Work around mouse capture SDL bug on macOS

On macOS, SDL relative mouse mode does not work correctly when the
cursor is outside the window.

As a workaround, move the cursor inside the window before setting the
relative mouse mode.

Refs SDL/#5340 <https://github.com/libsdl-org/SDL/issues/5340>
PR #3031 <https://github.com/Genymobile/scrcpy/pull/3031>

BUILD.md

@@ -199,7 +199,7 @@ Install the packages with [Homebrew]:
 
 ```bash
 # runtime dependencies
-brew install sdl2 ffmpeg
+brew install sdl2 ffmpeg libusb
 
 # client build dependencies
 brew install pkg-config meson

app/meson.build

@@ -74,7 +74,7 @@ if v4l2_support
     src += [ 'src/v4l2_sink.c' ]
 endif
 
-usb_support = get_option('usb') and host_machine.system() == 'linux'
+usb_support = get_option('usb') and host_machine.system() != 'windows'
 if usb_support
     src += [
         'src/usb/aoa_hid.c',

app/scrcpy.1

@@ -100,7 +100,7 @@ Simulate a physical keyboard by using HID over AOAv2.
 
 This provides a better experience for IME users, and allows to generate non-ASCII characters, contrary to the default injection method.
 
-It may only work over USB, and is currently only supported on Linux.
+It may only work over USB.
 
 The keyboard layout must be configured (once and for all) on the device, via Settings -> System -> Languages and input -> Physical keyboard. This settings page can be started directly:
 
@@ -142,7 +142,7 @@ In this mode, the computer mouse is captured to control the device directly (rel
 
 LAlt, LSuper or RSuper toggle the capture mode, to give control of the mouse back to the computer.
 
-It may only work over USB, and is currently only supported on Linux.
+It may only work over USB.
 
 Also see \fB\-\-hid\-keyboard\fR.
 
@@ -190,7 +190,7 @@ LAlt, LSuper or RSuper toggle the mouse capture mode, to give control of the mou
 
 If any of \fB\-\-hid\-keyboard\fR or \fB\-\-hid\-mouse\fR is set, only enable keyboard or mouse respectively, otherwise enable both.
 
-It may only work over USB, and is currently only supported on Linux.
+It may only work over USB.
 
 See \fB\-\-hid\-keyboard\fR and \fB\-\-hid\-mouse\fR.
 

app/src/adb/adb.c

@@ -412,7 +412,7 @@ sc_adb_list_devices(struct sc_intr *intr, unsigned flags,
         // The implementation assumes that the output of "adb devices -l" fits
         // in the buffer in a single pass
         LOGW("Result of \"adb devices -l\" does not fit in 4Kb. "
-             "Please report an issue.\n");
+             "Please report an issue.");
         return -1;
     }
 
@@ -676,7 +676,7 @@ sc_adb_get_device_ip(struct sc_intr *intr, const char *serial, unsigned flags) {
         // The implementation assumes that the output of "ip route" fits in the
         // buffer in a single pass
         LOGW("Result of \"ip route\" does not fit in 1Kb. "
-             "Please report an issue.\n");
+             "Please report an issue.");
         return NULL;
     }
 

app/src/cli.c

@@ -118,7 +118,7 @@ static const struct sc_option options[] = {
         .text = "Crop the device screen on the server.\n"
                 "The values are expressed in the device natural orientation "
                 "(typically, portrait for a phone, landscape for a tablet). "
-                "Any --max-size value is cmoputed on the cropped size.",
+                "Any --max-size value is computed on the cropped size.",
     },
     {
         .shortopt = 'd',
@@ -186,8 +186,7 @@ static const struct sc_option options[] = {
                 "It provides a better experience for IME users, and allows to "
                 "generate non-ASCII characters, contrary to the default "
                 "injection method.\n"
-                "It may only work over USB, and is currently only supported "
-                "on Linux.\n"
+                "It may only work over USB.\n"
                 "The keyboard layout must be configured (once and for all) on "
                 "the device, via Settings -> System -> Languages and input -> "
                 "Physical keyboard. This settings page can be started "
@@ -239,8 +238,7 @@ static const struct sc_option options[] = {
                 "device directly (relative mouse mode).\n"
                 "LAlt, LSuper or RSuper toggle the capture mode, to give "
                 "control of the mouse back to the computer.\n"
-                "It may only work over USB, and is currently only supported "
-                "on Linux.\n"
+                "It may only work over USB.\n"
                 "Also see --hid-keyboard.",
     },
     {
@@ -311,8 +309,7 @@ static const struct sc_option options[] = {
                 "control of the mouse back to the computer.\n"
                 "If any of --hid-keyboard or --hid-mouse is set, only enable "
                 "keyboard or mouse respectively, otherwise enable both.\n"
-                "It may only work over USB, and is currently only supported "
-                "on Linux.\n"
+                "It may only work over USB.\n"
                 "See --hid-keyboard and --hid-mouse.",
     },
     {

app/src/screen.c

@@ -163,7 +163,27 @@ sc_screen_is_relative_mode(struct sc_screen *screen) {
 }
 
 static void
-sc_screen_set_mouse_capture(bool capture) {
+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());
@@ -171,13 +191,16 @@ sc_screen_set_mouse_capture(bool capture) {
 }
 
 static inline bool
-sc_screen_get_mouse_capture(void) {
+sc_screen_get_mouse_capture(struct sc_screen *screen) {
+    (void) screen;
     return SDL_GetRelativeMouseMode();
 }
 
 static inline void
-sc_screen_toggle_mouse_capture(void) {
-    sc_screen_set_mouse_capture(!sc_screen_get_mouse_capture());
+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
@@ -721,7 +744,7 @@ sc_screen_update_frame(struct sc_screen *screen) {
 
         if (sc_screen_is_relative_mode(screen)) {
             // Capture mouse on start
-            sc_screen_set_mouse_capture(true);
+            sc_screen_set_mouse_capture(screen, true);
         }
     }
 
@@ -834,7 +857,7 @@ sc_screen_handle_event(struct sc_screen *screen, SDL_Event *event) {
                     break;
                 case SDL_WINDOWEVENT_FOCUS_LOST:
                     if (relative_mode) {
-                        sc_screen_set_mouse_capture(false);
+                        sc_screen_set_mouse_capture(screen, false);
                     }
                     break;
             }
@@ -864,7 +887,7 @@ sc_screen_handle_event(struct sc_screen *screen, SDL_Event *event) {
                     if (key == cap) {
                         // A mouse capture key has been pressed then released:
                         // toggle the capture mouse mode
-                        sc_screen_toggle_mouse_capture();
+                        sc_screen_toggle_mouse_capture(screen);
                     }
                     // Mouse capture keys are never forwarded to the device
                     return;
@@ -874,7 +897,7 @@ sc_screen_handle_event(struct sc_screen *screen, SDL_Event *event) {
         case SDL_MOUSEWHEEL:
         case SDL_MOUSEMOTION:
         case SDL_MOUSEBUTTONDOWN:
-            if (relative_mode && !sc_screen_get_mouse_capture()) {
+            if (relative_mode && !sc_screen_get_mouse_capture(screen)) {
                 // Do not forward to input manager, the mouse will be captured
                 // on SDL_MOUSEBUTTONUP
                 return;
@@ -890,8 +913,8 @@ sc_screen_handle_event(struct sc_screen *screen, SDL_Event *event) {
             }
             break;
         case SDL_MOUSEBUTTONUP:
-            if (relative_mode && !sc_screen_get_mouse_capture()) {
-                sc_screen_set_mouse_capture(true);
+            if (relative_mode && !sc_screen_get_mouse_capture(screen)) {
+                sc_screen_set_mouse_capture(screen, true);
                 return;
             }
             break;

app/src/usb/screen_otg.c

@@ -5,7 +5,27 @@
 #include "util/log.h"
 
 static void
-sc_screen_otg_set_mouse_capture(bool capture) {
+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());
@@ -13,13 +33,16 @@ sc_screen_otg_set_mouse_capture(bool capture) {
 }
 
 static inline bool
-sc_screen_otg_get_mouse_capture(void) {
+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(void) {
-    sc_screen_otg_set_mouse_capture(!sc_screen_otg_get_mouse_capture());
+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
@@ -86,7 +109,7 @@ sc_screen_otg_init(struct sc_screen_otg *screen,
 
     if (screen->mouse) {
         // Capture mouse on start
-        sc_screen_otg_set_mouse_capture(true);
+        sc_screen_otg_set_mouse_capture(screen, true);
     }
 
     return true;
@@ -198,7 +221,7 @@ sc_screen_otg_handle_event(struct sc_screen_otg *screen, SDL_Event *event) {
                     break;
                 case SDL_WINDOWEVENT_FOCUS_LOST:
                     if (screen->mouse) {
-                        sc_screen_otg_set_mouse_capture(false);
+                        sc_screen_otg_set_mouse_capture(screen, false);
                     }
                     break;
             }
@@ -232,7 +255,7 @@ sc_screen_otg_handle_event(struct sc_screen_otg *screen, SDL_Event *event) {
                     if (key == cap) {
                         // A mouse capture key has been pressed then released:
                         // toggle the capture mouse mode
-                        sc_screen_otg_toggle_mouse_capture();
+                        sc_screen_otg_toggle_mouse_capture(screen);
                     }
                     // Mouse capture keys are never forwarded to the device
                     return;
@@ -244,26 +267,26 @@ sc_screen_otg_handle_event(struct sc_screen_otg *screen, SDL_Event *event) {
             }
             break;
         case SDL_MOUSEMOTION:
-            if (screen->mouse && sc_screen_otg_get_mouse_capture()) {
+            if (screen->mouse && sc_screen_otg_get_mouse_capture(screen)) {
                 sc_screen_otg_process_mouse_motion(screen, &event->motion);
             }
             break;
         case SDL_MOUSEBUTTONDOWN:
-            if (screen->mouse && sc_screen_otg_get_mouse_capture()) {
+            if (screen->mouse && sc_screen_otg_get_mouse_capture(screen)) {
                 sc_screen_otg_process_mouse_button(screen, &event->button);
             }
             break;
         case SDL_MOUSEBUTTONUP:
             if (screen->mouse) {
-                if (sc_screen_otg_get_mouse_capture()) {
+                if (sc_screen_otg_get_mouse_capture(screen)) {
                     sc_screen_otg_process_mouse_button(screen, &event->button);
                 } else {
-                    sc_screen_otg_set_mouse_capture(true);
+                    sc_screen_otg_set_mouse_capture(screen, true);
                 }
             }
             break;
         case SDL_MOUSEWHEEL:
-            if (screen->mouse && sc_screen_otg_get_mouse_capture()) {
+            if (screen->mouse && sc_screen_otg_get_mouse_capture(screen)) {
                 sc_screen_otg_process_mouse_wheel(screen, &event->wheel);
             }
             break;

app/tests/test_adb_parser.c

@@ -91,7 +91,6 @@ static void test_adb_devices_daemon_start_mixed() {
     struct sc_adb_device *device = &devices[0];
     assert(!strcmp("0123456789abcdef", device->serial));
     assert(!strcmp("unauthorized", device->state));
-    fprintf(stderr, "==== [%s]\n", device->model);
     assert(!device->model);
 
     device = &devices[1];