Added Button to save - updated SplitView functionality - updated SplitViewOpenButton

Views/MainWindow.axaml.cs

@@ -1,5 +1,12 @@
+using System;
+using System.IO;
+using System.Threading.Tasks;
+using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Input;
+using Avalonia.Interactivity;
+using Avalonia.Media.Imaging;
+using Avalonia.Platform.Storage;
 using SimpleDraw.ViewModels;
 
 namespace SimpleDraw.Views;
@@ -13,4 +20,39 @@ public partial class MainWindow : Window
         Topmost = true;
         Topmost = false;
     }
+
+    private async void SaveFileButton_Clicked(object sender, RoutedEventArgs args)
+    {
+        TopLevel? topLevel = TopLevel.GetTopLevel(this);
+        if(topLevel == null) return;
+
+        var file = await topLevel.StorageProvider.SaveFilePickerAsync(new FilePickerSaveOptions
+        {
+            Title = "Save Drawing",
+            DefaultExtension = ".png",
+            SuggestedFileName = "unnamed",
+            SuggestedStartLocation = await topLevel.StorageProvider.TryGetFolderFromPathAsync(Environment.GetFolderPath(Environment.SpecialFolder.MyPictures)),
+        });
+
+        if (file is not null)
+        {
+            SaveCanvasAsPngAsync(Canvas, file.Path.AbsolutePath);
+        }
+    }
+
+    public async Task SaveCanvasAsPngAsync(Canvas canvas, string filePath)
+    {
+        Rect bounds = canvas.Bounds;
+        PixelSize pixelSize = new PixelSize((int)bounds.Width, (int)bounds.Height);
+        Vector dpi = new Vector(96, 96);
+
+        RenderTargetBitmap renderBitmap = new RenderTargetBitmap(pixelSize, dpi);
+
+        renderBitmap.Render(canvas);
+
+        await using (FileStream stream = File.OpenWrite(filePath))
+        {
+            renderBitmap.Save(stream);
+        }
+    }
 }