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Accepted
Andrey Ferzh
Asked:2023-09-11 22:28:52 +0000 UTC2023-09-11 22:28:52 +0000 UTC

如何使用 MVVM 模式更新镜像

  • 772

创建照片后，界面上显示照片，显示第一张照片，但创建新照片后，出现错误：

该进程无法访问文件“...tmp\Photo.jpeg”，因为该文件正在被另一个进程使用。

System.IO.IOException：进程无法访问文件“...tmp\Photo.jpeg”，因为它正在被另一个进程使用。在 System.IO.FileSystem.DeleteFile（字符串 fullPath） 在 System.IO.File.Delete（字符串路径） 在 PhotoMerge.ViewModel.MainViewModel.CreatePhoto（Int32 通道，相机相机） ...\ViewModel\MainViewModel.cs

模型：

public class Camera : INotifyPropertyChanged
{
   public event PropertyChangedEventHandler PropertyChanged;
   private string _address;
   private string _login;
   private string _password;
   private string _name;
   private string _path;
   private Uri? _imagePath;

   public string Address { get { return _address; } }
   public string Login { get { return _login; } }
   public string Password { get { return _password; } }
   public string Name { get { return _name; } }
   public string Path { get { return _path; } }

   public Uri? ImagePath
   {
      get { return _imagePath; }

      set
      {
         _imagePath = value;
         OnPropertyChanged("ImagePath");
      }
   }

   public Camera(string address, string login, string password, string name, string path)
   {
      _address = address;
      _login = login;
      _password = password;
      _name = name;
      _path = path; 
   }

   public void OnPropertyChanged([CallerMemberName] string prop = "")
   {
      if (PropertyChanged != null)
         PropertyChanged(this, new PropertyChangedEventArgs(prop));
   }
}

视图模型：

internal class MainViewModel : INotifyPropertyChanged
{
   private Camera camera;
   private ICommand createPhoto;

   public Camera Camera
   {
      get { return this.camera; }
   }

   public ICommand CreatePhoto
   {
      get { return this.createPhoto; }
   }

   public MainViewModel()
   {
      camera = new Camera("192.168.3.103", "admin", "1", "Photo", @"C:\tmp\");
      createPhoto = new DelegateCommand(parameter => CreateTestPhoto(1, camera));
   }

   private void CreateTestPhoto(int channel, Camera camera)
   {
      if (File.Exists(camera.Path + camera.Name + ".jpeg"))
         File.Delete(camera.Path + camera.Name + ".jpeg");

      if (HiWatch.Create(channel, camera.Login, camera.Password, camera.Path, camera.Name, 550))
      {
         BitmapImage bitmap = new BitmapImage();
         bitmap.BeginInit();
         bitmap.UriSource = new Uri(camera.Path + camera.Name + ".jpeg", UriKind.Absolute);
         bitmap.CacheOption = BitmapCacheOption.OnLoad;
         bitmap.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
         bitmap.EndInit();

         camera.ImagePath = bitmap.UriSource;
      }
   }
}

XAML：

<Image Source="{Binding Camera.ImagePath}" DockPanel.Dock="Top" Margin="0" Width="Auto" Height="Auto" Stretch="Uniform" MinWidth="364" MinHeight="205" />

如何在UI中正确实现照片更新？

c#

1 个回答

  1. Best Answer

    我是这样解决的：

    模型：

    public class Camera : INotifyPropertyChanged
{
   public event PropertyChangedEventHandler PropertyChanged;

   private string _address;
   private string _login;
   private string _password;
   private string _name;
   private string _path;
   private BitmapImage? _bitmapImage;

   public event Action PhotoCreated;

   public string Address { get => _address; }
   public string Login { get => _login; }
   public string Password { get => _password; }
   public string Name { get => _name; }
   public string Path { get => _path; }

   public BitmapImage? BitmapImage
   {
      get => _bitmapImage;
      set
      {
         _bitmapImage = value;
         OnPropertyChanged("BitmapImage");
      }
   }

   public Camera(string address, string login, string password, string name, string path)
   {
      _address = address;
      _login = login;
      _password = password;
      _name = name;
      _path = path; 
   }

   public void OnPropertyChanged([CallerMemberName] string prop = "")
   {
      if (PropertyChanged != null)
         PropertyChanged(this, new PropertyChangedEventArgs(prop));
   }

   public void CreatePhoto()
   {
      if (File.Exists(_path + _name  + ".jpeg"))
         File.Delete(_path  + _name  + ".jpeg");

      if (HiWatch.Create(_login, _password, _path, _name))
      {
         BitmapImage bitmap = new BitmapImage();
         bitmap.BeginInit();
         bitmap.UriSource = new Uri(_path + _name + ".jpeg", UriKind.Absolute);
         bitmap.CacheOption = BitmapCacheOption.OnLoad;
         bitmap.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
         bitmap.EndInit();

         _bitmapImage = bitmap;
         PhotoCreated?.Invoke();
      }
   }
}

    视图模型：

    internal class MainViewModel : INotifyPropertyChanged
{
   private Camera camera;
   private ImageSource image;
   private ICommand createPhoto;

   public Camera Camera
   {
      get => camera;
   }

   public ImageSource Image
   {
       get => image;
       set
       {
          image = value;
          image.Freeze();
          OnPropertyChanged("Image");
       }
   }

   public ICommand CreatePhoto
   {
      get { return this.createPhoto; }
   }

   public MainViewModel()
   {
      camera = new Camera("192.168.3.103", "admin", "1", "Photo", @"C:\tmp\");
      createPhoto = new DelegateCommand(parameter => camera.CreatePhoto()));
      camera.PhotoCreated += PhotoUpdate;
   }

   private void PhotoUpdate()
   {
      Image = camera.BitmapImage;
   }
}

    XAML：

    <Image Source="{Binding Image}" Width="Auto" Height="Auto" Stretch="Uniform" />
    • 0

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