java中使用Graphics绘制线条

发布于 2024-12-12 04:55:37 字数 597 浏览 1 评论 0原文

下面是一个在两个点中绘制 1 条线的方法的示例

public void paintComponent(Graphics comp) {
   Graphics2D comp2D = (Graphics2D)comp; 
   comp2D.drawLine(0,60,100,60);
 }

我试图为这些点传递一个构造函数，但是当我在 main 中运行它时，我无法确定当我调用 PaintComponent 时应该为 comp 传递什么

public class DrawLines{
      public void paintComponent(Graphics comp,int x0, int y0, int x1, int y1) {
           Graphics2D comp2D = (Graphics2D)comp; 
           comp2D.drawLine(x0,y0,x1,y1);
      }

     public static void main(String[]args){
          drawLine(?,100,200,200,300);
     }
}

值我通过在？

原文

Heres an example of a method to draw 1 line passing in two points

public void paintComponent(Graphics comp) {
   Graphics2D comp2D = (Graphics2D)comp; 
   comp2D.drawLine(0,60,100,60);
 }

Im trying to pass in a constructor for the points but when I go to run it in main I cannot figure what value I should pass in for comp when I call paintComponent

public class DrawLines{
      public void paintComponent(Graphics comp,int x0, int y0, int x1, int y1) {
           Graphics2D comp2D = (Graphics2D)comp; 
           comp2D.drawLine(x0,y0,x1,y1);
      }

     public static void main(String[]args){
          drawLine(?,100,200,200,300);
     }
}

What should I pass in at the ?

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作业与我同在 2024-12-19 04:55:37

您需要一个 Graphics（使用 Swing 时通常是一个 Graphics2D 实例）对象，它为您提供了一些实际绘制的上下文。看看你的主类...你想画一条线，但是你必须在什么上画呢？不会神奇地弹出一些窗口或画布供您绘画，您需要设置这些东西。

我建议查看 Java Swing 教程。也就是说，如果您已经相当精通 Java。如果没有，请确保您的 Java 知识首先达到了适当的水平。

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等往事风中吹 2024-12-19 04:55:37

您需要为您的类提供两个 Point 字段，或者四个 int 字段，x1、y1、x2、y2，传递用于在构造函数中初始化这些字段的值，然后最重要的是，使用该值绘图时保留在这些字段中。

例如，

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

public class LinePanel extends JPanel {
   private Point p1; // java.awt.Point objects
   private Point p2;

   // TODO: create constructor that accepts
   // and updates the two points

   public void paintComponent(Graphics g) {

      super.paintComponent(g); // don't forget this!

      // TODO: Change the method below so that it uses
      // the two points to do the drawing with
      // rather than use hard coded magic numbers.
      g.drawLine(0, 0, 90, 90);
   }

   @Override
   public Dimension getPreferredSize() {
      return new Dimension(500, 500);
   }

   public static void main(String args[]) {
      JFrame jf = new JFrame();
      jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      jf.add(new LinePanel()); // TODO: add parameters to constructor call.
      // jf.setSize(500, 500);
      jf.pack();
      jf.setVisible(true);
   }
}

You'll want to give your class two Point fields, either that or four int fields, x1, y1, x2, y2, pass the values used to initialize these fields in your constructor, and then most important, use the value held in these fields when doing your drawing.

e.g.,

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

public class LinePanel extends JPanel {
   private Point p1; // java.awt.Point objects
   private Point p2;

   // TODO: create constructor that accepts
   // and updates the two points

   public void paintComponent(Graphics g) {

      super.paintComponent(g); // don't forget this!

      // TODO: Change the method below so that it uses
      // the two points to do the drawing with
      // rather than use hard coded magic numbers.
      g.drawLine(0, 0, 90, 90);
   }

   @Override
   public Dimension getPreferredSize() {
      return new Dimension(500, 500);
   }

   public static void main(String args[]) {
      JFrame jf = new JFrame();
      jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      jf.add(new LinePanel()); // TODO: add parameters to constructor call.
      // jf.setSize(500, 500);
      jf.pack();
      jf.setVisible(true);
   }
}

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