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。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，忽略那些）

这是 Jframe class:

(在此class绘制黑白图必须指定路径)

`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);
    }

}
`

这里是 Starthere class（class 包含主要方法）：

    package Code;

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

}

这是存储所有地图数据的地图class：

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地图的地图加载器 class：

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，这困扰了我好几天，我没有主意。

这里还有一个我一直在使用的示例文件： Example File

Answer 1

您的绘制方法有效，但没有人可以看到 PaintSurface 对象。你有：

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

您正在将 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。

解决方法：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。

此外，根据我的评论：

始终覆盖 paintComponent，而不是绘制。任何体面的图形教程都会告诉你这一点。
总是调用 super 的绘画方法，super.paintComponent(...) 如果您要覆盖它，请在您的覆盖范围内。
以这样的方式创建您的代码，以便每个 class 都可以独立测试和调试，使用小型模拟 classes 来帮助您做到这一点。
这样如果您运行遇到错误，您可以创建并 post 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 class 和接口名称应以大写字母开头。

为什么我的 Paint surface 方法不起作用？

Why is my Paint surface method not working?

java

swing

paint