feat: add terminal text measurer

- measure terminal display width for text and escape sequences

- truncate rendered lines to terminal columns

- add width and truncation examples

src/TinyTUI/Text/TerminalTextMeasurer.cs

@@ -0,0 +1,166 @@
+using System.Buffers;
+using System.Globalization;
+using System.Text;
+
+namespace TinyTUI.Text;
+
+/// <summary>
+/// 基于常见终端字符单元规则的文本测量器
+/// </summary>
+public sealed class TerminalTextMeasurer : ITextMeasurer
+{
+    /// <inheritdoc />
+    public int GetWidth(string value)
+    {
+        var width = 0;
+
+        for (var index = 0; index < value.Length;)
+        {
+            if (TryReadEscape(value, index, out var escapeLength))
+            {
+                index += escapeLength;
+                continue;
+            }
+
+            var status = Rune.DecodeFromUtf16(value.AsSpan(index), out var rune, out var charsConsumed);
+            if (status != OperationStatus.Done)
+            {
+                index++;
+                continue;
+            }
+
+            width += GetRuneWidth(rune);
+            index += charsConsumed;
+        }
+
+        return width;
+    }
+
+    /// <inheritdoc />
+    public string Truncate(string value, int maxWidth)
+    {
+        if (maxWidth <= 0)
+        {
+            return string.Empty;
+        }
+
+        var builder = new StringBuilder();
+        var width = 0;
+
+        for (var index = 0; index < value.Length;)
+        {
+            if (TryReadEscape(value, index, out var escapeLength))
+            {
+                builder.Append(value.AsSpan(index, escapeLength));
+                index += escapeLength;
+                continue;
+            }
+
+            var status = Rune.DecodeFromUtf16(value.AsSpan(index), out var rune, out var charsConsumed);
+            if (status != OperationStatus.Done)
+            {
+                index++;
+                continue;
+            }
+
+            var runeWidth = GetRuneWidth(rune);
+            if (width + runeWidth > maxWidth)
+            {
+                break;
+            }
+
+            builder.Append(value.AsSpan(index, charsConsumed));
+            width += runeWidth;
+            index += charsConsumed;
+        }
+
+        return builder.ToString();
+    }
+
+    private static int GetRuneWidth(Rune rune)
+    {
+        if (Rune.IsControl(rune))
+            return 0;
+
+        var category = Rune.GetUnicodeCategory(rune);
+        if (category is UnicodeCategory.NonSpacingMark or UnicodeCategory.EnclosingMark or UnicodeCategory.Format)
+            return 0;
+
+        return IsWide(rune.Value) ? 2 : 1;
+    }
+
+    private static bool IsWide(int value) =>
+        value is
+            >= 0x1100 and <= 0x115f or
+            >= 0x2329 and <= 0x232a or
+            >= 0x2e80 and <= 0xa4cf or
+            >= 0xac00 and <= 0xd7a3 or
+            >= 0xf900 and <= 0xfaff or
+            >= 0xfe10 and <= 0xfe19 or
+            >= 0xfe30 and <= 0xfe6f or
+            >= 0xff00 and <= 0xff60 or
+            >= 0xffe0 and <= 0xffe6 or
+            >= 0x1f000 and <= 0x1faff;
+
+    private static bool TryReadEscape(string value, int start, out int length)
+    {
+        length = 0;
+
+        if (value[start] != '\e')
+            return false;
+
+        if (start + 1 >= value.Length)
+        {
+            length = 1;
+            return true;
+        }
+
+        return value[start + 1] switch
+        {
+            '[' => TryReadCsi(value, start, out length),
+            ']' or '_' or 'P' => TryReadStringEscape(value, start, out length),
+            _ => ReadSimpleEscape(value, start, out length),
+        };
+    }
+
+    private static bool TryReadCsi(string value, int start, out int length)
+    {
+        for (var index = start + 2; index < value.Length; index++)
+        {
+            var ch = value[index];
+            if (ch is >= '@' and <= '~')
+            {
+                length = index - start + 1;
+                return true;
+            }
+        }
+
+        length = value.Length - start;
+        return true;
+    }
+
+    private static bool TryReadStringEscape(string value, int start, out int length)
+    {
+        for (var index = start + 2; index < value.Length; index++)
+        {
+            switch (value[index])
+            {
+                case '\a':
+                    length = index - start + 1;
+                    return true;
+                case '\e' when index + 1 < value.Length && value[index + 1] == '\\':
+                    length = index - start + 2;
+                    return true;
+            }
+        }
+
+        length = value.Length - start;
+        return true;
+    }
+
+    private static bool ReadSimpleEscape(string value, int start, out int length)
+    {
+        length = Math.Min(2, value.Length - start);
+        return true;
+    }
+}