Question

我试图将基本对象绘制到JPanel 虽然它似乎没有起作用。

我确定我在使用paint方法做错了被称为

import javax.swing.*;
import java.awt.*;
import java.awt.image.*;

public class testGui {

   static colors   gc_colors;
   static gui      gc_gui;

   public static void main(String[] args) {

      gc_colors = new colors();
      gc_gui = new gui();

      gc_gui.cv_frame.setVisible(true);

   }

   public static class colors {

      Color   cv_ltGrey;
      Color   cv_mdGrey;
      Color   cv_dkGrey;

      public colors() {

         cv_ltGrey = Color.decode("#DDDDDD");
         cv_mdGrey = Color.decode("#CCCCCC");
         cv_dkGrey = Color.decode("#111111");

      }

   }

   public static class gui {

      JFrame   cv_frame;
      JPanel   cv_panel;
      JPanel   cv_content;

      public gui() {

         cv_frame = new JFrame();
         cv_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         cv_frame.setTitle("Test GUI");
         cv_frame.setSize(600, 400);
         cv_frame.setLayout(new FlowLayout());

         cv_panel = new JPanel();
         cv_panel.setBackground(gc_colors.cv_ltGrey);
         cv_panel.setPreferredSize(new Dimension(500, 300));

         cv_frame.add(cv_panel);

         cv_content = new content();
         cv_panel.add(cv_content);

      }

   }

   public static class content extends JPanel {

      public void paint(Graphics graphic) {
         super.paint(graphic);
         draw(graphic);
      }

      public void update() {
         repaint();
      }

      public void draw(Graphics graphic) {

         Graphics2D graphic2D = (Graphics2D) graphic;
         graphic2D.setPaint(gc_colors.cv_ltGrey);
         graphic2D.fillRect(10, 10, 100, 100);

      }

   }

}

我有一个我的gui课程，我正在添加一个JPanel（浅灰色的）。然后我尝试将我的绘图添加到使用JPanel扩展类叫做内容。

当我运行它虽然它似乎创建了我想要的灰色JPanel但是这幅画只是一个小小的白色方块，我不知道为什么。

Answer 1

因此，content小组的默认首选大小为0x0，FlowLayout尊重其preferredSize组件（略有差距），因此之所以如此你有一个漂亮的小白色矩形。

您需要做的是覆盖getPreferredSize面板的content方法并返回合适的尺寸，例如

public static class content extends JPanel {

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(120, 120);
    }

    public void paint(Graphics graphic) {
        super.paint(graphic);
        draw(graphic);
    }

    public void update() {
        repaint();
    }

    public void draw(Graphics graphic) {

        Graphics2D graphic2D = (Graphics2D) graphic;
        graphic2D.setPaint(gc_colors.cv_ltGrey);
        graphic2D.fillRect(10, 10, 100, 100);

    }

}

Answer 2

我决定完全放弃第二个JPanel。将JPanel放入另一个JPanel中太麻烦了所以相反，我只会使用一个JPanel

  public static class gui {

  JFrame   cv_frame;
  JPanel   cv_panel;
  JPanel   cv_content;

  public gui() {

     cv_frame = new JFrame();
     cv_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     cv_frame.setTitle("Test GUI");
     cv_frame.setSize(600, 400);
     cv_frame.setLayout(new FlowLayout());

     cv_content = new content();
     cv_content.setBackground(gc_colors.cv_ltGrey);
     cv_content.setPreferredSize(new Dimension(500, 300));
     cv_frame.add(cv_content);

  }

  }

Java绘图到JPanel（调试）

2 个答案: