ビューモデルから画像の高さと幅を読み取るにはどうすればよいですか？

Question

私のViewModelからいくつかの線描画操作を行いたいです（つまり、私のビュー上のItemsControlに結びついた線の集合に追加します）。

これについては、私の見解ではImageの高さと幅を知る必要があります。どうすれば入手できますか？

他のSOの投稿にはいくつかの回避策がありますが、they are for WPFはMetroで動作しません。

Answer 1

public static class SizeObserver 
{ 
    public static readonly DependencyProperty ObserveProperty = DependencyProperty.RegisterAttached(
     "Observe", 
     typeof(bool), 
     typeof(SizeObserver), new PropertyMetadata(null, OnObserveChanged)); 
    //new FrameworkPropertyMetadata(OnObserveChanged)); 

    public static readonly DependencyProperty ObservedWidthProperty = DependencyProperty.RegisterAttached(
     "ObservedWidth", 
     typeof(double), 
     typeof(SizeObserver), null); 

    public static readonly DependencyProperty ObservedHeightProperty = DependencyProperty.RegisterAttached(
     "ObservedHeight", 
     typeof(double), 
     typeof(SizeObserver), null); 




    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.SetValue(ObservedWidthProperty, frameworkElement.ActualWidth); 
     frameworkElement.SetValue(ObservedHeightProperty, frameworkElement.ActualHeight); 

     // WPF 3.5 and prior 
     ////SetObservedWidth(frameworkElement, frameworkElement.ActualWidth); 
     ////SetObservedHeight(frameworkElement, frameworkElement.ActualHeight); 
    } 
}