Terminal.Gui/UICatalog/Scenarios/Animation.cs

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.ColorSpaces;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Processing;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using Terminal.Gui;
using Attribute = Terminal.Gui.Attribute;

namespace UICatalog.Scenarios {
	[ScenarioMetadata (Name: "Animation", Description: "Demonstration of how to render animated images with threading.")]
	[ScenarioCategory ("Colors")]
	public class Animation : Scenario {
		private bool isDisposed;

		public override void Setup ()
		{
			base.Setup ();

			var imageView = new ImageView () {
				Width = Dim.Fill (),
				Height = Dim.Fill () - 2,
			};

			Win.Add (imageView);

			var lbl = new Label ("Image by Wikiscient") {
				Y = Pos.AnchorEnd (2)
			};
			Win.Add (lbl);

			var lbl2 = new Label ("https://commons.wikimedia.org/wiki/File:Spinning_globe.gif") {
				Y = Pos.AnchorEnd (1)
			};
			Win.Add (lbl2);

			var dir = new DirectoryInfo (Path.GetDirectoryName (Assembly.GetExecutingAssembly ().Location));

			var f = new FileInfo (
				Path.Combine (dir.FullName, "Scenarios", "Spinning_globe_dark_small.gif"));
			if (!f.Exists) {
				MessageBox.ErrorQuery ("Could not find gif", "Could not find " + f.FullName, "Ok");
				return;
			}

			imageView.SetImage (Image.Load<Rgba32> (File.ReadAllBytes (f.FullName)));

			Task.Run (() => {
				while (!isDisposed) {
					// When updating from a Thread/Task always use Invoke
					Application.MainLoop.Invoke (() => {
						imageView.NextFrame ();
						imageView.SetNeedsDisplay ();
					});

					Task.Delay (100).Wait ();
				}
			});
		}

		protected override void Dispose (bool disposing)
		{
			isDisposed = true;
			base.Dispose (disposing);
		}

		// This is a C# port of https://github.com/andraaspar/bitmap-to-braille by Andraaspar

		/// <summary>
		/// Renders an image as unicode Braille.
		/// </summary>
		public class BitmapToBraille {

			public const int CHAR_WIDTH = 2;
			public const int CHAR_HEIGHT = 4;

			const string CHARS = " ⠁⠂⠃⠄⠅⠆⠇⡀⡁⡂⡃⡄⡅⡆⡇⠈⠉⠊⠋⠌⠍⠎⠏⡈⡉⡊⡋⡌⡍⡎⡏⠐⠑⠒⠓⠔⠕⠖⠗⡐⡑⡒⡓⡔⡕⡖⡗⠘⠙⠚⠛⠜⠝⠞⠟⡘⡙⡚⡛⡜⡝⡞⡟⠠⠡⠢⠣⠤⠥⠦⠧⡠⡡⡢⡣⡤⡥⡦⡧⠨⠩⠪⠫⠬⠭⠮⠯⡨⡩⡪⡫⡬⡭⡮⡯⠰⠱⠲⠳⠴⠵⠶⠷⡰⡱⡲⡳⡴⡵⡶⡷⠸⠹⠺⠻⠼⠽⠾⠿⡸⡹⡺⡻⡼⡽⡾⡿⢀⢁⢂⢃⢄⢅⢆⢇⣀⣁⣂⣃⣄⣅⣆⣇⢈⢉⢊⢋⢌⢍⢎⢏⣈⣉⣊⣋⣌⣍⣎⣏⢐⢑⢒⢓⢔⢕⢖⢗⣐⣑⣒⣓⣔⣕⣖⣗⢘⢙⢚⢛⢜⢝⢞⢟⣘⣙⣚⣛⣜⣝⣞⣟⢠⢡⢢⢣⢤⢥⢦⢧⣠⣡⣢⣣⣤⣥⣦⣧⢨⢩⢪⢫⢬⢭⢮⢯⣨⣩⣪⣫⣬⣭⣮⣯⢰⢱⢲⢳⢴⢵⢶⢷⣰⣱⣲⣳⣴⣵⣶⣷⢸⢹⢺⢻⢼⢽⢾⢿⣸⣹⣺⣻⣼⣽⣾⣿";

			public int WidthPixels { get; }
			public int HeightPixels { get; }

			public Func<int, int, bool> PixelIsLit { get; }

			public BitmapToBraille (int widthPixels, int heightPixels, Func<int, int, bool> pixelIsLit)
			{
				WidthPixels = widthPixels;
				HeightPixels = heightPixels;
				PixelIsLit = pixelIsLit;
			}

			public string GenerateImage ()
			{
				int imageHeightChars = (int)Math.Ceiling ((double)HeightPixels / CHAR_HEIGHT);
				int imageWidthChars = (int)Math.Ceiling ((double)WidthPixels / CHAR_WIDTH);

				var result = new StringBuilder ();

				for (int y = 0; y < imageHeightChars; y++) {

					for (int x = 0; x < imageWidthChars; x++) {
						int baseX = x * CHAR_WIDTH;
						int baseY = y * CHAR_HEIGHT;

						int charIndex = 0;
						int value = 1;

						for (int charX = 0; charX < CHAR_WIDTH; charX++) {
							for (int charY = 0; charY < CHAR_HEIGHT; charY++) {
								int bitmapX = baseX + charX;
								int bitmapY = baseY + charY;
								bool pixelExists = bitmapX < WidthPixels && bitmapY < HeightPixels;

								if (pixelExists && PixelIsLit (bitmapX, bitmapY)) {
									charIndex += value;
								}
								value *= 2;
							}
						}

						result.Append (CHARS [charIndex]);
					}
					result.Append ('\n');
				}
				return result.ToString ().TrimEnd ();
			}
		}

		class ImageView : View {
			private int frameCount;
			private int currentFrame = 0;

			private Image<Rgba32> [] fullResImages;
			private Image<Rgba32> [] matchSizes;
			private string [] brailleCache;

			Rect oldSize = Rect.Empty;

			internal void SetImage (Image<Rgba32> image)
			{
				frameCount = image.Frames.Count;

				fullResImages = new Image<Rgba32> [frameCount];
				matchSizes = new Image<Rgba32> [frameCount];
				brailleCache = new string [frameCount];

				for (int i = 0; i < frameCount - 1; i++) {
					fullResImages [i] = image.Frames.ExportFrame (0);
				}
				fullResImages [frameCount - 1] = image;

				this.SetNeedsDisplay ();
			}
			public void NextFrame ()
			{
				currentFrame = (currentFrame + 1) % frameCount;
			}

			public override void OnDrawContent (Rect contentArea)
			{
				base.OnDrawContent (contentArea);

				if (oldSize != Bounds) {
					// Invalidate cached images now size has changed
					matchSizes = new Image<Rgba32> [frameCount];
					brailleCache = new string [frameCount];
					oldSize = Bounds;
				}

				var imgScaled = matchSizes [currentFrame];
				var braille = brailleCache [currentFrame];

				if (imgScaled == null) {
					var imgFull = fullResImages [currentFrame];

					// keep aspect ratio
					var newSize = Math.Min (Bounds.Width, Bounds.Height);

					// generate one
					matchSizes [currentFrame] = imgScaled = imgFull.Clone (
						x => x.Resize (
							 newSize * BitmapToBraille.CHAR_HEIGHT,
							 newSize * BitmapToBraille.CHAR_HEIGHT));
				}

				if (braille == null) {
					brailleCache [currentFrame] = braille = GetBraille (matchSizes [currentFrame]);
				}

				var lines = braille.Split ('\n');

				for (int y = 0; y < lines.Length; y++) {
					var line = lines [y];
					for (int x = 0; x < line.Length; x++) {
						AddRune (x, y, line [x]);
					}
				}
			}

			private string GetBraille (Image<Rgba32> img)
			{
				var braille = new BitmapToBraille (
					img.Width,
					img.Height,
					(x, y) => IsLit (img, x, y));

				return braille.GenerateImage ();
			}

			private bool IsLit (Image<Rgba32> img, int x, int y)
			{
				var rgb = img [x, y];
				return rgb.R + rgb.G + rgb.B > 50;
			}
		}
	}
}