Terminal.Gui/UICatalog/Scenarios/CharacterMap.cs

using NStack;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Terminal.Gui;

namespace UICatalog {
	/// <summary>
	/// This Scenario demonstrates building a custom control (a class deriving from View) that:
	///   - Provides a simple "Character Map" application (like Windows' charmap.exe).
	///   - Helps test unicode character rendering in Terminal.Gui
	///   - Illustrates how to use ScrollView to do infinite scrolling
	/// </summary>
	[ScenarioMetadata (Name: "Character Map", Description: "Illustrates a custom control and Unicode")]
	[ScenarioCategory ("Text")]
	[ScenarioCategory ("Controls")]
	class CharacterMap : Scenario {
		public override void Setup ()
		{
			var charMap = new CharMap () {
				X = 0,
				Y = 0,
				Width = CharMap.RowWidth + 2,
				Height = Dim.Fill (),
				Start = 0x2500,
				ColorScheme = Colors.Dialog
			};

			Win.Add (charMap);
			var label = new Label ("Jump To Unicode Block:") { X = Pos.Right (charMap) + 1, Y = Pos.Y (charMap) };
			Win.Add (label);

			(ustring radioLabel, int start, int end) CreateRadio (ustring title, int start, int end)
			{
				return ($"{title} (U+{start:x5}-{end:x5})", start, end);
			}

			var radioItems = new (ustring radioLabel, int start, int end) [] {
				CreateRadio("Currency Symbols", 0x20A0, 0x20CF),
				CreateRadio("Letterlike Symbols", 0x2100, 0x214F),
				CreateRadio("Arrows", 0x2190, 0x21ff),
				CreateRadio("Mathematical symbols", 0x2200, 0x22ff),
				CreateRadio("Miscellaneous Technical", 0x2300, 0x23ff),
				CreateRadio("Box Drawing & Geometric Shapes", 0x2500, 0x25ff),
				CreateRadio("Miscellaneous Symbols", 0x2600, 0x26ff),
				CreateRadio("Dingbats", 0x2700, 0x27ff),
				CreateRadio("Braille", 0x2800, 0x28ff),
				CreateRadio("Miscellaneous Symbols and Arrows", 0x2b00, 0x2bff),
				CreateRadio("Alphabetic Presentation Forms", 0xFB00, 0xFb4f),
				CreateRadio("Cuneiform Numbers and Punctuation", 0x12400, 0x1240f),
				CreateRadio("Chess Symbols", 0x1FA00, 0x1FA0f),
				CreateRadio("End", CharMap.MaxCodePointVal - 16, CharMap.MaxCodePointVal),
			};

			var jumpList = new RadioGroup (radioItems.Select (t => t.radioLabel).ToArray ());
			jumpList.X = Pos.X (label);
			jumpList.Y = Pos.Bottom (label);
			jumpList.Width = Dim.Fill ();
			jumpList.SelectedItemChanged = (args) => {
				charMap.Start = radioItems[args.SelectedItem].start;
			};

			Win.Add (jumpList);
		}
	}

	class CharMap : ScrollView {

		/// <summary>
		/// Specifies the starting offset for the character map. The default is 0x2500 
		/// which is the Box Drawing characters.
		/// </summary>
		public int Start {
			get => _start;
			set {
				_start = value;
				ContentOffset = new Point (0, _start / 16);
				SetNeedsDisplay ();
			}
		}
		int _start = 0x2500;

		public static int MaxCodePointVal => 0xE0FFF;

		// Row Header + space + (space + char + space)
		public static int RowHeaderWidth => $"U+{MaxCodePointVal:x5}".Length;
		public static int RowWidth => RowHeaderWidth + (" c".Length * 16);

		public CharMap ()
		{
			ContentSize = new Size (CharMap.RowWidth, MaxCodePointVal / 16);
			ShowVerticalScrollIndicator = true;
			ShowHorizontalScrollIndicator = false;
			LayoutComplete += (args) => {
				if (Bounds.Width <= RowWidth) {
					ShowHorizontalScrollIndicator = true;
				} else {
					ShowHorizontalScrollIndicator = false;
				}
			};

			DrawContent += CharMap_DrawContent;
		}

#if true
		private void CharMap_DrawContent (Rect viewport)
		{
			for (int header = 0; header < 16; header++) {
				Move (viewport.X + RowHeaderWidth + (header * 2), 0);
				Driver.AddStr ($" {header:x} ");
			}
			for (int row = 0, y = 0; row < viewport.Height / 2 - 1; row++, y += 2) {
				int val = (-viewport.Y + row) * 16;
				if (val < MaxCodePointVal) {
					var rowLabel = $"U+{val / 16:x4}x";
					Move (0, y + 1);
					Driver.AddStr (rowLabel);
					for (int col = 0; col < 16; col++) {
						Move (viewport.X + RowHeaderWidth + (col * 2), 0 + y + 1);
						Driver.AddStr ($" {(char)((-viewport.Y + row) * 16 + col)}");
					}
				}
			}
		}
#else
		public override void OnDrawContent (Rect viewport)
		{
			CharMap_DrawContent(this, viewport);
			base.OnDrawContent (viewport);
		}
#endif
	}
}