Question

控件仅显示第一个图像，如果属性发生更改（并且事件被触发），控件甚至不会尝试再次获取该值。如果窗口初始化时属性为null，那么如果稍后对图像进行了修改，则也不会显示任何内容。图像大约是2MB位图

这是XAML

<Image
    Grid.Row="1" 
    Grid.Column="0" 
    Grid.ColumnSpan="2"    
    Source="{Binding Path=CurrentImg,UpdateSourceTrigger=PropertyChanged, Mode= TwoWay}"/>

这是在视图模型中：

private BitmapImage _CurrentImg;

public BitmapImage CurrentImg
{
    get { return _CurrentImg; }
    set
    {
        _CurrentImg = value;
        RaisePropertyChanged("CurrentImg");
    }
}

public void ButtonCommandExecute()
{
    TestAlgo.Next();

    this.CurrentImg = TestAlgo.toWpfBitmapImage();  
}

最后，这是从System.Drawing.Bitmap

创建BitmapImage的方法

 public BitmapImage toWpfBitmapImage()
    { return convertBitmapToBitmapSource(this.CurBitmap); }

    /// <summary>
    /// Converts a <see cref="System.Drawing.Bitmap"/> to <see cref="System.Windows.Media.Imaging.BitmapSource"/>
    /// </summary>
    /// <param name="bitmap">Source</param>
    /// <returns>Converted image</returns>
    public static BitmapImage convertBitmapToBitmapSource(System.Drawing.Bitmap bitmap)
    {


        //salvo la bitmap nel MemoryStream, in modo che lo posso usare come sorgente per una nuova BitmapSource
        BitmapImage imageToReturn = new BitmapImage();
        using (MemoryStream stream = new MemoryStream())
        {


            bitmap.Save(stream, System.Drawing.Imaging.ImageFormat.Bmp);
            //creo la nuova BitmapSource da ritornare
            stream.Seek(0, SeekOrigin.Begin);
            imageToReturn.BeginInit();
            imageToReturn.CacheOption = BitmapCacheOption.OnLoad;
            imageToReturn.CreateOptions = BitmapCreateOptions.PreservePixelFormat;
            imageToReturn.StreamSource = stream;
            imageToReturn.EndInit();
        }
        return imageToReturn;

    }

这是实例化主窗口的地方，视图模型作为参数传递并在构造函数中设置。

    public partial class App : Application
    {
        MainWindowVM MainWinVM;
        protected override void OnStartup(StartupEventArgs e)
        {
            base.OnStartup(e);
            MainWinVM = new MainWindowVM();
            MainWindow win = new MainWindow(MainWinVM);
            win.Show();
        }
        protected override void OnExit(ExitEventArgs e)
        {
            MainWinVM.SaveDb();
            base.OnExit(e);
        }
    }


     public partial class MainWindow : Window
     {
       public MainWindow()
       {
          this.DataContext = new MainWindowVM();
          InitializeComponent();

       }
       public MainWindow(MainWindowVM vm)
       {
          DataContext = vm;
          InitializeComponent();

       }
     }

Answer 1

您是否实施了INotifyPropertyChanged接口???

设置值后，请在CurrentImg的setter上使用sendPropertyChanged（“CurrentImg”）。

    private BitmapImage  currentImg;

    public BitmapImage  CurrentImg
    {
        get { return currentImg; }
        set 
        { 
            currentImg = value;
            SendPropertyChanged("CurrentImg");
        }
    }

请参阅以下链接。

http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged(v=vs.110).aspx

Wpf图像控件（绑定到属性）第一次后没有刷新

1 个答案: