如何访问我的 ViewModel 中的 XAML 对象?我真的很困惑。我想访问 <Controls:ModalContentPresenter>
目的。我怎么能以符合 MVVM 的方式实现这一点?我想在这个对象上调用一个方法 ShowModalContent
<Controls:ModalContentPresenter x:Name="modalContent">
<ScrollViewer Behaviors:AdvancedZooming.KeepInCenter="true" Visibility="{Binding LeerformularIsVisible}" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto">
<Viewbox Stretch="Uniform">
<Grid>
<DataGrid BorderBrush="{x:Null}">
<DataGrid.ContextMenu>
<ContextMenu>
<MenuItem Command="{Binding AddFieldDefinitionCommand}" Header="Feld hinterlegen" Icon="pack://application:,,,/Images/Designer/field.png" />
<MenuItem Command="{Binding AddFunctionCommand}" Header="Funktion hinterlegen" Icon="pack://application:,,,/Images/Designer/FI_Taschenmesser_16x16.png" />
<MenuItem Command="{Binding RemoveFieldDefinitionCommand}" Header="Aktuelle Felddefinition entfernen" Icon="pack://application:,,,/Images/Designer/remove_field.png" />
<MenuItem Command="{Binding CutCommand}" Header="Ausschneiden" Icon="pack://application:,,,/Images/Zwischenablage/FI_Ausschneiden_16x16.png" />
<MenuItem Command="{Binding CopyCommand}" Header="Kopieren" Icon="pack://application:,,,/Images/Zwischenablage/FI_Kopieren_16x16.png" />
<MenuItem Command="{Binding PasteCommand}" Header="Einfügen" Icon="pack://application:,,,/Images/Zwischenablage/FI_Einfuegen_16x16.png" />
</ContextMenu>
</DataGrid.ContextMenu>
</DataGrid>
</Grid>
</Viewbox>
</ScrollViewer>
<Controls:ModalContentPresenter.ModalContent>
<StackPanel>
<TextBlock>Test</TextBlock>
<Button>Hide</Button>
</StackPanel>
</Controls:ModalContentPresenter.ModalContent>
</Controls:ModalContentPresenter>
ModalContentPresenter 的代码可以在这里找到:
using System;
using System.Collections;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Markup;
using System.Windows.Media;
namespace Controls
{
[ContentProperty("Content")]
public class ModalContentPresenter : FrameworkElement
{
#region private fields
private Panel layoutRoot;
private ContentPresenter primaryContentPresenter;
private ContentPresenter modalContentPresenter;
private Border overlay;
private object[] logicalChildren;
private KeyboardNavigationMode cachedKeyboardNavigationMode;
private static readonly TraversalRequest traversalDirection;
#endregion
#region dependency properties
public static readonly DependencyProperty IsModalProperty = DependencyProperty.Register("IsModal", typeof(bool), typeof(ModalContentPresenter),
new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnIsModalChanged));
public static readonly DependencyProperty ContentProperty = DependencyProperty.Register("Content", typeof(object), typeof(ModalContentPresenter),
new UIPropertyMetadata(null, OnContentChanged));
public static readonly DependencyProperty ModalContentProperty = DependencyProperty.Register("ModalContent", typeof(object), typeof(ModalContentPresenter),
new UIPropertyMetadata(null, OnModalContentChanged));
public static readonly DependencyProperty OverlayBrushProperty = DependencyProperty.Register("OverlayBrush", typeof(Brush), typeof(ModalContentPresenter),
new UIPropertyMetadata(new SolidColorBrush(Color.FromArgb(204, 169, 169, 169)), OnOverlayBrushChanged));
public bool IsModal
{
get { return (bool)GetValue(IsModalProperty); }
set { SetValue(IsModalProperty, value); }
}
public object Content
{
get { return (object)GetValue(ContentProperty); }
set { SetValue(ContentProperty, value); }
}
public object ModalContent
{
get { return (object)GetValue(ModalContentProperty); }
set { SetValue(ModalContentProperty, value); }
}
public Brush OverlayBrush
{
get { return (Brush)GetValue(OverlayBrushProperty); }
set { SetValue(OverlayBrushProperty, value); }
}
#endregion
#region routed events
public static readonly RoutedEvent PreviewModalContentShownEvent = EventManager.RegisterRoutedEvent("PreviewModalContentShown", RoutingStrategy.Tunnel,
typeof(RoutedEventArgs), typeof(ModalContentPresenter));
public static readonly RoutedEvent ModalContentShownEvent = EventManager.RegisterRoutedEvent("ModalContentShown", RoutingStrategy.Bubble,
typeof(RoutedEventArgs), typeof(ModalContentPresenter));
public static readonly RoutedEvent PreviewModalContentHiddenEvent = EventManager.RegisterRoutedEvent("PreviewModalContentHidden", RoutingStrategy.Tunnel,
typeof(RoutedEventArgs), typeof(ModalContentPresenter));
public static readonly RoutedEvent ModalContentHiddenEvent = EventManager.RegisterRoutedEvent("ModalContentHidden", RoutingStrategy.Bubble,
typeof(RoutedEventArgs), typeof(ModalContentPresenter));
public event RoutedEventHandler PreviewModalContentShown
{
add { AddHandler(PreviewModalContentShownEvent, value); }
remove { RemoveHandler(PreviewModalContentShownEvent, value); }
}
public event RoutedEventHandler ModalContentShown
{
add { AddHandler(ModalContentShownEvent, value); }
remove { RemoveHandler(ModalContentShownEvent, value); }
}
public event RoutedEventHandler PreviewModalContentHidden
{
add { AddHandler(PreviewModalContentHiddenEvent, value); }
remove { RemoveHandler(PreviewModalContentHiddenEvent, value); }
}
public event RoutedEventHandler ModalContentHidden
{
add { AddHandler(ModalContentHiddenEvent, value); }
remove { RemoveHandler(ModalContentHiddenEvent, value); }
}
#endregion
#region ModalContentPresenter implementation
static ModalContentPresenter()
{
traversalDirection = new TraversalRequest(FocusNavigationDirection.First);
}
public ModalContentPresenter()
{
layoutRoot = new ModalContentPresenterPanel();
primaryContentPresenter = new ContentPresenter();
modalContentPresenter = new ContentPresenter();
overlay = new Border();
AddVisualChild(layoutRoot);
logicalChildren = new object[2];
overlay.Background = OverlayBrush;
overlay.Child = modalContentPresenter;
overlay.Visibility = Visibility.Hidden;
layoutRoot.Children.Add(primaryContentPresenter);
layoutRoot.Children.Add(overlay);
}
public void ShowModalContent()
{
if (!IsModal)
IsModal = true;
}
public void HideModalContent()
{
if (IsModal)
IsModal = false;
}
private void RaiseModalContentShownEvents()
{
RoutedEventArgs args = new RoutedEventArgs(PreviewModalContentShownEvent);
OnPreviewModalContentShown(args);
if (!args.Handled)
{
args = new RoutedEventArgs(ModalContentShownEvent);
OnModalContentShown(args);
}
}
private void RaiseModalContentHiddenEvents()
{
RoutedEventArgs args = new RoutedEventArgs(PreviewModalContentHiddenEvent);
OnPreviewModalContentHidden(args);
if (!args.Handled)
{
args = new RoutedEventArgs(ModalContentHiddenEvent);
OnModalContentHidden(args);
}
}
protected virtual void OnPreviewModalContentShown(RoutedEventArgs e)
{
RaiseEvent(e);
}
protected virtual void OnModalContentShown(RoutedEventArgs e)
{
RaiseEvent(e);
}
protected virtual void OnPreviewModalContentHidden(RoutedEventArgs e)
{
RaiseEvent(e);
}
protected virtual void OnModalContentHidden(RoutedEventArgs e)
{
RaiseEvent(e);
}
#endregion
#region property changed callbacks
private static void OnIsModalChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ModalContentPresenter control = (ModalContentPresenter)d;
if ((bool)e.NewValue == true)
{
control.cachedKeyboardNavigationMode = KeyboardNavigation.GetTabNavigation(control.primaryContentPresenter);
KeyboardNavigation.SetTabNavigation(control.primaryContentPresenter, KeyboardNavigationMode.None);
control.overlay.Visibility = Visibility.Visible;
control.overlay.MoveFocus(traversalDirection);
control.RaiseModalContentShownEvents();
}
else
{
control.overlay.Visibility = Visibility.Hidden;
KeyboardNavigation.SetTabNavigation(control.primaryContentPresenter, control.cachedKeyboardNavigationMode);
control.primaryContentPresenter.MoveFocus(traversalDirection);
control.RaiseModalContentHiddenEvents();
}
}
private static void OnContentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ModalContentPresenter control = (ModalContentPresenter)d;
if (e.OldValue != null)
control.RemoveLogicalChild(e.OldValue);
control.primaryContentPresenter.Content = e.NewValue;
control.AddLogicalChild(e.NewValue);
control.logicalChildren[0] = e.NewValue;
}
private static void OnModalContentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ModalContentPresenter control = (ModalContentPresenter)d;
if (e.OldValue != null)
control.RemoveLogicalChild(e.OldValue);
control.modalContentPresenter.Content = e.NewValue;
control.AddLogicalChild(e.NewValue);
control.logicalChildren[1] = e.NewValue;
}
private static void OnOverlayBrushChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ModalContentPresenter control = (ModalContentPresenter)d;
control.overlay.Background = (Brush)e.NewValue;
}
#endregion
#region FrameworkElement overrides
protected override Visual GetVisualChild(int index)
{
if (index < 0 || index > 1)
throw new ArgumentOutOfRangeException("index");
return layoutRoot;
}
protected override int VisualChildrenCount
{
get { return 1; }
}
protected override IEnumerator LogicalChildren
{
get { return logicalChildren.GetEnumerator(); }
}
protected override Size ArrangeOverride(Size finalSize)
{
layoutRoot.Arrange(new Rect(finalSize));
return finalSize;
}
protected override Size MeasureOverride(Size availableSize)
{
layoutRoot.Measure(availableSize);
return layoutRoot.DesiredSize;
}
#endregion
#region layout panel
class ModalContentPresenterPanel : Panel
{
protected override Size MeasureOverride(Size availableSize)
{
Size resultSize = new Size(0, 0);
foreach (UIElement child in Children)
{
child.Measure(availableSize);
resultSize.Width = Math.Max(resultSize.Width, child.DesiredSize.Width);
resultSize.Height = Math.Max(resultSize.Height, child.DesiredSize.Height);
}
return resultSize;
}
protected override Size ArrangeOverride(Size finalSize)
{
foreach (UIElement child in InternalChildren)
{
child.Arrange(new Rect(finalSize));
}
return finalSize;
}
}
#endregion
}
}
最佳答案
你不应该这样做(至少,这绝对不是 MVVM 方式)。
改为使用 IsModal
属性和数据绑定(bind):
<Controls:ModalContentPresenter x:Name="modalContent" IsModal="{Binding IsModal}">
绑定(bind)表达式中的 IsModal
是 View 模型中的绑定(bind)数据属性。
关于c# - 在 ViewModel 中访问 XAML 对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25119470/