如何获取WPF Visual元素的缩放大小

Question

我正在将WPF Visual(UserControl)渲染到位图,但问题是渲染的图像在缩放/转换之前是UserControl的大小.所以我们假设UserControl的设计是200x200像素.当我渲染到BMP时,我正在使用UserControl的ActualWidth和ActualHeightt,它们分别报告200和200.问题是UserControl在Canvas中并且是自动调整大小(设置为按窗口大小缩放/填充)到接近1200 x 1200(它更改)的值

我做了一些阅读和搜索,到目前为止还无法弄清楚如何确定有效大小,即控件在屏幕上绘制的大小.

我遇到了这个问题听起来很有希望,但返回的Transform不包含缩放数据.它确实如此,但它们都是1. 转换后获取元素位置

关于在哪里寻找渲染缩放的任何建议都会很棒!

[更新]根据建议,我包括相关代码:

public static Bitmap PngBitmap(this Visual visual)
{
    // Get height and width
    int width = (int)(double)visual.GetValue(
        FrameworkElement.ActualWidthProperty);
    int height = (int)(double)visual.GetValue(
        FrameworkElement.ActualHeightProperty);

    // Render
    RenderTargetBitmap rtb =
        new RenderTargetBitmap(
            width,
            height,
            96,
            96,
            PixelFormats.Default);
    rtb.Render(visual);

    // Encode
    PngBitmapEncoder encoder = new PngBitmapEncoder();
    encoder.Frames.Add(BitmapFrame.Create(rtb));
    System.IO.MemoryStream stream = new System.IO.MemoryStream();
    encoder.Save(stream);

    // Create Bitmap
    Bitmap bmp = new Bitmap(stream);
    stream.Close();

    return bmp;
}

public static BitmapSource BitmapSource(this Visual visual)
{
    Bitmap bmp = visual.PngBitmap();
    IntPtr hBitmap = bmp.GetHbitmap();
    BitmapSizeOptions sizeOptions = BitmapSizeOptions.FromEmptyOptions();
    return Imaging.CreateBitmapSourceFromHBitmap(
                        hBitmap,
                        IntPtr.Zero,
                        Int32Rect.Empty,
                        sizeOptions);
}

[更新#2]添加了XAML - Grid元素已被删除,因为它是巨大的,从我对XAML的读取,包含键盘UserControl的Canvas不是Grid元素的一部分.

<UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    xmlns:local="clr-namespace:PMD.HECAT.DashboardModule" 
    xmlns:PMD_HECAT_DashboardModule_VirtualKeyboard="clr-namespace:PMD.HECAT.DashboardModule.VirtualKeyboard" 
    xmlns:System_Windows_Controls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Input.Toolkit" 
    xmlns:PMD_HECAT_DashboardModule_Input="clr-namespace:PMD.HECAT.DashboardModule.Input"
    xmlns:control="clr-namespace:PMD.HECAT.DashboardModule.Controls"    
    x:Class="PMD.HECAT.DashboardModule.CandidateElectrodeView"             
    x:Name="UserControl"
    mc:Ignorable="d"
    d:DesignWidth="1024" d:DesignHeight="768" Width="640" Height="360">
    <UserControl.Resources>
         <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="../Themes/DashboardStyles.xaml" />
                <ResourceDictionary Source="../Themes/ImageButtons.xaml" />
                <ResourceDictionary Source="CandidateViewResources.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>        
    </UserControl.Resources>
    <UserControl.Triggers>
        <EventTrigger RoutedEvent="PMD_HECAT_DashboardModule_VirtualKeyboard:VirtualKeyboardView.KeyboardClose" SourceName="virtualKeyboardView">
            <BeginStoryboard Storyboard="{StaticResource OnKeyboardClose1}"/>
        </EventTrigger>
    </UserControl.Triggers>
    <Canvas Width="100" HorizontalAlignment="Left">

        <PMD_HECAT_DashboardModule_VirtualKeyboard:VirtualKeyboardView x:Name="virtualKeyboardView" Height="222" Width="550" RenderTransformOrigin="0.5,0.5" Opacity="0" Active="False">
            <PMD_HECAT_DashboardModule_VirtualKeyboard:VirtualKeyboardView.RenderTransform>
                <TransformGroup>
                    <ScaleTransform/>
                    <SkewTransform/>
                    <RotateTransform/>
                    <TranslateTransform X="40" Y="400"/>
                </TransformGroup>
            </PMD_HECAT_DashboardModule_VirtualKeyboard:VirtualKeyboardView.RenderTransform>
        </PMD_HECAT_DashboardModule_VirtualKeyboard:VirtualKeyboardView>
        <Rectangle Stroke="White" Opacity="0.7" Fill="White" Height="370" Width="654.851" Canvas.Left="687" Canvas.Top="0" />
    </Canvas>
</UserControl>

Answer 1

我知道自问题问题以来已经过了很多时间,但发布更多信息并没有什么坏处:)

我使用此代码通过应用渲染变换查找视觉效果的大小(比例).

GeneralTransform t = transformedVisual.TransformToVisual(parentVisual);

Vector topLeft = (Vector) t.Transform(new Point(0,0));
Vector topRight = (Vector) t.Transform(new Point(originalWidthOfTransformedVisual, 0));

double renderedWidth = (topRight-topLeft).Length;
double widthScale = renderedWidth / originalWidthOfTransformedVisual;