜色的错误效果

我如何概括我的方法绘制阴影？

这是此代码的最小示例

import javax.swing.*;
import javax.swing.plaf.basic.BasicButtonUI;
import java.awt.*;

/**
 * @author https://github.com/vincenzopalazzo
 */
public class MaterialMain extends JFrame {

    static {
        UIManager.put("Button[Default].shadowPixel", 3);
    }


    public void init() {
        JPanel panel = new JPanel();


        JButton witheRightEffect = new JButton("shadow withe");
        witheRightEffect.setUI(new ShadowButtonUI());

        JButton otherColorWrongEffect = new JButton("shadow other color");
        otherColorWrongEffect.setBackground(Color.GREEN);
        otherColorWrongEffect.setUI(new ShadowButtonUI());

        panel.add(witheRightEffect);
        panel.add(otherColorWrongEffect);

        setTitle("Look and feel");

        setDefaultCloseOperation(EXIT_ON_CLOSE);

        setSize(630, 360);

        add(panel);

        setLocationRelativeTo(null);

        setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                MaterialMain main = new MaterialMain();
                main.init();
            }
        });
    }

    public class ShadowButtonUI extends BasicButtonUI{

        @Override
        public void installUI(JComponent c) {
            super.installUI(c);
            c.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
        }

        @Override
        public void paint(Graphics g, JComponent c) {
            super.paint(g, c);
            paintShadow(g, c);
        }

        protected void paintShadow( Graphics g,  JComponent c){
            int shade = 0;
            int topOpacity = 80;
            int pixels = UIManager.getInt("Button[Default].shadowPixel");
            JButton b = (JButton) c;
            for (int i = 0; i < pixels; i++) {
                g.setColor(new Color(shade, shade, shade, ((topOpacity / pixels) * i)));
                g.drawRoundRect(i, i, b.getWidth() - ((i * 2) + 1), b.getHeight() - ((i * 2) + 1), 7, 7);
            }
        }
    }

}

按钮白色是正确的效果但是按钮绿色阴影是错误的

Answer 1

我想回答这个问题，我有一个在 JButton 上创建阴影的原始解决方案。

这是我的方法的代码

public class ShadowButton {
    public static void main(String... args) {
        SwingUtilities.invokeLater(ShadowButton::new);
    }

    public ShadowButton() {
        var fadeWidth = 30;
        var p = new JPanel();
        var b = new JButton("with fading out border!!!") {
            @Override
            public void paintBorder(Graphics g) {
                var rec = g.getClip().getBounds();
                var c = this.getBackground();
                var d = this.getParent().getBackground();
                for (int i = 0; i < fadeWidth; i++) {
                    var col = mixColor(c, d, 1.0 * (i + 1) / fadeWidth);
                    g.setColor(col);
                    g.drawRect(rec.x + i, rec.y + i, rec.width - 2 * i, rec.height - 2 * i);
                }
            }
        };
        b.setFocusable(false);
        b.setBackground(Color.GREEN);
        b.setForeground(Color.BLACK);
        Font f = new Font("Arial", Font.BOLD, 36);
        b.setFont(f);
        b.setBorder(BorderFactory.createLineBorder(b.getBackground(), fadeWidth, false));
        p.setBackground(Color.RED);
        p.add(b);
        var frame = new JFrame("Shadoe Demo");
        frame.setContentPane(p);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    private static Color mixColor(Color c, Color d, double factor) {
        float[] cc = c.getComponents(null);
        float[] dd = d.getComponents(null);
        float[] result = new float[cc.length];
        for (int i = 0; i < 4; i++) {
            result[i] = (float) (factor * cc[i] + (1 - factor) * dd[i]);
        }
        return new Color(result[0], result[1], result[2], result[3]);
    }
}

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