依赖项属性依赖于另一个(Dependency Property dependent on anoth

一个如何注册一个依赖属性，其值使用其他依赖项属性的值计算出来的？

由于.NET属性包装用WPF在运行时绕过，不应该包括在getter和setter逻辑。 该解决方案是通常使用PropertyChangedCallback秒。 但是，这些被声明为static。

例如，什么是完成这一任务做作的正确方法：

public bool TestBool
{
  get { return (bool)GetValue(TestBoolProperty); }
  set 
  { 
    SetValue(TestBoolProperty, value);
    TestDouble = ((value)?(100.0):(200.0)); // HERE IS THE DEPENDENCY
  }
}
public static readonly DependencyProperty TestBoolProperty =
  DependencyProperty.Register("TestBool", typeof(bool), typeof(ViewModel));

public double TestDouble
{
  get { return ((double)GetValue(TestDoubleProperty)); }
  set { SetValue(TestDoubleProperty, value); }
}
public static readonly DependencyProperty TestDoubleProperty =
  DependencyProperty.Register("TestDouble", typeof(double), typeof(ViewModel));

只要依赖性不是圆形，有没有做到这一点的适当手段？

Answer 1:

嗯...我想你最好看一下依赖属性值强制 。 下面是强制的例子：

public class ViewModel : DependencyObject
{
  public bool TestBool
  {
    get { return (bool)GetValue(TestBoolProperty); }
    set { SetValue(TestBoolProperty, value); }
  }
  public static readonly DependencyProperty TestBoolProperty =
    DependencyProperty.Register("TestBool", typeof(bool), typeof(ViewModel), new PropertyMetadata(false, OnTestBoolPropertyChanged));

  private static void OnTestBoolPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
  {
    var vm = (ViewModel)d;
    vm.CoerceValue(TestDoubleProperty);
  }

  public double TestDouble
  {
    get { return ((double)GetValue(TestDoubleProperty)); }
    set { SetValue(TestDoubleProperty, value); }
  }
  public static readonly DependencyProperty TestDoubleProperty =
    DependencyProperty.Register("TestDouble", typeof(double), typeof(ViewModel), new PropertyMetadata(0.0, null, OnCoerceTestDouble));

  private static object OnCoerceTestDouble(DependencyObject d, object baseValue)
  {
    var vm = (ViewModel) d;
    var testBool = vm.TestBool;
    return ((testBool) ? (100.0) : (200.0));
  }
}

Answer 2:

你实际上是正确的，你应该使用PropertyChangedCallback。 这是如何做：

public bool TestBool
{
  get { return (bool)GetValue(TestBoolProperty); }
  set 
  { 
    SetValue(TestBoolProperty, value);
  }
}
public static readonly DependencyProperty TestBoolProperty =
  DependencyProperty.Register("TestBool", typeof(bool), typeof(ViewModel),
  new PropertyMetadata(false, new PropertyChangedCallback(OnTestBoolChanged)));

private static void OnTestBoolChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
  ViewModel vm = d as ViewModel;
  vm.TestDouble = value ? 100.0 : 200.0;
}

public double TestDouble
{
  get { return ((double)GetValue(TestDoubleProperty)); }
  set { SetValue(TestDoubleProperty, value); }
}
public static readonly DependencyProperty TestDoubleProperty =
  DependencyProperty.Register("TestDouble", typeof(double), typeof(ViewModel));

文章来源: Dependency Property dependent on another