Drucken eines WPF Visual mit Bildern

Question

Ich versuche, ein WPF Visual (ein Canvas um genau zu sein) zu drucken, das mehrere Bilder enthält. Die Bildquellen werden aus Base64-Strings geladen, die in BitmapSources konvertiert werden. Wenn die Zeichenfläche in einem Fenster angezeigt wird, werden die 2 Bilder korrekt angezeigt. Wenn sie jedoch mit der PrintVisual-Methode von PrintDialog gedruckt werden, erscheinen beide Bilder gleich. Ich habe ein verkleinertes Beispiel erstellt, das das Verhalten zeigt, das ich sehe. Hier

ist die XAML Ich verwende:

<Window x:Class="ImagePrintTest.MainWindow" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    xmlns:local="clr-namespace:ImagePrintTest" 
    mc:Ignorable="d" 
    Title="MainWindow" Height="800" Width="600"> 
<StackPanel> 
    <Button Content="Print" Click="Button_Click" /> 
    <Canvas x:Name="ImageCanvas"> 
     <Image x:Name="ImageA" Canvas.Left="50" Canvas.Top="50" Width="380" Height="56" /> 
     <Image x:Name="ImageB" Canvas.Left="50" Canvas.Top="150" Width="380" Height="56" /> 
    </Canvas> 
</StackPanel> 

Und das ist der Code hinter:

public partial class MainWindow : Window 
{ 
    string ABC_DATA = @"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"; 
    string DEF_DATA = @"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"; 

    public MainWindow() 
    { 
     InitializeComponent(); 

     ImageA.Source = Convert(ABC_DATA); 
     ImageB.Source = Convert(DEF_DATA); 
    } 

    private void Button_Click(object sender, RoutedEventArgs e) 
    { 
     PrintDialog printDialog = new PrintDialog(); 

     if (printDialog.ShowDialog() == true) 
     { 
      printDialog.PrintVisual(ImageCanvas, "image print test"); 
     } 
    } 

    public static BitmapSource Convert(string s) 
    { 
     byte[] bytes; 
     bytes = System.Convert.FromBase64String(s); 

     BitmapSource source; 

     using (System.IO.MemoryStream ms = new System.IO.MemoryStream(bytes)) 
     { 
      source = PngBitmapDecoder.Create(ms, BitmapCreateOptions.None, BitmapCacheOption.OnLoad).Frames[0]; 
     } 

     return source; 
    } 
} 

Ich gehe davon aus, dass die Bildquellen irgendwie irgendwo zwischengespeichert werden aber ich kann dieses Verhalten wirklich nicht erklären. Kann mir jemand erklären, was hier passiert?

Answer 1

Es funktioniert für mich, wenn ich ein zweites Bitmapframe wie folgt zu erstellen:

public static BitmapSource Convert(string s) 
{ 
    using (var ms = new MemoryStream(System.Convert.FromBase64String(s))) 
    { 
     return BitmapFrame.Create(
      BitmapFrame.Create(ms, BitmapCreateOptions.None, BitmapCacheOption.OnLoad)); 
    } 
} 

Allerdings habe ich keine Erklärung haben für dieses Verhalten.

Ich bemerkte auch, dass das Drucken das Layout zu verderben scheint. Nach dem Drucken bewegt sich ImageCanvas in Position (0,0) in seinem übergeordneten StackPanel.