在对象之间切换时如何摆脱矩形内的圆圈 [英] How to get rid of circle inside rectangle when switching between objects
问题描述
我有一个组合框，我可以在其中选择绘制矩形、圆形或徒手绘制.如果我选择绘制一个圆圈，它会完美地绘制它.如果我然后切换到绘制一个矩形，它会在矩形内绘制一个圆.如果我先选择绘制一个矩形，然后再绘制一个圆形，也会发生同样的情况.(见下图)
I have a combobox in which I can choose to draw either a rectangle, a circle or by freehand. If I choose to draw a circle it draws it perfectly. If I then switch to draw a rectangle it draws a circle inside the rectangle. The same happens if I first choose to draw a rectangle and then a circle. (See Picture below)
我的问题是:
如何在绘制圆和矩形之间切换，而圆不会出现在矩形内?
How can I switch between drawing a circle and a rectangle without the circle appearing inside the rectangle?
如何在拖动鼠标时显示矩形/圆形.我的意思是，在我松开鼠标单击之前，线条如何显示?
How can I get the rectangle/circle to show while I'm dragging the mouse. What I mean is how can the lines show until I release the mouse click?
为什么不能徒手画画?
这是我的测试类:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class Lab6 extends JFrame implements ActionListener {
int startX, startY, endX, endY, w, h;
ArrayList<Shape> shapeList = new ArrayList<Shape>();
Container cp = getContentPane();
private JPanel topPanel;
private JComboBox comboBox;
private final String[] boxOptions = new String[] {"Rektangel", "Cirkel", "Frihand"};
public Lab6(String title) {
super(title);
this.setLayout(new BorderLayout());
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
this.setSize(840, 500);
this.initComponents();
this.setVisible(true);
}
private void initComponents() {
topPanel = new JPanel(new GridLayout(1,2));
topPanel.setPreferredSize(new Dimension(0,40));
comboBox = new JComboBox(boxOptions);
comboBox.setSelectedIndex(0);
comboBox.addActionListener(this);
topPanel.add(comboBox);
this.add(topPanel, BorderLayout.PAGE_START);
}
@Override
public void paint(Graphics g) {
for (Shape s : shapeList) {
s.draw(g);
}
}
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource().equals(comboBox)) {
JComboBox cb = (JComboBox)e.getSource();
if (cb.getSelectedItem().equals("Rektangel")) {
cp.addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
startX = e.getX();
startY = e.getY();
}
@Override
public void mouseReleased(MouseEvent e) {
endX = e.getX();
endY = e.getY();
int width = startX - endX;
int height = startY - endY;
w = Math.abs(width);
h = Math.abs(height);
Rectangle r = new Rectangle(startX, startY, w, h);
shapeList.add(r);
repaint();
}
});
}
else if (cb.getSelectedItem().equals("Cirkel")) {
cp.addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
startX = e.getX();
startY = e.getY();
}
@Override
public void mouseReleased(MouseEvent e) {
endX = e.getX();
endY = e.getY();
int width = startX - endX;
int height = startY - endY;
w = Math.abs(width);
h = Math.abs(height);
Circle c = new Circle(startX, startY, w, h);
shapeList.add(c);
repaint();
}
});
}
else if (cb.getSelectedItem().equals("Frihand")) { //I need help with this part
cp.addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
startX = e.getX();
startY = e.getY();
}
@Override
public void mouseDragged(MouseEvent e) {
FreeHand fh = new FreeHand(startX, startY, e.getX(), e.getY());
shapeList.add(fh);
repaint();
}
});
}
}
}
public static void main(String args[]) {
new Lab6("Drawing Program");
}
}
在 Rectangle 类中(Circle 类看起来一样):
In class Rectangle (class Circle looks the same):
import java.awt.*;
public class Rectangle extends Shape {
public Rectangle(int x, int y, int width, int height) {
super(x, y, width, height);
}
public Rectangle() {
super();
}
@Override
public void draw(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.RED);
g2.setStroke(new BasicStroke(4));
g.drawRect(getX(), getY(), getWidth(), getHeight());
}
}
在 FreeHand 课上(我需要这部分的帮助):
In class FreeHand (I need help with this part):
import java.awt.*;
public class FreeHand extends Shape {
public FreeHand(int x, int y, int width, int height) {
super(x, y, width, height);
}
public FreeHand() {
super();
}
@Override
public void draw(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.BLUE);
g2.setStroke(new BasicStroke(4));
g2.drawLine(getX(), getY(), getWidth(), getHeight());
}
}
在课堂上:
import java.awt.Graphics;
import javax.swing.JPanel;
public abstract class Shape extends JPanel {
private int startX, startY, width, height;
public Shape() {
this(0, 0, 1, 1);
}
public Shape(int startX, int startY, int width, int height) {
this.startX = startX;
this.startY = startY;
this.width = width;
this.height = height;
}
public abstract void draw(Graphics g);
@Override
public int getX() {
return startX;
}
@Override
public int getY() {
return startY;
}
@Override
public int getWidth() {
return width;
}
@Override
public int getHeight() {
return height;
}
}
推荐答案
有很多事情正在发生...
There are a multitude of things going on...
- 覆盖
JFrame的 - 在执行自定义绘画之前不调用
super.paint. - 每次更改形状时都添加一个新的
MosueListener
paint相反，创建一个自定义组件，从类似 JPanel 的东西扩展并覆盖它的 paintComponent 方法.使用此组件具有您的基本绘图表面(您的控件应包含在另一个组件中).
Instead, create a custom component, extending from something like JPanel and override it's paintComponent method. Use this component has your basic drawing surface (your controls should contained in another component).
确保在执行任何自定义绘制之前调用 super.paintComponent 以免中断绘制链
Make sure you call super.paintComponent before performing any custom painting so you don't break the paint chain
请参阅执行自定义绘画和在 AWT 和 Swing 中绘画 了解更多详情
See Performing Custom Painting and Painting in AWT and Swing for more details
创建一个 SINGLE MouseListener 并将其注册到面板.当用户选择不同的形状时，更改面板内的状态变量(通过设置器)，它告诉 MouseListener 当用户开始绘图时它应该做什么.
Create a SINGLE MouseListener and register it to the panel. When the use selects a different shape, change a state variable within the panel (via a setter) which tells the MouseListener what it should do when the user starts drawing.
更新...
创建一个继承自 JPanel...
Create a custom class that extends from JPanel...
public static class ShapePane extends JPanel {
}
覆盖类 paintComponent 方法...
public static class ShapePane extends JPanel {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Custom Painting here...
}
}
为布局管理器提供一些尺寸提示...
Provide some sizing hints for the layout manager...
public static class ShapePane extends JPanel {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Custom Painting here...
}
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
提供一种可以改变形状类型的方法......这样你就知道要画什么......
Provide a means by which the type of shape can be changed...so you know what to paint...
public static class ShapePane extends JPanel {
public enum ShapeType {
CIRCLE,
RECTANGLE
}
private ShapeType currentShapeType;
public void setCurrentShapeType(ShapeType currentShapeType) {
this.currentShapeType = currentShapeType;
}
public ShapeType getCurrentShapeType() {
return currentShapeType;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Custom Painting here...
}
}
向自定义类添加单个 MouseListener 以创建所需类型的形状...
Add a SINGLE MouseListener to the custom class to create the required type of shapes...
public static class ShapePane extends JPanel {
public enum ShapeType {
CIRCLE,
RECTANGLE
}
private ShapeType currentShapeType;
public ShapePane() {
addMouseListener(new MouseAdapter() {
private Point clickPoint;
@Override
public void mousePressed(MouseEvent e) {
clickPoint = e.getPoint();
}
@Override
public void mouseReleased(MouseEvent e) {
Point releasePoint = e.getPoint();
int x = Math.min(releasePoint.x, clickPoint.x);
int y = Math.min(releasePoint.y, clickPoint.y);
int width = Math.abs(clickPoint.x - releasePoint.x);
int height = Math.abs(clickPoint.y - releasePoint.y);
switch (getCurrentShapeType()) {
case CIRCLE:
// Make a circle
break;
case RECTANGLE:
// Make a rectangle...
break;
}
repaint();
}
});
}
public void setCurrentShapeType(ShapeType currentShapeType) {
this.currentShapeType = currentShapeType;
}
public ShapeType getCurrentShapeType() {
return currentShapeType;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Custom Painting here...
}
}
填空...
创建另一个JPanel(这次你可以简单地创建一个实例)，将你的控件添加到其中
Create another JPanel (you can simply create an instance this time), add your controls to it
创建一个 JFrame 的实例，向其中添加自定义类和控件面板(确保它们布局正确，以免相互覆盖 - 请参阅 在容器内布置组件 了解更多详情)
Create an instance of a JFrame, add the custom class to it and the controls panel (make sure they are laid out correctly so they don't override each other - see Laying Out Components Within a Container for more details)
使用适当的控件侦听器来确定用户想要绘制的形状类型并相应地设置 currentShapeType 属性...
Use appropriate listeners to the controls to determine the type of shape the user wants to draw and set the currentShapeType property accordingly...
这篇关于在对象之间切换时如何摆脱矩形内的圆圈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IT屋！
