问题描述

据我了解，我应该使用样式触发器来更新 TextBox 的边框颜色.但是无论我做什么，它总是变成系统默认的蓝色，而不是我指定的黑色.

As far as I understand I should be using Style triggers to update the TextBox's border colour when it is focused. However no matter what I do it always turns to the system default blue, not the black I have specified.

有人有什么想法吗?

代码如下:

<UserControl.Resources>
    <Style TargetType="TextBox">
        <Style.Triggers>
            <Trigger Property="IsFocused" Value="True">
                <Setter Property="BorderBrush" Value="Black" />
            </Trigger>
        </Style.Triggers>
    </Style>
</UserControl.Resources>

推荐答案

尝试设置BorderThickness值大于1(默认):

Try set for BorderThickness value more than 1 (by default):

<Window.Resources>
    <Style TargetType="{x:Type TextBox}">
        <Style.Triggers>
            <Trigger Property="IsFocused" Value="True">
                <Setter Property="BorderBrush" Value="Pink" />
            </Trigger>
        </Style.Triggers>
    </Style>
</Window.Resources>

<Grid>
    <TextBox Width="100"
             Height="30"
             Text="Test" 
             BorderThickness="4" />
</Grid>

在 Windows 7 上测试.

Tested on Windows Seven.

为什么会这样?

我在 Windows 7 下的 Blend 中查看了 TextBox 的默认样式，这里是 ControlTemplate:

I looked in the default style for TextBox in Blend under Windows 7, here it is ControlTemplate:

<ControlTemplate x:Key="TextBoxControlTemplate1" TargetType="{x:Type TextBox}">
    <Microsoft_Windows_Themes:ListBoxChrome x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" RenderMouseOver="{TemplateBinding IsMouseOver}" RenderFocused="{TemplateBinding IsKeyboardFocusWithin}" SnapsToDevicePixels="true">
        <ScrollViewer x:Name="PART_ContentHost" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
    </Microsoft_Windows_Themes:ListBoxChrome>

    <ControlTemplate.Triggers>
        <Trigger Property="IsEnabled" Value="false">
            <Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
            <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
        </Trigger>
    </ControlTemplate.Triggers>
</ControlTemplate>

这里有两个参数:

RenderMouseOver="{TemplateBinding IsMouseOver}"
RenderFocused="{TemplateBinding IsKeyboardFocusWithin}"

当状态 Focus 和 MouseOver 时，它们负责蓝色渐变边框，并且可能在 BorderThickness 和 BorderBrush<上存在条件/代码>.如果他们remove/reset蓝色渐变边框将消失，并且不需要将 BorderThickness 的值设置为大于 1.

internal override void ChangeVisualState(bool useTransitions)
{
    if (!base.IsEnabled)
    {
        VisualStateManager.GoToState(this, "Disabled", useTransitions);
    }
    else
    {
        if (this.IsReadOnly)
        {
            VisualStateManager.GoToState(this, "ReadOnly", useTransitions);
        }
        else
        {
            if (base.IsMouseOver)
            {
                VisualStateManager.GoToState(this, "MouseOver", useTransitions);
            }
            else
            {
                VisualStateManager.GoToState(this, "Normal", useTransitions);
            }
        }
    }

    if (base.IsKeyboardFocused)
    {
        VisualStateManager.GoToState(this, "Focused", useTransitions);
    }
    else
    {
        VisualStateManager.GoToState(this, "Unfocused", useTransitions);
    }

    base.ChangeVisualState(useTransitions);
}