淡入效果

<Application x:Class="EnergeMonitorEVK.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             StartupUri="MainWindow.xaml">
    <Application.Resources>
                <Style x:Key="windowOpacity" TargetType="{x:Type Window}">
            <Style.Triggers>
                <EventTrigger RoutedEvent="Window.Loaded">                                        
                    <BeginStoryboard>
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetProperty="Opacity"
                                            From="0.0" To="1.0" Duration="0:0:1"
                                            />
                        </Storyboard>
                    </BeginStoryboard>                                   
                </EventTrigger>               
            </Style.Triggers>
        </Style>

    </Application.Resources>
</Application>