Saving a Window or Canvas as a PNG Bitmap in WPF

The following code snippet takes a file name and a DPI value and you can chose weather to save the canvas or window to a PNG Bitmap image.

Usage:

Code Snippet

1. Microsoft.Win32.SaveFileDialog dlg = new Microsoft.Win32.SaveFileDialog();
2. dlg.FileName = "Image"; // Default file name
3. dlg.DefaultExt = ".png"; // Default file extension
4. dlg.Filter = "PNG File (.png)|*.png"; // Filter files by extension
5.  
6. // Show save file dialog box
7. Nullable<bool> result = dlg.ShowDialog();
8.  
9. // Process save file dialog box results
10. if (result == true)
11. {
12.     // Save document
13.     string filename = dlg.FileName;
14.     SaveCanvasToFile(this, DrawingCanvas, 96, filename);
15. }

End of Code Snippet

Code Snippet

1. public static void SaveCanvasToFile(Window window, Canvas canvas, int dpi, string filename)
2. {
3.     Size size = new Size(window.Width, window.Height);
4.     canvas.Measure(size);
5.     //canvas.Arrange(new Rect(size));
6.  
7.     var rtb = new RenderTargetBitmap(
8.         (int)window.Width, //width
9.         (int)window.Height, //height
10.         dpi, //dpi x
11.         dpi, //dpi y
12.         PixelFormats.Pbgra32 // pixelformat
13.         );
14.     rtb.Render(canvas);
15.  
16.     SaveRTBAsPNGBMP(rtb, filename);
17. }
18.  
19. public static void SaveWindowToFile(Window window, int dpi, string filename)
20. {
21.     var rtb = new RenderTargetBitmap(
22.         (int)window.Width, //width
23.         (int)window.Width, //height
24.         dpi, //dpi x
25.         dpi, //dpi y
26.         PixelFormats.Pbgra32 // pixelformat
27.         );
28.     rtb.Render(window);
29.  
30.     SaveRTBAsPNGBMP(rtb, filename);
31. }
32.  
33. private static void SaveRTBAsPNGBMP(RenderTargetBitmap bmp, string filename)
34. {
35.     var enc = new System.Windows.Media.Imaging.PngBitmapEncoder();
36.     enc.Frames.Add(System.Windows.Media.Imaging.BitmapFrame.Create(bmp));
37.  
38.     using (var stm = System.IO.File.Create(filename))
39.     {
40.         enc.Save(stm);
41.     }
42. }

End of Code Snippet