问题描述
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.ArrayList;
@SuppressWarnings("serial")
public class GUI extends JFrame implements ActionListener, MouseListener {
private boolean drawLine = false;
private boolean drawRec = false;
private boolean drawOval = false;
private final JButton line;
private final JButton oval;
private final JButton rectangle;
private final JPanel buttonPanel;
public DrawStuff drawPanel = new DrawStuff();
public int x1;
public int x2;
public int y1;
public int y2;
public int click;
public GUI() {
super("Graphics IO");
this.click = 1;
setSize(600, 600);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(1, 3));
line = new JButton("Line");
line.addActionListener(this);
buttonPanel.add(line);
oval = new JButton("Oval");
oval.addActionListener(this);
buttonPanel.add(oval);
rectangle = new JButton("Rectangle");
rectangle.addActionListener(this);
buttonPanel.add(rectangle);
Container contentPane = this.getContentPane();
contentPane.add(buttonPanel, BorderLayout.SOUTH);
//add(drawPanel);
addMouseListener((MouseListener) this);
setVisible(true);
}
@Override
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
if (source == line) {
drawLine = true;
repaint();
} else if (source == oval) {
drawOval = true;
repaint();
} else if (source == rectangle) {
drawRec = true;
repaint();
}
}
public static void main(String[] args) {
GUI guiIO = new GUI();
}
class DrawStuff extends JPanel {
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
this.setBackground(Color.BLUE);
ArrayList<Shape> shapes = new ArrayList<>();
if (drawLine) {
drawLine = false;
} else if (drawOval) {
//no clue how to add an oval
drawOval = false;
} else if (drawRec) {
Rectangle rec = new Rectangle(x1, y1,Math.abs(x2-x1) , Math.abs(y2-y1));
shapes.add(rec);
drawRec = false;
}
Graphics2D j = (Graphics2D)g;
shapes.stream().map((s) -> {
((Graphics2D) j).draw((Shape) s);
return s;
}).forEach((_item) -> {
repaint();
});
}
}
@Override
public void mousePressed(MouseEvent me) {
if (click == 1){
x1 = me.getX();
y1 = me.getY();
System.out.println(x1);
System.out.println(y1);
click = 2;
}else if (click == 2) {
x2 = me.getX();
y2 = me.getY();
System.out.println(x2);
System.out.println(y2);
click = 1;
}
}
@Override
public void mouseReleased(MouseEvent e) {
}
@Override
public void mouseEntered(MouseEvent e) {
}
@Override
public void mouseExited(MouseEvent e) {
}
@Override
public void mouseClicked(MouseEvent e) {
}
}
好了，所以我必须做出一个程序来创建使用两个鼠标点击的形状，然后可以导出/导入。我试图使用ArrayList这个即时通讯，但有一个困难时期设法得到它的工作。矩形的IM创造不会在面板上显示出来。我究竟做错了什么？请帮我。
Okay so i have to make a program to create shapes using two mouseclicks and then be able to export/import them. I am trying to use arraylist for this but im having a hard time trying to get it to work. The rectangle im creating will not show up on the panel. What am i doing wrong? Please help me.
推荐答案
让我们开始，能够画的事实，即 DrawStuff 实际上并没有被添加到任何东西吧。
Lets start with the fact that DrawStuff hasn't actually been added to anything that is capable of painting it.
DrawStuff＃的paintComponent 应有关更新形状 列表的状态来做出决定，相反，你的的ActionListener 和的MouseListener 应作出这些决定（添加什么，在那里，什么都修改），在 DrawStuff 面板应该只画什么的在图形列表
DrawStuff#paintComponent should be making decisions about updating the state of the shapes List, instead, your ActionListener and MouseListener should be making these decisions (what to add, where and what do modify), the DrawStuff panel should just be painting what's in the Shape list
您也不应该从内部的paintComponent 呼叫之类的东西的setBackground 可以修改组件的状态成立了反复重画请求这可能削弱你的应用程序，如果不是你的电脑
You also shouldn't be modifying the state of the component from within the paintComponent calling things like setBackground could set up a repeated repaint request which could cripple your application if not your PC
修改 DrawStuff 所以它有它自己的的MouseListener ，并且让你的 GUI 问它来创建新的形状。让形状 列表一个实例字段，以便您可以从内部 DrawStuff 更容易
Modify DrawStuff so it has it's own MouseListener and methods that allow your GUI to ask it to create new shapes. Make the shapes List a instance field so you can manage from within DrawStuff more easily
喜欢的东西...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class GUI extends JFrame implements ActionListener {
private boolean drawLine = false;
private boolean drawRec = false;
private boolean drawOval = false;
private final JButton line;
private final JButton oval;
private final JButton rectangle;
private final JPanel buttonPanel;
public DrawStuff drawPanel = new DrawStuff();
public int x1;
public int x2;
public int y1;
public int y2;
public int click;
public GUI() {
super("Graphics IO");
this.click = 1;
setSize(600, 600);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(1, 3));
line = new JButton("Line");
line.addActionListener(this);
buttonPanel.add(line);
oval = new JButton("Oval");
oval.addActionListener(this);
buttonPanel.add(oval);
rectangle = new JButton("Rectangle");
rectangle.addActionListener(this);
buttonPanel.add(rectangle);
Container contentPane = this.getContentPane();
contentPane.add(buttonPanel, BorderLayout.SOUTH);
add(drawPanel);
setVisible(true);
}
@Override
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
if (source == line) {
drawPanel.setDrawShape(DrawStuff.DrawShape.LINE);
} else if (source == oval) {
drawPanel.setDrawShape(DrawStuff.DrawShape.OVAL);
} else if (source == rectangle) {
drawPanel.setDrawShape(DrawStuff.DrawShape.RECTANGLE);
}
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
GUI guiIO = new GUI();
}
});
}
public static class DrawStuff extends JPanel {
public enum DrawShape {
LINE, OVAL, RECTANGLE;
}
private ArrayList<Shape> shapes = new ArrayList<>();
private DrawShape drawShape = DrawShape.LINE;
private Shape currentShape;
public DrawStuff() {
setBackground(Color.BLUE);
MouseAdapter ma = new MouseAdapter() {
private Point clickPoint;
@Override
public void mousePressed(MouseEvent e) {
clickPoint = e.getPoint();
currentShape = null;
}
@Override
public void mouseReleased(MouseEvent e) {
if (currentShape != null) {
shapes.add(currentShape);
currentShape = null;
repaint();
}
}
@Override
public void mouseDragged(MouseEvent e) {
Point p = e.getPoint();
switch (getDrawShape()) {
case LINE:
currentShape = new Line2D.Double(clickPoint, e.getPoint());
break;
case OVAL:
case RECTANGLE:
int x = clickPoint.x;
int y = clickPoint.y;
int width = p.x - clickPoint.x;
int height = p.y - clickPoint.y;
if (width < 0) {
x = p.x;
width *= -1;
}
if (height < 0) {
y = p.y;
height *= -1;
}
switch (getDrawShape()) {
case OVAL:
currentShape = new Ellipse2D.Double(x, y, width, height);
break;
case RECTANGLE:
currentShape = new Rectangle2D.Double(x, y, width, height);
break;
}
break;
}
repaint();
}
};
addMouseListener(ma);
addMouseMotionListener(ma);
}
public DrawShape getDrawShape() {
return drawShape;
}
public void setDrawShape(DrawShape drawShape) {
this.drawShape = drawShape;
currentShape = null;
repaint();
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.BLACK);
for (Shape shape : shapes) {
g2d.draw(shape);
}
if (currentShape != null) {
g2d.setColor(Color.RED);
g2d.draw(currentShape);
}
}
}
}
例如。你总是需要问自己谁是负责做什么。在这种情况下， DrawStuff 面板是决定，其中东西绘制实际负责，但它需要约是什么，然后根据这些信息就可以执行更多信息实际操作
For example. You always need to be asking yourself "who is responsible for doing what". In this case the DrawStuff panel is actually responsible for determine "where" something is drawn, but it needs more information about "what", then based on that information it can perform the actual operation
这篇关于我添加了一个矩形形状的ArrayList但是外形不会在面板上显示出来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！