我有以下类将作为绑定(bind)源:
public class Timeline : Canvas, INotifyPropertyChanged
{
public static readonly DependencyProperty TimeTextBindingPropProperty;
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string name)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
public double TimeTextBindingProp
{
get { return (double)GetValue(TimeTextBindingPropProperty); }
set
{
SetValue(TimeTextBindingPropProperty, value);
OnPropertyChanged("TimeTextBindingProp");
}
}
static Timeline()
{
TimeTextBindingPropProperty = DependencyProperty.Register("TimeTextBindingProp", typeof(double), typeof(Timeline));
}
}
然后我在主窗口中设置文本框的 Text
属性和 timeline 的 TimeTextBindingProp
属性之间的绑定(bind):
private void InitTextBinding()
{
timeTextBinding = new Binding();
timeTextBinding.Mode = BindingMode.OneWay;
timeTextBinding.Source = timeline;
timeTextBinding.Path = new PropertyPath("TimeTextBindingProp");
timeTextBinding.Converter = new TimeTextConverter();
BindingOperations.SetBinding(this.timeTextBox, TextBox.TextProperty, timeTextBinding);
}
timeline
的 PropertyChanged
处理程序保持为空,即使在设置绑定(bind)并呈现 timeline
之后也是如此。我做错了什么?
编辑:
我在xaml中声明timeTextBox和timeline如下:
<StackPanel Orientation="Horizontal" Margin="0,10,0,5" HorizontalAlignment="Center" VerticalAlignment="Center">
<TextBox Name="timeTextBox" Margin="0,0,20,0" VerticalAlignment="Center" HorizontalContentAlignment="Center" Height="20"
FontFamily="Tahoma" FontSize="14" BorderBrush="White" Background="White"/>
<Button Name="playButton" Style="{StaticResource buttonStyle}" Click="PlayButton_Click" Margin="0,0,5,0" HorizontalAlignment="Center"
VerticalAlignment="Center">
Play
</Button>
<Button Name="stopButton" Style="{StaticResource buttonStyle}" Click="StopButton_Click" Margin="0,0,20,0" HorizontalAlignment="Center"
VerticalAlignment="Center">
Stop
</Button>
<Slider Name="controlSlider" Height="Auto" Width="200" HorizontalAlignment="Center" VerticalAlignment="Center" IsEnabled="False">
<Slider.ToolTip>
<TextBlock Style="{StaticResource textStyleTextBlock}">Time Slider</TextBlock>
</Slider.ToolTip>
</Slider>
</StackPanel>
<ScrollViewer Name="scrollViewer" Margin="0,0,10,20" Height="500" HorizontalAlignment="Stretch" VerticalAlignment="Center" Focusable="False"
HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto">
<StackPanel>
<UI:FittingCanvas x:Name="containerCanvas">
<timelinePanel:Timeline x:Name="timeline" TimeCursorEnabled="True" TimeMode="Minutes" Canvas.Left="0" Canvas.Top="0" Canvas.ZIndex="0" Visibility="Hidden"
CursorAnimBoundaryChanged="Timeline_CursorAnimBoundaryChanged" AnimationCompleted="Timeline_AnimationCompleted"/>
</UI:FittingCanvas>
<Canvas x:Name="waveFormCanvas" Height="80" Margin="0,10,0,0"/>
</StackPanel>
</ScrollViewer>
最佳答案
除了设置 timeTextBinding
之外,您的代码是否以任何其他方式更新 timeTextBox.Text
?也许您直接在代码隐藏中将 timeTextBox.Text 设置为某个值,或者您有一些其他绑定(bind)连接到它?
因为 timeTextBinding 只是OneWay,这样的更改不能写回 TimeTextBindingProp
,绑定(bind)将被简单地覆盖和删除(没有任何警告),并且 timeline.PropertyChanged
将重置为 null
。
关于c# - PropertyChangedEventHandler 为空,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/14266007/