platform: [fixed] modstate on android system may not the same as uos system.

Remember capslock and numlock state on android system.When an anbox window
is used, compare state between android and uos. If different, make capslock
or numlock key event and send to android to change it.

src/anbox/platform/sdl/platform.cpp

@@ -391,6 +391,12 @@ void Platform::process_input_event(const SDL_Event &event) {
         input_key_event(SDL_SCANCODE_AC_BACK, 0);
         break;
       }
+      if (code == KEY_CAPSLOCK) {
+        key_mod_ ^= KMOD_CAPS;
+      }
+      if (code == KEY_NUMLOCK) {
+        key_mod_ ^= KMOD_NUM;
+      }
       keyboard_events.push_back({EV_KEY, code, 0});
       break;
     }
@@ -574,7 +580,23 @@ void Platform::window_deleted(const Window::Id &id) {
 
 void Platform::window_wants_focus(const Window::Id &id) {
   auto w = windows_.find(id);
-  if (w == windows_.end()) return;
+  if (w == windows_.end()) {
+    return;
+  }
+
+  // if window's modstate is not the same as android, send
+  // capslock or numlock message to android to change it.
+  auto mod_state = SDL_GetModState();
+  if ((key_mod_ & KMOD_NUM) != (mod_state & KMOD_NUM)) {
+    input_key_event(SDL_SCANCODE_NUMLOCKCLEAR, 1);
+    input_key_event(SDL_SCANCODE_NUMLOCKCLEAR, 0);
+    key_mod_ ^= KMOD_NUM;
+  }
+  if ((key_mod_ & KMOD_CAPS) != (mod_state & KMOD_CAPS)) {
+    input_key_event(SDL_SCANCODE_CAPSLOCK, 1);
+    input_key_event(SDL_SCANCODE_CAPSLOCK, 0);
+    key_mod_ ^= KMOD_CAPS;
+  }
 
   if (auto window = w->second.lock()) {
     focused_sdl_window_id_ = window->window_id();

src/anbox/platform/sdl/platform.h

@@ -125,6 +125,7 @@ class Platform : public std::enable_shared_from_this<Platform>,
   void push_finger_motion(int x, int y, int finger_id, std::vector<input::Event> &touch_events);
 
   int user_window_event = 0;
+  std::uint32_t key_mod_{ KMOD_NONE };
 };
 } // namespace sdl
 } // namespace platform

src/anbox/platform/sdl/window.cpp

@@ -57,7 +57,7 @@ const std::map<std::string, Window::mini_size>Window::custom_window_map = {
   {"微信", {WX_MINI_WIDTH, MINI_HEIGHT}}
 };
 
-Window::Id Window::Invalid{-1};
+Window::Id Window::Invalid{ -1 };
 
 Window::Observer::~Observer() {}
 
@@ -294,7 +294,9 @@ void Window::switch_window_state() {
 void Window::process_event(const SDL_Event &event) {
   switch (event.window.event) {
     case SDL_WINDOWEVENT_FOCUS_GAINED:
-      if (observer_) observer_->window_wants_focus(id_);
+      if (observer_) {
+        observer_->window_wants_focus(id_);
+      }
       break;
     case SDL_WINDOWEVENT_FOCUS_LOST:
       break;