Java Graphics如何无缩放渲染图像？Windows高DPI适配问题

• 环境：4K分辨率显示器，Windows系统设置150%缩放
• 现有Java代码结构：

  Main类代码 #

  public static void main(String[] args) throws IOException {
          JFrame frame = new JFrame();
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
          frame.setPreferredSize(new Dimension(displayMode.getWidth(), displayMode.getHeight()));
          frame.setUndecorated(true);
          frame.add(new Background());
          frame.setLocationRelativeTo(null);
          frame.setVisible(true);
  }
  

  Background类代码 #

  public class Background extends JPanel implements ActionListener {
      public Background() throws IOException {
          backGround = ImageIO.read(getClass().getClassLoader().getResourceAsStream("background.jpg"));
          
          setBackground(Color.BLACK);
          addMouseListener(new MyMouseListener(this));
          addKeyListener(new MyKeyboardListener(this));
          setFocusable(true);
          requestFocusInWindow();
          setOpaque(true);
  }
  

  paintComponent多线程绘制逻辑 #

  @Override
      protected void paintComponent(Graphics g) {
  for (Map.Entry<String, Map<BaseShip, Integer>> player : playersShips.entrySet()) {
  
              Thread thread = new Thread(new Runnable() {
  @Override
                  public void run() {
                      DisplayMode displayMode = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDisplayMode();
                      BufferedImage bufferedImage = new BufferedImage( displayMode.getWidth(), displayMode.getHeight(), BufferedImage.TYPE_INT_ARGB);
                      Graphics graphics = bufferedImage.getGraphics();
                      Map<BaseShip, Integer> value = new HashMap<>(player.getValue());
                      Iterator<Map.Entry<BaseShip, Integer>> iterator = value.entrySet().iterator();
                      while (iterator.hasNext()) {
                          Map.Entry<BaseShip, Integer> entry = iterator.next();
                          BaseShip baseShip = entry.getKey();
                          if (!baseShip.isKilled()) {
                              baseShip.paint(graphics);
                          } else {
                              iterator.remove();
                          }
                      }
  
                      graphics.dispose();
                      bufferedImages.put(player.getKey(), bufferedImage);
                      player.setValue(value);
                  }
              });
              threads.add(thread);
              thread.start();
          }
          for (Thread thread : threads) {
              try {
                  thread.join();
              } catch (InterruptedException e) {
                  e.printStackTrace();
              }
          }
          for (Map.Entry<String, BufferedImage> bufferedImage : bufferedImages.entrySet()) {
              g.drawImage(bufferedImage.getValue(), 0, 0, null);
          }
  }
  

• 核心问题：
  BufferedImage按DisplayMode创建为3840x2160，但JPanel的paint方法实际以2600x1440分辨率绘制内容，经窗口拉伸后导致画质损失。尝试过移除最大化设置、手动设置尺寸、使用Graphics2D等方法均无效，仅系统缩放调至100%时正常，但不可行；放弃多线程则运行卡顿，需兼顾多线程与无缩放渲染。

1. 开启Java高DPI感知 #

强制Java忽略系统缩放，按原生分辨率渲染，避免拉伸模糊：

// 程序启动时设置
System.setProperty("sun.java2d.uiScale", "1.0");
// 或在JVM启动参数中添加：-Dsun.java2d.uiScale=1.0

2. 修正BufferedImage尺寸计算 #

不要硬编码DisplayMode尺寸，改用面板实际物理像素尺寸：
在paintComponent中获取系统缩放比例，计算对应的物理分辨率：

Graphics2D g2d = (Graphics2D) g;
double scale = g2d.getTransform().getScaleX();
int physicalWidth = (int) (getWidth() * scale);
int physicalHeight = (int) (getHeight() * scale);

用该尺寸创建BufferedImage，确保与实际渲染像素匹配。

3. 优化多线程绘制逻辑 #

• 用线程池替代频繁创建线程，减少开销：

// 提前初始化线程池，复用线程
private ExecutorService executor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());

@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    List<Future<?>> futures = new ArrayList<>();
    Graphics2D g2d = (Graphics2D) g;
    double scale = g2d.getTransform().getScaleX();
    int physicalWidth = (int) (getWidth() * scale);
    int physicalHeight = (int) (getHeight() * scale);

    for (Map.Entry<String, Map<BaseShip, Integer>> player : playersShips.entrySet()) {
        Future<?> future = executor.submit(() -> {
            BufferedImage bufferedImage = new BufferedImage(physicalWidth, physicalHeight, BufferedImage.TYPE_INT_ARGB);
            Graphics graphics = bufferedImage.createGraphics();
            // 应用缩放比例，保证绘制内容与物理像素对齐
            ((Graphics2D)graphics).scale(scale, scale);
            
            Map<BaseShip, Integer> value = new HashMap<>(player.getValue());
            Iterator<Map.Entry<BaseShip, Integer>> iterator = value.entrySet().iterator();
            while (iterator.hasNext()) {
                Map.Entry<BaseShip, Integer> entry = iterator.next();
                BaseShip baseShip = entry.getKey();
                if (!baseShip.isKilled()) {
                    baseShip.paint(graphics);
                } else {
                    iterator.remove();
                }
            }

            graphics.dispose();
            bufferedImages.put(player.getKey(), bufferedImage);
            player.setValue(value);
        });
        futures.add(future);
    }

    // 等待所有绘制任务完成
    for (Future<?> future : futures) {
        try {
            future.get();
        } catch (InterruptedException | ExecutionException e) {
            e.printStackTrace();
        }
    }

    // 按面板逻辑尺寸绘制BufferedImage，避免拉伸
    for (Map.Entry<String, BufferedImage> entry : bufferedImages.entrySet()) {
        g2d.drawImage(entry.getValue(), 0, 0, getWidth(), getHeight(), null);
    }
}

• 必须调用super.paintComponent(g)，确保面板正常刷新，避免绘制残留。

4. 调整窗口初始化逻辑 #

去掉硬编码的PreferredSize，直接按物理屏幕尺寸设置窗口：

public static void main(String[] args) throws IOException {
    // 开启高DPI感知
    System.setProperty("sun.java2d.uiScale", "1.0");
    
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setUndecorated(true);
    Background background = new Background();
    frame.add(background);
    
    // 按物理屏幕尺寸设置窗口
    DisplayMode displayMode = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDisplayMode();
    frame.setSize(displayMode.getWidth(), displayMode.getHeight());
    
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
}

内容的提问来源于stack exchange，提问作者Ярослав