国内的WPF技术先行者周银辉曾介绍过如何动态改变应用程序的主题样式,今天我们来介绍一种轻量级的改变界面风格的方式——动态改变主题色。 程序允许用户根据自己的喜好来对界面进行配色,这种技术在很多软件中都有应用,比如这款名为AirPlay的音乐播放器软件:

下面我们就来自己动手实现这种技术: 首先在App.xaml文件中定义一个键值为“color”的单色笔刷,这个笔刷就是可以被用户改变的动态资源:

<SolidColorBrush x:Key="color" Color="SkyBlue" />

然后来设计这样一个界面:

我们让用户通过4个滑块来分别定制颜色的ARGB值,其完整代码为:

<Grid>

    <Grid.RowDefinitions>

        <RowDefinition Height="28" />

        <RowDefinition Height="28" />

        <RowDefinition Height="28" />

        <RowDefinition Height="28" />

        <RowDefinition Height="*" />

    </Grid.RowDefinitions>

    <Grid.ColumnDefinitions>

        <ColumnDefinition Width="65*" />

        <ColumnDefinition Width="213*" />

    </Grid.ColumnDefinitions>

    <Label Grid.Row="0" HorizontalContentAlignment="Right">透明度:</Label>

    <Label Grid.Row="1" HorizontalContentAlignment="Right">红色:</Label>

    <Label Grid.Row="2" HorizontalContentAlignment="Right">绿色:</Label>

    <Label Grid.Row="3" HorizontalContentAlignment="Right">蓝色:</Label>

    <Slider Grid.Row="0" Grid.Column="1" Margin="3" Name="a" SmallChange="1" LargeChange="15" Maximum="255" Value="255" />

    <Slider Grid.Row="1" Grid.Column="1" Margin="3" Name="r" SmallChange="1" LargeChange="15" Maximum="255" Value="255" />

    <Slider Grid.Row="2" Grid.Column="1" Margin="3" Name="g" SmallChange="1" LargeChange="15" Maximum="255" Value="255" />

    <Slider Grid.Row="3" Grid.Column="1" Margin="3" Name="b" SmallChange="1" LargeChange="15" Maximum="255" Value="255" />

    <Button Grid.Column="1" Grid.Row="4" HorizontalAlignment="Left" Margin="3,5,0,5" Name="button1" Width="75" Click="button1_Click">更新颜色</Button>

</Grid>

需注意,要把滑块的最大值设为255

然后回到App.xaml中,我们来定义窗口、标签及按钮的样式:

窗口样式代码如下:

<Style x:Key="window" TargetType="Window">

    <Setter Property="OverridesDefaultStyle" Value="true" />

    <Setter Property="AllowsTransparency" Value="true" />

    <Setter Property="SnapsToDevicePixels" Value="true" />

    <Setter Property="WindowStyle" Value="None" />

    <Setter Property="Template">

        <Setter.Value>

            <ControlTemplate TargetType="Window">

                <Border BorderBrush="{DynamicResource color}" BorderThickness="3" CornerRadius="5" Padding="4">

                    <Border BorderBrush="{DynamicResource color}" BorderThickness="3" CornerRadius="5" Background="{DynamicResource color}">

                        <Border BorderBrush="#1000" BorderThickness="3" CornerRadius="5" Padding="6">

                            <Border.Background>

                                <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">

                                    <GradientStop Color="#3FFF" Offset="0.5" />

                                    <GradientStop Color="#1666" Offset="0.5" />

                                </LinearGradientBrush>

                            </Border.Background>

                            <ContentPresenter />

                        </Border>

                    </Border>

                 </Border>

            </ControlTemplate>

        </Setter.Value>

    </Setter>

</Style>

定义样式为几个Border进行嵌套,在最底层引用的之前定义的单色笔刷,在上层用低不透明度的白色和黑色覆盖以产生不同的层次效果。

标签样式为:

<Style TargetType="Label">

    <Setter Property="Foreground" Value="#AAFFFFFF" />

</Style>

按钮样式为:

<Style TargetType="Button">

    <Setter Property="Template">

        <Setter.Value>

            <ControlTemplate TargetType="Button">

                <Border Background="{DynamicResource color}" CornerRadius="3">

                    <Border BorderThickness="2" CornerRadius="3" Padding="{TemplateBinding Padding}">

                        <Border.Background>

                            <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">

                                <GradientStop Color="#6FFF" Offset="0" />

                                <GradientStop Color="#2000" Offset="1" />

                            </LinearGradientBrush>

                        </Border.Background>

                        <Border.BorderBrush>

                            <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">

                                <GradientStop Color="#1000" Offset="0" />

                                <GradientStop Color="#4000" Offset="1" />

                            </LinearGradientBrush>

                        </Border.BorderBrush>

                        <TextBlock TextAlignment="Center" Foreground="#AFFF"><ContentPresenter /></TextBlock>

                    </Border>

                </Border>

            </ControlTemplate>

        </Setter.Value>

    </Setter>

</Style>

其原理与窗口样式相同。

然后回到主界面设计窗口,设置窗体的样式:

Style="{StaticResource window}"

接下来编辑后台代码,首先为窗体增加事件处理以提供拖动功能:

MouseLeftButtonDown="Window_MouseLeftButtonDown"

后台事件处理代码:

private void Window_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)

{

    this.DragMove();

}

为按钮增加事件处理来更新界面颜色:

private void button1_Click(object sender, RoutedEventArgs e)

{

    更新颜色(Color.FromArgb((byte)a.Value, (byte)r.Value, (byte)g.Value, (byte)b.Value));

}

“更新颜色”方法代码如下:

public void 更新颜色(Color c)

{

    this.Resources.Remove("color");

    this.Resources.Add("color", new SolidColorBrush(c));

}

此方法首先移除资源“color”,然后再添加一个同名的新笔刷,这样就完成了动态替换工作。

现在编译并执行程序,可以看到如下效果:

源代码下载

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