+ a Defragment ribbon tab gives the block map the whole window

Compression.NativeUI/Controls/LogView.cs

@@ -0,0 +1,95 @@
+using System.Drawing;
+using Hawkynt.NativeForms;
+using Hawkynt.NativeForms.Drawing;
+
+namespace Compression.NativeUI.Controls;
+
+/// <summary>
+/// A read-only log that wraps every line to its width and keeps the newest line in view; the mouse
+/// wheel scrolls back through older ones.
+/// </summary>
+/// <remarks>
+/// A multiline text box neither wraps nor scrolls sideways on every backend, so a long outcome line
+/// ran off its right edge. Drawing the lines here wraps them the same way everywhere.
+/// </remarks>
+internal sealed class LogView : OwnerDrawnControl {
+  private const int Inset = 3;
+
+  private readonly List<string> _lines = [];
+  private int _scrollBack;
+
+  /// <summary>Every line logged since the last <see cref="Clear"/>, unwrapped.</summary>
+  public string LogText => string.Join(Environment.NewLine, this._lines);
+
+  public void Append(string line) {
+    this._lines.AddRange(line.Replace("\r\n", "\n").Split('\n'));
+    this._scrollBack = 0;
+    this.Invalidate();
+  }
+
+  public void Clear() {
+    this._lines.Clear();
+    this._scrollBack = 0;
+    this.Invalidate();
+  }
+
+  /// <summary>
+  /// Breaks <paramref name="line"/> into rows no wider than <paramref name="width"/>: at spaces where
+  /// it can, inside a word only when the word alone is wider than the row.
+  /// </summary>
+  internal static List<string> Wrap(string line, int width, Func<string, int> measure) {
+    var rows = new List<string>();
+    if (line.Length == 0 || width <= 0 || measure(line) <= width) {
+      rows.Add(line);
+      return rows;
+    }
+
+    var rest = line;
+    while (rest.Length > 0) {
+      if (measure(rest) <= width) {
+        rows.Add(rest);
+        break;
+      }
+
+      // The longest prefix that fits, found by halving rather than one character at a time.
+      int lo = 1, hi = rest.Length;
+      while (lo < hi) {
+        var mid = (lo + hi + 1) / 2;
+        if (measure(rest[..mid]) <= width) lo = mid;
+        else hi = mid - 1;
+      }
+
+      var cut = lo;
+      var space = rest.LastIndexOf(' ', Math.Min(cut, rest.Length - 1));
+      if (space > 0) cut = space;
+      rows.Add(rest[..cut].TrimEnd());
+      rest = rest[cut..].TrimStart();
+    }
+
+    return rows;
+  }
+
+  protected override void OnPaint(PaintEventArgs e) {
+    var g = e.Graphics;
+    var theme = DefaultTheme.Instance;
+    g.FillRectangle(theme.FieldBackground, new(0, 0, this.Width, this.Height));
+    g.DrawRectangle(theme.Border, new(0, 0, this.Width - 1, this.Height - 1));
+
+    var width = this.Width - 2 * Inset;
+    var rowHeight = Math.Max(1, g.MeasureText("Ag", this.Font).Height);
+    var rows = this._lines.SelectMany(l => Wrap(l, width, s => g.MeasureText(s, this.Font).Width)).ToList();
+    var visible = Math.Max(1, (this.Height - 2 * Inset) / rowHeight);
+    this._scrollBack = Math.Clamp(this._scrollBack, 0, Math.Max(0, rows.Count - visible));
+
+    var first = Math.Max(0, rows.Count - visible - this._scrollBack);
+    var y = Inset;
+    for (var i = first; i < rows.Count && y + rowHeight <= this.Height - Inset + 1; ++i, y += rowHeight)
+      g.DrawText(rows[i], this.Font, theme.ControlText, new(Inset, y, width, rowHeight), ContentAlignment.MiddleLeft);
+  }
+
+  protected override void OnMouseWheel(MouseEventArgs e) {
+    this._scrollBack += e.Delta > 0 ? 3 : -3;
+    if (this._scrollBack < 0) this._scrollBack = 0;
+    this.Invalidate();
+  }
+}