Question

如何在XAML中实现这样的效果：

    <LinearGradientBrush x:Key="BrightSeparatorGradient" StartPoint="0.0, 0.5" EndPoint="1.0, 0.5">
        <GradientStop Offset="0.0" Color="{StaticResource {x:Static SystemColors.ControlLightColorKey}}" /> <!-- But fully transparent -->
        <GradientStop Offset="0.5" Color="{StaticResource {x:Static SystemColors.ControlLightColorKey}}" />
        <GradientStop Offset="1.0" Color="{StaticResource {x:Static SystemColors.ControlLightColorKey}}" /> <!-- But fully transparent -->
    </LinearGradientBrush>

我试图创建两个分别具有适当颜色和不透明度设置的画笔，分别为0.0和1.0，但是编译器拒绝将画笔作为一种颜色（这是非常逻辑的，在第二个想法上:)）。 / p>

致敬 - Spook。

Answer 1

我会创建一个MarkupExtension来获取Color并返回具有指定不透明度的Color：

public class OpacityExtension : MarkupExtension
{
    private readonly Color color;
    public byte Opacity { get; set; } // defaults to 0, so you don't have 
                                      // to set it for the color to be transparent

    public OpacityExtension(Color color)
    {
        this.color = color;           
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return Color.FromArgb(Opacity, color.R, color.G, color.B);
    }
}

然后你就这样使用它：

<LinearGradientBrush x:Key="BrightSeparatorGradient" StartPoint="0.0, 0.5" EndPoint="1.0, 0.5">
    <GradientStop Offset="0" Color="{lcl:Opacity {StaticResource {x:Static SystemColors.ControlLightColorKey}}}" />
    <GradientStop Offset=".5" Color="{StaticResource {x:Static SystemColors.ControlLightColorKey}}" />
    <GradientStop Offset="1" Color="{lcl:Opacity {StaticResource {x:Static SystemColors.ControlLightColorKey}}}" />
</LinearGradientBrush>

Answer 2

幽灵，

为什么以下内容对您不起作用？

<LinearGradientBrush x:Key="BrightSeparatorGradient" StartPoint="0.0, 0.5" EndPoint="1.0, 0.5">
    <GradientStop Offset="0.0" Color="Transparent" /> 
    <GradientStop Offset="0.5" Color="{StaticResource {x:Static SystemColors.ControlLightColorKey}}" />
    <GradientStop Offset="1.0" Color="Transparent" /> 
 </LinearGradientBrush>

透明系统颜色渐变（WPF）

2 个答案: