视频播放器与图片预览器功能增强开发笔记

// 保存
Future<void> _savePosition() async {
  final position = _player.state.position.inMilliseconds;
  if (position > 0) {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setInt(_positionKey, position);
  }
}
 
// 恢复
Future<void> _restorePosition() async {
  final prefs = await SharedPreferences.getInstance();
  final savedPosition = prefs.getInt(_positionKey);
  if (savedPosition != null && savedPosition > 0) {
    final duration = _player.state.duration.inMilliseconds;
    if (savedPosition < duration * 0.9) {
      await _player.seek(Duration(milliseconds: savedPosition));
    }
  }
}

void _onDoubleTap(TapDownDetails details) {
  final position = details.localPosition;
  Matrix4 targetMatrix;
  
  if (_currentScale < 1.5) {
    targetScale = 2.0;
  } else if (_currentScale < 3.0) {
    targetScale = 4.0;
  } else {
    targetScale = 1.0; // 还原
  }
  
  if (targetScale == 1.0) {
    targetMatrix = Matrix4.identity();
  } else {
    // 计算以双击点为中心的变换矩阵
    final scaleFactor = targetScale / _currentScale;
    final dx = (1 - scaleFactor) * position.dx;
    final dy = (1 - scaleFactor) * position.dy;
    targetMatrix = Matrix4.diagonal3Values(targetScale, targetScale, 1.0)
      ..setTranslationRaw(dx, dy, 0);
  }
  
  // 动画过渡
  _animation = Matrix4Tween(
    begin: _transformationController.value,
    end: targetMatrix,
  ).animate(_animController);
  _animController.forward(from: 0);
}

MaterialVideoControlsTheme(
  normal: MaterialVideoControlsThemeData(
    // 竖屏：不需要顶部按钮（已在 AppBar 中）
    topButtonBar: [],
    bottomButtonBar: const [
      MaterialPositionIndicator(),
      Spacer(),
      MaterialFullscreenButton(),
    ],
  ),
  fullscreen: MaterialVideoControlsThemeData(
    // 横屏：添加自定义按钮到顶部栏
    topButtonBar: [
      const MaterialFullscreenButton(),
      const Spacer(),
      MaterialCustomButton(
        onPressed: _showSpeedMenu,
        icon: Container(
          padding: EdgeInsets.symmetric(horizontal: 8, vertical: 4),
          decoration: BoxDecoration(
            color: Colors.white24,
            borderRadius: BorderRadius.circular(4),
          ),
          child: Text('${_currentSpeed}x', style: TextStyle(color: Colors.white)),
        ),
      ),
      MaterialCustomButton(
        onPressed: _showVideoSettings,
        icon: Icon(TablerIcons.settings, color: Colors.white),
      ),
      MaterialCustomButton(
        onPressed: () => _showFileActions(context),
        icon: Icon(TablerIcons.dots, color: Colors.white),
      ),
    ],
    bottomButtonBar: const [
      MaterialPositionIndicator(),
      Spacer(),
    ],
  ),
  child: Video(
    controller: _controller,
    controls: AdaptiveVideoControls,
    fit: _currentFit,
  ),
)

ListTile(
  title: Text('1.0x', textAlign: TextAlign.center),
  trailing: isSelected ? Icon(Icons.check) : null,  // 导致偏移
)

ListTile(
  leading: SizedBox(
    width: 24,
    child: isSelected
        ? Icon(TablerIcons.check, color: primaryColor, size: 20)
        : null,  // 即使为 null，SizedBox 仍保持宽度
  ),
  title: Text('1.0x'),  // 不再需要居中
)

// 错误
Matrix4.identity()..translate(dx, dy)..scale(targetScale);
 
// 正确
Matrix4.diagonal3Values(targetScale, targetScale, 1.0)
  ..setTranslationRaw(dx, dy, 0);

void _onPageChanged(int index) {
  setState(() => _currentIndex = index);
  
  // 预加载相邻图片
  if (index > 0) _preloadImage(index - 1);
  if (index < _imageList.length - 1) _preloadImage(index + 1);
}
 
Future<void> _preloadImage(int index) async {
  if (_imageCache.containsKey(index)) return;
  
  final file = _imageList[index];
  final bytes = await appState.api.downloadFileToMemory(file.id);
  if (mounted && bytes != null) {
    setState(() => _imageCache[index] = bytes);
  }
}

final Map<int, int> _rotationQuarters = {};
 
int _getRotation(int index) => _rotationQuarters[index] ?? 0;
 
void _rotateImage() {
  setState(() {
    final current = _rotationQuarters[_currentIndex] ?? 0;
    _rotationQuarters[_currentIndex] = (current + 1) % 4;
  });
}