Add a Cheats menu tab with engine cheat buttons and unlimited-resource switches

The new Cheats tab exposes the engine's own cheat handlers as buttons:
give all items and weapons, toggle physics, next level and previous
level. Physics shows its state through the button highlight. The buttons
need a running game and show a message otherwise.

It also has four independent session-only switches for unlimited health,
energy, ammo and items (grenades and drugs). While a switch is on, its
resource is topped up every frame by qs_cheat_refill() from the new
engine patch 26. The switches are not saved to the config.

android/app/src/main/cpp/qs_config.c

@@ -1250,6 +1250,7 @@ static Uint32 s_begin_control_capture_event_type;
 static Uint32 s_cancel_control_capture_event_type;
 static Uint32 s_reset_player_controls_event_type;
 static Uint32 s_menu_visibility_event_type;
+static Uint32 s_cheat_event_type;
 
 void qs_config_load_startup(void) {
     // Registers the custom SDL event types qs_config_request_save()/_load()/
@@ -1260,7 +1261,7 @@ void qs_config_load_startup(void) {
     // exist yet, rather than lazily from those functions themselves (which
     // run on Android's UI thread and could otherwise race each other doing
     // this lazily).
-    Uint32 base = SDL_RegisterEvents(14);
+    Uint32 base = SDL_RegisterEvents(15);
     s_save_event_type = base;
     s_load_event_type = base + 1;
     s_set_renderer_event_type = base + 2;
@@ -1275,6 +1276,7 @@ void qs_config_load_startup(void) {
     s_cancel_control_capture_event_type = base + 11;
     s_reset_player_controls_event_type = base + 12;
     s_menu_visibility_event_type = base + 13;
+    s_cheat_event_type = base + 14;
 
     QsParsedConfig parsed;
     bool haveConfig = qs_config_read_file(&parsed);
@@ -1407,6 +1409,14 @@ void qs_config_request_cancel_control_capture(void) {
     SDL_PushEvent(&event);
 }
 
+void qs_config_request_cheat(int cheat_id) {
+    SDL_Event event;
+    SDL_zero(event);
+    event.type = s_cheat_event_type;
+    event.user.code = cheat_id;
+    SDL_PushEvent(&event);
+}
+
 void qs_config_notify_menu_visibility(bool visible) {
     SDL_Event event;
     SDL_zero(event);
@@ -1449,6 +1459,77 @@ static void qs_apply_menu_pause(bool menu_visible) {
     }
 }
 
+// hkeyfunc.c - the engine's own cheat hotkey handlers, and the refill added by
+// android/engine-patches/26-android-cheat-refill.patch.
+extern uchar toggle_giveall_func(ushort keycode, uint32_t context, intptr_t data);
+extern uchar toggle_physics_func(ushort keycode, uint32_t context, intptr_t data);
+extern uchar toggle_up_level_func(ushort keycode, uint32_t context, intptr_t data);
+extern uchar toggle_down_level_func(ushort keycode, uint32_t context, intptr_t data);
+extern void qs_cheat_refill(int what);
+extern uchar physics_running;
+
+#define QS_CHEAT_GIVE_ALL 0
+#define QS_CHEAT_PHYSICS 1
+#define QS_CHEAT_LEVEL_UP 2
+#define QS_CHEAT_LEVEL_DOWN 3
+#define QS_CHEAT_UNLIMITED_HEALTH 4
+#define QS_CHEAT_UNLIMITED_ENERGY 5
+#define QS_CHEAT_UNLIMITED_AMMO 6
+#define QS_CHEAT_UNLIMITED_ITEMS 7
+
+// Bits of s_cheat_unlimited; the values match qs_cheat_refill() in patch 26.
+#define QS_CHEAT_MASK_HEALTH 1
+#define QS_CHEAT_MASK_ENERGY 2
+#define QS_CHEAT_MASK_AMMO 4
+#define QS_CHEAT_MASK_ITEMS 8
+
+static int s_cheat_unlimited = 0;
+
+int qs_config_cheat_unlimited_mask(void) { return s_cheat_unlimited; }
+bool qs_config_cheat_physics_running(void) { return physics_running != 0; }
+
+void qs_config_frame_tick(void) {
+    if (s_cheat_unlimited && s_screen_profile_is_game)
+        qs_cheat_refill(s_cheat_unlimited);
+}
+
+static void qs_apply_cheat(int cheat_id) {
+    if (cheat_id >= QS_CHEAT_UNLIMITED_HEALTH && cheat_id <= QS_CHEAT_UNLIMITED_ITEMS) {
+        static const struct {
+            int mask;
+            const char *on, *off;
+        } kUnlimited[] = {
+            {QS_CHEAT_MASK_HEALTH, "Unlimited health on", "Unlimited health off"},
+            {QS_CHEAT_MASK_ENERGY, "Unlimited energy on", "Unlimited energy off"},
+            {QS_CHEAT_MASK_AMMO, "Unlimited ammo on", "Unlimited ammo off"},
+            {QS_CHEAT_MASK_ITEMS, "Unlimited items on", "Unlimited items off"},
+        };
+        const int i = cheat_id - QS_CHEAT_UNLIMITED_HEALTH;
+        s_cheat_unlimited ^= kUnlimited[i].mask;
+        message_info((s_cheat_unlimited & kUnlimited[i].mask) ? kUnlimited[i].on : kUnlimited[i].off);
+        return;
+    }
+    // The engine's own handlers assume a running game (player state, levels).
+    if (!s_screen_profile_is_game) {
+        message_info("Cheats need a running game");
+        return;
+    }
+    switch (cheat_id) {
+    case QS_CHEAT_GIVE_ALL:
+        toggle_giveall_func(0, 0, 0);
+        break;
+    case QS_CHEAT_PHYSICS:
+        toggle_physics_func(0, 0, 0);
+        break;
+    case QS_CHEAT_LEVEL_UP:
+        toggle_up_level_func(0, 0, 0);
+        break;
+    case QS_CHEAT_LEVEL_DOWN:
+        toggle_down_level_func(0, 0, 0);
+        break;
+    }
+}
+
 bool qs_config_handle_event(const SDL_Event *event) {
     if (event->type == s_save_event_type) {
         if (qs_config_write_file())
@@ -1531,6 +1612,10 @@ bool qs_config_handle_event(const SDL_Event *event) {
         xr_input_capture_cancel();
         return true;
     }
+    if (event->type == s_cheat_event_type) {
+        qs_apply_cheat(event->user.code);
+        return true;
+    }
     if (event->type == s_menu_visibility_event_type) {
         qs_apply_menu_pause(event->user.code != 0);
         return true;