如何移除WPF中ImageBrush的模糊投影效果？

问题根源是MaterialDesign主题的Button默认带有投影效果或特定背景渲染逻辑，和自定义ImageBrush叠加后产生了异常模糊。以下是几种可行的解决方法：

方法1：完全重写按钮模板，移除默认视觉效果 #

直接自定义按钮的ControlTemplate，替换掉MaterialDesign自带的带投影的模板：

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style TargetType="Button" x:Key="SeamlessBtn">
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="BorderBrush" Value="Transparent"/>
        <Setter Property="BorderThickness" Value="0"/>
        <Setter Property="Padding" Value="0"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Button">
                    <Border Background="{TemplateBinding Background}" 
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}">
                        <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter Property="Background" Value="Transparent"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

方法2：直接禁用MaterialDesign的投影效果 #

引入MaterialDesign命名空间后，通过ShadowAssist关闭按钮投影：

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes">
    <Style BasedOn="{StaticResource {x:Type Button}}" TargetType="Button" x:Key="SeamlessBtn">
        <Setter Property="materialDesign:ShadowAssist.ShadowDepth" Value="None"/>
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="BorderBrush" Value="Transparent"/>
        <Style.Triggers>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter Property="Background" Value="Transparent"/>
                <Setter Property="BorderBrush" Value="Transparent"/>
            </Trigger>
        </Style.Triggers>
    </Style>
</ResourceDictionary>

方法3：改用Image作为按钮内容（更推荐） #

放弃用ImageBrush做背景，直接将Image放在按钮的Content区域，避免背景层叠加的渲染冲突：
按钮代码：

<Button Style="{StaticResource SeamlessBtn}" Width="30" Height="30" Click="ToggleTheme" 
        BorderBrush="Transparent" Margin="10,10,105,408">
    <Image Source="/Images/BootstrapIcons-MoonFill.png" Width="24" Height="24"/>
</Button>

配套样式：

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style BasedOn="{StaticResource {x:Type Button}}" TargetType="Button" x:Key="SeamlessBtn">
        <Setter Property="Padding" Value="0"/>
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="BorderBrush" Value="Transparent"/>
        <Style.Triggers>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter Property="Background" Value="Transparent"/>
                <Setter Property="BorderBrush" Value="Transparent"/>
            </Trigger>
        </Style.Triggers>
    </Style>
</ResourceDictionary>

内容的提问来源于stack exchange，提问作者probablydiary