1     private void CaptureButton_OnClick(object sender, RoutedEventArgs e)
 2     {
 3         var dpi = GetAppStartDpi();
 4         var bitmapSource = ToImageSource(Grid1, Grid1.RenderSize, dpi.X, dpi.Y);
 5         CaptureImage.Source = bitmapSource;
 6     }
 7     /// <summary>
 8     /// Visual轉(zhuǎn)圖片
 9     /// </summary>
10     public static BitmapSource ToImageSource(Visual visual, Size size, double dpiX, double dpiY)
11     {
12         var validSize = size.Width > 0 && size.Height > 0;
13         if (!validSize) throw new ArgumentException($"{nameof(size)}值無(wú)效:${size.Width},${size.Height}");
14         if (Math.Abs(size.Width) > 0.0001 && Math.Abs(size.Height) > 0.0001)
15         {
16             RenderTargetBitmap bitmap = new RenderTargetBitmap((int)(size.Width * dpiX), (int)(size.Height * dpiY), dpiX * 96, dpiY * 96, PixelFormats.Pbgra32);
17             bitmap.Render(visual);
18             return bitmap;
19         }
20         return new BitmapImage();
21     }

 1     /// <summary>
 2     /// WPF位圖轉(zhuǎn)換
 3     /// </summary>
 4     private static BitmapImage ToBitmapImage(BitmapSource bitmap,Size size,double dpiX,double dpiY)
 5     {
 6         MemoryStream memoryStream = new MemoryStream();
 7         BitmapEncoder encoder = new PngBitmapEncoder();
 8         encoder.Frames.Add(BitmapFrame.Create(bitmap));
 9         encoder.Save(memoryStream);
10         memoryStream.Seek(0L, SeekOrigin.Begin);
11 
12         BitmapImage bitmapImage = new BitmapImage();
13         bitmapImage.BeginInit();
14         bitmapImage.DecodePixelWidth = (int)(size.Width * dpiX);
15         bitmapImage.DecodePixelHeight = (int)(size.Height * dpiY);
16         bitmapImage.StreamSource = memoryStream;
17         bitmapImage.EndInit();
18         bitmapImage.Freeze();
19         return bitmapImage;
20     }

1     var encoder = new PngBitmapEncoder();
2     encoder.Frames.Add(BitmapFrame.Create(bitmapSource));
3     using Stream stream = File.Create(imagePath);
4     encoder.Save(stream);

1     //未加載到視覺(jué)樹的，按指定大小布局
2     //按size顯示，如果設(shè)計(jì)寬高大于size則按sie裁剪，如果設(shè)計(jì)寬度小于size則按size放大顯示。
3     element.Measure(size);
4     element.Arrange(new Rect(size));

 1     public BitmapSource ToImageSource(Visual visual, Size size = default)
 2     {
 3         if (!(visual is FrameworkElement element))
 4         {
 5             return null;
 6         }
 7         if (!element.IsLoaded)
 8         {
 9             if (size == default)
10             {
11                 //計(jì)算元素的渲染尺寸
12                 element.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
13                 element.Arrange(new Rect(new Point(), element.DesiredSize));
14                 size = element.DesiredSize;
15             }
16             else
17             {
18                 //未加載到視覺(jué)樹的，按指定大小布局
19                 //按size顯示，如果設(shè)計(jì)寬高大于size則按sie裁剪，如果設(shè)計(jì)寬度小于size則按size放大顯示。
20                 element.Measure(size);
21                 element.Arrange(new Rect(size));
22             }
23         }
24         else if (size == default)
25         {
26             Rect rect = VisualTreeHelper.GetDescendantBounds(visual);
27             if (rect.Equals(Rect.Empty))
28             {
29                 return null;
30             }
31             size = rect.Size;
32         }
33 
34         var dpi = GetAppStartDpi();
35         return ToImageSource(visual, size, dpi.X, dpi.Y);
36     }

 1 <Window x:Class="VisualBrushDemo.MainWindow"
 2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 5         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 6         xmlns:local="clr-namespace:VisualBrushDemo"
 7         mc:Ignorable="d" Title="MainWindow" Height="450" Width="800">
 8     <Grid>
 9         <Grid.ColumnDefinitions>
10             <ColumnDefinition Width="*"/>
11             <ColumnDefinition Width="10"/>
12             <ColumnDefinition/>
13         </Grid.ColumnDefinitions>
14         <Canvas x:Name="Grid1" Background="BlueViolet">
15             <TextBlock x:Name="TestTextBlock" Text="截圖測(cè)試" VerticalAlignment="Center" HorizontalAlignment="Center" 
16                        Width="100" Height="30" Background="Red" TextAlignment="Center" LineHeight="30" Padding="0 6 0 0"
17                        MouseDown="TestTextBlock_OnMouseDown" 
18                        MouseMove="TestTextBlock_OnMouseMove"
19                        MouseUp="TestTextBlock_OnMouseUp"/>
20         </Canvas>
21         <Grid x:Name="Grid2" Grid.Column="2">
22             <Grid.Background>
23                 <VisualBrush Stretch="UniformToFill"
24                              AlignmentX="Center" AlignmentY="Center"
25                              Visual="{Binding ElementName=Grid1}"/>
26             </Grid.Background>
27         </Grid>
28     </Grid>
29 </Window>

 1     private bool _isDown;
 2     private Point _relativeToBlockPosition;
 3     private void TestTextBlock_OnMouseDown(object sender, MouseButtonEventArgs e)
 4     {
 5         _isDown = true;
 6         _relativeToBlockPosition = e.MouseDevice.GetPosition(TestTextBlock);
 7         TestTextBlock.CaptureMouse();
 8     }
 9 
10     private void TestTextBlock_OnMouseMove(object sender, MouseEventArgs e)
11     {
12         if (_isDown)
13         {
14             var position = e.MouseDevice.GetPosition(Grid1);
15             Canvas.SetTop(TestTextBlock, position.Y - _relativeToBlockPosition.Y);
16             Canvas.SetLeft(TestTextBlock, position.X - _relativeToBlockPosition.X);
17         }
18     }
19 
20     private void TestTextBlock_OnMouseUp(object sender, MouseButtonEventArgs e)
21     {
22         TestTextBlock.ReleaseMouseCapture();
23         _isDown = false;
24     }

 1     // We need 2 ways of initiating layout on the VisualBrush root.
 2     // 1. We add a handler such that when the layout is done for the
 3     // main tree and LayoutUpdated is fired, then we do layout for the
 4     // VisualBrush tree.
 5     // However, this can fail in the case where the main tree is composed
 6     // of just Visuals and never does layout nor fires LayoutUpdated. So
 7     // we also need the following approach.
 8     // 2. We do a BeginInvoke to start layout on the Visual. This approach 
 9     // alone, also falls short in the scenario where if we are already in 
10     // MediaContext.DoWork() then we will do layout (for main tree), then look
11     // at Loaded callbacks, then render, and then finally the Dispather will 
12     // fire us for layout. So during loaded callbacks we would not have done
13     // layout on the VisualBrush tree.
14     //
15     // Depending upon which of the two layout passes comes first, we cancel
16     // the other layout pass.
17     element.LayoutUpdated += OnLayoutUpdated;
18     _DispatcherLayoutResult = Dispatcher.BeginInvoke(
19         DispatcherPriority.Normal,
20         new DispatcherOperationCallback(LayoutCallback),
21         element);
22     _pendingLayout = true;

1     RenderContext rc = new RenderContext();
2     rc.Initialize(channel, DUCE.ResourceHandle.Null);
3     vVisual.Render(rc, 0);