采用Windows Phone 8 XAML + Direct3D应用程序（Unity3D）的屏幕截图

Question

使用以下代码：

Dispatcher.BeginInvoke(
() =>
{
    byte[] imageBytes = null;

    WriteableBitmap bmpCurrentScreenImage = new WriteableBitmap(_Width, _Height);
    bmpCurrentScreenImage.Render(DrawingSurfaceBackground, new MatrixTransform());
    bmpCurrentScreenImage.Invalidate();

    using (var stream = new MemoryStream())
    {
        bmpCurrentScreenImage.SaveJpeg(stream, bmpCurrentScreenImage.PixelWidth,
            bmpCurrentScreenImage.PixelHeight, 0, 100);
        stream.Seek(0, SeekOrigin.Begin);

        imageBytes = stream.ToArray();
    }
});       

其中DrawingSurfaceBackground是MainPage.xaml的属性。

<phone:PhoneApplicationPage 
    x:Class="Roulettist.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}" Orientation="Landscape" SupportedOrientations="Landscape" BackKeyPress="PhoneApplicationPage_BackKeyPress" OrientationChanged="PhoneApplicationPage_OrientationChanged">

    <!--LayoutRoot is the root grid where all page content is placed-->
    <DrawingSurfaceBackgroundGrid x:Name="DrawingSurfaceBackground" Loaded="DrawingSurfaceBackground_Loaded">
    </DrawingSurfaceBackgroundGrid>

</phone:PhoneApplicationPage>

我正在尝试获取该应用的截图，但我收到了黑色像素的纹理。 我看到有些人遇到同样的问题，但在任何地方都没有看到问题的答案。

那么有没有办法在XAML + Direct3D应用程序中使用UIElement.Render方法获取屏幕截图？