(UWP)如何使密码显示按钮始终可见，并使其始终在PasswordBox中工作

Question

我在我的UWP应用程序中使用PasswordBox，我想在其中始终显示密码显示按钮。此外，按下它应该像预期的那样工作，应该显示密码。

我已经修改了PasswordBox控件的默认样式，将密码显示按钮的可见性设置为true。它的工作和按钮总是可见的现在。但问题是密码显示功能只有在清除密码并从头输入时才有效。

<Style x:Key="PasswordBoxStyle" TargetType="PasswordBox">
        <Setter Property="Foreground" Value="Black"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="PasswordBox">
                    <Grid Background="Transparent">
                        <Grid.Resources>
                            <Style x:Name="RevealButtonStyle" TargetType="Button">
                                <Setter Property="Template">
                                    <Setter.Value>
                                        <ControlTemplate TargetType="Button">
                                            <Grid x:Name="ButtonLayoutGrid" BorderBrush="{ThemeResource TextBoxButtonBorderThemeBrush}"
                                                    BorderThickness="{TemplateBinding BorderThickness}"
                                                    Background="{ThemeResource TextBoxButtonBackgroundThemeBrush}">
                                                <VisualStateManager.VisualStateGroups>
                                                    <VisualStateGroup x:Name="CommonStates">
                                                        <VisualState x:Name="Normal" />
                                                        <VisualState x:Name="PointerOver">
                                                            <Storyboard>
                                                                <ObjectAnimationUsingKeyFrames Storyboard.TargetName="GlyphElement"
                                                             Storyboard.TargetProperty="Foreground">
                                                                    <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAccentBrush}" />
                                                                </ObjectAnimationUsingKeyFrames>
                                                            </Storyboard>
                                                        </VisualState>
                                                        <VisualState x:Name="Pressed">
                                                            <Storyboard>
                                                                <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ButtonLayoutGrid"
                                                             Storyboard.TargetProperty="Background">
                                                                    <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAccentBrush}" />
                                                                </ObjectAnimationUsingKeyFrames>
                                                                <ObjectAnimationUsingKeyFrames Storyboard.TargetName="GlyphElement"
                                                             Storyboard.TargetProperty="Foreground">
                                                                    <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltChromeWhiteBrush}" />
                                                                </ObjectAnimationUsingKeyFrames>
                                                            </Storyboard>
                                                        </VisualState>
                                                        <VisualState x:Name="Disabled">
                                                            <Storyboard>
                                                                <DoubleAnimation Storyboard.TargetName="ButtonLayoutGrid"
                                               Storyboard.TargetProperty="Opacity"
                                               To="0"
                                               Duration="0" />
                                                            </Storyboard>
                                                        </VisualState>
                                                    </VisualStateGroup>
                                                </VisualStateManager.VisualStateGroups>
                                                <TextBlock x:Name="GlyphElement"
                                  Foreground="{ThemeResource SystemControlForegroundChromeBlackMediumBrush}"
                                  VerticalAlignment="Center"
                                  HorizontalAlignment="Center"
                                  FontStyle="Normal"
                                  FontSize="16"
                                  Text="&#xE052;"
                                  FontFamily="{ThemeResource SymbolThemeFontFamily}"
                                  AutomationProperties.AccessibilityView="Raw"/>
                                            </Grid>
                                        </ControlTemplate>
                                    </Setter.Value>
                                </Setter>
                            </Style>
                        </Grid.Resources>
                        <VisualStateManager.VisualStateGroups>
                            <VisualStateGroup x:Name="CommonStates">
                                <VisualState x:Name="Disabled">
                                    <Storyboard>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HeaderContentPresenter"
                                                   Storyboard.TargetProperty="Foreground">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseMediumLowBrush}" />
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="BackgroundElement"
                                                 Storyboard.TargetProperty="Background">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledTransparentBrush}" />
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="BorderElement"
                                                 Storyboard.TargetProperty="Background">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlBackgroundBaseLowBrush}" />
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="BorderElement"
                                                 Storyboard.TargetProperty="BorderBrush">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseLowBrush}" />
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentElement"
                                                 Storyboard.TargetProperty="Foreground">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledChromeDisabledLowBrush}" />
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="PlaceholderTextContentPresenter"
                                                 Storyboard.TargetProperty="Foreground">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledChromeDisabledLowBrush}" />
                                        </ObjectAnimationUsingKeyFrames>
                                    </Storyboard>
                                </VisualState>
                                <VisualState x:Name="Normal">
                                    <Storyboard>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="BorderElement">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="Gray"/>
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderThickness" Storyboard.TargetName="BorderElement">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="0.5"/>
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="BackgroundElement">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="White"/>
                                        </ObjectAnimationUsingKeyFrames>
                                    </Storyboard>
                                </VisualState>
                                <VisualState x:Name="PointerOver">
                                    <Storyboard>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="BorderElement">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="Gray"/>
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderThickness" Storyboard.TargetName="BorderElement">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="1"/>
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="BackgroundElement">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="White"/>
                                        </ObjectAnimationUsingKeyFrames>
                                    </Storyboard>
                                </VisualState>
                                <VisualState x:Name="Focused">
                                    <Storyboard>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="BorderElement">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="Gray"/>
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderThickness" Storyboard.TargetName="BorderElement">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="1"/>
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="BackgroundElement">
                                            <DiscreteObjectKeyFrame KeyTime="0" Value="White"/>
                                        </ObjectAnimationUsingKeyFrames>
                                    </Storyboard>
                                </VisualState>
                            </VisualStateGroup>
                            <VisualStateGroup x:Name="ButtonStates">
                                <VisualState x:Name="ButtonVisible">
                                    <Storyboard>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="RevealButton"
                                                 Storyboard.TargetProperty="Visibility">
                                            <DiscreteObjectKeyFrame KeyTime="0">
                                                <DiscreteObjectKeyFrame.Value>
                                                    <Visibility>Visible</Visibility>
                                                </DiscreteObjectKeyFrame.Value>
                                            </DiscreteObjectKeyFrame>
                                        </ObjectAnimationUsingKeyFrames>
                                    </Storyboard>
                                </VisualState>
                                <VisualState x:Name="ButtonCollapsed" />
                            </VisualStateGroup>
                        </VisualStateManager.VisualStateGroups>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*" />
                            <ColumnDefinition Width="Auto" />
                        </Grid.ColumnDefinitions>
                        <Grid.RowDefinitions>
                            <RowDefinition Height="Auto" />
                            <RowDefinition Height="*" />
                        </Grid.RowDefinitions>
                        <Border x:Name="BackgroundElement"
                  Grid.Row="1"
                  Background="{TemplateBinding Background}"
                  Margin="{TemplateBinding BorderThickness}"
                  Opacity="{ThemeResource TextControlBackgroundRestOpacity}"
                  Grid.ColumnSpan="2"
                  Grid.RowSpan="1"/>
                        <Border x:Name="BorderElement"
                  Grid.Row="1"
                  BorderBrush="{TemplateBinding BorderBrush}"
                  BorderThickness="{TemplateBinding BorderThickness}"
                  Grid.ColumnSpan="2"
                  Grid.RowSpan="1"/>
                        <ContentPresenter x:Name="HeaderContentPresenter"
                            x:DeferLoadStrategy="Lazy"
                            Visibility="Collapsed"
                            Grid.Row="0"
                            Foreground="{ThemeResource SystemControlForegroundBaseHighBrush}"
                            Margin="0,0,0,8"
                            Grid.ColumnSpan="2"
                            Content="{TemplateBinding Header}"
                            ContentTemplate="{TemplateBinding HeaderTemplate}"
                            FontWeight="Normal" />
                        <ScrollViewer x:Name="ContentElement"
                  Grid.Row="1"
                        HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}"
                        HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
                        VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}"
                        VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}"
                        IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}"
                        IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}"
                        Margin="{TemplateBinding BorderThickness}"
                        Padding="{TemplateBinding Padding}"
                        IsTabStop="False"
                        ZoomMode="Disabled"
                        AutomationProperties.AccessibilityView="Raw"/>
                        <ContentControl x:Name="PlaceholderTextContentPresenter"
                        Grid.Row="1"
                        Foreground="{ThemeResource SystemControlPageTextBaseMediumBrush}"
                        Margin="{TemplateBinding BorderThickness}"
                        Padding="{TemplateBinding Padding}"
                        IsTabStop="False"
                        Grid.ColumnSpan="2"
                        Content="{TemplateBinding PlaceholderText}"
                        IsHitTestVisible="False"/>
                        <Button x:Name="RevealButton"
                  Grid.Row="1"
                  Style="{StaticResource RevealButtonStyle}"
                  BorderThickness="{TemplateBinding BorderThickness}"
                  Margin="{ThemeResource HelperButtonThemePadding}"
                  IsTabStop="False"
                  Grid.Column="1"
                  Visibility="Visible"
                  FontSize="{TemplateBinding FontSize}"
                  VerticalAlignment="Stretch"
                  MinWidth="34" />
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

请注意，我已经改变了下面的样式显示密码按钮有可见性设置为true(它是默认折叠):

<Button x:Name="RevealButton"
                  Grid.Row="1"
                  Style="{StaticResource RevealButtonStyle}"
                  BorderThickness="{TemplateBinding BorderThickness}"
                  Margin="{ThemeResource HelperButtonThemePadding}"
                  IsTabStop="False"
                  Grid.Column="1"
                  Visibility="Visible"
                  FontSize="{TemplateBinding FontSize}"
                  VerticalAlignment="Stretch"
                  MinWidth="34" />

Answer 1

这是设计的，您可以参考PasswordBox:

密码显示按钮仅在PasswordBox第一次收到焦点并输入字符时显示。如果PasswordBox失去焦点，然后恢复焦点，显示按钮不会再次显示，除非密码被清除，字符输入重新开始。

默认情况下，它的行为是这样的，即使你使RevealButton始终可见，现在的问题是这个Button不能正常工作。

官方推荐的方法是创建一个类似的UI，例如CheckBox，让用户切换显示模式。我还注意到，你在样式中将默认的ToggleButton更改为Button，如果你坚持使用这个Button来切换显示模式，你可以在后面编写代码，例如:

public Page21()
{
    this.InitializeComponent();
    this.Loaded += Page21_Loaded;
}
private Button RevealButton;
private void Page21_Loaded(object sender, RoutedEventArgs e)
{
    RevealButton = FindChildOfType<Button>(passwordbox);
    RevealButton.Tapped += RevealButton_Tapped;
    RevealButton.ClickMode = ClickMode.Press;
    RevealButton.Click += RevealButton_Click;
    RevealButton.RightTapped += RevealButton_RightTapped;
}
private void RevealButton_RightTapped(object sender, RightTappedRoutedEventArgs e)
{
    Debug.WriteLine("RevealButton_RightTapped");
    passwordbox.PasswordRevealMode = PasswordRevealMode.Hidden;
}
private void RevealButton_Tapped(object sender, TappedRoutedEventArgs e)
{
    Debug.WriteLine("RevealButton_Tapped");
    passwordbox.PasswordRevealMode = PasswordRevealMode.Hidden;
}
private void RevealButton_Click(object sender, RoutedEventArgs e)
{
    Debug.WriteLine("RevealButton_Click");
    passwordbox.PasswordRevealMode = PasswordRevealMode.Visible;
}
public static T FindChildOfType<T>(DependencyObject root) where T : class
{
    var queue = new Queue<DependencyObject>();
    queue.Enqueue(root);
    while (queue.Count > 0)
    {
        DependencyObject current = queue.Dequeue();
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(current); i++)
        {
            var child = VisualTreeHelper.GetChild(current, i);
            var typedChild = child as T;
            if (typedChild != null)
            {
                return typedChild;
            }
            queue.Enqueue(child);
        }
    }
    return null;
}

这里的基本思想是首先在PasswordBox中获得RevealButton，然后更改RevealButton的ClickMode，因此当Button被按下时Click事件将被触发，默认情况下Button的Tapped/RightTapped事件将在指针被释放时被触发，最后您可以在这两个事件中更改PasswordRevealMode。点击事件在PC上运行良好，但在手机上，我使用RightTapped作为Button发布的点。

Answer 2

您可以通过简单地找到按钮并将其可见性设置为Visibility.Visible来使按钮始终可见。我假设默认模板中的按钮使用TemplateBinding，并且它的可见性不是通过编程切换的，因为直接设置它的可见性会破坏任何现有的绑定，比如前面提到的。

我使用以下扩展方法来查找按钮:

public static T GetChildOfType<T>(this DependencyObject Object) where T : DependencyObject
{
    if (Object == null)
        return null;
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(Object); i++)
    {
        var Child = VisualTreeHelper.GetChild(Object, i);
        var Result = (Child as T) ?? GetChildOfType<T>(Child);
        if (Result != null) return Result;
    }
    return null;
}

然后，当PasswordBox加载时，执行如下操作:

private void OnLoaded(object sender, RoutedEventArgs e)
{
    var RevealButton = (sender as PasswordBox).GetChildOfType<Button>();
    if (RevealButton != null)
        RevealButton.Visibility = Visibility.Visible;
}

如果你愿意，你可以定义一个通用的ContentControl类来子类PasswordBox;否则，只需将上述Loaded事件附加到每个实例。

不过有一个缺点:失去焦点后，按钮不再具有切换密码可见性的能力，尽管它是可见的。原因尚不清楚