Question

我声明了两个Dependency属性：首先，类型为Color的FilterColor 和第二个类型为BrushBrush的Brush。当FilterBrush.Color属性发生变化时，我需要更新FilterColor的值，当FilterColor属性发生变化时，我需要更新FilterBrush.Color的值。我怎么能意识到它？

Answer 1

使用TwoWay绑定绑定两个属性，如果在UI中更改一个属性，请在属性设置器和反向Versa中更改另一个属性，并使用INotifyPropertyChanged通知UI该属性已更改。

Answer 2

您可以在DependencyProperty定义中执行此操作，也可以使用DependencyPropertyDescriptor之后执行此操作

例如......

DependencyProperty定义：

public static readonly DependencyProperty FilterColorProperty =
    DependencyProperty.Register("FilterColor", typeof(Color),
    typeof(MyUserControl),
    new PropertyMetadata(Colors.White, FilterColorChanged));

public static void FilterColorChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
    if (!(obj is MyUserControl))
        return;

    MyUserControl ctrl = (MyUserControl)obj;
    var brush = ctrl.GetBrushProperty();

    if (brush.Color != (Color)e.NewValue)
        brush.Color = (Color)e.NewValue;
}

DependencyProperty Descriptor：

DependencyPropertyDescriptor dpd = DependencyPropertyDescriptor.FromProperty(
    MyUserControl.FilterColorProperty, typeof(MyUserControl));

if (dpd != null) 
    dpd.AddValueChanged(this, delegate { FilterColor_Changed(); });

...

private void FilterColor_Changed()
{
    Color filterColor = GetFilterColor(this);
    var brush = GetBrush(this);
    if (filterColor != brush.Color)
        brush.Color = filterColor;
}

我可能有一些语法错误......我没有编译器来检查代码

Answer 3

您在哪里定义了这些属性：在视图模型中还是在控件中？

如果它在视图模型中，你应该使用INotifyPropertyChanged而不是像这样的依赖属性：

Color _filterColor;

public Color FilterColor
{
    get
    {
        return _filterColor;
    }
    {
        if (_filterColor != value)
        {
            _filterColor = value;
            RaisePropertyChanged(() => FilterColor);

            _OnFilterColorChanged();
        }
}

void _OnFilterColorChanged()
{
    _filterBrush= ...
    RaisePropertyChanged(() => FilterBrush);
}

Brush _filterBrush;

public Brush FilterBrush
{
    get
    {
        return _filterBrush;
    }
    {
        if (_filterBrush != value)
        {
            _filterBrush = value;
            RaisePropertyChanged(() => FilterBrush);

            _OnFilterBrushChanged();
        }
}

void _OnFilterBrushChanged()
{
    _filterColor= ...
    RaisePropertyChanged(() =. FilterColor);
}

如果它在控制中，请执行以下操作：

public Color FilterColor
{
    get { return (Color)GetValue(FilterColorProperty); }
    set { SetValue(FilterColorProperty, value); }
}
public static readonly DependencyProperty FilterColorProperty =
    DependencyProperty.Register("FilterColor", typeof(Color), typeof(MainWindow), new UIPropertyMetadata(Colors.Transparent, new PropertyChangedCallback(_OnFilterColorPropertyChanged)));

static void _OnFilterColorPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    var mw = d as MainWindow;

    Color oldValue = (Color)e.OldValue;
    Color newValue = (Color)e.NewValue;

    if (null != mw && oldValue != newValue)
    {
        mw._OnFilterColorChanged(oldValue, newValue);
    }
}

bool _isFilterColorUpdating = false;

void _OnFilterColorChanged(Color oldValue, Color newValue)
{
    if (_isFilterBrushUpdating )
        return;

    _isFilterColorUpdating = true;
    Brush = ...
    _isFilterColorUpdating = false;
}

public Brush FilterBrush
{
    get { return (Brush)GetValue(FilterBrushProperty); }
    set { SetValue(FilterBrushProperty, value); }
}
public static readonly DependencyProperty FilterBrushProperty =
    DependencyProperty.Register("FilterBrush", typeof(Brush), typeof(MainWindow), new UIPropertyMetadata(Brushs.Transparent, new PropertyChangedCallback(_OnFilterBrushPropertyChanged)));

static void _OnFilterBrushPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    var mw = d as MainWindow;

    Brush oldValue = (Brush)e.OldValue;
    Brush newValue = (Brush)e.NewValue;

    if (null != mw && oldValue != newValue)
    {
        mw._OnFilterBrushChanged(oldValue, newValue);
    }
}

bool _isFilterBrushUpdating = false;
void _OnFilterBrushChanged(Brush oldValue, Brush newValue)
{
    if (_isFilterColorUpdating )
        return;

    _isFilterBrushUpdating = true;
    Color = ...
    _isFilterBrushUpdating = false;
}

请注意，最后一种方式只是破解，这是非常糟糕的方式，我更喜欢第一种方式。

在WPF中绑定两个依赖项属性

3 个答案: