JAVA GUI图形上的坐标系

Question

我有一个名为“GridPanel中”即在屏幕上画出坐标系类。

public class GridPanel extends JPanel 
{ 
    protected paintComponent(Graphics g){ 
      // draws the Coordinate System with grid 
    } 
} 

另一个叫做“形状”的类在坐标系上绘制自定义形状。

public class Shape extends JComponent{ 
      protected paintComponent(Graphics g){ 
       // draws the shape on to the coordinate system 
      } 
    } 

我正在寻找一种方式做造型类里面的画，而不必一次又一次地绘制坐标系。

Answer 1

“如何”将归结为“什么”。

一般来说，如果你自己动手绘制东西，你会发现将东西绘制到GridPane上更容易，而不是依赖布局管理器之类的东西。

例如。这创建了一个简单的interface，使用单个方法将事物绘制到网格上。

public interface GridShape { 
    public void draw(Graphics2D g2d, JComponent parent); 
} 

然后，这是由什么都想要画到网格

public class WaveShape implements GridShape { 

    @Override 
    public void draw(Graphics2D g2d, JComponent parent) { 
     g2d.setColor(Color.RED); 

     int xDiff = parent.getWidth()/4; 
     int height = parent.getHeight() - 1; 

     int xPos = 0; 

     GeneralPath path = new GeneralPath(); 
     path.moveTo(0, 0); 
     path.curveTo(xPos + xDiff, 0, xPos, height, xPos + xDiff, height); 
     xPos += xDiff; 
     path.curveTo(xPos + xDiff, height, xPos, 0, xPos + xDiff, 0); 
     xPos += xDiff; 
     path.curveTo(xPos + xDiff, 0, xPos, height, xPos + xDiff, height); 
     xPos += xDiff; 
     path.curveTo(xPos + xDiff, height, xPos, 0, xPos + xDiff, 0); 
     g2d.draw(path); 
    } 

} 

的GridPane然后绘制本身，然后画什么都“形”它（这个例子是非常基本的实现，但你可以有一个setter从而改变其如果需要涂或，“形”，有一个List它允许你同时绘制多个形状）

import java.awt.Color; 
import java.awt.Dimension; 
import java.awt.EventQueue; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.geom.GeneralPath; 
import javax.swing.JComponent; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.UIManager; 
import javax.swing.UnsupportedLookAndFeelException; 

public class TestGrid { 

    public static void main(String[] args) { 
     new TestGrid(); 
    } 

    public TestGrid() { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
       } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { 
        ex.printStackTrace(); 
       } 

       JFrame frame = new JFrame("Testing"); 
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
       frame.add(new GridPane()); 
       frame.pack(); 
       frame.setLocationRelativeTo(null); 
       frame.setVisible(true); 
      } 
     }); 
    } 

    public class GridPane extends JPanel { 

     private WaveShape waveShape; 

     public GridPane() { 
      waveShape = new WaveShape(); 
     } 

     @Override 
     public Dimension getPreferredSize() { 
      return new Dimension(200, 200); 
     } 

     protected void paintComponent(Graphics g) { 
      super.paintComponent(g); 
      Graphics2D g2d = (Graphics2D) g.create(); 
      g2d.drawLine(getWidth()/2, 0, getWidth()/2, getHeight()); 
      g2d.drawLine(0, getHeight()/2, getWidth(), getHeight()/2); 
      g2d.dispose(); 

      // I don't trust you 
      g2d = (Graphics2D) g.create(); 
      waveShape.draw(g2d, this); 
      g2d.dispose(); 
     } 

    } 

    public interface GridShape { 
     public void draw(Graphics2D g2d, JComponent parent); 
    } 

    public class WaveShape implements GridShape { 

     @Override 
     public void draw(Graphics2D g2d, JComponent parent) { 
      g2d.setColor(Color.RED); 

      int xDiff = parent.getWidth()/4; 
      int height = parent.getHeight() - 1; 

      int xPos = 0; 

      GeneralPath path = new GeneralPath(); 
      path.moveTo(0, 0); 
      path.curveTo(xPos + xDiff, 0, xPos, height, xPos + xDiff, height); 
      xPos += xDiff; 
      path.curveTo(xPos + xDiff, height, xPos, 0, xPos + xDiff, 0); 
      xPos += xDiff; 
      path.curveTo(xPos + xDiff, 0, xPos, height, xPos + xDiff, height); 
      xPos += xDiff; 
      path.curveTo(xPos + xDiff, height, xPos, 0, xPos + xDiff, 0); 
      g2d.draw(path); 
     } 

    } 

}