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问题描述

我正在开展一个项目,我正在尝试制作一个绘画程序。
到目前为止,我已经使用Netbeans创建了一个GUI并设置了程序。

I'm working on a project in which I am trying to make a paint program.So far I've used Netbeans to create a GUI and set up the program.

到目前为止,我可以调用所有必需的协调来在里面绘制,但我对如何在其中进行实际绘制非常困惑。

As of right now I am able to call all the coordinated necessary to draw inside it but I am very confused with how to actually paint inside it.

在我的代码结束时,我尝试在面板内绘图失败。

Towards the end of my code I have a failed attempt at drawing inside the panel.

任何人都可以在这样的例子中解释/展示如何使用图形吗?

Can anyone explain/show how to use graphics in a example like this?

我找到的所有例子都是使用 JPanel 来扩展它,但我不知道是否可以这样做,因为它是在netbeans中生成的。

All examples I have found make a class and extend it with JPanel but I don't know if I can do this since it was generated in netbeans.

我需要在 JFrame 中的 JPanel 中绘制。我不知道在哪里放图形类。

I need to draw inside a JPanel, inside my JFrame. I don't know where to put the graphics class.

package javapaint;

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

public class JavaPaintUI extends javax.swing.JFrame {

public JavaPaintUI() {
    initComponents();
}


private void initComponents() {


    jPanel2 = new javax.swing.JPanel();

    jPanel2.setBackground(new java.awt.Color(255, 255, 255));
    jPanel2.setBorder(javax.swing.BorderFactory.createBevelBorder(javax.swing.border.BevelBorder.RAISED));
    jPanel2.addMouseListener(new java.awt.event.MouseAdapter() {
        public void mousePressed(java.awt.event.MouseEvent evt) {
            jPanel2MousePressed(evt);
        }
        public void mouseReleased(java.awt.event.MouseEvent evt) {
            jPanel2MouseReleased(evt);
        }
    });
    jPanel2.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
        public void mouseDragged(java.awt.event.MouseEvent evt) {
            jPanel2MouseDragged(evt);
        }
    });
    pack();
}// </editor-fold>

int currentX, currentY, oldX, oldY;

private void jPanel2MouseDragged(java.awt.event.MouseEvent evt) {
    if (tool == 1) {
        currentX = evt.getX();
        currentY = evt.getY();
        oldX = currentX;
        oldY = currentY;
        System.out.println(currentX + " " + currentY);
        System.out.println("PEN!!!!");
    }

}

private void jPanel2MousePressed(java.awt.event.MouseEvent evt) {
    oldX = evt.getX();
    oldY = evt.getY();
    System.out.println(oldX + " " + oldY);
}


//mouse released//
private void jPanel2MouseReleased(java.awt.event.MouseEvent evt) {
    if (tool == 2) {
        currentX = evt.getX();
        currentY = evt.getY();
        System.out.println("line!!!! from" + oldX + "to" + currentX);
    }
}

//set ui visible//
public static void main(String args[]) {
    java.awt.EventQueue.invokeLater(new Runnable() {

        public void run() {
            new JavaPaintUI().setVisible(true);
        }
    });
}

// Variables declaration - do not modify
private javax.swing.JPanel jPanel2;
// End of variables declaration

class jPanel2 extends JPanel {

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        g.drawString("BLAH", 20, 20);
        g.drawRect(200, 200, 200, 200);
    }
}
}



截屏



整个事情是 JFrame ,中心的白色部分是 jPanel2 这是我想要绘制的内容。

Screen shot

The whole thing is a JFrame and the white section in the center is jPanel2 which is what I want to draw on.

推荐答案

请注意额外的评论。

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

class JavaPaintUI extends JFrame {

    private int tool = 1;
    int currentX, currentY, oldX, oldY;

    public JavaPaintUI() {
        initComponents();
    }

    private void initComponents() {
        // we want a custom Panel2, not a generic JPanel!
        jPanel2 = new Panel2();

        jPanel2.setBackground(new java.awt.Color(255, 255, 255));
        jPanel2.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));
        jPanel2.addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent evt) {
                jPanel2MousePressed(evt);
            }
            public void mouseReleased(MouseEvent evt) {
                jPanel2MouseReleased(evt);
            }
        });
        jPanel2.addMouseMotionListener(new MouseMotionAdapter() {
            public void mouseDragged(MouseEvent evt) {
                jPanel2MouseDragged(evt);
            }
        });

        // add the component to the frame to see it!
        this.setContentPane(jPanel2);
        // be nice to testers..
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
    }// </editor-fold>

    private void jPanel2MouseDragged(MouseEvent evt) {
        if (tool == 1) {
            currentX = evt.getX();
            currentY = evt.getY();
            oldX = currentX;
            oldY = currentY;
            System.out.println(currentX + " " + currentY);
            System.out.println("PEN!!!!");
        }
    }

    private void jPanel2MousePressed(MouseEvent evt) {
        oldX = evt.getX();
        oldY = evt.getY();
        System.out.println(oldX + " " + oldY);
    }


    //mouse released//
    private void jPanel2MouseReleased(MouseEvent evt) {
        if (tool == 2) {
            currentX = evt.getX();
            currentY = evt.getY();
            System.out.println("line!!!! from" + oldX + "to" + currentX);
        }
    }

    //set ui visible//
    public static void main(String args[]) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                new JavaPaintUI().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private JPanel jPanel2;
    // End of variables declaration

    // This class name is very confusing, since it is also used as the
    // name of an attribute!
    //class jPanel2 extends JPanel {
    class Panel2 extends JPanel {

        Panel2() {
            // set a preferred size for the custom panel.
            setPreferredSize(new Dimension(420,420));
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);

            g.drawString("BLAH", 20, 20);
            g.drawRect(200, 200, 200, 200);
        }
    }
}



屏幕截图



Screen Shot

HFOE将一个好的链接作为此线程的第一条评论。 Camickr还在文章。

HFOE put a good link as the first comment on this thread. Camickr also has a description of active painting vs. drawing to a BufferedImage in the Custom Painting Approaches article.

使用中绘制。

See also this approach using painting in a BufferedImage.

这篇关于如何在JPanel中绘图? (Swing /图形Java)的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

08-03 19:31