[Feature] 添加截图功能

概述 | Summary

用户按下 F2 后，使用当前时间等信息作为截图文件名称并保存在指定的截图目录下。

该功能使用频率可能不高因此可默认禁用，并在设置中启用后 F2 才生效。

原因 | Reason

使用第三方截图工具截取 HMCL 时，可能会出现截图尺寸比窗口略大，从而导致截图中包含额外的背景内容。

支持截图后，生成的图片可用于问题反馈及文档截图。

详情 | Description

添加全局 F2 监听事件，事件触发后获取所有 Window 对象，根据该对象获取其位置坐标及使用透明背景填充的截图，然后将所有截图根据位置关系合成为一张图片。

// press F2 to take a screenshot
navigator.addEventHandler(KeyEvent.KEY_PRESSED, e -> {
    if (e.getCode() != KeyCode.F2) return;
    SnapshotParameters transparentParams = new SnapshotParameters();
    transparentParams.setFill(Color.TRANSPARENT);
    record Shot(BufferedImage img, double x, double y) {
    }

    List<Shot> shots = new ArrayList<>();
    for (Window window : Window.getWindows()) {
        if (!window.isShowing() || window.getScene() == null || window.getScene().getRoot() == null) continue;
        WritableImage snapshot = window.getScene().getRoot().snapshot(transparentParams, null);
        BufferedImage image = SwingFXUtils.fromFXImage(snapshot, null);
        if (image != null) {
            shots.add(new Shot(image, window.getX(), window.getY()));
        }
    }
    if (shots.isEmpty()) return;

    double minX = shots.stream().mapToDouble(shot -> shot.x).min().orElse(0);
    double minY = shots.stream().mapToDouble(shot -> shot.y).min().orElse(0);
    double maxX = shots.stream().mapToDouble(shot -> shot.x + shot.img.getWidth()).max().orElse(0);
    double maxY = shots.stream().mapToDouble(shot -> shot.y + shot.img.getHeight()).max().orElse(0);

    int width = (int)(maxX - minX);
    int height = (int)(maxY - minY);

    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
    Graphics2D graphics = image.createGraphics();
    shots.forEach(shot -> graphics.drawImage(shot.img, (int)(shot.x - minX), (int)(shot.y - minY), null));
    graphics.dispose();

    try {
        ImageIO.write(image, "png", new File("out.png"));
    } catch (IOException ignored) {
    }
});

截图效果

Start by locating the global key event entry point represented by navigator.addEventHandler and the settings code for enabling F2. Review Window.getWindows(), JavaFX snapshots, and the ImageIO output flow described in the issue. Done means F2 is disabled by default, can be enabled in settings, and saves a timestamped PNG of the visible windows in the configured screenshot directory.