自定义渐变按钮 - 看不到文字

Question

我正在制作一个具有渐变效果的自定义按钮。我可以设置渐变效果，但看不到文字。我哪里错了？

class CustomButton extends JButton {   
    Color color1, color2;   

    public CustomButton(String text, Color color1, Color color2) {   
        super(text);   
        this.color1 = color1;   
        this.color2 = color2;   
        setOpaque(false);   
        setSize(new Dimension(450, 350));
        setForeground(Color.white);
        setText(text);
        setContentAreaFilled(false);
    }   

    protected void paintComponent(Graphics g) {    
        super.paintComponent(g);
        int width = getWidth();   
        int height = getHeight();   

        GradientPaint paint = new GradientPaint(0, 0, color1, width, height,
                color2, true);
        Graphics2D g2d = (Graphics2D)g;
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);   
        Paint oldPaint = g2d.getPaint();
        g2d.setPaint(paint);
        g2d.fillRect(0, 0, width, height);
        g2d.drawString("Button 1", getWidth()/2, 10);
        g2d.setPaint(oldPaint);
    }   
}  

注意：我允许用户在运行时更改颜色。根据更改为的颜色，我相应地设置了背景。

Answer 1

正如 Stan 已经回答的那样，解决方案的一部分是

button.setOpaque(false)

按钮有点疯狂，他们想缩进真的不画背景

button.setContentAreaFilled(false)

当心：确切的结果可能仍然高度依赖 LAF - f.i.看起来真的很糟糕。对于基于合成器（如 f.i. Nimbus），您可能会考虑安装一个自定义 Painter，该 Painter 配置了用户选择的渐变/颜色

编辑

刚刚仔细检查：

// tell ui to not paint the background
button.setOpaque(false);
button.setContentAreaFilled(false);

// override paintComponent
protected void paintComponent(...) {
     // do custom backgroudn painting
     ...
     // let ui handle the foreground (it wont touch the background due to the false settings above)
     super.paintComponent()
}

适用于所有核心 LAF（获胜时）

Answer 2

设置组件 opaque=false 避免背景绘制。

调用所有渐变绘制代码并在方法结束时调用super.paintComponent()。

Answer 3

看起来您使用相同的 Paint 对象来绘制背景和前景，所以我猜文本只是与背景合并。

Paint oldPaint = g2d.getPaint();  
g2d.setPaint(paint);  
g2d.fillRect(0, 0, width, height);  
g2d.setPaint( oldPaint ); // try adding this
g2d.drawString("Button 1", getWidth()/2, 10);
//g2d.setPaint( oldPaint );

Answer 4

你重写了paintComponent方法并且不调用它的超级版本。

paintComponent 负责编写实际的文本——所以如果它没有被调用，你就没有文本。

所以在这一点上：

自己编写代码来绘制标签，这可能会也可能不会复杂，具体取决于您将如何处理调整大小等

调用 super.paintComponent -- 如果它重新绘制背景可能不起作用。

Answer 5

我认为使用paintComponent()为自定义JButton创建背景不是正确的方法，这个背景可以改变两种方式

1) 替换默认BackGround

2) 覆盖BasicButtonUI，example for MetalButtonUI，注意MetalButtonUI 仅适用于CrossPlatformLookAndFeel == MetalLookAndFeel

编辑（最好从 ButtonModel 移除/禁用镇流器）

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.AbstractBorder;
import javax.swing.border.Border;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.basic.BasicButtonUI;
import javax.swing.plaf.metal.MetalButtonUI;

public class TextAreaInButton {

    private JFrame frame = new JFrame("sssssssss");
    private JButton tip1Null = new JButton(" test button ");

    public TextAreaInButton() {
        Border line, raisedbevel, loweredbevel, title, empty;
        line = BorderFactory.createLineBorder(Color.black);
        raisedbevel = BorderFactory.createRaisedBevelBorder();
        loweredbevel = BorderFactory.createLoweredBevelBorder();
        title = BorderFactory.createTitledBorder("");
        empty = BorderFactory.createEmptyBorder(1, 1, 1, 1);
        final Border compound;
        Color crl = (Color.blue);
        compound = BorderFactory.createCompoundBorder(empty, new OldRoundedBorderLine(crl));
        Color crl1 = (Color.red);
        final Border compound1;
        compound1 = BorderFactory.createCompoundBorder(empty, new OldRoundedBorderLine(crl1));
        Color crl2 = (Color.black);
        final Border compound2;
        compound2 = BorderFactory.createCompoundBorder(empty, new OldRoundedBorderLine(crl2));
        tip1Null.setFont(new Font("Serif", Font.BOLD, 14));
        tip1Null.setForeground(Color.darkGray);
        tip1Null.setPreferredSize(new Dimension(50, 30));
        tip1Null.addActionListener(new java.awt.event.ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
            }
        });
        tip1Null.setBorderPainted(true);
        tip1Null.setFocusPainted(false);
        tip1Null.setBorder(compound);
        tip1Null.setHorizontalTextPosition(SwingConstants.CENTER);
        tip1Null.setVerticalTextPosition(SwingConstants.BOTTOM);
        tip1Null.setUI(new ModifButtonUI());

        tip1Null.getModel().addChangeListener(new ChangeListener() {

            @Override
            public void stateChanged(ChangeEvent e) {
                ButtonModel model = (ButtonModel) e.getSource();
                if (model.isRollover()) {
                    tip1Null.setBorder(compound1);
                } else {
                    tip1Null.setBorder(compound);
                }
                if (model.isPressed()) {
                    tip1Null.setBorder(compound2);
                }
            }
        });
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(tip1Null, BorderLayout.CENTER);
        frame.setLocation(150, 150);
        frame.setPreferredSize(new Dimension(310, 75));
        frame.setLocationRelativeTo(null);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String args[]) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                TextAreaInButton taib = new TextAreaInButton();
            }
        });
    }
}

class OldRoundedBorderLine extends AbstractBorder {

    private final static int MARGIN = 5;
    private static final long serialVersionUID = 1L;
    private Color color;

    OldRoundedBorderLine(Color clr) {
        color = clr;
    }

    public void setColor(Color clr) {
        color = clr;
    }

    @Override
    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
        ((Graphics2D) g).setRenderingHint(
                RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g.setColor(color);
        g.drawRoundRect(x, y, width, height, MARGIN, MARGIN);
    }

    @Override
    public Insets getBorderInsets(Component c) {
        return new Insets(MARGIN, MARGIN, MARGIN, MARGIN);
    }

    @Override
    public Insets getBorderInsets(Component c, Insets insets) {
        insets.left = MARGIN;
        insets.top = MARGIN;
        insets.right = MARGIN;
        insets.bottom = MARGIN;
        return insets;
    }
}

class ModifButtonUI extends BasicButtonUI {

    //private static final ModifButtonUI buttonUI = new ModifButtonUI();

    ModifButtonUI() {
    }

    public static ComponentUI createUI(JComponent c) {
        return new ModifButtonUI();
    }

    @Override
    public void paint(Graphics g, JComponent c) {
        //final Color color1 = new Color(230, 255, 255, 0);
        //final Color color2 = new Color(255, 230, 255, 64);
        final Color color1 = new Color(00, 0, 200, 0);
        final Color color2 = new Color(255, 230, 255, 64);
        final Color alphaColor = new Color(00, 200, 230, 64);
        final Color color3 = new Color(
                alphaColor.getRed(), alphaColor.getGreen(), alphaColor.getBlue(), 0);
        final Color color4 = new Color(
                alphaColor.getRed(), alphaColor.getGreen(), alphaColor.getBlue(), 64);
        super.paint(g, c);
        Graphics2D g2D = (Graphics2D) g;
        GradientPaint gradient1 = new GradientPaint(
                0.0F, (float) c.getHeight() / (float) 2, color1, 0.0F, 0.0F, color2);
        Rectangle rec1 = new Rectangle(0, 0, c.getWidth(), c.getHeight() / 2);
        g2D.setPaint(gradient1);
        g2D.fill(rec1);
        GradientPaint gradient2 = new GradientPaint(
                0.0F, (float) c.getHeight() / (float) 2, color3, 0.0F, c.getHeight(), color4);
        Rectangle rec2 = new Rectangle(0, c.getHeight() / 2, c.getWidth(), c.getHeight());
        g2D.setPaint(gradient2);
        g2D.fill(rec2);
    }

    @Override
    protected void paintText(Graphics g, AbstractButton b, Rectangle textRect, String text) {
        Font f = b.getFont();
        g.setFont(f);
        FontMetrics fm = g.getFontMetrics(f);

        if (b.isEnabled()) {
            g.setColor(b.getForeground());
            g.drawString(text, textRect.x, textRect.y + fm.getAscent());
        } else {
            g.setColor(b.getBackground().brighter());
            g.drawString(text, textRect.x, textRect.y + fm.getAscent());
            g.setColor(b.getBackground().darker());
            g.drawString(text, textRect.x + 1, textRect.y + fm.getAscent() + 1);

        }
    }

    @Override
    public void paintButtonPressed(Graphics g, AbstractButton b) {
        paintText(g, b, b.getBounds(), b.getText());
        g.setColor(Color.red.brighter());
        g.fillRect(0, 0, b.getSize().width, b.getSize().height);
    }

    public void paintBorder(Graphics g) {
    }

    @Override
    protected void paintFocus(Graphics g, AbstractButton b,
            Rectangle viewRect, Rectangle textRect, Rectangle iconRect) {
    }
}