Initial commit

ViewModels/BaseViewModel.cs

@@ -0,0 +1,47 @@
+using Avalonia.Controls;
+using ReceiptPDFBuilder.Helpers;
+using ReceiptPDFBuilder.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace ReceiptPDFBuilder.ViewModels
+{
+    class BaseViewModel : ChangeNotifier
+    {
+        IChangeViewModel _viewModelChanger;
+        ITopLevelGrabber? _topLevelGrabber;
+
+        public BaseViewModel(IChangeViewModel viewModelChanger)
+        {
+            _viewModelChanger = viewModelChanger;
+            _topLevelGrabber = null;
+        }
+
+        public ITopLevelGrabber? TopLevelGrabber
+        {
+            get => _topLevelGrabber;
+            set { _topLevelGrabber = value; }
+        }
+
+        public IChangeViewModel ViewModelChanger
+        {
+            get { return _viewModelChanger; }
+            set { _viewModelChanger = value; }
+        }
+
+        #region IChangeViewModel
+
+        public void PopViewModel()
+        {
+            _viewModelChanger?.PopViewModel();
+        }
+
+        public void PushViewModel(BaseViewModel model)
+        {
+            _viewModelChanger?.PushViewModel(model);
+        }
+
+        #endregion
+    }
+}