update Android raylib example so that asset loading can work

examples/raylib/build.zig

@@ -32,6 +32,10 @@ pub fn build(b: *std.Build) void {
         apk.setAndroidManifest(b.path("android/AndroidManifest.xml"));
         apk.addResourceDirectory(b.path("android/res"));
 
+        const generated_asset_dir = b.addNamedWriteFiles("android_asset_directory");
+        _ = generated_asset_dir.addCopyFile(b.path("src/zig.bmp"), "zig.bmp");
+        apk.addAssetDirectory(generated_asset_dir.getDirectory());
+
         break :blk apk;
     };
 

examples/raylib/src/main.zig

@@ -7,15 +7,22 @@ const rl = @import("raylib");
 pub fn main() !void {
     const screenWidth = 800;
     const screenHeight = 450;
+
     rl.initWindow(screenWidth, screenHeight, "raylib-zig [core] example - basic window");
     defer rl.closeWindow();
+
+    const zig_tex = try rl.loadTexture("zig.bmp");
+    defer rl.unloadTexture(zig_tex);
+
     rl.setTargetFPS(60);
     while (!rl.windowShouldClose()) {
         rl.beginDrawing();
         defer rl.endDrawing();
 
         rl.clearBackground(.white);
 
+        rl.drawTexture(zig_tex, screenWidth / 2 - @divTrunc(zig_tex.width, 2), screenHeight / 2, .white);
+
         rl.drawText("Congrats! You created your first window!", 190, 200, 20, .light_gray);
     }
 }
@@ -43,28 +50,70 @@ comptime {
         //
         // Then Raylib makes the "android_main" entrypoint call the exported "main" C-function
         // https://github.com/raysan5/raylib/blob/f89d38b086c1d0a0c7e38c9c648aa91c05646300/src/platforms/rcore_android.c#L322
-        @export(&androidMain, .{ .name = "main" });
+        @export(&RaylibAndroidGlue.androidMain, .{ .name = "main" });
 
         // NOTE(jae): 2026-04-12
-        // As of March 2026, Raylib requires a linker flag to make __real_fopen exist
+        // As of March 2026, Raylib requires a linker flag to make __real_fopen and needs to override "fopen" to call "__wrap_fopen" (provided by Raylib)
         // https://github.com/raysan5/raylib/pull/5624
         //
         // Because Zig doesn't give access to linker flags to add (-Wl,--wrap=fopen), we just export __real_fopen ourselves and call it here:
         // -Wl,--wrap=fopen
         // Related comment: https://github.com/raysan5/raylib/blob/f89d38b086c1d0a0c7e38c9c648aa91c05646300/src/platforms/rcore_android.c#L299-L300
-        @export(&raylibFileOpen, .{ .name = "__real_fopen" });
+        //
+        // Borrowed fix from @maiconpintoabreu:
+        // https://gist.github.com/maiconpintoabreu/f5eb68d467ba6105256daf03e3ede51c
+        @export(&RaylibAndroidGlue.fopen, .{ .name = "fopen" });
+        @export(&RaylibAndroidGlue.__real_fopen, .{ .name = "__real_fopen" });
     }
 }
 
-fn raylibFileOpen(filename: [*c]const u8, modes: [*c]const u8) callconv(.c) ?*anyopaque {
-    return @import("std").c.fopen(filename, modes);
-}
+const RaylibAndroidGlue = struct {
+    /// General error message for a malformed return type
+    const bad_main_ret = "expected return type of main to be 'void', '!void', 'noreturn', 'u8', or '!u8'";
 
-fn androidMain() callconv(.c) c_int {
-    main() catch |err| {
-        std.log.err("{t}", .{err});
-        if (@errorReturnTrace()) |trace| std.debug.dumpErrorReturnTrace(trace);
-        return 1;
-    };
-    return 0;
-}
+    fn androidMain() callconv(.c) c_int {
+        const result = main();
+        const ReturnType = @TypeOf(result);
+        switch (ReturnType) {
+            void => return 0,
+            noreturn => unreachable,
+            u8 => return result,
+            else => {},
+        }
+        if (@typeInfo(ReturnType) != .error_union) @compileError(bad_main_ret);
+
+        const unwrapped_result = result catch |err| {
+            std.log.err("{t}", .{err});
+            if (@errorReturnTrace()) |trace| std.debug.dumpErrorReturnTrace(trace);
+            return 1;
+        };
+
+        return switch (@TypeOf(unwrapped_result)) {
+            noreturn => unreachable,
+            void => 0,
+            u8 => unwrapped_result,
+            else => @compileError(bad_main_ret),
+        };
+    }
+
+    /// Override fopen to call __wrap_fopen (provided by Raylib to load asset files)
+    fn fopen(filename: [*c]const u8, modes: [*c]const u8) callconv(.c) ?*anyopaque {
+        return __wrap_fopen(filename, modes);
+    }
+
+    /// Must implement __real_fopen as Raylib needs it to open files that are not inside assets folder
+    fn __real_fopen(filename: [*c]const u8, modes: [*c]const u8) callconv(.c) ?*anyopaque {
+        const RTLD_NEXT = @as(?*anyopaque, @ptrFromInt(@as(usize, @bitCast(@as(isize, -1)))));
+        const c_fopen_ptr = RaylibAndroidGlue.dlsym(RTLD_NEXT, "fopen") orelse return null;
+        const c_fopen: *const fn ([*c]const u8, [*c]const u8) callconv(.c) ?*anyopaque = @ptrCast(@alignCast(c_fopen_ptr));
+
+        return c_fopen(filename, modes);
+    }
+
+    extern "c" fn __wrap_fopen(filename: [*c]const u8, modes: [*c]const u8) callconv(.c) ?*anyopaque;
+
+    // Zig version used to write was 0.16.0
+    // Define dlsym and RTLD_NEXT to be able to call system fopen as I am overriding it bellow
+    // https://pubs.opengroup.org/onlinepubs/009604299/functions/dlsym.html
+    extern "c" fn dlsym(handle: ?*anyopaque, symbol: [*c]const u8) callconv(.c) ?*anyopaque;
+};

examples/sdl2/build.zig

@@ -25,25 +25,16 @@ pub fn build(b: *std.Build) void {
             .api_level = .android15,
             .build_tools_version = "36.1.0",
             .ndk_version = "29.0.14206865",
-            // NOTE(jae): 2025-03-09
-            // Previously this example used 'ndk' "27.0.12077973".
-            //
-            // However that has issues with the latest SDL2 version when including 'hardware_buffer.h'
-            // for 32-bit builds.
-            //
-            // - AHARDWAREBUFFER_USAGE_FRONT_BUFFER = 1UL << 32
-            //  - ndk/27.0.12077973/toolchains/llvm/prebuilt/{OS}-x86_64/sysroot/usr/include/android/hardware_buffer.h:322:42:
-            //  - error: expression is not an integral constant expression
         });
 
         const key_store_file = android_sdk.createKeyStore(.example);
         apk.setKeyStore(key_store_file);
         apk.setAndroidManifest(b.path("android/AndroidManifest.xml"));
+        apk.addResourceDirectory(b.path("android/res"));
 
         const generated_asset_dir = b.addNamedWriteFiles("android_asset_directory");
         _ = generated_asset_dir.addCopyFile(b.path("src/zig.bmp"), "zig.bmp");
         apk.addAssetDirectory(generated_asset_dir.getDirectory());
-        apk.addResourceDirectory(b.path("android/res"));
 
         // Add Java files
         if (!crash_on_exception) {