Question

我正在尝试将一个OpenGL上下文添加到jFrame。

当我这样做时它会起作用：

jframe.setVisible( true );
jframe.getContentPane().add( glcanvas, BorderLayout.CENTER );
jframe.revalidate();
jframe.repaint();

但是，如果我尝试在按钮上创建上下文，请单击：

JButton startButton = new JButton("Start");
startButton.addActionListener(
    new ActionListener()
{
    @Override
    public void actionPerformed(ActionEvent e) 
    {
            jframe.getContentPane().add( glcanvas, BorderLayout.CENTER );
        jframe.revalidate();
        jframe.repaint();
        }
});
jframe.add(startButton);

然后没有任何反应。如果我尝试调试它，程序将运行revalidate（）和repaint（）命令但没有任何变化。

有人可以告诉我为什么会这样 - 当我尝试按下按钮时，为什么会有所不同？你也可以建议一种方法来解决这个问题吗？我需要能够从菜单系统中打开上下文。

- 编辑：这是我的测试程序的完整代码

/* -- OpenGL -- */
import javax.media.opengl.GL2ES2;
import javax.media.opengl.GLAutoDrawable;
import javax.media.opengl.GLCapabilities;
import javax.media.opengl.GLEventListener;
import javax.media.opengl.GLProfile;
import javax.media.opengl.awt.GLCanvas;
import javax.media.opengl.awt.GLJPanel;
import javax.swing.JComponent;

/* -- Swing -- */
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JLabel;

import javax.swing.JPanel;

/* -- jFrame Layouts -- */
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class Menu 
{
public static void main(String[] args) 
{

        GLProfile glprofile = GLProfile.getDefault();
        GLCapabilities glcapabilities = new GLCapabilities( glprofile );
        final GLCanvas glcanvas = new GLCanvas( glcapabilities );

        glcanvas.addGLEventListener( new GLEventListener() 
        {
            @Override
            public void init( GLAutoDrawable glautodrawable ) 
            {
                System.out.println("INIT");
            }

            @Override
            public void reshape( GLAutoDrawable glautodrawable, int x, int y, int width, int height ) 
            {
                GL2ES2 gl = glautodrawable.getGL().getGL2ES2(); //Get OpenGL

                gl.glViewport( 0, 0, width, height );   //Set the viewport
            }

            @Override
            public void display( GLAutoDrawable glautodrawable ) 
            {
                GL2ES2 gl = glautodrawable.getGL().getGL2ES2();

                gl.glClearColor(+0.0f, +0.2f, +0.9f, +0.0f);  // Blue background

                //Clear the screen so that we can draw the new one
                gl.glClear(
                    GL2ES2.GL_STENCIL_BUFFER_BIT |
                    GL2ES2.GL_COLOR_BUFFER_BIT   |
                    GL2ES2.GL_DEPTH_BUFFER_BIT   
                );
            }

            @Override
            public void dispose( GLAutoDrawable glautodrawable ) 
            {

            }

        }); /* Add GLEventListner to glCanvas */

        final JFrame jframe = new JFrame( "One Triangle Swing GLCanvas" ); 
        jframe.addWindowListener( new WindowAdapter() 
        {
            public void windowClosing( WindowEvent windowevent ) 
            {
                jframe.dispose();
                System.exit( 0 );
            }
        });        

        jframe.setSize( 800, 600 );
        jframe.setVisible( true );

        /* --- IF I ADD THE ContentPane HERE AND REVALIDATE/REPAINT IT WORKS --- */
        //jframe.getContentPane().add( glcanvas, BorderLayout.CENTER );
        //jframe.revalidate();
        //jframe.repaint();

        jframe.setLayout(new FlowLayout());

        JButton startButton = new JButton("Start");
        startButton.addActionListener(
            new ActionListener()
            {
                @Override
                public void actionPerformed(ActionEvent e) 
                {     
                    /* --- I NEED TO ADD THE ContentPane HERE, BUT IF I DO THIS THE REPAINT DOESN'T WORK --- */                          
                    jframe.getContentPane().add( glcanvas, BorderLayout.CENTER );
                    jframe.revalidate();
                    jframe.repaint();

                        /* -- I added this because I was told elsewhere that repainting 
                         *    in a different thread would make it work, however I haven't
                         *    been successful in getting this to work. Included for information
                         */
                    //repaintThread(jframe);

            }
            });
        jframe.add(startButton);      

}

private static void repaintThread(final JFrame jframe) 
    {  
    Thread thread = new Thread(new Runnable() 
    {  
        public void run() 
        {  
            for( int i = 0; i < 200; i++)
            {
                jframe.revalidate();
                jframe.repaint();


                    try
                    {  
                        Thread.currentThread().sleep( 50 );  
                    } 
                    catch( Exception ex )
                    {  
                        break;  
                    }
            }
        }  
    });

    thread.setPriority(Thread.NORM_PRIORITY);  
    thread.start();  
}  

}

Answer 1

这是让一切混乱的路线：

jframe.setLayout(new FlowLayout());

您正在将布局更改为FlowLayout，然后在glcanvas旁边添加startButton。 glcanvas的首选大小为0，因此不可见，但单击按钮时可以看到startButton的轻微移动。

我认为设置FlowLayout并非故意，因为您使用BorderLayout.CENTER约束来添加glcanvas。所以这是一个简单的修复：

评论：

//jframe.setLayout(new FlowLayout());

将startButton添加到面板的NORTH而不是CENTER，因为glcanvas将转到CENTER。变化：

jframe.add(startButton);

到：

jframe.add(startButton, BorderLayout.NORTH);

修复了重新验证问题，至少在Windows 7 Java 7上。

另外，请参阅A Visual Guide to Layout Managers以获取有关布局的更多详细信息和示例。

revalidate（）/ repaint（）在ActionListener中不起作用

1 个答案: