writing in the text editor? easy!

Qrakhen.Qamp.Editor/Controls/Caret.cs

@@ -1,35 +1,52 @@
-using System;
-using System.Collections.Generic;
-using System.Text;
-using System.Windows;
+using System.Windows;
 using System.Windows.Documents;
 using System.Windows.Media;
+using System.Windows.Threading;
 
 namespace Qrakhen.Qamp.Editor.Controls;
 
 public class Caret : Adorner
 {
-    private readonly Pen _caretPen;
-    private readonly double _lineHeight;
+    private readonly Pen _pen;
+    private readonly double _height;
+    private readonly Brush _brush;
+    private bool _blink;
     private Point _cursorPosition;
+    private DispatcherTimer _timer;
 
-    public Caret(UIElement adornedElement, double lineHeight) : base(adornedElement)
+    public Caret(UIElement adornedElement, Brush brush, double height = 18, double thickness = 1.72) : base(adornedElement)
     {
-        _lineHeight = lineHeight;
-        _caretPen = new Pen(Brushes.LimeGreen, 1.5);
         IsHitTestVisible = false;
+
+        _height = height;
+        _brush = brush;
+        _pen = new Pen(brush, 1.5);
+        _timer = new DispatcherTimer();
+        _timer.Interval = TimeSpan.FromMilliseconds(428);
+        _timer.Tick += new EventHandler((s, e) => {
+            Toggle(_blink = !_blink);
+        });
+        _timer.Start();
+    }
+
+    public void Toggle(bool hide)
+    {
+        _pen.Brush = hide ? Brushes.Transparent : _brush;
     }
 
     public void UpdatePosition(Point newPosition)
     {
+        _timer.Stop();
+        Toggle(_blink = false);
         _cursorPosition = newPosition;
         InvalidateVisual();
+        _timer.Start();
     }
 
     protected override void OnRender(DrawingContext drawingContext)
     {
         Point startPoint = new(_cursorPosition.X, _cursorPosition.Y);
-        Point endPoint = new(_cursorPosition.X, _cursorPosition.Y + _lineHeight);
-        drawingContext.DrawLine(_caretPen, startPoint, endPoint);
+        Point endPoint = new(_cursorPosition.X, _cursorPosition.Y + _height);
+        drawingContext.DrawLine(_pen, startPoint, endPoint);
     }
 }

Qrakhen.Qamp.Editor/Controls/EditorFrame.xaml

@@ -12,6 +12,7 @@
     <UserControl.Style>
         <Style TargetType="{x:Type local:EditorFrame}">
             <Setter Property="CursorPosition" Value="{Binding CursorPosition}" />
+            <Setter Property="CurrentLineBuffer" Value="{Binding CurrentLineBuffer}" />
         </Style>
     </UserControl.Style>
 

Qrakhen.Qamp.Editor/Controls/EditorFrame.xaml.cs

@@ -1,9 +1,12 @@
 using Qrakhen.Qamp.Editor.Primitives;
 using Qrakhen.Qamp.Editor.ViewModel;
+using Qrakhen.Qamp.Memory;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Documents;
 using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Threading;
 
 namespace Qrakhen.Qamp.Editor.Controls;
 
@@ -28,10 +31,22 @@ public partial class EditorFrame : UserControl
                 Key.Down => new(1, 0),
                 _ => new(0, 0)
             };
-            if (vm.MoveCaretCommand.CanExecute(position)) {
+            if (position != CursorPosition.Void &&
+                vm.MoveCaretCommand.CanExecute(position)) 
+            {
                 vm.MoveCaretCommand.Execute(position);
-                e.Handled = true;
+            } else {
+                if (e.Key == Key.Back) {
+                    vm.Delete(1);
+                } else {
+                    string c = e.Key.ToString();
+                    if (c.Length == 1) {
+                        vm.Insert(c);
+                    }
+                }
             }
+
+            e.Handled = true;
         }
     }
 
@@ -40,7 +55,7 @@ public partial class EditorFrame : UserControl
         Focus();
         AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(this);
         if (adornerLayer != null) {
-            Caret = new Caret(this, 18);
+            Caret = new Caret(this, Brushes.LimeGreen);
             adornerLayer.Add(Caret);
         } else {
             System.Diagnostics.Debug.WriteLine("AdornerLayer still null. Check parent hierarchy.");
@@ -50,7 +65,8 @@ public partial class EditorFrame : UserControl
 
     private Point CalculateCaretPosition(int line, int index, double scrollY, double scrollX)
     {
-        return new Point(10 * index + scrollX, line * 18 + scrollY);
+        var ft = TextHelper.GetText(new string('_', index), 14, null, VisualTreeHelper.GetDpi(this).PixelsPerDip);
+        return new Point(ft.Width + scrollX + 2, line * TextHelper.LineHeight + scrollY);
     }
 
     private void MoveCaret(Point point)
@@ -74,6 +90,18 @@ public partial class EditorFrame : UserControl
                 scrollX));
     }
 
+    public LineBuffer CurrentLineBuffer {
+        get => (LineBuffer)GetValue(CurrentLineBufferProperty);
+        set => SetValue(CurrentLineBufferProperty, value);
+    }
+
+    public static readonly DependencyProperty CurrentLineBufferProperty =
+        DependencyProperty.Register(
+            nameof(CurrentLineBuffer),
+            typeof(LineBuffer),
+            typeof(EditorFrame),
+            new PropertyMetadata(null));
+
     public CursorPosition CursorPosition {
         get => (CursorPosition)GetValue(CursorPositionProperty);
         set => SetValue(CursorPositionProperty, value);

Qrakhen.Qamp.Editor/Controls/LineRenderer.xaml.cs

@@ -1,6 +1,7 @@
 using Qrakhen.Qamp.Memory;
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Text;
 using System.Windows;
 using System.Windows.Controls;
@@ -21,7 +22,7 @@ public partial class LineRenderer : UserControl
             nameof(LineBuffer), 
             typeof(LineBuffer), 
             typeof(LineRenderer), 
-            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender));
+            new FrameworkPropertyMetadata(null, OnLineBufferChanged));
 
     public LineBuffer LineBuffer {
         get => (LineBuffer)GetValue(LineBufferProperty);
@@ -45,11 +46,8 @@ public partial class LineRenderer : UserControl
         if (string.IsNullOrEmpty(LineBuffer.Cached))
             return;
 
-        var formattedText = new FormattedText(
+        var formattedText = TextHelper.GetText(
             LineBuffer.Cached,
-            System.Globalization.CultureInfo.CurrentCulture,
-            FlowDirection.LeftToRight,
-            _typeface,
             FontSize,
             Brushes.White,
             VisualTreeHelper.GetDpi(this).PixelsPerDip
@@ -57,4 +55,25 @@ public partial class LineRenderer : UserControl
 
         drawingContext.DrawText(formattedText, new Point(2, 0));
     }
+
+    private static void OnLineBufferChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+    {
+        if (d is LineRenderer renderer) {
+            if (e.OldValue is LineBuffer oldBuffer && oldBuffer != null) {
+                oldBuffer.PropertyChanged -= renderer.OnLineBufferPropertyChanged;
+            }
+
+            if (e.NewValue is LineBuffer newBuffer && newBuffer != null) {
+                newBuffer.PropertyChanged += renderer.OnLineBufferPropertyChanged;
+            }
+
+            renderer.InvalidateVisual();
+        }
+    }
+
+    private void OnLineBufferPropertyChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        if (e.PropertyName == nameof(LineBuffer.Cached))
+            InvalidateVisual();
+    }
 }

Qrakhen.Qamp.Editor/Primitives/CursorPosition.cs

@@ -8,8 +8,8 @@ public record struct CursorPosition(int line = 0, int column = 0)
     public static readonly CursorPosition Up = new(-1, 0);
     public static readonly CursorPosition Down = new(1, 0);
 
-    public int Line = line < 0 ? 0 : line;
-    public int Column = column < 0 ? 0 : column;
+    public int Line = line;
+    public int Column = column;
 
     public static CursorPosition operator +(CursorPosition left, CursorPosition right) 
         => new(left.Line + right.Line, left.Column + right.Column);

Qrakhen.Qamp.Editor/TextHelper.cs

@@ -0,0 +1,29 @@
+using System.Windows;
+using System.Windows.Media;
+
+namespace Qrakhen.Qamp.Editor;
+
+public static class TextHelper // temp
+{
+    public static double Size { get; set; } = 14;
+    public static double LineHeight { get; set; } = 18;
+    public static Brush DefaultColor { get; set; } = Brushes.AntiqueWhite;
+    public static Typeface Typeface { get; set; } = new(
+        new FontFamily("Consolas"), 
+        FontStyles.Normal, 
+        FontWeights.Normal, 
+        FontStretches.Normal);
+
+    public static FormattedText GetText(string text, double size, Brush? brush = null, double dpiScale = 1f)
+    {
+        return new FormattedText(
+            text,
+            System.Globalization.CultureInfo.CurrentCulture,
+            FlowDirection.LeftToRight,
+            Typeface,
+            size,
+            brush ?? DefaultColor,
+            dpiScale
+        );
+    }
+}

Qrakhen.Qamp.Editor/ViewModel/EditorFrameViewModel.cs

@@ -51,6 +51,7 @@ public class EditorFrameViewModel : ObservableObject
     public void MoveCursor(int lines, int columns)
     {
         SetCursor(CursorLine + lines, CursorColumn + columns);
+        OnPropertyChanged(nameof(CurrentLineBuffer));
     }
 
     public bool CanMoveCaret(object? relativeUpdate)
@@ -64,9 +65,19 @@ public class EditorFrameViewModel : ObservableObject
             MoveCursor(pos.Line, pos.Column);
     }
 
-    public void Insert(string data)
+    public void Delete(int count = 1, bool follow = true)
+    {
+        if (follow)
+            MoveCursor(0, -count);
+        CurrentLineBuffer.Delete(CursorColumn, count);
+        OnPropertyChanged(nameof(Lines));
+    }
+
+    public void Insert(string data, bool follow = true)
     {
         CurrentLineBuffer.Insert(CursorColumn, data);
+        if (follow)
+            MoveCursor(0, data.Length);
         OnPropertyChanged(nameof(Lines));
     }
 }

Qrakhen.Qamp.Memory/LineBuffer.cs

@@ -1,11 +1,13 @@
-using System.Text;
+using System.ComponentModel;
+using System.Text;
 
 namespace Qrakhen.Qamp.Memory;
 
-public sealed class LineBuffer : TailBuffer<byte>
+public sealed class LineBuffer : TailBuffer<byte>, INotifyPropertyChanged
 {
     public Encoding Encoding { get; }
     public string Cached { get; private set; } = "";
+    public event PropertyChangedEventHandler? PropertyChanged;
 
     public LineBuffer(Encoding encoding, int size = 0x80) : base(size)
     {
@@ -23,6 +25,7 @@ public sealed class LineBuffer : TailBuffer<byte>
     {
         base.SetTail(tail);
         Cached = ToString();
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Cached)));
     }
 
     public void Insert(int cursor, string data)

Qrakhen.Qamp.Memory/TailBuffer.cs

@@ -60,9 +60,9 @@ public abstract class TailBuffer<T>
     private void Prepare(int index, int count)
     {
         ArgumentOutOfRangeException.ThrowIfNegative(index);
-        if (index + count <= _data.Length)
+        if (count + Tail <= _data.Length)
             return;
-        while (index + count > _data.Length) {
+        while (count + Tail > _data.Length) {
             T[] grow = new T[_data.Length * 2];
             Array.Copy(_data, grow, _data.Length);
             _data = grow;