feat: backporting existing raylib-cs examples and new official raylib examples to WASM, adopting raylib's original code style

Examples/Textures/GifPlayer.cs

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+/*******************************************************************************************
+*
+*   raylib [textures] example - gif player
+*
+*   Example complexity rating: [★★★☆] 3/4
+*
+*   Example originally created with raylib 4.2, last time updated with raylib 4.2
+*
+*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+*   BSD-like license that allows static linking with closed source software
+*
+*   Copyright (c) 2021-2025 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+using static Raylib_cs.Raylib;
+
+namespace Examples.Textures;
+
+public partial class GifPlayer : IExample
+{
+    private const int screenWidth = 800;
+    private const int screenHeight = 450;
+
+    private const int MaxFrameDelay = 20;
+    private const int MinFrameDelay = 1;
+
+    public string Name => "Textures / Gif Player";
+
+    public string Title => "raylib [textures] example - gif player";
+
+    private int animFrames;
+    private Image imScarfyAnim;
+    private Texture2D texScarfyAnim;
+    private uint nextFrameDataOffset;  // Current byte offset to next frame in image.data
+    private int currentAnimFrame;      // Current animation frame to load and draw
+    private int frameDelay;            // Frame delay to switch between animation frames
+    private int frameCounter;          // General frames counter
+
+    public void Init()
+    {
+        animFrames = 0;
+
+        // Load all GIF animation frames into a single Image
+        // NOTE: GIF data is always loaded as RGBA (32bit) by default
+        // NOTE: Frames are just appended one after another in image.data memory
+        imScarfyAnim = LoadImageAnim("resources/scarfy_run.gif", out animFrames);
+
+        // Load texture from image
+        // NOTE: We will update this texture when required with next frame data
+        // WARNING: It's not recommended to use this technique for sprites animation,
+        // use spritesheets instead, like illustrated in textures_sprite_anim example
+        texScarfyAnim = LoadTextureFromImage(imScarfyAnim);
+
+        nextFrameDataOffset = 0;
+
+        currentAnimFrame = 0;
+        frameDelay = 8;
+        frameCounter = 0;
+    }
+
+    public unsafe void Update()
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        frameCounter++;
+        if (frameCounter >= frameDelay)
+        {
+            // Move to next frame
+            // NOTE: If final frame is reached we return to first frame
+            currentAnimFrame++;
+            if (currentAnimFrame >= animFrames)
+            {
+                currentAnimFrame = 0;
+            }
+
+            // Get memory offset position for next frame data in image.data
+            nextFrameDataOffset = (uint)(imScarfyAnim.Width * imScarfyAnim.Height * 4 * currentAnimFrame);
+
+            // Update GPU texture data with next frame image data
+            // WARNING: Data size (frame size) and pixel format must match already created texture
+            UpdateTexture(texScarfyAnim, (byte*)imScarfyAnim.Data + nextFrameDataOffset);
+
+            frameCounter = 0;
+        }
+
+        // Control frames delay
+        if (IsKeyPressed(KeyboardKey.Right))
+        {
+            frameDelay++;
+        }
+        else if (IsKeyPressed(KeyboardKey.Left))
+        {
+            frameDelay--;
+        }
+
+        if (frameDelay > MaxFrameDelay)
+        {
+            frameDelay = MaxFrameDelay;
+        }
+        else if (frameDelay < MinFrameDelay)
+        {
+            frameDelay = MinFrameDelay;
+        }
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+        ClearBackground(Color.RayWhite);
+
+        DrawText($"TOTAL GIF FRAMES:  {animFrames:D2}", 50, 30, 20, Color.LightGray);
+        DrawText($"CURRENT FRAME: {currentAnimFrame:D2}", 50, 60, 20, Color.Gray);
+        DrawText($"CURRENT FRAME IMAGE.DATA OFFSET: {nextFrameDataOffset:D2}", 50, 90, 20, Color.Gray);
+
+        DrawText("FRAMES DELAY: ", 100, 305, 10, Color.DarkGray);
+        DrawText($"{frameDelay:D2} frames", 620, 305, 10, Color.DarkGray);
+        DrawText("PRESS RIGHT/LEFT KEYS to CHANGE SPEED!", 290, 350, 10, Color.DarkGray);
+
+        for (var i = 0; i < MaxFrameDelay; i++)
+        {
+            if (i < frameDelay)
+            {
+                DrawRectangle(190 + 21 * i, 300, 20, 20, Color.Red);
+            }
+            DrawRectangleLines(190 + 21 * i, 300, 20, 20, Color.Maroon);
+        }
+
+        DrawTexture(texScarfyAnim, GetScreenWidth() / 2 - texScarfyAnim.Width / 2, 140, Color.White);
+
+        DrawText("(c) Scarfy sprite by Eiden Marsal", screenWidth - 200, screenHeight - 20, 10, Color.Gray);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    public void Unload()
+    {
+        UnloadTexture(texScarfyAnim);   // Unload texture
+        UnloadImage(imScarfyAnim);      // Unload image (contains all frames)
+    }
+
+    public static int Main()
+    {
+        // Initialization
+        //--------------------------------------------------------------------------------------
+        InitWindow(screenWidth, screenHeight, "raylib [textures] example - gif player");
+
+        SetTargetFPS(60);
+        //--------------------------------------------------------------------------------------
+
+        var game = new GifPlayer();
+        game.Init();
+
+        // Main game loop
+        while (!WindowShouldClose())    // Detect window close button or ESC key
+        {
+            game.Update();
+        }
+
+        game.Unload();
+
+        // De-Initialization
+        //--------------------------------------------------------------------------------------
+        CloseWindow();                // Close window and OpenGL context
+        //--------------------------------------------------------------------------------------
+
+        return 0;
+    }
+}