Java - 如何在JFrame中的IDE生成的JPanel上绘制形状

Question

I am using NetBeans IDE to program a GUI application. It is going to calculate the area/volume of all kinds of primitive 2D/3D shapes. I have created a new JFrame , inside it - a JTabbedPane , which has two tabs for 2D and 3D shapes.

I plan to create custom jpegs for tabs of each shape, that's not a problem, but I can't really draw shapes inside shape-type tabs (see picture).

There's only one .java file, I'm pasting the contents of that in here. Please help me, I am extremely confused as to how can I get around this.

// @author Žanas Stundys
package geometrinis.projektas;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

//
public class PagrindinisLangas extends javax.swing.JFrame {


/* Creates new form PagrindinisLangas */
public PagrindinisLangas() {
    initComponents();

}
//
/* This method is called from within the constructor to initialize the form */
//@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jScrollPane1 = new javax.swing.JScrollPane();
    jEditorPane1 = new javax.swing.JEditorPane();
    jTabbedPane1 = new javax.swing.JTabbedPane();
    jPanel1 = new javax.swing.JPanel();
    jTabbedPane2 = new javax.swing.JTabbedPane();
    jPanel3 = new javax.swing.JPanel();
    jPanel4 = new javax.swing.JPanel();
    jPanel2 = new javax.swing.JPanel();

    jScrollPane1.setViewportView(jEditorPane1);

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
    setResizable(false);
    setSize(new java.awt.Dimension(960, 480));

    jTabbedPane1.setToolTipText("");

    jTabbedPane2.setTabPlacement(javax.swing.JTabbedPane.LEFT);

    javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
    jPanel3.setLayout(jPanel3Layout);
    jPanel3Layout.setHorizontalGroup(
        jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 0, Short.MAX_VALUE)
    );
    jPanel3Layout.setVerticalGroup(
        jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 0, Short.MAX_VALUE)
    );

    jTabbedPane2.addTab("", new javax.swing.ImageIcon(getClass().getResource("/Assets/2D/square.png")), jPanel3, "Kvadratas / Stačiakampis"); // NOI18N

    javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4);
    jPanel4.setLayout(jPanel4Layout);
    jPanel4Layout.setHorizontalGroup(
        jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 0, Short.MAX_VALUE)
    );
    jPanel4Layout.setVerticalGroup(
        jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 0, Short.MAX_VALUE)
    );

    jTabbedPane2.addTab("", new javax.swing.ImageIcon(getClass().getResource("/Assets/2D/circle.png")), jPanel4, "Apskritimas"); // NOI18N

    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
    jPanel1.setLayout(jPanel1Layout);
    jPanel1Layout.setHorizontalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jTabbedPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 876, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );
    jPanel1Layout.setVerticalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jTabbedPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 387, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );

    jTabbedPane1.addTab("2D", new javax.swing.ImageIcon(getClass().getResource("/Assets/icon2d.png")), jPanel1); // NOI18N

    javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
    jPanel2.setLayout(jPanel2Layout);
    jPanel2Layout.setHorizontalGroup(
        jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 0, Short.MAX_VALUE)
    );
    jPanel2Layout.setVerticalGroup(
        jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 0, Short.MAX_VALUE)
    );

    jTabbedPane1.addTab("3D", new javax.swing.ImageIcon(getClass().getResource("/Assets/icon3d.png")), jPanel2, ""); // NOI18N

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jTabbedPane1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 960, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jTabbedPane1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 480, Short.MAX_VALUE)
    );

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

/* @param args the command line arguments */
public static void main(String args[]){
    /* Create and display the form */

    java.awt.EventQueue.invokeLater(() -> {
        new PagrindinisLangas().setVisible(true);
    });

}
// Variables declaration - do not modify                     
private javax.swing.JEditorPane jEditorPane1;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JPanel jPanel3;
private javax.swing.JPanel jPanel4;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTabbedPane jTabbedPane1;
private javax.swing.JTabbedPane jTabbedPane2;
// End of variables declaration                   
}

Answer 1

To add a component that is useful for custom drawing, what I do is this:

1. Create a new class that exends JPanel
2. Within the class override paintComponent() method to draw the rectangle or whatever other shapes you want. It is helpful if the constructor sets the preferred size to be non-zero.
3. Compile the new class.
4. Open the Design view of the JPanel or JFrame I want to use the JPanel in.
5. Drag the new class from the Projects tab onto the JFrame / Jpanel you want to use it in. (If you are going to use the same custom Panel multiple times it may be helpful to select the class in the projects tab and right-click for Tools -> Add To Pallet so that it is on the Pallet in the design view. )

Here is an example class to be used this way:

public class PanelWithRectangle extends JPanel {

    public PanelWithRectangle() {
        setPreferredSize(new Dimension(200,100));
    }


    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g); 
        Graphics2D g2d = (Graphics2D) g;
        g2d.draw(new Rectangle2D.Double(10, 10,20, 25));
    }
}

For 3D Drawing it is somewhat different. Swing doesn't support 3D, so we need to use some JavaFX. For JavaFX instead of extending JPanel extend JFXPanel and instead of overriding paintComponent, create a scene object and use setScene. Also JavaFX methods need to be called on the JavaFX Thread so we need to use Platform.runLater() to have functions called on that thread.

public class PanelWithBox extends JFXPanel {

    public PanelWithBox() {
        setPreferredSize(new Dimension(200,100));
        Platform.runLater(this::initFx);
    }

    private void initFx() {
        Group g = new Group();
        Scene scene = new Scene(g);
        Box box = new Box(20, 30, 40);
        box.setMaterial(new PhongMaterial(Color.RED));
        box.getTransforms().addAll(Transform.translate(50, 25), new Rotate(30, new Point3D(1, 1, 1)));
        g.getChildren().add(box);
        setScene(scene);
    }
}