wpf - 按钮的前景在属性触发器中没有改变

Question

为什么这个触发器起作用(当鼠标悬停时将按钮的前景更改为“红色”)

<Grid>
 <Grid.Resources>
  <Style TargetType="{x:Type Button}">
   <Style.Triggers>
    <Trigger Property="IsMouseOver" Value="True">
     <Setter Property="Foreground" Value="Red"/>
    </Trigger>
   </Style.Triggers>
  </Style>
 </Grid.Resources>
 <Button Content="Hello"/>
</Grid>

但不是这个触发器，当按钮的前景设置为颜色(在这种情况下为“蓝色”)？

<Grid>
 <Grid.Resources>
  <Style TargetType="{x:Type Button}">
   <Style.Triggers>
    <Trigger Property="IsMouseOver" Value="True">
     <Setter Property="Foreground" Value="Red"/>
    </Trigger>
   </Style.Triggers>
  </Style>
 </Grid.Resources>
 <Button Foreground="Blue" Content="Hello"/>
</Grid>

Answer 1

按钮的本地值会覆盖样式。尝试:

<Grid>

    <Grid.Resources>
        <Style TargetType="{x:Type Button}">
            <Setter Property="Foreground" Value="Blue"/>
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter Property="Foreground" Value="Red"/>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Grid.Resources>

    <Button Content="Hello"/>

</Grid>