Implement basic UI using AvaloniaUI.

CsvView/CsvView.csproj

@@ -17,4 +17,9 @@
         <!--Condition below is needed to remove Avalonia.Diagnostics package from build output in Release configuration.-->
         <PackageReference Condition="'$(Configuration)' == 'Debug'" Include="Avalonia.Diagnostics" Version="11.0.2"/>
     </ItemGroup>
+
+
+    <ItemGroup>
+      <ProjectReference Include="..\CsvLib\CsvLib.csproj" />
+    </ItemGroup>
 </Project>

CsvView/MainWindow.axaml

@@ -2,10 +2,37 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:csvView="clr-namespace:CsvView"
         mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="600"
         x:Class="CsvView.MainWindow"
+        x:DataType="csvView:MainWindowViewModel"
         Width="800"
         Height="600"
         Title="CsvView">
-    Hello CvsView!
+    <Grid RowDefinitions="Auto,Auto,*">
+        <StackPanel Orientation="Horizontal" Grid.Row="0">
+            <Button Name="BtnLoad" Click="BtnLoad_OnClick">...</Button>
+            <TextBlock Name="TxtFileName" />
+        </StackPanel>
+        <StackPanel Orientation="Horizontal" Grid.Row="1">
+            <Button Name="BtnFirst" Click="BtnFirst_OnClick">|◁</Button>
+            <Button Name="BtnPrevious" Click="BtnPrevious_OnClick">◁</Button>
+            <TextBox Name="TxtIndex" Text="{Binding Index}" TextChanged="TxtIndex_OnTextChanged" ></TextBox>
+            <TextBlock>/</TextBlock>
+            <TextBox Name="TxtMaxIndex" Text="{Binding MaxIndex}" IsEnabled="false"></TextBox>
+            <Button Name="BtnNext" Click="BtnNext_OnClick">▷</Button>
+            <Button Name="BtnLast" Click="BtnLast_OnClick">▷|</Button>
+        </StackPanel>
+        <ScrollViewer Grid.Row="2" >
+            <StackPanel Orientation="Vertical" >
+                <ItemsControl ItemsSource="{Binding Fields}">
+                    <ItemsControl.DataTemplates>
+                        <DataTemplate x:DataType="csvView:FieldViewModel">
+                            <TextBox Text="{Binding Text}" IsEnabled="False"/>
+                        </DataTemplate>
+                    </ItemsControl.DataTemplates>
+                </ItemsControl>
+            </StackPanel>
+        </ScrollViewer>
+    </Grid>
 </Window>

CsvView/MainWindow.axaml.cs

@@ -1,5 +1,9 @@
+using System.Collections.Generic;
+using System.Linq;
 using Avalonia.Controls;
 using Avalonia.Interactivity;
+using Avalonia.Platform.Storage;
+using CsvLib;
 
 namespace CsvView;
 
@@ -8,5 +12,160 @@ public partial class MainWindow : Window
     public MainWindow()
     {
         InitializeComponent();
+        RenderReg(0);
     }
+
+    private async void BtnLoad_OnClick(object? sender, RoutedEventArgs e)
+    {
+        TopLevel? topLevel = GetTopLevel(this);
+        if (topLevel == null) { return; }
+
+        IReadOnlyList<IStorageFile> files = await topLevel.StorageProvider.OpenFilePickerAsync(new FilePickerOpenOptions
+        {
+            Title = "Open CSV File",
+            AllowMultiple = false,
+            FileTypeFilter = new List<FilePickerFileType>
+            {
+                new("CSV Files") { Patterns = new[] { "*.csv" } },
+                new("Any File") { Patterns = new[] { "*" } },
+            },
+        });
+
+        if (files.Count <= 0) { return; }
+
+        LoadFile(files[0].Path.LocalPath);
+    }
+
+    private void BtnFirst_OnClick(object? sender, RoutedEventArgs e)
+    {
+        RenderReg(0);
+    }
+
+    private void BtnPrevious_OnClick(object? sender, RoutedEventArgs e)
+    {
+        RenderReg(_currentReg - 1);
+    }
+
+    private void TxtIndex_OnTextChanged(object? sender, TextChangedEventArgs e)
+    {
+        RenderReg(int.TryParse(TxtIndex.Text, out int newReg) ? newReg : _currentReg);
+    }
+
+    private void BtnNext_OnClick(object? sender, RoutedEventArgs e)
+    {
+        RenderReg(_currentReg + 1);
+    }
+
+    private void BtnLast_OnClick(object? sender, RoutedEventArgs e)
+    {
+        RenderReg(_totalRegs - 1);
+    }
+
+    private string _loadedFile = string.Empty;
+    private long _currentReg;
+    private int _totalRegs;
+    private List<long> _index = new();
+
+
+    private void LoadFile(string fileName)
+    {
+        _loadedFile = fileName;
+        TxtFileName.Text = fileName;
+
+        CsvIndexer csvIndexer = new();
+        csvIndexer.LoadIndexOfFile(_loadedFile);
+        _index = csvIndexer.Index;
+        _totalRegs = _index.Count - 1;
+
+        RenderReg(0);
+    }
+
+    private MainWindowViewModel Index_LoadReg(int idx, int maxIndex)
+    {
+        CsvParser csvParser = new();
+        csvParser.ParseFile(_loadedFile, _index[idx], 1);
+        MainWindowViewModel viewModel = new()
+        {
+            Index = idx,
+            MaxIndex = maxIndex,
+            Fields = csvParser.Data[0].Select(f => new FieldViewModel { Text = f, }).ToList(),
+        };
+        return viewModel;
+    }
+
+    bool _rendering;
+    private void RenderReg(long currentReg)
+    {
+        if (_rendering) { return; }
+        _rendering = true;
+
+        if (_index.Count <= 0)
+        {
+            _currentReg = -1;
+            BtnFirst.IsEnabled = false;
+            BtnPrevious.IsEnabled = false;
+            TxtIndex.IsEnabled = false;
+            BtnNext.IsEnabled = false;
+            BtnLast.IsEnabled = false;
+
+            DataContext = new MainWindowViewModel { Index = 0, Fields = new(), };
+            _rendering = false;
+            return;
+        }
+
+        bool first = false;
+        bool last = false;
+        if (currentReg <= 0)
+        {
+            currentReg = 0;
+            first = true;
+        }
+        if (currentReg >= (_totalRegs - 1))
+        {
+            currentReg = _totalRegs - 1;
+            last = true;
+        }
+
+        BtnFirst.IsEnabled = (first == false);
+        BtnPrevious.IsEnabled = (first == false);
+        TxtIndex.IsEnabled = true;
+        BtnNext.IsEnabled = (last == false);
+        BtnLast.IsEnabled = (last == false);
+
+        if (_currentReg == currentReg)
+        {
+            _rendering = false;
+            return;
+        }
+
+        _currentReg = currentReg;
+
+        CsvParser csvParser = new();
+        csvParser.ParseFile(_loadedFile, _index[(int)currentReg], 1);
+        MainWindowViewModel viewModel = new()
+        {
+            Index = (int)currentReg,
+            MaxIndex = _totalRegs,
+            Fields = csvParser.Data[0].Select(f => new FieldViewModel { Text = f, }).ToList(),
+        };
+
+        DataContext = viewModel;
+
+        _rendering = false;
+    }
+
+}
+
+public class FieldViewModel
+{
+    public string Text { get; set; } = string.Empty;
+}
+
+public class MainWindowViewModel
+{
+    public int? Index { get; set; }
+
+    public int? MaxIndex { get; set; }
+
+    public List<FieldViewModel>? Fields { get; set; }
 }