發送BitmapSource任務計算-wpf c＃

Question

我的程序中有兩個圖像，我有一個函數來比較兩個BitmapSources，問題是我將一個ImageSource轉換爲BitmapSource並將其分配給一個變量，並將其發送給任務內部的函數（因爲函數相當慢，我更喜歡使用任務，然後在完成時更新用戶），它給我一個錯誤，即任務不能使用此變量，因爲另一個線程擁有它...請幫助我解決它。從DispatcherObject衍生

private async void btnAnalyze_Click(object sender, RoutedEventArgs e) 
    { 
     if (AnalyzeImage?.Status == TaskStatus.Running) await AnalyzeImage; 
     var baseSource = (BitmapSource)imgBase.Source; 
     var newSource = (BitmapSource)imgNew.Source; 
     if (baseSource?.CompareSizeTo(newSource) == false) 
     { 
      ShowStatus("Images are different in size or at least one of them is null"); 
      return; 
     } 
     btnAnalyze.IsEnabled = false; 
     ShowStatus(); 
     try 
     { 
      AnalyzeImage = Task<BitmapSource>.Factory.StartNew(() => baseSource?.ConvertToBitmap().CompareTo(newSource?.ConvertToBitmap()).BitmapToImageSource()); 
      InvokeA(() => waitingPanel.Visibility = Visibility.Visible); 
      await AnalyzeImage; 
      imgNew.Source = AnalyzeImage.Result; 
     } 
     catch (Exception ex) { Notify("Error in btnAnalyzeClick", ex, true); } 
     finally { InvokeA(() => waitingPanel.Visibility = Visibility.Hidden); } 
    } 

Answer 1

對象具有由調用線程線程關聯，即一旦被創建他們是「擁有」。在WPF應用程序中，它通常是UI線程。

如果BimtapSource實例化被放置await後它將使用當前的上下文（UI在這種情況下），使該對象的消費由UI組件：

private async void btnAnalyze_Click(object sender, RoutedEventArgs e) 
{ 
    if (AnalyzeImage?.Status == TaskStatus.Running) await AnalyzeImage; 
    var baseSource = (BitmapSource)imgBase.Source; 
    var newSource = (BitmapSource)imgNew.Source; 
    if (baseSource?.CompareSizeTo(newSource) == false) 
    { 
     ShowStatus("Images are different in size or at least one of them is null"); 
     return; 
    } 
    btnAnalyze.IsEnabled = false; 
    ShowStatus(); 
    try 
    { 
     waitingPanel.Visibility = Visibility.Visible; 
     var worker = Task<Bitmap>.Factory.StartNew(() =>   
         baseSource?.ConvertToBitmap() 
        .CompareTo(newSource?.ConvertToBitmap())); 

     var bmp = await worker; 

     // The next statement is executed in UI synchronization context 
     imageNew.Source = bmp.BitmapToImageSource(); 

    } 
    catch (Exception ex) 
    { 
     Notify("Error in btnAnalyzeClick", ex, true); 
    } 
    finally 
    { 
     waitingPanel.Visibility = Visibility.Hidden; 
    } 
}