從視圖模型打印WPF視覺

Question

如何通過調用打印方法來打印視圖或窗口，而不使用如本示例中所示的RelayCommand進行打印：Print WPF Visuals with MVVM pattern？

var printDlg = new PrintDialog(); 
printDlg.PrintVisual(View, "JOB PRINTING") 

Answer 1

好吧，這是一個快速，骯髒但可重複使用的附加行爲類。 免責聲明：我只是在幾分鐘之內就砍掉了它，它有缺陷，應該很容易克服。

首先我們需要我們的服務類。

public class VisualPrinter 
{ 
    private static RoutedUICommand PrintVisualCommand = new RoutedUICommand("PrintVisualCommand", "PrintVisualCommand", typeof(VisualPrinter)); 

    #region ab PrintCommand 

    public static ICommand GetPrintCommand(DependencyObject aTarget) 
    { 
     return (ICommand)aTarget.GetValue(PrintCommandProperty); 
    } 

    public static void SetPrintCommand(DependencyObject aTarget, ICommand aValue) 
    { 
     aTarget.SetValue(PrintCommandProperty, aValue); 
    } 

    public static readonly DependencyProperty PrintCommandProperty = 
     DependencyProperty.RegisterAttached("PrintCommand", typeof(ICommand), typeof(VisualPrinter), new FrameworkPropertyMetadata(PrintVisualCommand)); 

    #endregion 

    #region ab EnablePrintCommand 

    public static bool GetEnablePrintCommand(DependencyObject aTarget) 
    { 
     return (bool)aTarget.GetValue(EnablePrintCommandProperty); 
    } 
    public static void SetEnablePrintCommand(DependencyObject aTarget, bool aValue) 
    { 
     aTarget.SetValue(EnablePrintCommandProperty, aValue); 
    } 

    public static readonly DependencyProperty EnablePrintCommandProperty = 
     DependencyProperty.RegisterAttached("EnablePrintCommand", typeof(bool), typeof(VisualPrinter), new FrameworkPropertyMetadata(false, OnEnablePrintCommandChanged)); 

    private static void OnEnablePrintCommandChanged(DependencyObject aDependencyObject, DependencyPropertyChangedEventArgs aArgs) 
    { 
     var newValue = (bool)aArgs.NewValue; 
     var element = aDependencyObject as UIElement; 
     if(newValue) 
     { 
      element.CommandBindings.Add(new CommandBinding(PrintVisualCommand, OnPrintVisual)); 
     } 
    } 

    private static void OnPrintVisual(object aSender, ExecutedRoutedEventArgs aE) 
    { 
     // the element is the one were you set the EnablePrintCommand 
     var element = aSender as Visual; 
     var printDlg = new PrintDialog(); 
     // do the printing 
    } 

    #endregion 
} 

這裏我們定義兩個附加屬性。 PrintCommand用於將實際的打印命令注入視圖模型，這必須使用OneWayToSource完成。 第二個是EnablePrintCommand，用於啓用打印，設置應打印哪個元素並註冊命令綁定。

我目前的版本有一個缺陷，即你不能在同一個元素上設置兩個屬性，但這很容易被克服。因此，要打印的按鈕，它看起來像這樣：

<Grid local:VisualPrinter.EnablePrintCommand="True"> 
    <Button Content="Test" local:VisualPrinter.PrintCommand="{Binding ViewModelPrint, Mode=OneWayToSource"> 
</Grid> 

雖然ViewModelPrint是類型的ICommand的視圖中的模型，其可以被執行，並且然後將打印網格（因此的按鈕）的性質。