1

我有滑块可以创建 RGB 值，然后使用它来创建一个框并填充其颜色。当我初始化我的程序时，它不会立即绘制正方形。它会绘制正方形并在移动滑块后开始填充它。

在构造函数期间调用了用于绘制矩形并用颜色填充它的方法，但没有做任何事情，没有错误，只是没有绘制正方形。滑块在状态更改时调用 SAME 方法，然后将绘制正方形。这没有道理。

我相信这是其他人在缺乏某些基础时可能会遇到的事情。

这是我的代码，您可以复制粘贴并在 jGrasp 或其他任何内容中运行以了解我的意思。谢谢！

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class Colors extends javax.swing.JFrame {

    public Colors() {
        initComponents();
        addSliderListeners();
        addSliderLabels();
        this.setTitle("Color Mixer");
        sliderRed.setValue(150);
        sliderGreen.setValue(125);
        sliderBlue.setValue(215);
        updateImage();
    }

    private void addSliderListeners(){
        sliderRed.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent e) {
                updateImage();
            }
        });
        sliderGreen.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent e) {
                updateImage();
            }
        });
        sliderBlue.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent e) {
                updateImage();
            }
        });
    }

    private void updateImage(){
        lblRedDec.setText(""+sliderRed.getValue());
        lblRedDec.setForeground(new Color(sliderRed.getValue(),0,0));
        lblRedHex.setText(Integer.toHexString(sliderRed.getValue()));
        lblRedHex.setForeground(lblRedDec.getForeground());

        lblGreenDec.setText(""+sliderGreen.getValue());
        lblGreenDec.setForeground(new Color(0,sliderGreen.getValue(),0));
        lblGreenHex.setText(Integer.toHexString(sliderGreen.getValue()));
        lblGreenHex.setForeground(lblGreenDec.getForeground());

        lblBlueDec.setText(""+sliderBlue.getValue());
        lblBlueHex.setText(Integer.toHexString(sliderBlue.getValue()));
        lblBlueDec.setForeground(new Color(0,0,sliderBlue.getValue()));
        lblBlueHex.setForeground(lblBlueDec.getForeground());

        Graphics2D g2 = (Graphics2D)this.getGraphics();
        g2.setColor(new Color(sliderRed.getValue(),sliderGreen.getValue(),sliderBlue.getValue()));
        g2.fill(new Rectangle(25,125,250,250));
    }

    private void addSliderLabels() {
        sliderRed.setPaintLabels(true);
        sliderGreen.setPaintLabels(true);
        sliderBlue.setPaintLabels(true);
    }
/**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        sliderRed = new javax.swing.JSlider();
        lblRed = new javax.swing.JLabel();
        lblRedHex = new javax.swing.JLabel();
        lblRedDec = new javax.swing.JLabel();
        sliderGreen = new javax.swing.JSlider();
        lblGreen = new javax.swing.JLabel();
        lblGreenHex = new javax.swing.JLabel();
        lblGreenDec = new javax.swing.JLabel();
        sliderBlue = new javax.swing.JSlider();
        lblBlue = new javax.swing.JLabel();
        lblBlueHex = new javax.swing.JLabel();
        lblBlueDec = new javax.swing.JLabel();
        lblTitle = new java.awt.Label();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setResizable(false);

        sliderRed.setMajorTickSpacing(15);
        sliderRed.setMaximum(255);
        sliderRed.setMinorTickSpacing(5);
        sliderRed.setOrientation(javax.swing.JSlider.VERTICAL);
        sliderRed.setPaintTicks(true);
        sliderRed.setValue(212);
        sliderRed.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
        sliderRed.setName(""); // NOI18N

        lblRed.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
        lblRed.setText("Red");

        lblRedHex.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        lblRedHex.setText("hex");

        lblRedDec.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        lblRedDec.setText("dec");

        sliderGreen.setMajorTickSpacing(15);
        sliderGreen.setMaximum(255);
        sliderGreen.setMinorTickSpacing(5);
        sliderGreen.setOrientation(javax.swing.JSlider.VERTICAL);
        sliderGreen.setPaintTicks(true);
        sliderGreen.setSnapToTicks(true);
        sliderGreen.setValue(35);
        sliderGreen.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
        sliderGreen.setName(""); // NOI18N

        lblGreen.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
        lblGreen.setText("Green");

        lblGreenHex.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        lblGreenHex.setText("hex");

        lblGreenDec.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        lblGreenDec.setText("dec");

        sliderBlue.setMajorTickSpacing(15);
        sliderBlue.setMaximum(255);
        sliderBlue.setMinorTickSpacing(5);
        sliderBlue.setOrientation(javax.swing.JSlider.VERTICAL);
        sliderBlue.setPaintTicks(true);
        sliderBlue.setSnapToTicks(true);
        sliderBlue.setValue(218);
        sliderBlue.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
        sliderBlue.setName(""); // NOI18N

        lblBlue.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
        lblBlue.setText("Blue");

        lblBlueHex.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        lblBlueHex.setText("hex");

        lblBlueDec.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        lblBlueDec.setText("dec");

        lblTitle.setFont(new java.awt.Font("Dialog", 0, 36)); // NOI18N
        lblTitle.setText("Color Mixer");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(lblTitle, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 125, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(27, 27, 27)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(lblRedHex)
                            .addComponent(lblRed)
                            .addComponent(lblRedDec))
                        .addGap(25, 25, 25))
                    .addComponent(sliderRed, javax.swing.GroupLayout.PREFERRED_SIZE, 71, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(sliderGreen, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 71, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(lblGreenHex)
                            .addComponent(lblGreen)
                            .addComponent(lblGreenDec))
                        .addGap(25, 25, 25)))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(sliderBlue, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 71, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(lblBlueHex)
                            .addComponent(lblBlue)
                            .addComponent(lblBlueDec))
                        .addGap(25, 25, 25))))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(23, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                        .addGroup(layout.createSequentialGroup()
                            .addComponent(lblBlueDec)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(lblBlueHex)
                            .addGap(18, 18, 18)
                            .addComponent(lblBlue)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(sliderBlue, javax.swing.GroupLayout.PREFERRED_SIZE, 285, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createSequentialGroup()
                            .addComponent(lblGreenDec)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(lblGreenHex)
                            .addGap(18, 18, 18)
                            .addComponent(lblGreen)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(sliderGreen, javax.swing.GroupLayout.PREFERRED_SIZE, 285, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createSequentialGroup()
                            .addComponent(lblRedDec)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(lblRedHex)
                            .addGap(16, 16, 16)
                            .addComponent(lblRed)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(sliderRed, javax.swing.GroupLayout.PREFERRED_SIZE, 285, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addComponent(lblTitle, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(38, 38, 38))
        );

        lblTitle.getAccessibleContext().setAccessibleName("");
        lblTitle.getAccessibleContext().setAccessibleDescription("");

        pack();
    }// </editor-fold>                        


    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Colors().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JLabel lblBlue;
    private javax.swing.JLabel lblBlueDec;
    private javax.swing.JLabel lblBlueHex;
    private javax.swing.JLabel lblGreen;
    private javax.swing.JLabel lblGreenDec;
    private javax.swing.JLabel lblGreenHex;
    private javax.swing.JLabel lblRed;
    private javax.swing.JLabel lblRedDec;
    private javax.swing.JLabel lblRedHex;
    private java.awt.Label lblTitle;
    private javax.swing.JSlider sliderBlue;
    private javax.swing.JSlider sliderGreen;
    private javax.swing.JSlider sliderRed;
    // End of variables declaration                   

}
4

1 回答 1

2

颜色方块最初没有显示的原因是因为它GroupLayout会导致重新绘制其所有子组件，从而有效地“绘制”方块。

要让您的广场出现，您可以：

  • 制作一个自定义JComponent颜色方块并添加到GroupLayout.
  • 将所有当前组件提取到一个新组件JComponent并覆盖该paintComponent方法，以便GroupLayout首先绘制所有组件。此选项将允许您不将颜色方块添加到GroupLayout.

代码：

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);
    updateImage();
}
于 2012-11-17T02:47:44.183 回答