Evet, bunu geçmişte her ikisi de salt okunur olan ActualWidth
ve ActualHeight
özellikleriyle yaptım . Özellikleri olan ObservedWidth
ve ObservedHeight
ekleyen ekli bir davranış oluşturdum . Aynı zamanda, Observe
ilk bağlanmayı yapmak için kullanılan bir özelliğe sahiptir . Kullanım şuna benzer:
<UserControl ...
SizeObserver.Observe="True"
SizeObserver.ObservedWidth="{Binding Width, Mode=OneWayToSource}"
SizeObserver.ObservedHeight="{Binding Height, Mode=OneWayToSource}"
Görünüm modeli vardır Yani Width
ve Height
özellikleri ile her zaman senkronize olduğunu ObservedWidth
ve ObservedHeight
ekli özellikleri. Observe
Mülkiyet basitçe bağlanır SizeChanged
durumunda FrameworkElement
. Sapta, ObservedWidth
ve ObservedHeight
özelliklerini günceller . Kaynayan Width
ve Height
görünüşüdür modeli ile her zaman senkronize edilir ActualWidth
ve ActualHeight
bir UserControl
.
Belki de değil mükemmel bir çözüm (Kabul ediyorum - salt okunur DPs gerektiğini destekleyen OneWayToSource
bağlamaları), ancak o inşaat ve MVVM desen onadı. Açıkçası, ObservedWidth
ve ObservedHeight
DP'ler salt okunur değildir .
GÜNCELLEME: Yukarıda açıklanan işlevselliği uygulayan kod:
public static class SizeObserver
{
public static readonly DependencyProperty ObserveProperty = DependencyProperty.RegisterAttached(
"Observe",
typeof(bool),
typeof(SizeObserver),
new FrameworkPropertyMetadata(OnObserveChanged));
public static readonly DependencyProperty ObservedWidthProperty = DependencyProperty.RegisterAttached(
"ObservedWidth",
typeof(double),
typeof(SizeObserver));
public static readonly DependencyProperty ObservedHeightProperty = DependencyProperty.RegisterAttached(
"ObservedHeight",
typeof(double),
typeof(SizeObserver));
public static bool GetObserve(FrameworkElement frameworkElement)
{
frameworkElement.AssertNotNull("frameworkElement");
return (bool)frameworkElement.GetValue(ObserveProperty);
}
public static void SetObserve(FrameworkElement frameworkElement, bool observe)
{
frameworkElement.AssertNotNull("frameworkElement");
frameworkElement.SetValue(ObserveProperty, observe);
}
public static double GetObservedWidth(FrameworkElement frameworkElement)
{
frameworkElement.AssertNotNull("frameworkElement");
return (double)frameworkElement.GetValue(ObservedWidthProperty);
}
public static void SetObservedWidth(FrameworkElement frameworkElement, double observedWidth)
{
frameworkElement.AssertNotNull("frameworkElement");
frameworkElement.SetValue(ObservedWidthProperty, observedWidth);
}
public static double GetObservedHeight(FrameworkElement frameworkElement)
{
frameworkElement.AssertNotNull("frameworkElement");
return (double)frameworkElement.GetValue(ObservedHeightProperty);
}
public static void SetObservedHeight(FrameworkElement frameworkElement, double observedHeight)
{
frameworkElement.AssertNotNull("frameworkElement");
frameworkElement.SetValue(ObservedHeightProperty, observedHeight);
}
private static void OnObserveChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
{
var frameworkElement = (FrameworkElement)dependencyObject;
if ((bool)e.NewValue)
{
frameworkElement.SizeChanged += OnFrameworkElementSizeChanged;
UpdateObservedSizesForFrameworkElement(frameworkElement);
}
else
{
frameworkElement.SizeChanged -= OnFrameworkElementSizeChanged;
}
}
private static void OnFrameworkElementSizeChanged(object sender, SizeChangedEventArgs e)
{
UpdateObservedSizesForFrameworkElement((FrameworkElement)sender);
}
private static void UpdateObservedSizesForFrameworkElement(FrameworkElement frameworkElement)
{
// WPF 4.0 onwards
frameworkElement.SetCurrentValue(ObservedWidthProperty, frameworkElement.ActualWidth);
frameworkElement.SetCurrentValue(ObservedHeightProperty, frameworkElement.ActualHeight);
// WPF 3.5 and prior
////SetObservedWidth(frameworkElement, frameworkElement.ActualWidth);
////SetObservedHeight(frameworkElement, frameworkElement.ActualHeight);
}
}