Add ViewModel for PreviewerWindow.

QuestPDF.Previewer/DocumentPreviewerExtensions.cs

@@ -1,5 +1,6 @@
 using Avalonia;
 using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.ReactiveUI;
 using QuestPDF.Infrastructure;
 
 namespace QuestPDF.Previewer
@@ -24,7 +25,10 @@ namespace QuestPDF.Previewer
             {
                 desktop.MainWindow = new PreviewerWindow()
                 {
-                    Document = document,
+                    DataContext = new PreviewerWindowViewModel()
+                    {
+                        Document = document,
+                    }
                 };
                 
                 desktop.MainWindow.Show();
@@ -39,6 +43,7 @@ namespace QuestPDF.Previewer
                     Document = document,
                 })
                 .UsePlatformDetect()
+                .UseReactiveUI()
                 .StartWithClassicDesktopLifetime(Array.Empty<string>());
         }
     }

QuestPDF.Previewer/PreviewerApp.axaml.cs

@@ -20,7 +20,10 @@ namespace QuestPDF.Previewer
             {
                 desktop.MainWindow = new PreviewerWindow()
                 {
-                    Document = Document
+                    DataContext = new PreviewerWindowViewModel()
+                    {
+                        Document = Document,
+                    }
                 };
             }
             

QuestPDF.Previewer/PreviewerWindowViewModel.cs

@@ -0,0 +1,97 @@
+using QuestPDF.Fluent;
+using System.Diagnostics;
+using ReactiveUI;
+using QuestPDF.Infrastructure;
+using Unit = System.Reactive.Unit;
+
+namespace QuestPDF.Previewer
+{
+    internal class PreviewerWindowViewModel : ReactiveObject
+    {
+        public DocumentRenderer DocumentRenderer { get; } = new();
+
+        private IDocument? _document;
+        public IDocument? Document
+        {
+            get => _document;
+            set
+            {
+                this.RaiseAndSetIfChanged(ref _document, value);
+                UpdateDocument(value);
+            }
+        }
+
+        private float _currentScroll;
+        public float CurrentScroll
+        {
+            get => _currentScroll;
+            set => this.RaiseAndSetIfChanged(ref _currentScroll, value);
+        }
+
+        private float _scrollViewportSize;
+        public float ScrollViewportSize
+        {
+            get => _scrollViewportSize;
+            set
+            {
+                this.RaiseAndSetIfChanged(ref _scrollViewportSize, value);
+                VerticalScrollbarVisible = value < 1;
+            }
+        }
+
+        private bool _verticalScrollbarVisible;
+        public bool VerticalScrollbarVisible
+        {
+            get => _verticalScrollbarVisible;
+            private set => this.RaiseAndSetIfChanged(ref _verticalScrollbarVisible, value);
+        }
+
+        public ReactiveCommand<Unit, Unit> ShowPdfCommand { get; }
+
+        public PreviewerWindowViewModel()
+        {
+            HotReloadManager.UpdateApplicationRequested += InvalidateDocument;
+            ShowPdfCommand = ReactiveCommand.Create(ShowPdf);
+        }
+
+        public void UnregisterHotReloadHandler()
+        {
+            HotReloadManager.UpdateApplicationRequested -= InvalidateDocument;
+        }
+
+        private void InvalidateDocument(object? sender, EventArgs e)
+        {
+            UpdateDocument(Document);
+        }
+
+        private Task UpdateDocument(IDocument? document)
+        {
+            return Task.Run(() => DocumentRenderer.UpdateDocument(document));
+        }
+
+        private void ShowPdf()
+        {
+            var path = Path.Combine(Path.GetTempPath(), ".pdf");
+
+            try
+            {
+                Document?.GeneratePdf(path);
+            }
+            catch (Exception exception)
+            {
+                new ExceptionDocument(exception).GeneratePdf(path);
+            }
+
+            var openBrowserProcess = new Process
+            {
+                StartInfo = new()
+                {
+                    UseShellExecute = true,
+                    FileName = path
+                }
+            };
+
+            openBrowserProcess.Start();
+        }
+    }
+}