Add --print-fps to enable FPS counter on start

The FPS counter could be enabled/disabled via MOD+i.

Add a command line option to enable it on start. This is consistent with
other features like --turn-screen-off or --fullscreen.

Fixes #468 <https://github.com/Genymobile/scrcpy/issues/468>
PR #3030 <https://github.com/Genymobile/scrcpy/pull/3030>

README.md

@@ -215,6 +215,15 @@ scrcpy --max-fps 15
 
 This is officially supported since Android 10, but may work on earlier versions.
 
+The actual capture framerate may be printed to the console:
+
+```
+scrcpy --print-fps
+```
+
+It may also be enabled or disabled at any time with <kbd>MOD</kbd>+<kbd>i</kbd>.
+
+
 #### Crop
 
 The device screen may be cropped to mirror only part of the screen.

app/scrcpy.1

@@ -211,6 +211,10 @@ Inject alpha characters and space as text events instead of key events.
 This avoids issues when combining multiple keys to enter special characters,
 but breaks the expected behavior of alpha keys in games (typically WASD).
 
+.TP
+.B "\-\-print\-fps
+Start FPS counter, to print framerate logs to the console. It can be started or stopped at any time with MOD+i.
+
 .TP
 .BI "\-\-push\-target " path
 Set the target directory for pushing files to the device by drag & drop. It is passed as\-is to "adb push".

app/src/cli.c

@@ -55,6 +55,7 @@
 #define OPT_NO_DOWNSIZE_ON_ERROR   1035
 #define OPT_OTG                    1036
 #define OPT_NO_CLEANUP             1037
+#define OPT_PRINT_FPS              1038
 
 struct sc_option {
     char shortopt;
@@ -336,6 +337,12 @@ static const struct sc_option options[] = {
                 "special character, but breaks the expected behavior of alpha "
                 "keys in games (typically WASD).",
     },
+    {
+        .longopt_id = OPT_PRINT_FPS,
+        .longopt = "print-fps",
+        .text = "Start FPS counter, to print framerate logs to the console. "
+                "It can be started or stopped at any time with MOD+i.",
+    },
     {
         .longopt_id = OPT_PUSH_TARGET,
         .longopt = "push-target",
@@ -1547,6 +1554,9 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
             case OPT_NO_CLEANUP:
                 opts->cleanup = false;
                 break;
+            case OPT_PRINT_FPS:
+                opts->start_fps_counter = true;
+                break;
             case OPT_OTG:
 #ifdef HAVE_USB
                 opts->otg = true;

app/src/options.c

@@ -63,4 +63,5 @@ const struct scrcpy_options scrcpy_options_default = {
     .select_tcpip = false,
     .select_usb = false,
     .cleanup = true,
+    .start_fps_counter = false,
 };

app/src/options.h

@@ -138,6 +138,7 @@ struct scrcpy_options {
     bool select_usb;
     bool select_tcpip;
     bool cleanup;
+    bool start_fps_counter;
 };
 
 extern const struct scrcpy_options scrcpy_options_default;

app/src/scrcpy.c

@@ -588,6 +588,7 @@ aoa_hid_end:
             .rotation = options->rotation,
             .mipmaps = options->mipmaps,
             .fullscreen = options->fullscreen,
+            .start_fps_counter = options->start_fps_counter,
             .buffering_time = options->display_buffer,
         };
 

app/src/screen.c

@@ -386,6 +386,7 @@ sc_screen_init(struct sc_screen *screen,
     screen->req.width = params->window_width;
     screen->req.height = params->window_height;
     screen->req.fullscreen = params->fullscreen;
+    screen->req.start_fps_counter = params->start_fps_counter;
 
     static const struct sc_video_buffer_callbacks cbs = {
         .on_new_frame = sc_video_buffer_on_new_frame,
@@ -562,6 +563,10 @@ sc_screen_show_initial_window(struct sc_screen *screen) {
         sc_screen_switch_fullscreen(screen);
     }
 
+    if (screen->req.start_fps_counter) {
+        sc_fps_counter_start(&screen->fps_counter);
+    }
+
     SDL_ShowWindow(screen->window);
 }
 

app/src/screen.h

@@ -35,6 +35,7 @@ struct sc_screen {
         uint16_t width;
         uint16_t height;
         bool fullscreen;
+        bool start_fps_counter;
     } req;
 
     SDL_Window *window;
@@ -93,6 +94,7 @@ struct sc_screen_params {
     bool mipmaps;
 
     bool fullscreen;
+    bool start_fps_counter;
 
     sc_tick buffering_time;
 };