我在WPF中有一个带有菜单项的菜单。不幸的是,当我点击菜单标题时,它会向右打开菜单。问题是右侧有一些我不想重叠的东西。我该如何告诉WPF将菜单向左打开?我需要做控件模板吗?(对于如此基本的样式更改,控件模板似乎太过繁琐了)。
谢谢!
KSG
public static PlacementMode GetMenuPlacement(DependencyObject obj)
{
return (PlacementMode)obj.GetValue(MenuPlacementProperty);
}
public static void SetMenuPlacement(DependencyObject obj, PlacementMode value)
{
obj.SetValue(MenuPlacementProperty, value);
}
// Using a DependencyProperty as the backing store for MenuPlacement. This enables animation, styling, binding, etc...
public static readonly DependencyProperty MenuPlacementProperty =
DependencyProperty.RegisterAttached("MenuPlacement",
typeof(PlacementMode),
typeof(Window1),
new FrameworkPropertyMetadata(PlacementMode.Bottom, FrameworkPropertyMetadataOptions.Inherits, new PropertyChangedCallback(OnMenuPlacementChanged)));
private static void OnMenuPlacementChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
var menuItem = o as MenuItem;
if (menuItem != null)
{
if (menuItem.IsLoaded)
{
SetPopupPlacement(menuItem, (PlacementMode)e.NewValue);
}
else
{
menuItem.Loaded += new RoutedEventHandler((m, v) => SetPopupPlacement(menuItem, (PlacementMode)e.NewValue));
}
}
}
private static void SetPopupPlacement(MenuItem menuItem, PlacementMode placementMode)
{
Popup popup = menuItem.Template.FindName("PART_Popup", menuItem) as Popup;
if (popup != null)
{
popup.Placement = placementMode;
}
}
现在我们有了AttachedProperty,很容易在UI中更改Popup的位置。
<Menu>
<MenuItem Header="Item 1"
local:Window1.MenuPlacement="Right">
<MenuItem Header="SubItem 1" />
<MenuItem Header="SubItem 2" />
<MenuItem Header="SubItem 3" />
<MenuItem Header="SubItem 4" />
</MenuItem>
<MenuItem Header="Item 2"
local:Window1.MenuPlacement="Left">
<MenuItem Header="SubItem 5" />
<MenuItem Header="SubItem 6" />
<MenuItem Header="SubItem 7" />
<MenuItem Header="SubItem 8" />
</MenuItem>
<MenuItem Header="Item 3"
local:Window1.MenuPlacement="Mouse">
<MenuItem Header="SubItem 9" />
<MenuItem Header="SubItem 10" />
<MenuItem Header="SubItem 11" />
<MenuItem Header="SubItem 12" />
</MenuItem>
</Menu>