UWP Button添加圓角陰影（一）

時間 2019-11-07

標籤 uwp button 添加圓角陰影简体版

原文原文鏈接

原文：UWP Button添加圓角陰影（一）
衆所周知，17763以前的UWP控件，大部分是沒有圓角屬性的；而陰影也只有17763中的ThemeShadow能夠直接在xaml中使用，以前的版本只能用DropShadow，用法極其彆扭。
本文就給出一個雖然很彆扭，可是效果還不錯的，比較通用的圓角+陰影的方案。html

概念

咱們先思考一下，用戶感知到的圓角按鈕，究竟是個什麼東西。
任何一個按鈕，不外乎Background和Content兩部分，用戶能夠從Content中獲取到按鈕的信息，而按鈕的形狀，在沒有Border的狀況下，用戶對Button形狀最直觀的感覺就是Background！
也就是說，咱們只要讓一個按鈕的Background是一個圓角矩形，他在大多數狀況下，就是一個圓角按鈕！
按照這個思路，咱們能夠在17763以前的UWP，也就是大多數控件都沒有CornerRadius這個屬性的環境裏，造出許多圓角的控件。佈局

圓角

從Generic.xaml中，把Button的Style複製出一份，刪除沒有必要的東西，就成了下面的樣子：spa

<Style TargetType="Button">
    <Setter Property="Background" Value="{ThemeResource ButtonBackground}" />
    <Setter Property="Foreground" Value="{ThemeResource ButtonForeground}" />
    <Setter Property="BorderBrush" Value="{ThemeResource ButtonBorderBrush}" />
    <Setter Property="BorderThickness" Value="{ThemeResource ButtonBorderThemeThickness}" />
    <Setter Property="Padding" Value="8,4,8,4" />
    <Setter Property="HorizontalAlignment" Value="Left" />
    <Setter Property="VerticalAlignment" Value="Center" />
    <Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
    <Setter Property="FontWeight" Value="Normal" />
    <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
    <Setter Property="UseSystemFocusVisuals" Value="True" />
    <Setter Property="FocusVisualMargin" Value="-3" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <Grid x:Name="RootGrid" Background="{TemplateBinding Background}">
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Normal" />
                            <VisualState x:Name="PointerOver">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="RootGrid" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonBackgroundPointerOver}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="BorderBrush">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonBorderBrushPointerOver}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonForegroundPointerOver}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Pressed">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="RootGrid" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonBackgroundPressed}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="BorderBrush">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonBorderBrushPressed}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonForegroundPressed}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Disabled">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="RootGrid" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonBackgroundDisabled}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="BorderBrush">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonBorderBrushDisabled}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonForegroundDisabled}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <ContentPresenter x:Name="ContentPresenter"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}"
                        Content="{TemplateBinding Content}"
                        ContentTransitions="{TemplateBinding ContentTransitions}"
                        ContentTemplate="{TemplateBinding ContentTemplate}"
                        Padding="{TemplateBinding Padding}"
                        HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
                        VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
                        AutomationProperties.AccessibilityView="Raw" />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

其實大部份內容不重要，咱們先來分析一下這個結構，刪掉全部佈局以外的屬性，就剩下很單純的Grid裝着一個ContentPresenter，是這樣的：code

<Style TargetType="Button" x:Key="CornerRadiusShadowButtonStyle">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <Grid x:Name="RootGrid">
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Normal" />
                            <VisualState x:Name="PointerOver"/>
                            <VisualState x:Name="Pressed"/>
                            <VisualState x:Name="Disabled"/>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <ContentPresenter x:Name="ContentPresenter"/>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

圓角的屬性呢，只有在Border，Rectangle中有，固然你要是足夠閒，也能夠擼Path...
結果很明顯了對吧，這就是圓角的兩個實現方式，ContentPresenter外面套Border，或者後面放Rectangle當Background。
Border的方式呢，優缺點都很明顯。
優勢是Border的CornerRadius能夠分別設置四個角的半徑，並且能夠設置給Button設置Border相關屬性的時候，讓Border的相關屬性按照咱們定義的Border的形狀去繪製。
缺點呢，就是在PC端，Border設置CornerRadius後，會Clip掉內容超出Border的部分（因爲17763以前的UWP沒有GeometryClip，因此這個圓角Clip也算是個特性...），其實咱們能夠利用這個特性作圓形頭像，圓形播放器啥的...
而Rectangle呢，雖然不能分別設置四個角的半徑，可是能夠分別設置X的半徑和Y的半徑...提及來感受好詭異...
出我的喜愛，還有我不喜歡畫Border的風格，就選Rectangle的解決方案了。修改完成以後的Style結構應該是這個模樣的：orm

<Style TargetType="Button" x:Key="CornerRadiusShadowButtonStyle">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <Grid x:Name="RootGrid">
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Normal" />
                            <VisualState x:Name="PointerOver"/>
                            <VisualState x:Name="Pressed"/>
                            <VisualState x:Name="Disabled"/>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <Rectangle x:Name="Background" />
                    <ContentPresenter x:Name="ContentPresenter"/>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

注意事項：VisualStateManager必須放到控件根元素內，好比Page的VisualStateManager就必須放到Page內第一個元素好比Grid或者StackPanel裏，否則是不會生效的。
xml

完整版是這樣的，有改顏色的需求能夠擼一下VisualState裏的顏色：htm

<Style TargetType="Button" x:Key="CornerRadiusShadowButtonStyle">
    <Setter Property="Background" Value="{ThemeResource ButtonBackground}"/>
    <Setter Property="Foreground" Value="{ThemeResource ButtonForeground}"/>
    <Setter Property="BorderBrush" Value="Transparent" />
    <Setter Property="BorderThickness" Value="0" />
    <Setter Property="Padding" Value="20,10,20,10" />
    <Setter Property="HorizontalAlignment" Value="Left" />
    <Setter Property="VerticalAlignment" Value="Center" />
    <Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
    <Setter Property="FontWeight" Value="Normal" />
    <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
    <Setter Property="UseSystemFocusVisuals" Value="True" />
    <Setter Property="FocusVisualMargin" Value="-3" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <Grid x:Name="RootGrid">
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Normal" />
                            <VisualState x:Name="PointerOver">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonBackgroundPointerOver}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Pressed">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonBackgroundPressed}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Disabled">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ButtonBackgroundDisabled}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <Rectangle x:Name="Background" Fill="{TemplateBinding Background}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" RadiusX="5" RadiusY="5" />
                    <ContentPresenter x:Name="ContentPresenter"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}"
                        Content="{TemplateBinding Content}"
                        ContentTransitions="{TemplateBinding ContentTransitions}"
                        ContentTemplate="{TemplateBinding ContentTemplate}"
                        Padding="{TemplateBinding Padding}"
                        HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
                        VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
                        AutomationProperties.AccessibilityView="Raw" />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

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