从绘图对象中清除窗口 [英] Clear window from drawing objects
问题描述
我有4个类：
Draw，Rectangle（extends Draw），FreeHand（extends Draw）和测试类。
Draw, Rectangle (extends Draw), FreeHand (extends Draw) and a test class.
我将自由手绘制的矩形和线条添加到arrayList中。
I add rectangles and lines drawn by free hand to an arrayList.
我有一个带有选项Back和Clear的菜单栏。返回删除最后绘制的对象。它是通过删除arraylist中的最后一个对象来完成的。清除窗户。这是通过清除所有项目中的arraylist来完成的。
I have a menubar with choices Back and Clear. Back removes the last drawn object. It is done by removing the last object in the arraylist. Clear clears the windows. It is done by clear the arraylist from all items.
现在我的问题：窗口不清除。我不知道如何编写代码使其重新正确重绘，以便从窗口中删除项目。
你能帮我解释一下这个代码的样子，以及我把它放在哪里。我很感激，谢谢。
Now to my problem: The window does not clear. I don't know how to write the code to make it repaint properly so that the items removes from the window. Can you please help me with how the code for this would look like, and where I put it. I appreciate it, thank you.
我的问题没有2：
我删除了arraylist中的最后一项后我需要绘制arrayList中的所有项。我已经尝试了
My problem no 2: After I have removed the last item in the arraylist I need to draw all the items in the arrayList. I have tried
for (Draw d : shapeList) {
d.draw(g2);
}
但它不起作用。有什么建议？
类别抽奖：
But it does not work. Any suggestions? Class Draw:
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;
public abstract class Draw extends JPanel {
public int startX, startY, endX, endY, width, height, w, h;
public String color = "Black";
public Draw(int startX, int startY, int width, int height) {
this.startX = startX;
this.startY = startY;
this.width = width;
this.height = height;
}
public abstract void draw(Graphics2D g);
@Override
public int getX() {
return startX;
}
public void setX(int startX) {
this.startX = startX;
}
@Override
public int getY() {
return startY;
}
public void setY(int startY) {
this.startY = startY;
}
@Override
public int getWidth() {
return width;
}
public void setWidth(int width) {
this.width = width;
}
@Override
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
public void setColor(String color) {
this.color = color;
}
}
类矩形：
import java.awt.Color;
import java.awt.Graphics2D;
public class Rectangle extends Draw {
public Rectangle(int x, int y, int width, int height) {
super(x, y, width, height);
}
@Override
public void draw(Graphics2D g2) {
switch (color) {
case "Red":
g2.setColor(Color.RED);
break;
case "Green":
g2.setColor(Color.GREEN);
break;
case "Blue":
g2.setColor(Color.BLUE);
break;
case "Yellow":
g2.setColor(Color.YELLOW);
break;
case "Orange":
g2.setColor(Color.ORANGE);
break;
case "Black":
g2.setColor(Color.BLACK);
break;
}
g2.drawRect(getX(), getY(), getWidth(), getHeight());
}
}
Class FreeHand：
Class FreeHand:
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics2D;
public class FreeHand extends Draw {
public FreeHand(int x, int y, int width, int height) {
super(x, y, width, height);
}
/* public FreeHand() {
super();
}*/
@Override
public void draw(Graphics2D g2) {
//Graphics2D g2 = (Graphics2D) g;
g2.setStroke(new BasicStroke(3));
switch (color) {
case "Red":
g2.setColor(Color.RED);
break;
case "Green":
g2.setColor(Color.GREEN);
break;
case "Blue":
g2.setColor(Color.BLUE);
break;
case "Yellow":
g2.setColor(Color.YELLOW);
break;
case "Orange":
g2.setColor(Color.ORANGE);
break;
case "Black":
g2.setColor(Color.BLACK);
break;
}
g2.drawLine(getX(), getY(), getWidth(), getHeight());
}
}
测试类：
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
public class JavaApplication30 extends JFrame implements ActionListener {
public ArrayList<Draw> shapeList = new ArrayList<>();
int startX, startY, endX, endY, w, h;
private JPanel topPanel;
private JPanel bottomPanel;
private JPanel orangePanel;
private JPanel greenPanel;
private JPanel bluePanel;
private JPanel blackPanel;
private JPanel redPanel;
private JPanel yellowPanel;
private JPanel leftPanel;
private JPanel rightPanel;
private JPanel colorPanel;
private JMenuBar menuBar;
private JMenu menu;
private JMenuItem menuItem1;
private JMenuItem menuItem2;
private JMenuItem menuItem3;
private JComboBox comboBox;
private JLabel leftLabel;
private JLabel commaLabel;
private JLabel colorLabel;
private static JLabel xLabel;
private static JLabel yLabel;
private final String labelText = "Coordinates: ";
private final String comma = ",";
private final String color = "Color: ";
private final String[] boxOptions = new String[] {"Rectangle", "Freehand"};
private String pickedColor = "Black";
private String x = "";
private String y = "";
Container cp = getContentPane();
private int count = 0;
public JavaApplication30(String title) {
super(title);
this.setLayout(new BorderLayout());
this.setLocationRelativeTo(null);
this.setSize(840, 500);
this.initComponents();
this.initMenu();
this.setVisible(true);
}
private void initComponents() {
cp.setBackground(Color.WHITE);
comboBox = new JComboBox(boxOptions);
topPanel = new JPanel(new GridLayout(1,7));
bottomPanel = new JPanel(new GridLayout(1,2));
orangePanel = new JPanel();
greenPanel = new JPanel();
bluePanel= new JPanel();
blackPanel = new JPanel();
redPanel = new JPanel();
yellowPanel = new JPanel();
colorPanel = new JPanel();
rightPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
leftPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
comboBox.setSelectedIndex(0);
comboBox.addActionListener(this);
topPanel.setPreferredSize(new Dimension(0,40));
bottomPanel.setPreferredSize(new Dimension(0,30));
colorPanel.setPreferredSize(new Dimension(60,20));
leftLabel = new JLabel(labelText);
commaLabel = new JLabel(comma);
colorLabel = new JLabel(color);
bottomPanel.setBackground(Color.LIGHT_GRAY);
orangePanel.setBackground(Color.ORANGE);
greenPanel.setBackground(Color.GREEN);
bluePanel.setBackground(Color.BLUE);
blackPanel.setBackground(Color.BLACK);
redPanel.setBackground(Color.RED);
yellowPanel.setBackground(Color.YELLOW);
colorPanel.setBackground(Color.BLACK);
topPanel.add(orangePanel);
topPanel.add(greenPanel);
topPanel.add(bluePanel);
topPanel.add(blackPanel);
topPanel.add(redPanel);
topPanel.add(yellowPanel);
topPanel.add(comboBox);
rightPanel.add(colorLabel);
rightPanel.add(colorPanel);
bottomPanel.add(leftPanel);
bottomPanel.add(rightPanel);
this.add(topPanel, BorderLayout.PAGE_START);
this.add(bottomPanel, BorderLayout.PAGE_END);
}
@Override
public void paint(Graphics g) {
if(count == 0) {
cp.repaint();
}
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setStroke(new BasicStroke(1));
for (Draw d : shapeList) {
d.draw(g2);
}
if (startX != 0 && startY != 0 && endX != 0 && endY != 0) {
int width = Math.abs(startX - endX);
int height = Math.abs(startY - endY);
int minX = Math.min(startX, endX);
int minY = Math.min(startY, endY);
Rectangle r = new Rectangle(minX, minY, width, height);
g2.setPaint(Color.WHITE);
g2.fillRect(r.getX(), r.getY(), r.getWidth(), r.getHeight());
r.setColor(pickedColor);
r.draw(g2);
}
}
@Override
public void actionPerformed(ActionEvent e) {
count++;
if (e.getSource().equals(menuItem1)) {
shapeList.clear();
//Code to clear window
}
if (e.getSource().equals(menuItem2)) {
shapeList.remove(shapeList.size() - 1);
//Code to clear window
Graphics g = getGraphics();
Graphics2D g2 = (Graphics2D) g;
for (Draw d : shapeList) {
d.draw(g2);
}
}
if (e.getSource().equals(menuItem3)) {
//Exit
}
if (e.getSource().equals(comboBox)) {
JComboBox cb = (JComboBox)e.getSource();
if (cb.getSelectedItem().equals("Rectangle")) {
this.addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
startX = e.getX();
startY = e.getY();
endX = startX;
endY = startY;
repaint();
}
@Override
public void mouseReleased(MouseEvent e) {
endX = e.getX();
endY = e.getY();
int width = Math.abs(startX - endX);
int height = Math.abs(startY - endY);
int minX = Math.min(startX, endX);
int minY = Math.min(startY, endY);
Rectangle r = new Rectangle(minX, minY, width, height);
shapeList.add(r);
r.setColor(pickedColor);
startX = 0;
startY = 0;
endX = 0;
endY = 0;
repaint();
}
});
this.addMouseMotionListener(new MouseMotionAdapter() {
@Override
public void mouseDragged(MouseEvent e) {
endX = e.getX();
endY = e.getY();
repaint();
}
});
}
else if (cb.getSelectedItem().equals("Freehand")) {
this.addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
startX = e.getX();
startY = e.getY();
}
});
this.addMouseMotionListener(new MouseMotionAdapter() {
@Override
public void mouseDragged(MouseEvent e) {
Graphics g = getGraphics();
Graphics2D g2 = (Graphics2D) g;
FreeHand fh = new FreeHand(startX, startY, e.getX(), e.getY());
shapeList.add(fh);
fh.setColor(pickedColor);
fh.draw(g2);
startX = e.getX();
startY = e.getY();
}
});
}
}
}
private void initMenu() {
menuBar = new JMenuBar();
menu = new JMenu("File");
menuBar.add(menu);
menuItem1 = new JMenuItem("Clear");
menuItem2 = new JMenuItem("Back");
menuItem3 = new JMenuItem("Exit");
menu.add(menuItem1);
menu.add(menuItem2);
menu.addSeparator();
menu.add(menuItem3);
menu.setMnemonic(KeyEvent.VK_A);
KeyStroke ks1 = KeyStroke.getKeyStroke(KeyEvent.VK_N, InputEvent.CTRL_MASK); //Crtl+n
KeyStroke ks2 = KeyStroke.getKeyStroke(KeyEvent.VK_I, InputEvent.CTRL_MASK); //Ctrl+i
KeyStroke ks3 = KeyStroke.getKeyStroke(KeyEvent.VK_A, InputEvent.CTRL_MASK); //Ctrl+e
menuItem1.setAccelerator(ks1);
menuItem2.setAccelerator(ks2);
menuItem3.setAccelerator(ks3);
menuItem1.addActionListener(this);
menuItem2.addActionListener(this);
menuItem3.addActionListener(this);
setJMenuBar(menuBar);
}
public static void main(String args[]) {
new JavaApplication30("Draw");
}
}
推荐答案
您的问题似乎是你的paint方法没有调用super的paint方法，因为这将使组件清除所有脏图像位。但话说回来，你不应该直接在JFrame中绘制。而是在JComponent或JPanel的paintComponent方法中绘制，并在该方法中确保调用super的paintComponent方法：
Your problem looks to be that your paint method is not calling the super's paint method since this will have the component clean itself of all "dirty" image bits. But having said that, you shouldn't draw directly in the JFrame. Instead draw in the paintComponent method of a JComponent or JPanel, and in that method be sure to call the super's paintComponent method:
public class MyDrawingPanel extends JPanel {
@Override
proteced void paintComponent(Graphics g) {
super.paintComponent(g); // don't forget this!
// do your drawing here
}
}
另外，为什么你的Draw类以及从它派生的所有类在没有被用作JPanel时扩展JPanel？你通过这种方式给这些课程带来了很多不必要的开销。
Also, why does your Draw class, and thus all classes that derive from it, extend JPanel when it is not being used as a JPanel? You are giving a lot of unnecessary overhead to these classes this way.
编辑
你问：
Edit
You ask:
所以你的意思是我应该将paint-method中的Everything移动到Draw中的paintComponent方法？为何受到保护？
So you mean I should move Everything in the paint-method to the paintComponent-method in Draw? Why protected?
否。我的意思是Draw不应该扩展JPanel，而应该是一个逻辑类，而不是一个Swing组件派生类。我认为你应该创建一个新类，比如名为MyDrawingPanel，你可以在其中完成所有绘图。请参阅上面的代码段。另外paintComponent在JComponent中声明是受保护的，而不是公共的，我认为在覆盖它时将其公开是没有优势的，所以我建议保护它。
No. I mean that Draw should not extend JPanel, but instead should be a logical class, not a Swing component-derived class. I think that you should create a new class, say called MyDrawingPanel where you do all of your drawing. Please see my code snippet above. Also paintComponent is declared in JComponent to be protected, not public, and I see no advantage to making it public when overriding it, so I recommend leaving it protected.
请阅读 Swing Info Links 查看Swing图形教程并给他们一个阅读。
Please read the Swing Info Links to see the Swing graphics tutorials and give them a read.
编辑2
您还使用 getGraphics（）调用组件来获取Graphics对象，这不好，因为这将返回一个不稳定的Graphics对象。而是在paintComponent方法中或在BufferedImage上绘制所有绘图（再次在paintComponent中绘制）。
Edit 2
You're also using a getGraphics() call on a component to get your Graphics object, not good as this will return an unstable Graphics object. Instead do all drawing in the paintComponent method or on a BufferedImage (that again is drawn in paintComponent).
编辑3
我的一些代码示例：
- < a href =https://stackoverflow.com/a/17383132/522444>制作可清洁绘图区域的最小方法
- 更改JPanel Graphics g颜色绘制线
- 重绘中的图形绘制随机行
- Minimal way to make a cleanable drawing area
- Changing JPanel Graphics g color drawing line
- Graphics in repaint draws random lines
这篇关于从绘图对象中清除窗口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！
