向仅在聚焦时可见的选择器添加边框？

Question

有没有办法给选择器添加一个只有在聚焦时才可见的边框？我不确定我是否在解释自己，但就像我只希望当用户尝试从选择器中选择一个项目时边框可见。我正在处理 xamarin 表单。这是我的代码。提前谢谢你

    <StackLayout Orientation="Horizontal">
        <Label  VerticalOptions="Start" HorizontalOptions="StartAndExpand"
                Text="Project"
                WidthRequest="100"/>
        <Picker Title="Please Select" HorizontalOptions="StartAndExpand" WidthRequest="255">
            <Picker.Items>
                <x:String>Andalucia</x:String>
                <x:String>Atlantico</x:String>
                <x:String>Berkley Square</x:String>
                <x:String>Cooper City</x:String>
                <x:String>Valencia Bay</x:String>
            </Picker.Items>
            <Picker.Triggers>
                <Trigger TargetType="Picker"
                             Property="IsFocused" Value="True">
                    <Setter Property="BackgroundColor" Value="Azure">
                    </Setter>
                </Trigger>
            </Picker.Triggers>

        </Picker>
    </StackLayout>

Answer 1

将您的 Picker 包含在 Frame（或最适合您需要的其他控件）中可能有效。

<StackLayout Orientation="Horizontal" VerticalOptions="Center">
    <Label  VerticalOptions="Start"
            HorizontalOptions="StartAndExpand"
            Text="Project"
            WidthRequest="100"/>
    <Frame OutlineColor="Transparent" 
           HorizontalOptions="StartAndExpand" 
           WidthRequest="255" 
           Padding="2">
        <Frame.Triggers>
            <Trigger TargetType="Frame" Property="IsFocused" Value="True">
                <Setter Property="OutlineColor" Value="Red" />
            </Trigger>
        </Frame.Triggers>

        <Picker Title="Please Select">
            <Picker.Items>
                <x:String>Andalucia</x:String>
                <x:String>Atlantico</x:String>
                <x:String>Berkley Square</x:String>
                <x:String>Cooper City</x:String>
                <x:String>Valencia Bay</x:String>
            </Picker.Items>
            <Picker.Triggers>
                <Trigger TargetType="Picker" Property="IsFocused" Value="True">
                    <Setter Property="BackgroundColor" Value="Blue" />
                </Trigger>
            </Picker.Triggers>
        </Picker>
    </Frame>
</StackLayout>

向仅在聚焦时可见的选择器添加边框？

add border to a picker that is only visible when focused?

c#

border

picker

xamarin

xamarin.forms