当MaxWidth或Width等属性发生变化时，UWP中的TimePicker控件不会重新调整大小，我应该设置另一个属性，还是只需要找到解决办法？
经过一些调查后，您似乎只能使用“填充”属性更改TimePicker的大小。
您需要更改TimePicker的默认样式。例如，请在Page.Ressources中添加以下样式。我更改的唯一值是MaxWidth到800 - 默认值为456.然后，您应该能够使用Width属性最大化您的控件。
<Page.Resources>
<!-- Default style for Windows.UI.Xaml.Controls.TimePicker -->
<Style TargetType="TimePicker">
<Setter Property="IsTabStop" Value="False" />
<Setter Property="MinWidth" Value="242" />
<Setter Property="MaxWidth" Value="800" />
<Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
<Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
<Setter Property="Foreground" Value="{ThemeResource SystemControlForegroundBaseHighBrush}"/>
<Setter Property="HorizontalAlignment" Value="Left" />
<Setter Property="VerticalAlignment" Value="Center"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TimePicker">
<StackPanel x:Name="LayoutRoot" Margin="{TemplateBinding Padding}">
<StackPanel.Resources>
<Style x:Key="TimePickerFlyoutButtonStyle" TargetType="Button">
<Setter Property="UseSystemFocusVisuals" Value="False" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Button">
<Grid Background="{TemplateBinding Background}">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal" />
<VisualState x:Name="PointerOver">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="BorderBrush">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumBrush}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlPageBackgroundAltMediumBrush}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseHighBrush}" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlBackgroundBaseLowBrush}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="BorderBrush">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumLowBrush}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseHighBrush}" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlBackgroundBaseLowBrush}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="BorderBrush">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseLowBrush}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseLowBrush}" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightListAccentLowBrush}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter"
Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltBaseHighBrush}" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused" />
<VisualState x:Name="PointerFocused" />
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<ContentPresenter x:Name="ContentPresenter"
BorderBrush="{ThemeResource SystemControlForegroundBaseMediumLowBrush}"
Background="{ThemeResource SystemControlBackgroundAltMediumLowBrush}"
BorderThickness="2"
Content="{TemplateBinding Content}"
Foreground="{TemplateBinding Foreground}"
HorizontalContentAlignment="Stretch"
VerticalContentAlignment="Stretch"
AutomationProperties.AccessibilityView="Raw"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</StackPanel.Resources>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal" />
<VisualState x:Name="Disabled">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="HeaderContentPresenter"
Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseLowBrush}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="FirstColumnDivider"
Storyboard.TargetProperty="Fill">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseLowBrush}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="SecondColumnDivider"
Storyboard.TargetProperty="Fill">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseLowBrush}" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<ContentPresenter x:Name="HeaderContentPresenter"
x:DeferLoadStrategy="Lazy"
Visibility="Collapsed"
Content="{TemplateBinding Header}"
ContentTemplate="{TemplateBinding HeaderTemplate}"
Margin="0,0,0,8"
Foreground="{ThemeResource SystemControlForegroundBaseHighBrush}"
AutomationProperties.AccessibilityView="Raw" />
<Button x:Name="FlyoutButton"
Style="{StaticResource TimePickerFlyoutButtonStyle}"
Foreground="{TemplateBinding Foreground}"
Background="{TemplateBinding Background}"
IsEnabled="{TemplateBinding IsEnabled}"
HorizontalAlignment="Stretch"
HorizontalContentAlignment="Stretch">
<Grid x:Name="FlyoutButtonContentGrid">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" x:Name="FirstTextBlockColumn" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" x:Name="SecondTextBlockColumn" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" x:Name="ThirdTextBlockColumn" />
</Grid.ColumnDefinitions>
<Border x:Name="FirstPickerHost" Grid.Column="0">
<TextBlock x:Name="HourTextBlock" TextAlignment="Center" Padding="0,3,0,5" FontFamily="{TemplateBinding FontFamily}" FontWeight="{TemplateBinding FontWeight}" FontSize="{TemplateBinding FontSize}" AutomationProperties.AccessibilityView="Raw"/>
</Border>
<Rectangle x:Name="FirstColumnDivider" Fill="{ThemeResource SystemControlForegroundBaseLowBrush}" HorizontalAlignment="Center" Width="2" Grid.Column="1" />
<Border x:Name="SecondPickerHost" Grid.Column="2">
<TextBlock x:Name="MinuteTextBlock" TextAlignment="Center" Padding="0,3,0,5" FontFamily="{TemplateBinding FontFamily}" FontWeight="{TemplateBinding FontWeight}" FontSize="{TemplateBinding FontSize}" AutomationProperties.AccessibilityView="Raw"/>
</Border>
<Rectangle x:Name="SecondColumnDivider" Fill="{ThemeResource SystemControlForegroundBaseLowBrush}" HorizontalAlignment="Center" Width="2" Grid.Column="3" />
<Border x:Name="ThirdPickerHost" Grid.Column="4">
<TextBlock x:Name="PeriodTextBlock" TextAlignment="Center" Padding="0,3,0,5" FontFamily="{TemplateBinding FontFamily}" FontWeight="{TemplateBinding FontWeight}" FontSize="{TemplateBinding FontSize}" AutomationProperties.AccessibilityView="Raw"/>
</Border>
</Grid>
</Button>
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Page.Resources>
根据项目的目标SDK，有不同的解决方法。
当项目以Windows 10 1709 10.0.16299.0设置为目标时，TimePicker的MinWidth属性足以减小其宽度。
当项目针对Windows 10 1803 10.0.17763.0替换App.xaml文件中的默认TimePickerThemeMinWidth值时，可以解决这个问题：
<ResourceDictionary.ThemeDictionaries>
<ResourceDictionary x:Key="Default">
<x:Double x:Key="TimePickerThemeMinWidth">140</x:Double>
</ResourceDictionary>
<ResourceDictionary x:Key="Dark">
<x:Double x:Key="TimePickerThemeMinWidth">140</x:Double>
</ResourceDictionary>
<ResourceDictionary x:Key="Light">
<x:Double x:Key="TimePickerThemeMinWidth">140</x:Double>
</ResourceDictionary>
</ResourceDictionary.ThemeDictionaries>