Extract mouse capture

Factorize mouse capture for relative mouse mode to reduce code
duplication between normal and OTG modes.

PR #5322 <https://github.com/Genymobile/scrcpy/pull/5322>

app/meson.build

@@ -23,6 +23,7 @@ src = [
     'src/frame_buffer.c',
     'src/input_manager.c',
     'src/keyboard_sdk.c',
+    'src/mouse_capture.c',
     'src/mouse_sdk.c',
     'src/opengl.c',
     'src/options.c',

app/src/mouse_capture.c

@@ -0,0 +1,120 @@
+#include "mouse_capture.h"
+
+#include "util/log.h"
+
+void
+sc_mouse_capture_init(struct sc_mouse_capture *mc, SDL_Window *window) {
+    mc->window = window;
+    mc->mouse_capture_key_pressed = SDLK_UNKNOWN;
+}
+
+static inline bool
+sc_mouse_capture_is_capture_key(SDL_Keycode key) {
+    return key == SDLK_LALT || key == SDLK_LGUI || key == SDLK_RGUI;
+}
+
+bool
+sc_mouse_capture_handle_event(struct sc_mouse_capture *mc,
+                              const SDL_Event *event) {
+    switch (event->type) {
+        case SDL_WINDOWEVENT:
+            if (event->window.event == SDL_WINDOWEVENT_FOCUS_LOST) {
+                sc_mouse_capture_set_active(mc, false);
+                return true;
+            }
+            break;
+        case SDL_KEYDOWN: {
+            SDL_Keycode key = event->key.keysym.sym;
+            if (sc_mouse_capture_is_capture_key(key)) {
+                if (!mc->mouse_capture_key_pressed) {
+                    mc->mouse_capture_key_pressed = key;
+                } else {
+                    // Another mouse capture key has been pressed, cancel
+                    // mouse (un)capture
+                    mc->mouse_capture_key_pressed = 0;
+                }
+                // Mouse capture keys are never forwarded to the device
+                return true;
+            }
+            break;
+        }
+        case SDL_KEYUP: {
+            SDL_Keycode key = event->key.keysym.sym;
+            SDL_Keycode cap = mc->mouse_capture_key_pressed;
+            mc->mouse_capture_key_pressed = 0;
+            if (sc_mouse_capture_is_capture_key(key)) {
+                if (key == cap) {
+                    // A mouse capture key has been pressed then released:
+                    // toggle the capture mouse mode
+                    sc_mouse_capture_toggle(mc);
+                }
+                // Mouse capture keys are never forwarded to the device
+                return true;
+            }
+            break;
+        }
+        case SDL_MOUSEWHEEL:
+        case SDL_MOUSEMOTION:
+        case SDL_MOUSEBUTTONDOWN:
+            if (!sc_mouse_capture_is_active(mc)) {
+                // The mouse will be captured on SDL_MOUSEBUTTONUP, so consume
+                // the event
+                return true;
+            }
+            break;
+        case SDL_MOUSEBUTTONUP:
+            if (!sc_mouse_capture_is_active(mc)) {
+                sc_mouse_capture_set_active(mc, true);
+                return true;
+            }
+            break;
+        case SDL_FINGERMOTION:
+        case SDL_FINGERDOWN:
+        case SDL_FINGERUP:
+            // Touch events are not compatible with relative mode
+            // (coordinates are not relative), so consume the event
+            return true;
+    }
+
+    return false;
+}
+
+void
+sc_mouse_capture_set_active(struct sc_mouse_capture *mc, bool capture) {
+#ifdef __APPLE__
+    // Workaround for SDL bug on macOS:
+    // <https://github.com/libsdl-org/SDL/issues/5340>
+    if (capture) {
+        int mouse_x, mouse_y;
+        SDL_GetGlobalMouseState(&mouse_x, &mouse_y);
+
+        int x, y, w, h;
+        SDL_GetWindowPosition(window, &x, &y);
+        SDL_GetWindowSize(window, &w, &h);
+
+        bool outside_window = mouse_x < x || mouse_x >= x + w
+                           || mouse_y < y || mouse_y >= y + h;
+        if (outside_window) {
+            SDL_WarpMouseInWindow(mc->window, w / 2, h / 2);
+        }
+    }
+#else
+    (void) mc;
+#endif
+    if (SDL_SetRelativeMouseMode(capture)) {
+        LOGE("Could not set relative mouse mode to %s: %s",
+             capture ? "true" : "false", SDL_GetError());
+    }
+}
+
+bool
+sc_mouse_capture_is_active(struct sc_mouse_capture *mc) {
+    (void) mc;
+    return SDL_GetRelativeMouseMode();
+}
+
+void
+sc_mouse_capture_toggle(struct sc_mouse_capture *mc) {
+    bool new_value = !sc_mouse_capture_is_active(mc);
+    sc_mouse_capture_set_active(mc, new_value);
+}

app/src/mouse_capture.h

@@ -0,0 +1,35 @@
+#ifndef SC_MOUSE_CAPTURE_H
+#define SC_MOUSE_CAPTURE_H
+
+#include "common.h"
+
+#include <stdbool.h>
+
+#include <SDL2/SDL.h>
+
+struct sc_mouse_capture {
+    SDL_Window *window;
+
+    // To enable/disable mouse capture, a mouse capture key (LALT, LGUI or
+    // RGUI) must be pressed. This variable tracks the pressed capture key.
+    SDL_Keycode mouse_capture_key_pressed;
+};
+
+void
+sc_mouse_capture_init(struct sc_mouse_capture *mc, SDL_Window *window);
+
+void
+sc_mouse_capture_set_active(struct sc_mouse_capture *mc, bool capture);
+
+bool
+sc_mouse_capture_is_active(struct sc_mouse_capture *mc);
+
+void
+sc_mouse_capture_toggle(struct sc_mouse_capture *mc);
+
+// Return true if it consumed the event
+bool
+sc_mouse_capture_handle_event(struct sc_mouse_capture *mc,
+                              const SDL_Event *event);
+
+#endif

app/src/screen.c

@@ -162,47 +162,6 @@ sc_screen_is_relative_mode(struct sc_screen *screen) {
     return screen->im.mp && screen->im.mp->relative_mode;
 }
 
-static void
-sc_screen_set_mouse_capture(struct sc_screen *screen, bool capture) {
-#ifdef __APPLE__
-    // Workaround for SDL bug on macOS:
-    // <https://github.com/libsdl-org/SDL/issues/5340>
-    if (capture) {
-        int mouse_x, mouse_y;
-        SDL_GetGlobalMouseState(&mouse_x, &mouse_y);
-
-        int x, y, w, h;
-        SDL_GetWindowPosition(screen->window, &x, &y);
-        SDL_GetWindowSize(screen->window, &w, &h);
-
-        bool outside_window = mouse_x < x || mouse_x >= x + w
-                           || mouse_y < y || mouse_y >= y + h;
-        if (outside_window) {
-            SDL_WarpMouseInWindow(screen->window, w / 2, h / 2);
-        }
-    }
-#else
-    (void) screen;
-#endif
-    if (SDL_SetRelativeMouseMode(capture)) {
-        LOGE("Could not set relative mouse mode to %s: %s",
-             capture ? "true" : "false", SDL_GetError());
-    }
-}
-
-static inline bool
-sc_screen_get_mouse_capture(struct sc_screen *screen) {
-    (void) screen;
-    return SDL_GetRelativeMouseMode();
-}
-
-static inline void
-sc_screen_toggle_mouse_capture(struct sc_screen *screen) {
-    (void) screen;
-    bool new_value = !sc_screen_get_mouse_capture(screen);
-    sc_screen_set_mouse_capture(screen, new_value);
-}
-
 static void
 sc_screen_update_content_rect(struct sc_screen *screen) {
     assert(screen->video);
@@ -371,7 +330,6 @@ sc_screen_init(struct sc_screen *screen,
     screen->fullscreen = false;
     screen->maximized = false;
     screen->minimized = false;
-    screen->mouse_capture_key_pressed = 0;
     screen->paused = false;
     screen->resume_frame = NULL;
     screen->orientation = SC_ORIENTATION_0;
@@ -486,6 +444,9 @@ sc_screen_init(struct sc_screen *screen,
 
     sc_input_manager_init(&screen->im, &im_params);
 
+    // Initialize even if not used for simplicity
+    sc_mouse_capture_init(&screen->mc, screen->window);
+
 #ifdef CONTINUOUS_RESIZING_WORKAROUND
     if (screen->video) {
         SDL_AddEventWatch(event_watcher, screen);
@@ -506,7 +467,7 @@ sc_screen_init(struct sc_screen *screen,
 
     if (!screen->video && sc_screen_is_relative_mode(screen)) {
         // Capture mouse immediately if video mirroring is disabled
-        sc_screen_set_mouse_capture(screen, true);
+        sc_mouse_capture_set_active(&screen->mc, true);
     }
 
     return true;
@@ -713,7 +674,7 @@ sc_screen_apply_frame(struct sc_screen *screen) {
 
         if (sc_screen_is_relative_mode(screen)) {
             // Capture mouse on start
-            sc_screen_set_mouse_capture(screen, true);
+            sc_mouse_capture_set_active(&screen->mc, true);
         }
     }
 
@@ -837,15 +798,8 @@ sc_screen_resize_to_pixel_perfect(struct sc_screen *screen) {
                                             content_size.height);
 }
 
-static inline bool
-sc_screen_is_mouse_capture_key(SDL_Keycode key) {
-    return key == SDLK_LALT || key == SDLK_LGUI || key == SDLK_RGUI;
-}
-
 bool
 sc_screen_handle_event(struct sc_screen *screen, const SDL_Event *event) {
-    bool relative_mode = sc_screen_is_relative_mode(screen);
-
     switch (event->type) {
         case SC_EVENT_SCREEN_INIT_SIZE: {
             // The initial size is passed via screen->frame_size
@@ -903,69 +857,14 @@ sc_screen_handle_event(struct sc_screen *screen, const SDL_Event *event) {
                     apply_pending_resize(screen);
                     sc_screen_render(screen, true);
                     break;
-                case SDL_WINDOWEVENT_FOCUS_LOST:
-                    if (relative_mode) {
-                        sc_screen_set_mouse_capture(screen, false);
-                    }
-                    break;
             }
             return true;
-        case SDL_KEYDOWN:
-            if (relative_mode) {
-                SDL_Keycode key = event->key.keysym.sym;
-                if (sc_screen_is_mouse_capture_key(key)) {
-                    if (!screen->mouse_capture_key_pressed) {
-                        screen->mouse_capture_key_pressed = key;
-                    } else {
-                        // Another mouse capture key has been pressed, cancel
-                        // mouse (un)capture
-                        screen->mouse_capture_key_pressed = 0;
-                    }
-                    // Mouse capture keys are never forwarded to the device
-                    return true;
-                }
-            }
-            break;
-        case SDL_KEYUP:
-            if (relative_mode) {
-                SDL_Keycode key = event->key.keysym.sym;
-                SDL_Keycode cap = screen->mouse_capture_key_pressed;
-                screen->mouse_capture_key_pressed = 0;
-                if (sc_screen_is_mouse_capture_key(key)) {
-                    if (key == cap) {
-                        // A mouse capture key has been pressed then released:
-                        // toggle the capture mouse mode
-                        sc_screen_toggle_mouse_capture(screen);
-                    }
-                    // Mouse capture keys are never forwarded to the device
-                    return true;
-                }
-            }
-            break;
-        case SDL_MOUSEWHEEL:
-        case SDL_MOUSEMOTION:
-        case SDL_MOUSEBUTTONDOWN:
-            if (relative_mode && !sc_screen_get_mouse_capture(screen)) {
-                // Do not forward to input manager, the mouse will be captured
-                // on SDL_MOUSEBUTTONUP
-                return true;
-            }
-            break;
-        case SDL_FINGERMOTION:
-        case SDL_FINGERDOWN:
-        case SDL_FINGERUP:
-            if (relative_mode) {
-                // Touch events are not compatible with relative mode
-                // (coordinates are not relative)
-                return true;
-            }
-            break;
-        case SDL_MOUSEBUTTONUP:
-            if (relative_mode && !sc_screen_get_mouse_capture(screen)) {
-                sc_screen_set_mouse_capture(screen, true);
-                return true;
-            }
-            break;
+    }
+
+    if (sc_screen_is_relative_mode(screen)
+            && sc_mouse_capture_handle_event(&screen->mc, event)) {
+        // The mouse capture handler consumed the event
+        return true;
     }
 
     sc_input_manager_handle_event(&screen->im, event);

app/src/screen.h

@@ -13,6 +13,7 @@
 #include "fps_counter.h"
 #include "frame_buffer.h"
 #include "input_manager.h"
+#include "mouse_capture.h"
 #include "opengl.h"
 #include "options.h"
 #include "trait/key_processor.h"
@@ -30,6 +31,7 @@ struct sc_screen {
 
     struct sc_display display;
     struct sc_input_manager im;
+    struct sc_mouse_capture mc; // only used in mouse relative mode
     struct sc_frame_buffer fb;
     struct sc_fps_counter fps_counter;
 
@@ -61,10 +63,6 @@ struct sc_screen {
     bool maximized;
     bool minimized;
 
-    // To enable/disable mouse capture, a mouse capture key (LALT, LGUI or
-    // RGUI) must be pressed. This variable tracks the pressed capture key.
-    SDL_Keycode mouse_capture_key_pressed;
-
     AVFrame *frame;
 
     bool paused;

app/src/usb/screen_otg.c

@@ -4,47 +4,6 @@
 #include "options.h"
 #include "util/log.h"
 
-static void
-sc_screen_otg_set_mouse_capture(struct sc_screen_otg *screen, bool capture) {
-#ifdef __APPLE__
-    // Workaround for SDL bug on macOS:
-    // <https://github.com/libsdl-org/SDL/issues/5340>
-    if (capture) {
-        int mouse_x, mouse_y;
-        SDL_GetGlobalMouseState(&mouse_x, &mouse_y);
-
-        int x, y, w, h;
-        SDL_GetWindowPosition(screen->window, &x, &y);
-        SDL_GetWindowSize(screen->window, &w, &h);
-
-        bool outside_window = mouse_x < x || mouse_x >= x + w
-                           || mouse_y < y || mouse_y >= y + h;
-        if (outside_window) {
-            SDL_WarpMouseInWindow(screen->window, w / 2, h / 2);
-        }
-    }
-#else
-    (void) screen;
-#endif
-    if (SDL_SetRelativeMouseMode(capture)) {
-        LOGE("Could not set relative mouse mode to %s: %s",
-             capture ? "true" : "false", SDL_GetError());
-    }
-}
-
-static inline bool
-sc_screen_otg_get_mouse_capture(struct sc_screen_otg *screen) {
-    (void) screen;
-    return SDL_GetRelativeMouseMode();
-}
-
-static inline void
-sc_screen_otg_toggle_mouse_capture(struct sc_screen_otg *screen) {
-    (void) screen;
-    bool new_value = !sc_screen_otg_get_mouse_capture(screen);
-    sc_screen_otg_set_mouse_capture(screen, new_value);
-}
-
 static void
 sc_screen_otg_render(struct sc_screen_otg *screen) {
     SDL_RenderClear(screen->renderer);
@@ -61,8 +20,6 @@ sc_screen_otg_init(struct sc_screen_otg *screen,
     screen->mouse = params->mouse;
     screen->gamepad = params->gamepad;
 
-    screen->mouse_capture_key_pressed = 0;
-
     const char *title = params->window_title;
     assert(title);
 
@@ -113,9 +70,11 @@ sc_screen_otg_init(struct sc_screen_otg *screen,
         LOGW("Could not load icon");
     }
 
+    sc_mouse_capture_init(&screen->mc, screen->window);
+
     if (screen->mouse) {
         // Capture mouse on start
-        sc_screen_otg_set_mouse_capture(screen, true);
+        sc_mouse_capture_set_active(&screen->mc, true);
     }
 
     return true;
@@ -137,11 +96,6 @@ sc_screen_otg_destroy(struct sc_screen_otg *screen) {
     SDL_DestroyWindow(screen->window);
 }
 
-static inline bool
-sc_screen_otg_is_mouse_capture_key(SDL_Keycode key) {
-    return key == SDLK_LALT || key == SDLK_LGUI || key == SDLK_RGUI;
-}
-
 static void
 sc_screen_otg_process_key(struct sc_screen_otg *screen,
                              const SDL_KeyboardEvent *event) {
@@ -298,80 +252,46 @@ sc_screen_otg_process_gamepad_button(struct sc_screen_otg *screen,
 
 void
 sc_screen_otg_handle_event(struct sc_screen_otg *screen, SDL_Event *event) {
+    if (sc_mouse_capture_handle_event(&screen->mc, event)) {
+        // The mouse capture handler consumed the event
+        return;
+    }
+
     switch (event->type) {
         case SDL_WINDOWEVENT:
             switch (event->window.event) {
                 case SDL_WINDOWEVENT_EXPOSED:
                     sc_screen_otg_render(screen);
                     break;
-                case SDL_WINDOWEVENT_FOCUS_LOST:
-                    if (screen->mouse) {
-                        sc_screen_otg_set_mouse_capture(screen, false);
-                    }
-                    break;
             }
             return;
         case SDL_KEYDOWN:
-            if (screen->mouse) {
-                SDL_Keycode key = event->key.keysym.sym;
-                if (sc_screen_otg_is_mouse_capture_key(key)) {
-                    if (!screen->mouse_capture_key_pressed) {
-                        screen->mouse_capture_key_pressed = key;
-                    } else {
-                        // Another mouse capture key has been pressed, cancel
-                        // mouse (un)capture
-                        screen->mouse_capture_key_pressed = 0;
-                    }
-                    // Mouse capture keys are never forwarded to the device
-                    return;
-                }
-            }
-
             if (screen->keyboard) {
                 sc_screen_otg_process_key(screen, &event->key);
             }
             break;
         case SDL_KEYUP:
-            if (screen->mouse) {
-                SDL_Keycode key = event->key.keysym.sym;
-                SDL_Keycode cap = screen->mouse_capture_key_pressed;
-                screen->mouse_capture_key_pressed = 0;
-                if (sc_screen_otg_is_mouse_capture_key(key)) {
-                    if (key == cap) {
-                        // A mouse capture key has been pressed then released:
-                        // toggle the capture mouse mode
-                        sc_screen_otg_toggle_mouse_capture(screen);
-                    }
-                    // Mouse capture keys are never forwarded to the device
-                    return;
-                }
-            }
-
             if (screen->keyboard) {
                 sc_screen_otg_process_key(screen, &event->key);
             }
             break;
         case SDL_MOUSEMOTION:
-            if (screen->mouse && sc_screen_otg_get_mouse_capture(screen)) {
+            if (screen->mouse) {
                 sc_screen_otg_process_mouse_motion(screen, &event->motion);
             }
             break;
         case SDL_MOUSEBUTTONDOWN:
-            if (screen->mouse && sc_screen_otg_get_mouse_capture(screen)) {
+            if (screen->mouse) {
                 sc_screen_otg_process_mouse_button(screen, &event->button);
             }
             break;
         case SDL_MOUSEBUTTONUP:
             if (screen->mouse) {
-                if (sc_screen_otg_get_mouse_capture(screen)) {
-                    sc_screen_otg_process_mouse_button(screen, &event->button);
-                } else {
-                    sc_screen_otg_set_mouse_capture(screen, true);
-                }
+                sc_screen_otg_process_mouse_button(screen, &event->button);
             }
             break;
         case SDL_MOUSEWHEEL:
-            if (screen->mouse && sc_screen_otg_get_mouse_capture(screen)) {
+            if (screen->mouse) {
                 sc_screen_otg_process_mouse_wheel(screen, &event->wheel);
             }
             break;

app/src/usb/screen_otg.h

@@ -8,6 +8,7 @@
 
 #include "keyboard_aoa.h"
 #include "mouse_aoa.h"
+#include "mouse_capture.h"
 #include "gamepad_aoa.h"
 
 struct sc_screen_otg {
@@ -19,8 +20,7 @@ struct sc_screen_otg {
     SDL_Renderer *renderer;
     SDL_Texture *texture;
 
-    // See equivalent mechanism in screen.h
-    SDL_Keycode mouse_capture_key_pressed;
+    struct sc_mouse_capture mc;
 };
 
 struct sc_screen_otg_params {