如何：创建投影可视化效果
更新：2007 年 11 月
DropShadowBitmapEffect 可用于创建可见对象后面有阴影的视觉效果。下面是对如下内容进行演示的一系列示例：
如何使用简单的标记将效果应用于对象
如何使用 Style 将效果应用于一个或多个对象
如何使用代码将效果应用于对象
如何使用动画对应用于对象的效果的属性进行动画处理
**注意：**下面的所有示例都只将单一效果应用于对象。若要应用多个效果，可以使用 BitmapEffectGroup。请参见如何：创建多个可视化效果中的示例。
示例
下面的示例演示如何使用 DropShadowBitmapEffect 在 Button 后面创建阴影外观。
<Page xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml">
<StackPanel>
<Button Margin="50" Width="200">DropShadow Under this Button
<Button.BitmapEffect>
<!-- <BitmapEffectGroup> would go here if you wanted to apply more
then one effect to the TextBox. However, in this example only
one effect is being applied so BitmapEffectGroup does not need
to be included. -->
<!-- The DropShadowBitmapEffect has several important properties that
determine characteristics of the drop shadow:
- Color: Specifies the color of the drop shadow (in this example black).
- ShadowDepth: Specifies how far displaced the shadow is from the object
casting the shadow. Default is 20.
- Direction: Specifies in what direction the shadow is cast from the object.
It is an angle between 0 and 360 with 0 starting on the right hand side
and moving counter-clockwise around the object. The value of 320 in this
example casts the shadow on the lower right hand side of the button.
- Noise: Specifies how grainy the drop-shadow is. Range is between 0 and 1.
Default is 0.
- Softness: Specifies how soft the shadow. The range is between 0 and 1 with 1
being the softest. Default is 0.5.
- Opacity: Specifies how transparent the shadow is. The range is between 0
and 1 with 1 being fully opaque and 0 fully transparent (not visible). The
default is 1. -->
<DropShadowBitmapEffect Color="Black" Direction="320" ShadowDepth="25" Softness="1"
Opacity="0.5"/>
</Button.BitmapEffect>
</Button>
</StackPanel>
</Page>
下面的插图演示了上一示例中创建的效果。
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下面的示例演示在按下页面上的任何 Button 时，如何使用 Style 向该按钮应用 DropShadowBitmapEffect。
<Page xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml">
<!-- Resources define Styles for the entire page. -->
<Page.Resources>
<!-- This style applies to any Button on the page. -->
<Style TargetType="{x:Type Button}">
<Style.Triggers>
<!-- When the Button is pressed, apply the drop shadow. -->
<Trigger Property="IsPressed" Value="true">
<Setter Property = "BitmapEffect" >
<Setter.Value>
<DropShadowBitmapEffect Color="Black" Direction="320"
ShadowDepth="25" Softness="1" Opacity="0.5"/>
</Setter.Value>
</Setter>
</Trigger>
</Style.Triggers>
</Style>
</Page.Resources>
<StackPanel>
<!-- The Style defined above applies to this Button which creates
a drop shadow when the button is pressed down. -->
<Button Width="200" >Press Me!</Button>
</StackPanel>
</Page>
下面的示例演示在单击 Button 时，如何使用代码向该按钮应用 DropShadowBitmapEffect。
下面是该示例的可扩展应用程序标记语言 (XAML) 版本。
<Page xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
x:Class="SDKSample.DropShadowExample" >
<StackPanel>
<Button Click="OnClickDropShadowButton" Margin="50" Width="200">
Click to Create Drop Shadow!</Button>
</StackPanel>
</Page>
下面是处理示例标记的事件的代码。
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Input;
using System.Windows.Media.Effects;
namespace SDKSample
{
public partial class DropShadowExample : Page
{
// Add Blur effect.
void OnClickDropShadowButton(object sender, RoutedEventArgs args)
{
// Get a reference to the Button.
Button myButton = (Button)sender;
// Initialize a new DropShadowBitmapEffect that will be applied
// to the Button.
DropShadowBitmapEffect myDropShadowEffect = new DropShadowBitmapEffect();
// Set the color of the shadow to Black.
Color myShadowColor = new Color();
myShadowColor.ScA = 1; // Note that the alpha value is ignored by Color property. The Opacity property is used to control the alpha.
myShadowColor.ScB = 0;
myShadowColor.ScG = 0;
myShadowColor.ScR = 0;
myDropShadowEffect.Color = myShadowColor;
// Set the direction of where the shadow is cast to 320 degrees.
myDropShadowEffect.Direction = 320;
// Set the depth of the shadow being cast.
myDropShadowEffect.ShadowDepth = 25;
// Set the shadow softness to the maximum (range of 0-1).
myDropShadowEffect.Softness = 1;
// Set the shadow opacity to half opaque or in other words - half transparent.
// The range is 0-1.
myDropShadowEffect.Opacity = 0.5;
// Apply the bitmap effect to the Button.
myButton.BitmapEffect = myDropShadowEffect;
}
}
}
下面的示例演示如何对 DropShadowBitmapEffect 的 ShadowDepth 和 Softness 进行动画处理，使其像 Button 一样在单击之后从屏幕表面浮现出来。
<Page xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml" >
<StackPanel>
<Button Margin="50" Width="200" Name="myButton">
Click Me to Animate Drop Shadow!
<Button.BitmapEffect>
<!-- This BitmapEffect is targeted by the animation. -->
<DropShadowBitmapEffect x:Name="myDropShadowBitmapEffect" Color="Black"
ShadowDepth="0" />
</Button.BitmapEffect>
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<!-- Animate the movement of the button. -->
<ThicknessAnimation
Storyboard.TargetProperty="Margin" Duration="0:0:0.5"
From="50,50,50,50" To="0,0,50,50" AutoReverse="True" />
<!-- Animate shadow depth of the effect. -->
<DoubleAnimation
Storyboard.TargetName="myDropShadowBitmapEffect"
Storyboard.TargetProperty="ShadowDepth"
From="0" To="30" Duration="0:0:0.5"
AutoReverse="True" />
<!-- Animate shadow softness of the effect. As
the Button appears to get farther from the shadow,
the shadow gets softer. -->
<DoubleAnimation
Storyboard.TargetName="myDropShadowBitmapEffect"
Storyboard.TargetProperty="Softness"
From="0" To="1" Duration="0:0:0.5"
AutoReverse="True" />
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
</StackPanel>
</Page>