java - 为什么我的 Paint surface 方法不起作用？

Question

所以有一段时间重写 JComponent 的 paint 方法给我带来了麻烦，我永远无法弄清楚为什么。我正在进行一个项目，该项目将拍摄一张黑白图像并将其绘制在屏幕上，其中图片中的每个像素都是屏幕上的 50 x 50 框，显然有些绘画将在屏幕外完成，但这没关系，因为这将是一款带有移动屏幕的 2D 自上而下游戏。无论我尝试过什么，当它运行时它永远不会在屏幕上绘制任何东西并且它与我的 1:50 逻辑无关，因为当我试图让它绘制一个简单的矩形时，它甚至没有绘制那个。所以问题一定出在 paint 方法上，但我不知道出了什么问题。我知道这是很多代码，但有人可以让我知道哪里出了问题吗？(我知道还有很多方法没用，先忽略那些)

这是 Jframe 类:

(必须在该类中指定绘制黑白图的路径)

`package Code;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

//class that stores all of the painting methods and the GUI methods:
public class Window extends JFrame{

    double WINDOWWIDTH, WINDOWHEIGHT;
    JPanel TitlePanel;
    JButton PlayGame, Quit;
    JLabel Title;
    Map DigitizedMap;
    PaintSurface PS;

    int x = 0;
    int y = 0;
    int TilesAcross;
    int TilesDown;

    public Window(){

        WINDOWWIDTH = 1200;
        WINDOWHEIGHT = (Math.floor(WINDOWWIDTH / 50)*0.66) * 50;
        TilesAcross = (int) (WINDOWWIDTH / 50);
        TilesDown = (int) (WINDOWHEIGHT / 50);

        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setSize((int) WINDOWWIDTH, (int) WINDOWHEIGHT);
        this.setTitle("Stealth Client    ||    Version 1.0");

        //all of the code for the user interface will go here:
        //DrawStartInterface(this);

        //creating the digitized verion of the map for the paint method to use:
        MapLoader ML = new MapLoader("C:\\Users\\Greg\\Desktop\\TestMap.png");
        DigitizedMap = ML.ConvertMap();
        PS = new PaintSurface();
        TitlePanel = new JPanel();
        TitlePanel.add(PS, BorderLayout.CENTER);
        this.add(TitlePanel);

        this.setVisible(true);
        this.setResizable(false);
    }

    private void DrawStartInterface(JFrame f){
        //all of the starting UI:

        TitlePanel = new JPanel(new GridBagLayout());
        TitlePanel.setBackground(Color.DARK_GRAY);

        Title = new JLabel("STEALTH");
        Title.setForeground(Color.ORANGE);
        Title.setFont(new Font("Calabri", Font.BOLD, 48));
        addItem(TitlePanel, Title, 0, 0, 1, 1, 1);

        PlayGame = new JButton("Play");
        PlayGame.setBackground(Color.BLACK);
        PlayGame.setForeground(Color.ORANGE);
        PlayGame.setFont(new Font("Calabri", Font.BOLD, 36));
        PlayGame.addActionListener(new ActionEvent());
        addItem(TitlePanel, PlayGame, 0, 1, 1, 1, 1);

        Quit = new JButton("Quit");
        Quit.setBackground(Color.BLACK);
        Quit.setForeground(Color.ORANGE);
        Quit.setFont(new Font("Calabri", Font.BOLD, 36));
        Quit.addActionListener(new ActionEvent());
        addItem(TitlePanel, Quit, 0, 2, 1, 1, 1);

        f.add(TitlePanel);
    }

    private class ActionEvent implements ActionListener{
        @Override
        public void actionPerformed(java.awt.event.ActionEvent e) {
            //which action has been heard:
            if(e.getSource() == PlayGame){
                //plays the game:
                StartGame();
            } else if(e.getSource() == Quit){
                //Quits the game:
                Terminate();
            }
        }

    }

    public void Terminate(){
        //exits the game:

        System.exit(0);
    }

    //Starts the game:
    private void StartGame(){
        TitlePanel.add(PS);
    }

    //The paint Surface class that will be stored in the panel and paint the game:
    class PaintSurface extends JComponent{
        @Override
        public void paint (Graphics g){
            //basic graphics shizel wizel:
            Graphics2D g2 = (Graphics2D) g;
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                    RenderingHints.VALUE_ANTIALIAS_ON);
            g2.drawRect(100, 100, 100, 100);
            render(g2);
            System.out.println("Painted");
        }

        private void render(Graphics2D g2){
            //renders only the squares within a certain distance of the center of the screen:
            int PlayerTileX = (int) Math.ceil((x + (WINDOWWIDTH / 2))/50);      // This is the x tile that the player is in
            int PlayerTileY = (int) Math.ceil((y + (WINDOWHEIGHT / 2))/50);     // this is the y tile that the player is in
            //now we are going through only the tiles around the player and rendering them:
            int XOffset = x - (int) (PlayerTileX - (Math.ceil(TilesAcross / 2)));
            int YOffset = y - (int) (PlayerTileY - (Math.ceil(TilesDown / 2)));
            for (int i = (int) (PlayerTileX - (Math.ceil(TilesAcross / 2))); i < (int) (PlayerTileX + (Math.ceil(TilesAcross / 2))); i++){
                for (int n = (int) (PlayerTileY - (Math.ceil(TilesDown / 2))); n < (int) (PlayerTileY + (Math.ceil(TilesDown / 2))); n++){
                    //this is where only the coorect boxes will be rendered because of the limiting for loops:
                    //The if statement for determining what type of thing it is:
                    if (DigitizedMap.getTile(i, n) == 1){
                        //Rendering the walls:
                        g2.drawRect((int)(((i * 50) % WINDOWWIDTH) - XOffset), (int)(((i * 50) % WINDOWHEIGHT) - YOffset), 50, 50);
                    }
                }
            }
        }
    }

    //used to add things to panels:
    public void addItem(JPanel p, JComponent c, int x, int y, int width, int height,
            int align /* Defines the spot on the coordinate */) {
        GridBagConstraints gc = new GridBagConstraints();
        gc.gridx = x;
        gc.gridy = y;
        gc.gridwidth = width;
        gc.gridheight = height;
        gc.insets = new Insets(10, 10, 10, 10);

        switch (align) {
        case 1:
            gc.anchor = GridBagConstraints.NORTH;
            break;
        case 2:
            gc.anchor = GridBagConstraints.EAST;
            break;
        case 3:
            gc.anchor = GridBagConstraints.SOUTH;
            break;
        case 4:
            gc.anchor = GridBagConstraints.WEST;
            break;
        case 5:
            gc.anchor = GridBagConstraints.CENTER;
            break;
        }
        p.add(c, gc);
    }

}
`

这是 Starthere 类(包含主要方法的类):

    package Code;

public class StartHere {
    public static void main(String[] args) {
        //Creating the frame:
        final Window Frame = new Window();
    }

}

这是存储所有 map 数据的 map 类:

package Code;

public class Map {

    //the Array for all of the codes:
    double Tiles[][];
    int width;
    int height;

    //setters and getters for the width and height:
    public int getWidth() {
        return width;
    }

    public void setWidth(int width) {
        this.width = width;
    }

    public int getHeight() {
        return height;
    }

    public void setHeight(int height) {
        this.height = height;
    }


    //the constructor for the double map:
    public Map(long Width, long Height){
        Tiles = new double[(int) Width][(int) Height];
    }

    //this is where the double array is going to be set:
    public void setTile(int x, int y, double type){
        Tiles[x][y] = type;
    }

    //this gets the given tile code:
    public double getTile(int x, int y){
        return Tiles[x][y];
    }

}

最后，这是负责从图像文件加载 map 的 map 加载器类:

package Code;

import java.awt.Color;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.ImageObserver;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

public class MapLoader {

    BufferedImage MapImage;

    public MapLoader(String MapPath){
        //loading the map image from the specified map path:
        try {
            MapImage = ImageIO.read(new File(MapPath));
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public Map ConvertMap(){
        Map m = new Map(MapImage.getWidth(), MapImage.getHeight());

        //now to read the individual pixels of the image and determine the code for the map object:
        for(int i = 0; i < MapImage.getWidth(); i++){
            for(int n = 0; n < MapImage.getHeight(); n++){
                if (MapImage.getRGB(i, n) == Color.BLACK.getRGB()){
                    //Black = Wall = 1
                    m.setTile(i, n, 1);
                    System.out.print("1");
                } else {
                    //else it is nothing so White = Space = 0
                    m.setTile(i, n, 0);
                    System.out.print("0");
                }
            }
            System.out.println("");
        }

        return m;
    }

}

非常感谢任何帮助我的人，这已经困扰我好几天了，我没有想法。

这里还有一个我一直在使用的示例文件: Example File

Answer 1

您的绘画方法有效，但没有人能看到 PaintSurface 对象。你有:

  PS = new PaintSurface();
  TitlePanel = new JPanel();
  TitlePanel.add(PS, BorderLayout.CENTER);

您将 PS 对象添加到 BorderLayout.CENTER 位置，但 TitlePanel 不使用 BorderLayout —— 它使用默认的 FlowLayout。现在 PaintSurface 的首选大小为 0,0，并且由于 TitlePanel 使用 FlowLayout，PS 将非常小。

解决方案:将TitlePanel的布局设置为BorderLayout。

  PS = new PaintSurface();
  TitlePanel = new JPanel(new BorderLayout());
  TitlePanel.add(PS, BorderLayout.CENTER);

这将使 PaintSurface 实例填充 TitlePanel。

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此外，根据我的评论:

• 始终覆盖 paintComponent，而不是 paint。任何体面的图形教程都会告诉你这一点。
• 如果您要覆盖它，请始终在您的覆盖范围内调用 super 的绘画方法 super.paintComponent(...)。
• 以这样的方式创建您的代码，以便每个类都可以独立测试和调试，使用小型模拟类来帮助您做到这一点。
• 这样，如果您遇到错误，您可以创建并发布您的最小、完整和可验证的示例，供我们测试，而不是要求我们检查整个大型程序。
• 请注意，您永远不会调用 DrawStartInterface(...)
• 请学习并遵循 Java 命名约定，因为这样做将有助于其他人更好地理解您的代码。字段和方法名称应全部以小写字母开头，而类和接口(interface)名称应以大写字母开头。