Enhance emscripten display settings (#24841)

* emscripten: Invoke HTML5 emscripten fullscreen API instead of using SDL

* emscripten: Disable OpenGL

* emscripten: Add fullscreen change to changelog

distribution/changelog.txt

@@ -19,6 +19,7 @@
 - Fix: [#24829] The pattern of long grass across tiles is different to RCT1 and RCT2.
 - Fix: [#24831] Park names are being overwritten for custom RCT1 scenarios that use competition id slots.
 - Fix: [#24838] Not using localized word for conjunction when having multiple shortcuts for the same action.
+- Fix: [#24841] Fullscreen options do not work correctly with Emscripten.
 
 0.4.24 (2025-07-05)
 ------------------------------------------------------------------------

scripts/build-emscripten

@@ -12,6 +12,7 @@ JSON_DIR=/usr/include/nlohmann/
 emcmake cmake ../ \
     -G Ninja \
 	-DDISABLE_NETWORK=ON \
+	-DDISABLE_OPENGL=ON \
 	-DDISABLE_HTTP=ON \
 	-DDISABLE_TTF=ON \
 	-DDISABLE_FLAC=ON \

src/openrct2-ui/UiContext.cpp

@@ -182,6 +182,7 @@ public:
 
     void SetFullscreenMode(FullscreenMode mode) override
     {
+#ifndef __EMSCRIPTEN__
         static constexpr int32_t kSDLFullscreenFlags[] = {
             0,
             SDL_WINDOW_FULLSCREEN,
@@ -212,6 +213,16 @@ public:
 
             // TODO try another display mode rather than just exiting the game
         }
+#else
+        if (mode == FullscreenMode::fullscreen)
+        {
+            emscripten_request_fullscreen("!canvas", false);
+        }
+        else if (mode == FullscreenMode::windowed)
+        {
+            emscripten_exit_fullscreen();
+        }
+#endif // __EMSCRIPTEN__
     }
 
     const std::vector<Resolution>& GetFullscreenResolutions() override