.NET 控件转图片

1privatevoidCaptureButton_OnClick(object sender, RoutedEventArgs e)2{3var dpi =GetAppStartDpi();4var bitmapSource = ToImageSource(Grid1, Grid1.RenderSize, dpi.X, dpi.Y);5 CaptureImage.Source =bitmapSource;6}7///<summary>8///Visual转图片9///</summary>10publicstatic BitmapSource ToImageSource(Visual visual, Size size, doubledpiX,doubledpiY)11{12var validSize = size.Width > 0 && size.Height > 0;13if(!validSize)thrownewArgumentException($"{nameof(size)}值无效:${size.Width},${size.Height}");14if (Math.Abs(size.Width) > 0.0001 && Math.Abs(size.Height) > 0.0001)15{16 RenderTargetBitmap bitmap = newRenderTargetBitmap((int)(size.Width * dpiX), (int)(size.Height * dpiY), dpiX * 96, dpiY * 96, PixelFormats.Pbgra32);17bitmap.Render(visual);18returnbitmap;19}20returnnewBitmapImage();21}

1///<summary>2///WPF位图转换3///</summary>4privatestatic BitmapImage ToBitmapImage(BitmapSource bitmap,Size size,doubledpiX,doubledpiY)5{6 MemoryStream memoryStream = newMemoryStream();7 BitmapEncoder encoder = newPngBitmapEncoder();8encoder.Frames.Add(BitmapFrame.Create(bitmap));9encoder.Save(memoryStream);10memoryStream.Seek(0L, SeekOrigin.Begin);1112 BitmapImage bitmapImage = newBitmapImage();13bitmapImage.BeginInit();14 bitmapImage.DecodePixelWidth = (int)(size.Width *dpiX);15 bitmapImage.DecodePixelHeight = (int)(size.Height *dpiY);16 bitmapImage.StreamSource =memoryStream;17bitmapImage.EndInit();18bitmapImage.Freeze();19returnbitmapImage;20}

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

1//未加载到视觉树的，按指定大小布局2//按size显示，如果设计宽高大于size则按sie裁剪，如果设计宽度小于size则按size放大显示。3element.Measure(size);4element.Arrange(newRect(size));

1public BitmapSource ToImageSource(Visual visual, Size size = default)2{3if(!(visualis FrameworkElement element))4{5returnnull;6}7if(!element.IsLoaded)8{9if (size == default)10{11//计算元素的渲染尺寸12element.Measure(newSize(double.PositiveInfinity,double.PositiveInfinity));13element.Arrange(newRect(new Point(), element.DesiredSize));14 size =element.DesiredSize;15}16else17{18//未加载到视觉树的，按指定大小布局19//按size显示，如果设计宽高大于size则按sie裁剪，如果设计宽度小于size则按size放大显示。20element.Measure(size);21element.Arrange(newRect(size));22}23}24elseif (size == default)25{26 Rect rect =VisualTreeHelper.GetDescendantBounds(visual);27if(rect.Equals(Rect.Empty))28{29returnnull;30}31 size =rect.Size;32}3334var dpi =GetAppStartDpi();35return ToImageSource(visual, size, dpi.X, dpi.Y);36}

1 <Window x:Class="VisualBrushDemo.MainWindow"2xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"3xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"4xmlns:d="http://schemas.microsoft.com/expression/blend/2008"5xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"6xmlns:local="clr-namespace:VisualBrushDemo"7mc: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="截图测试"VerticalAlignment="Center"HorizontalAlignment="Center"16Width="100"Height="30"Background="Red"TextAlignment="Center"LineHeight="30"Padding="0 6 0 0"17MouseDown="TestTextBlock_OnMouseDown"18MouseMove="TestTextBlock_OnMouseMove"19MouseUp="TestTextBlock_OnMouseUp"/>20</Canvas>21 <Grid x:Name="Grid2"Grid.Column="2">22<Grid.Background>23 <VisualBrush Stretch="UniformToFill"24AlignmentX="Center"AlignmentY="Center"25Visual="{Binding ElementName=Grid1}"/>26</Grid.Background>27</Grid>28</Grid>29</Window>

1privatebool_isDown;2private Point _relativeToBlockPosition;3privatevoidTestTextBlock_OnMouseDown(object sender, MouseButtonEventArgs e)4{5 _isDown = true;6 _relativeToBlockPosition =e.MouseDevice.GetPosition(TestTextBlock);7TestTextBlock.CaptureMouse();8}910privatevoidTestTextBlock_OnMouseMove(object sender, MouseEventArgs e)11{12if(_isDown)13{14var position =e.MouseDevice.GetPosition(Grid1);15 Canvas.SetTop(TestTextBlock, position.Y -_relativeToBlockPosition.Y);16 Canvas.SetLeft(TestTextBlock, position.X -_relativeToBlockPosition.X);17}18}1920privatevoidTestTextBlock_OnMouseUp(object sender, MouseButtonEventArgs e)21{22TestTextBlock.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 the3// main tree and LayoutUpdated is fired, then we do layout for the4// VisualBrush tree.5// However, this can fail in the case where the main tree is composed6// of just Visuals and never does layout nor fires LayoutUpdated. So7// 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 look11// at Loaded callbacks, then render, and then finally the Dispather will 12// fire us for layout. So during loaded callbacks we would not have done13// layout on the VisualBrush tree.14//15// Depending upon which of the two layout passes comes first, we cancel16// the other layout pass.17 element.LayoutUpdated +=OnLayoutUpdated;18 _DispatcherLayoutResult =Dispatcher.BeginInvoke(19DispatcherPriority.Normal,20newDispatcherOperationCallback(LayoutCallback),21element);22 _pendingLayout = true;

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