我已经发布了几个与此问题相关的问题,但我开始相信这是无法完成的。以下是背景。
我有一个ASP.NET应用程序,我想从中生成一个.png图像。这个.png图像需要从XAML或WPF可视树中构建。因此,我必须在STA线程中生成.png图像。一切都很好,直到我的XAML/WPF可视树包含一个图片(如System.Windows.Controls.Image)。我的.png文件被正确生成,但图片元素不显示引用的图片。引用的图片位于远程URL上。没有错误或异常抛出。
如何从包括System.Windows.Controls.Image元素的XAML/WPF可视树中创建.png图像?结果.png必须包括Image元素中引用的图片。我已经尝试了以下代码:
string address = "http://imgtops.sourceforge.net/bakeoff/o-png24.png";
WebClient webClient = new WebClient();
byte[] imageContent = webClient.DownloadData(address);
Image image = new Image();
using (MemoryStream memoryStream = new MemoryStream(imageContent))
{
BitmapImage imageSource = new BitmapImage();
imageSource.BeginInit();
imageSource.StreamSource = memoryStream;
imageSource.EndInit();
image.Source = imageSource;
}
// Set the size
image.Height = 200;
image.Width = 300;
// Position the Image within a Canvas
image.SetValue(Canvas.TopProperty, 1.0);
image.SetValue(Canvas.LeftProperty, 1.0);
Canvas canvas = new Canvas();
canvas.Height = 200;
canvas.Width = 300;
canvas.Background = new SolidColorBrush(Colors.Purple);
canvas.Children.Add(image);
// Create the area
Size availableSize = new Size(300, 200);
frameworkElement.Measure(availableSize);
frameworkElement.Arrange(new Rect(availableSize));
// Convert the WPF representation to a PNG file
BitmapSource bitmap = RenderToBitmap(frameworkElement);
PngBitmapEncoder encoder = new PngBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(bitmap));
// Generate the .png
FileStream fileStream = new FileStream(filename, FileMode.Create);
encoder.Save(fileStream);
public BitmapSource RenderToBitmap(FrameworkElement target)
{
int actualWidth = 300;
int actualHeight = 200;
Rect boundary = VisualTreeHelper.GetDescendantBounds(target);
RenderTargetBitmap renderBitmap = new RenderTargetBitmap(actualWidth, actualHeight, 96, 96, PixelFormats.Pbgra32);
DrawingVisual drawingVisual = new DrawingVisual();
using (DrawingContext context = drawingVisual.RenderOpen())
{
VisualBrush visualBrush = new VisualBrush(target);
context.DrawRectangle(visualBrush, null, new Rect(new Point(), boundary.Size));
}
renderBitmap.Render(drawingVisual);
return renderBitmap;
}
感谢您的帮助。