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

Examples/Web/Host.cs

@@ -0,0 +1,132 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices.JavaScript;
+
+namespace Examples.Web;
+
+/// <summary>
+/// Browser host: owns the single raylib window and the "current" example. The frame loop is
+/// driven from JavaScript (main.js, via requestAnimationFrame) since a blocking C# loop would
+/// freeze the page. Methods marked [JSExport] are called from main.js.
+///
+/// <para>
+/// Every switch applies <see cref="IExample.TargetFps"/> and resets the cursor to visible.
+/// Cursor hiding, <see cref="IExample.ConfigFlags"/>, and per-example window size are not
+/// honored in the browser; the canvas stays 800x450 and the pointer stays visible.
+/// </para>
+/// </summary>
+public partial class Host
+{
+    public const int screenWidth = 800;
+    public const int screenHeight = 450;
+
+    private static readonly List<IExample> _examples = new(ExampleRegistry.BrowserExamples);
+
+    private static IExample _current;
+
+    public static void Main()
+    {
+        InitWindow(screenWidth, screenHeight, "raylib-cs web examples");
+        SetTargetFPS(60);
+
+        // main.js selects the first example, so its init failures surface through SetExample.
+    }
+
+    /// <summary>Render one frame of the current example; false if it threw and was torn down.</summary>
+    [JSExport]
+    public static bool UpdateFrame()
+    {
+        if (_current == null)
+        {
+            return true;
+        }
+
+        try
+        {
+            _current.Update();
+            return true;
+        }
+        catch (Exception ex)
+        {
+            // Don't let one misbehaving example kill the whole page; log and stop driving it.
+            Console.WriteLine($"[Examples.Web] '{_current.Name}' threw during Update: {ex}");
+            TryUnload(_current);
+            _current = null;
+            return false;
+        }
+    }
+
+    /// <summary>Switch the active example by name; false on unknown name or failed Init.</summary>
+    [JSExport]
+    public static bool SetExample(string name)
+    {
+        var next = _examples.Find(e => e.Name == name);
+        if (next == null)
+        {
+            return false;
+        }
+
+        if (_current != null)
+        {
+            TryUnload(_current);
+            _current = null;
+        }
+
+        // Reset the baseline; an example may hide/lock the cursor from its own Update(), and
+        // CursorDisabled/CursorHidden are deliberately never applied in the browser.
+        EnableCursor();
+        ShowCursor();
+        SetTargetFPS(next.TargetFps);
+
+        try
+        {
+            next.Init();
+            _current = next;
+            return true;
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine($"[Examples.Web] '{next.Name}' failed to initialize: {ex}");
+            TryUnload(next);
+            return false;
+        }
+    }
+
+    /// <summary>Target FPS of the current example; main.js paces the frame loop with it.</summary>
+    [JSExport]
+    public static int GetCurrentTargetFps()
+    {
+        return _current?.TargetFps ?? 60;
+    }
+
+    /// <summary>Newline-separated example names, used to populate the nav dropdown.</summary>
+    [JSExport]
+    public static string GetExampleNames()
+    {
+        return string.Join("\n", _examples.ConvertAll(e => e.Name));
+    }
+
+    /// <summary>
+    /// Map browser CSS mouse coordinates to the fixed 800x450 framebuffer when the canvas
+    /// is CSS-scaled (integer/fit/native display modes in main.js).
+    /// </summary>
+    [JSExport]
+    public static void SetMouseScaleFromDisplay(float scaleX, float scaleY)
+    {
+        SetMouseOffset(0, 0);
+        SetMouseScale(scaleX, scaleY);
+    }
+
+    /// <summary>Best-effort Unload that never lets a failure cascade.</summary>
+    private static void TryUnload(IExample example)
+    {
+        try
+        {
+            example.Unload();
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine($"[Examples.Web] '{example.Name}' threw during Unload: {ex}");
+        }
+    }
+}