如果没有绑定元素,则会使默认可见性折叠

Question

我有一个带有文本框和按钮的用户控件,它们绑定到viewmodel的属性.

    <Grid>
        <StackPanel>
            <TextBox Text=" Hi" IsEnabled="{Binding IsReadOnly, UpdateSourceTrigger=PropertyChanged}"></TextBox>
            <Button Content="B" Visibility="{Binding IsVisible, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource BooleanToVisibilityConverter}}"></Button>
        </StackPanel>
    </Grid>

如果没有为此usercontrol提供datacontext,如何使按钮不可见？

Answer 1

FallbackValue

<Button Content="B" Visibility="{Binding IsVisible,
                                 UpdateSourceTrigger=PropertyChanged,  
                                 Converter={StaticResource BooleanToVisibilityConverter}}, 
                                 FallbackValue=Collapsed"></Button>