Forward all clicks by default for UHID and AOA

In relative mouse modes (when the cursor appears on the device), it
makes more sense to forward all clicks (disable HOME/BACK shortcuts on
secondary clicks).

Transform the boolean option --forward-all-clicks into a 3-state option:
 - --forward-all-clicks=true or --forward-all-clicks: enable
 - --forward-all-clicks=false: disable
 - --forward-all-clicks=auto (default): enable only for UHID and AOA

That way, by default, all clicks are forwarded with `scrcpy -M`.

Refs <https://github.com/Genymobile/scrcpy/issues/4727#issuecomment-2069869750>
PR #4877 <https://github.com/Genymobile/scrcpy/pull/4877>

app/scrcpy.1

@@ -165,7 +165,14 @@ Do not attempt to use "adb reverse" to connect to the device.
 
 .TP
 .B \-\-forward\-all\-clicks
-By default, right-click triggers BACK (or POWER on) and middle-click triggers HOME. This option disables these shortcuts and forward the clicks to the device instead.
+Two behaviors are possible: either right-click triggers BACK (or POWER on) and middle-click triggers HOME, or these shortcuts are disabled and the clicks are forwarded to the device.
+
+Possible values are "auto" (forward all clicks only for UHID and AOA mouse modes), "true" (fordward all clicks) and "false" (enable shortcuts for right-click and middle-click).
+
+Default is "auto".
+
+Passing the option without argument is equivalent to passing "true".
+
 
 .TP
 .B \-h, \-\-help
@@ -316,6 +323,10 @@ Disable video forwarding.
 .B \-\-no\-video\-playback
 Disable video playback on the computer.
 
+.TP
+.B \-\-no\-window
+Disable scrcpy window. Implies --no-video-playback and --no-control.
+
 .TP
 .BI "\-\-orientation " value
 Same as --display-orientation=value --record-orientation=value.
@@ -420,9 +431,9 @@ Turn the device screen off immediately.
 .BI "\-\-shortcut\-mod " key\fR[+...]][,...]
 Specify the modifiers to use for scrcpy shortcuts. Possible keys are "lctrl", "rctrl", "lalt", "ralt", "lsuper" and "rsuper".
 
-A shortcut can consist in several keys, separated by '+'. Several shortcuts can be specified, separated by ','.
+Several shortcut modifiers can be specified, separated by ','.
 
-For example, to use either LCtrl+LAlt or LSuper for scrcpy shortcuts, pass "lctrl+lalt,lsuper".
+For example, to use either LCtrl or LSuper for scrcpy shortcuts, pass "lctrl,lsuper".
 
 Default is "lalt,lsuper" (left-Alt or left-Super).
 

app/src/audio_player.c

@@ -194,7 +194,11 @@ sc_audio_player_frame_sink_push(struct sc_frame_sink *sink,
             // Still insufficient, drop old samples to make space
             skipped_samples = sc_audiobuf_read(&ap->buf, NULL, remaining);
             assert(skipped_samples == remaining);
+        }
 
+        SDL_UnlockAudioDevice(ap->device);
+
+        if (written < samples) {
             // Now there is enough space
             uint32_t w = sc_audiobuf_write(&ap->buf,
                                            swr_buf + TO_BYTES(written),
@@ -202,8 +206,6 @@ sc_audio_player_frame_sink_push(struct sc_frame_sink *sink,
             assert(w == remaining);
             (void) w;
         }
-
-        SDL_UnlockAudioDevice(ap->device);
     }
 
     uint32_t underflow = 0;

app/src/cli.c

@@ -97,6 +97,7 @@ enum {
     OPT_MOUSE,
     OPT_HID_KEYBOARD_DEPRECATED,
     OPT_HID_MOUSE_DEPRECATED,
+    OPT_NO_WINDOW,
 };
 
 struct sc_option {
@@ -353,9 +354,18 @@ static const struct sc_option options[] = {
     {
         .longopt_id = OPT_FORWARD_ALL_CLICKS,
         .longopt = "forward-all-clicks",
-        .text = "By default, right-click triggers BACK (or POWER on) and "
-                "middle-click triggers HOME. This option disables these "
-                "shortcuts and forwards the clicks to the device instead.",
+        .argdesc = "value",
+        .optional_arg = true,
+        .text = "Two behaviors are possible: either right-click triggers BACK "
+                "(or POWER on) and middle-click triggers HOME, or these "
+                "shortcuts are disabled and the clicks are forwarded to the "
+                "device.\n"
+                "Possible values are \"auto\" (forward all clicks only for "
+                "UHID and AOA mouse modes), \"true\" (forward all clicks) and "
+                "\"false\" (enable shortcuts for right and middle clicks).\n"
+                "Default is \"auto\".\n"
+                "Passing the option without argument is equivalent to passing "
+                "\"true\".",
     },
     {
         .shortopt = 'h',
@@ -566,6 +576,12 @@ static const struct sc_option options[] = {
         .longopt = "no-video-playback",
         .text = "Disable video playback on the computer.",
     },
+    {
+        .longopt_id = OPT_NO_WINDOW,
+        .longopt = "no-window",
+        .text = "Disable scrcpy window. Implies --no-video-playback and "
+                "--no-control.",
+    },
     {
         .longopt_id = OPT_ORIENTATION,
         .longopt = "orientation",
@@ -709,10 +725,10 @@ static const struct sc_option options[] = {
         .text = "Specify the modifiers to use for scrcpy shortcuts.\n"
                 "Possible keys are \"lctrl\", \"rctrl\", \"lalt\", \"ralt\", "
                 "\"lsuper\" and \"rsuper\".\n"
-                "A shortcut can consist in several keys, separated by '+'. "
-                "Several shortcuts can be specified, separated by ','.\n"
-                "For example, to use either LCtrl+LAlt or LSuper for scrcpy "
-                "shortcuts, pass \"lctrl+lalt,lsuper\".\n"
+                "Several shortcut modifiers can be specified, separated by "
+                "','.\n"
+                "For example, to use either LCtrl or LSuper for scrcpy "
+                "shortcuts, pass \"lctrl,lsuper\".\n"
                 "Default is \"lalt,lsuper\" (left-Alt or left-Super).",
     },
     {
@@ -1524,6 +1540,28 @@ parse_lock_video_orientation(const char *s,
     return false;
 }
 
+static bool
+parse_forward_all_clicks(const char *s, enum sc_forward_all_clicks *value) {
+    if (!s || !strcmp(s, "true")) {
+        *value = SC_FORWARD_ALL_CLICKS_TRUE;
+        return true;
+    }
+
+    if (!strcmp(s, "false")) {
+        *value = SC_FORWARD_ALL_CLICKS_FALSE;
+        return true;
+    }
+
+    if (!strcmp(s, "auto")) {
+        *value = SC_FORWARD_ALL_CLICKS_AUTO;
+        return true;
+    }
+
+    LOGE("Unsupported --forward-all-clicks value: %s (expected auto, true or "
+         "false).", s);
+    return false;
+}
+
 static bool
 parse_rotation(const char *s, uint8_t *rotation) {
     long value;
@@ -1680,82 +1718,62 @@ parse_log_level(const char *s, enum sc_log_level *log_level) {
     return false;
 }
 
-// item is a list of mod keys separated by '+' (e.g. "lctrl+lalt")
-// returns a bitwise-or of SC_SHORTCUT_MOD_* constants (or 0 on error)
-static unsigned
+static enum sc_shortcut_mod
 parse_shortcut_mods_item(const char *item, size_t len) {
-    unsigned mod = 0;
-
-    for (;;) {
-        char *plus = strchr(item, '+');
-        // strchr() does not consider the "len" parameter, to it could find an
-        // occurrence too far in the string (there is no strnchr())
-        bool has_plus = plus && plus < item + len;
-
-        assert(!has_plus || plus > item);
-        size_t key_len = has_plus ? (size_t) (plus - item) : len;
-
 #define STREQ(literal, s, len) \
     ((sizeof(literal)-1 == len) && !memcmp(literal, s, len))
 
-        if (STREQ("lctrl", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_LCTRL;
-        } else if (STREQ("rctrl", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_RCTRL;
-        } else if (STREQ("lalt", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_LALT;
-        } else if (STREQ("ralt", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_RALT;
-        } else if (STREQ("lsuper", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_LSUPER;
-        } else if (STREQ("rsuper", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_RSUPER;
-        } else {
-            LOGE("Unknown modifier key: %.*s "
-                 "(must be one of: lctrl, rctrl, lalt, ralt, lsuper, rsuper)",
-                 (int) key_len, item);
-            return 0;
-        }
+    if (STREQ("lctrl", item, len)) {
+        return SC_SHORTCUT_MOD_LCTRL;
+    }
+    if (STREQ("rctrl", item, len)) {
+        return SC_SHORTCUT_MOD_RCTRL;
+    }
+    if (STREQ("lalt", item, len)) {
+        return SC_SHORTCUT_MOD_LALT;
+    }
+    if (STREQ("ralt", item, len)) {
+        return SC_SHORTCUT_MOD_RALT;
+    }
+    if (STREQ("lsuper", item, len)) {
+        return SC_SHORTCUT_MOD_LSUPER;
+    }
+    if (STREQ("rsuper", item, len)) {
+        return SC_SHORTCUT_MOD_RSUPER;
+    }
 #undef STREQ
 
-        if (!has_plus) {
-            break;
-        }
-
-        item = plus + 1;
-        assert(len >= key_len + 1);
-        len -= key_len + 1;
+    bool has_plus = strchr(item, '+');
+    if (has_plus) {
+        LOGE("Shortcut mod combination with '+' is not supported anymore: "
+             "'%.*s' (see #4741)", (int) len, item);
+        return 0;
     }
 
-    return mod;
+    LOGE("Unknown modifier key: %.*s "
+         "(must be one of: lctrl, rctrl, lalt, ralt, lsuper, rsuper)",
+         (int) len, item);
+
+    return 0;
 }
 
 static bool
-parse_shortcut_mods(const char *s, struct sc_shortcut_mods *mods) {
-    unsigned count = 0;
-    unsigned current = 0;
+parse_shortcut_mods(const char *s, uint8_t *shortcut_mods) {
+    uint8_t mods = 0;
 
-    // LCtrl+LAlt or RCtrl or LCtrl+RSuper: "lctrl+lalt,rctrl,lctrl+rsuper"
+    // A list of shortcut modifiers, for example "lctrl,rctrl,rsuper"
 
     for (;;) {
         char *comma = strchr(s, ',');
-        if (comma && count == SC_MAX_SHORTCUT_MODS - 1) {
-            assert(count < SC_MAX_SHORTCUT_MODS);
-            LOGW("Too many shortcut modifiers alternatives");
-            return false;
-        }
-
         assert(!comma || comma > s);
         size_t limit = comma ? (size_t) (comma - s) : strlen(s);
 
-        unsigned mod = parse_shortcut_mods_item(s, limit);
+        enum sc_shortcut_mod mod = parse_shortcut_mods_item(s, limit);
         if (!mod) {
-            LOGE("Invalid modifier keys: %.*s", (int) limit, s);
             return false;
         }
 
-        mods->data[current++] = mod;
-        ++count;
+        mods |= mod;
 
         if (!comma) {
             break;
@@ -1764,7 +1782,7 @@ parse_shortcut_mods(const char *s, struct sc_shortcut_mods *mods) {
         s = comma + 1;
     }
 
-    mods->count = count;
+    *shortcut_mods = mods;
 
     return true;
 }
@@ -1772,7 +1790,7 @@ parse_shortcut_mods(const char *s, struct sc_shortcut_mods *mods) {
 #ifdef SC_TEST
 // expose the function to unit-tests
 bool
-sc_parse_shortcut_mods(const char *s, struct sc_shortcut_mods *mods) {
+sc_parse_shortcut_mods(const char *s, uint8_t *mods) {
     return parse_shortcut_mods(s, mods);
 }
 #endif
@@ -2335,7 +2353,10 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
                 }
                 break;
             case OPT_FORWARD_ALL_CLICKS:
-                opts->forward_all_clicks = true;
+                if (!parse_forward_all_clicks(optarg,
+                        &opts->forward_all_clicks)) {
+                    return false;
+                }
                 break;
             case OPT_LEGACY_PASTE:
                 opts->legacy_paste = true;
@@ -2486,6 +2507,9 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
             case OPT_CAMERA_HIGH_SPEED:
                 opts->camera_high_speed = true;
                 break;
+            case OPT_NO_WINDOW:
+                opts->window = false;
+                break;
             default:
                 // getopt prints the error message on stderr
                 return false;
@@ -2523,6 +2547,12 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
     v4l2 = !!opts->v4l2_device;
 #endif
 
+    if (!opts->window) {
+        // Without window, there cannot be any video playback or control
+        opts->video_playback = false;
+        opts->control = false;
+    }
+
     if (!opts->video) {
         opts->video_playback = false;
         // Do not power on the device on start if video capture is disabled
@@ -2544,8 +2574,8 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
         opts->audio = false;
     }
 
-    if (!opts->video && !opts->audio && !otg) {
-        LOGE("No video, no audio, no OTG: nothing to do");
+    if (!opts->video && !opts->audio && !opts->control && !otg) {
+        LOGE("No video, no audio, no control, no OTG: nothing to do");
         return false;
     }
 
@@ -2569,6 +2599,11 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
 
 #ifdef HAVE_V4L2
     if (v4l2) {
+        if (!opts->video) {
+            LOGE("V4L2 sink requires video capture, but --no-video was set.");
+            return false;
+        }
+
         if (opts->lock_video_orientation ==
                 SC_LOCK_VIDEO_ORIENTATION_UNLOCKED) {
             LOGI("Video orientation is locked for v4l2 sink. "
@@ -2588,13 +2623,34 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
     }
 #endif
 
-    if (opts->keyboard_input_mode == SC_KEYBOARD_INPUT_MODE_AUTO) {
-        opts->keyboard_input_mode = otg ? SC_KEYBOARD_INPUT_MODE_AOA
-                                        : SC_KEYBOARD_INPUT_MODE_SDK;
-    }
-    if (opts->mouse_input_mode == SC_MOUSE_INPUT_MODE_AUTO) {
-        opts->mouse_input_mode = otg ? SC_MOUSE_INPUT_MODE_AOA
-                                     : SC_MOUSE_INPUT_MODE_SDK;
+    if (opts->control) {
+        if (opts->keyboard_input_mode == SC_KEYBOARD_INPUT_MODE_AUTO) {
+            opts->keyboard_input_mode = otg ? SC_KEYBOARD_INPUT_MODE_AOA
+                                            : SC_KEYBOARD_INPUT_MODE_SDK;
+        }
+        if (opts->mouse_input_mode == SC_MOUSE_INPUT_MODE_AUTO) {
+            if (otg) {
+                opts->mouse_input_mode = SC_MOUSE_INPUT_MODE_AOA;
+            } else if (!opts->video_playback) {
+                LOGI("No video mirroring, mouse mode switched to UHID");
+                opts->mouse_input_mode = SC_MOUSE_INPUT_MODE_UHID;
+            } else {
+                opts->mouse_input_mode = SC_MOUSE_INPUT_MODE_SDK;
+            }
+        } else if (opts->mouse_input_mode == SC_MOUSE_INPUT_MODE_SDK
+                    && !opts->video_playback) {
+            LOGE("SDK mouse mode requires video playback. Try --mouse=uhid.");
+            return false;
+        }
+
+        if (opts->forward_all_clicks == SC_FORWARD_ALL_CLICKS_AUTO) {
+            // By default, forward all clicks only for UHID and AOA
+            if (opts->mouse_input_mode == SC_MOUSE_INPUT_MODE_SDK) {
+                opts->forward_all_clicks = SC_FORWARD_ALL_CLICKS_FALSE;
+            } else {
+                opts->forward_all_clicks = SC_FORWARD_ALL_CLICKS_TRUE;
+            }
+        }
     }
 
     if (otg) {
@@ -2705,6 +2761,11 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
     }
 
     if (opts->record_filename) {
+        if (!opts->video && !opts->audio) {
+            LOGE("Video and audio disabled, nothing to record");
+            return false;
+        }
+
         if (!opts->record_format) {
             opts->record_format = guess_record_format(opts->record_filename);
             if (!opts->record_format) {
@@ -2811,6 +2872,11 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
     }
 # endif
 
+    if (opts->start_fps_counter && !opts->video_playback) {
+        LOGW("--print-fps has no effect without video playback");
+        opts->start_fps_counter = false;
+    }
+
     if (otg) {
         // OTG mode is compatible with only very few options.
         // Only report obvious errors.

app/src/cli.h

@@ -28,7 +28,7 @@ scrcpy_parse_args(struct scrcpy_cli_args *args, int argc, char *argv[]);
 
 #ifdef SC_TEST
 bool
-sc_parse_shortcut_mods(const char *s, struct sc_shortcut_mods *mods);
+sc_parse_shortcut_mods(const char *s, uint8_t *shortcut_mods);
 #endif
 
 #endif

app/src/controller.c

@@ -6,8 +6,19 @@
 
 #define SC_CONTROL_MSG_QUEUE_MAX 64
 
+static void
+sc_controller_receiver_on_error(struct sc_receiver *receiver, void *userdata) {
+    (void) receiver;
+
+    struct sc_controller *controller = userdata;
+    // Forward the event to the controller listener
+    controller->cbs->on_error(controller, controller->cbs_userdata);
+}
+
 bool
-sc_controller_init(struct sc_controller *controller, sc_socket control_socket) {
+sc_controller_init(struct sc_controller *controller, sc_socket control_socket,
+                   const struct sc_controller_callbacks *cbs,
+                   void *cbs_userdata) {
     sc_vecdeque_init(&controller->queue);
 
     bool ok = sc_vecdeque_reserve(&controller->queue, SC_CONTROL_MSG_QUEUE_MAX);
@@ -15,7 +26,12 @@ sc_controller_init(struct sc_controller *controller, sc_socket control_socket) {
         return false;
     }
 
-    ok = sc_receiver_init(&controller->receiver, control_socket);
+    static const struct sc_receiver_callbacks receiver_cbs = {
+        .on_error = sc_controller_receiver_on_error,
+    };
+
+    ok = sc_receiver_init(&controller->receiver, control_socket, &receiver_cbs,
+                          controller);
     if (!ok) {
         sc_vecdeque_destroy(&controller->queue);
         return false;
@@ -39,6 +55,10 @@ sc_controller_init(struct sc_controller *controller, sc_socket control_socket) {
     controller->control_socket = control_socket;
     controller->stopped = false;
 
+    assert(cbs && cbs->on_error);
+    controller->cbs = cbs;
+    controller->cbs_userdata = cbs_userdata;
+
     return true;
 }
 
@@ -125,10 +145,16 @@ run_controller(void *data) {
         sc_control_msg_destroy(&msg);
         if (!ok) {
             LOGD("Could not write msg to socket");
-            break;
+            goto error;
         }
     }
+
     return 0;
+
+error:
+    controller->cbs->on_error(controller, controller->cbs_userdata);
+
+    return 1; // ignored
 }
 
 bool

app/src/controller.h

@@ -22,10 +22,19 @@ struct sc_controller {
     bool stopped;
     struct sc_control_msg_queue queue;
     struct sc_receiver receiver;
+
+    const struct sc_controller_callbacks *cbs;
+    void *cbs_userdata;
+};
+
+struct sc_controller_callbacks {
+    void (*on_error)(struct sc_controller *controller, void *userdata);
 };
 
 bool
-sc_controller_init(struct sc_controller *controller, sc_socket control_socket);
+sc_controller_init(struct sc_controller *controller, sc_socket control_socket,
+                   const struct sc_controller_callbacks *cbs,
+                   void *cbs_userdata);
 
 void
 sc_controller_configure(struct sc_controller *controller,

app/src/display.c

@@ -5,8 +5,30 @@
 
 #include "util/log.h"
 
+static bool
+sc_display_init_novideo_icon(struct sc_display *display,
+                             SDL_Surface *icon_novideo) {
+    assert(icon_novideo);
+
+    if (SDL_RenderSetLogicalSize(display->renderer,
+                                 icon_novideo->w, icon_novideo->h)) {
+        LOGW("Could not set renderer logical size: %s", SDL_GetError());
+        // don't fail
+    }
+
+    display->texture = SDL_CreateTextureFromSurface(display->renderer,
+                                                    icon_novideo);
+    if (!display->texture) {
+        LOGE("Could not create texture: %s", SDL_GetError());
+        return false;
+    }
+
+    return true;
+}
+
 bool
-sc_display_init(struct sc_display *display, SDL_Window *window, bool mipmaps) {
+sc_display_init(struct sc_display *display, SDL_Window *window,
+                SDL_Surface *icon_novideo, bool mipmaps) {
     display->renderer =
         SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
     if (!display->renderer) {
@@ -68,6 +90,18 @@ sc_display_init(struct sc_display *display, SDL_Window *window, bool mipmaps) {
     display->pending.frame = NULL;
     display->has_frame = false;
 
+    if (icon_novideo) {
+        // Without video, set a static scrcpy icon as window content
+        bool ok = sc_display_init_novideo_icon(display, icon_novideo);
+        if (!ok) {
+#ifdef SC_DISPLAY_FORCE_OPENGL_CORE_PROFILE
+            SDL_GL_DeleteContext(display->gl_context);
+#endif
+            SDL_DestroyRenderer(display->renderer);
+            return false;
+        }
+    }
+
     return true;
 }
 

app/src/display.h

@@ -44,7 +44,8 @@ enum sc_display_result {
 };
 
 bool
-sc_display_init(struct sc_display *display, SDL_Window *window, bool mipmaps);
+sc_display_init(struct sc_display *display, SDL_Window *window,
+                SDL_Surface *icon_novideo, bool mipmaps);
 
 void
 sc_display_destroy(struct sc_display *display);

app/src/events.h

@@ -7,3 +7,4 @@
 #define SC_EVENT_RECORDER_ERROR           (SDL_USEREVENT + 6)
 #define SC_EVENT_SCREEN_INIT_SIZE         (SDL_USEREVENT + 7)
 #define SC_EVENT_TIME_LIMIT_REACHED       (SDL_USEREVENT + 8)
+#define SC_EVENT_CONTROLLER_ERROR         (SDL_USEREVENT + 9)

app/src/icon.c

@@ -78,7 +78,19 @@ decode_image(const char *path) {
         goto close_input;
     }
 
-    int stream = av_find_best_stream(ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);
+
+// In ffmpeg/doc/APIchanges:
+// 2021-04-27 - 46dac8cf3d - lavf 59.0.100 - avformat.h
+//   av_find_best_stream now uses a const AVCodec ** parameter
+//   for the returned decoder.
+#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(59, 0, 100)
+    const AVCodec *codec;
+#else
+    AVCodec *codec;
+#endif
+
+    int stream =
+        av_find_best_stream(ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &codec, 0);
     if (stream < 0 ) {
         LOGE("Could not find best image stream");
         goto close_input;
@@ -86,12 +98,6 @@ decode_image(const char *path) {
 
     AVCodecParameters *params = ctx->streams[stream]->codecpar;
 
-    const AVCodec *codec = avcodec_find_decoder(params->codec_id);
-    if (!codec) {
-        LOGE("Could not find image decoder");
-        goto close_input;
-    }
-
     AVCodecContext *codec_ctx = avcodec_alloc_context3(codec);
     if (!codec_ctx) {
         LOG_OOM();

app/src/input_manager.c

@@ -10,7 +10,7 @@
 #define SC_SDL_SHORTCUT_MODS_MASK (KMOD_CTRL | KMOD_ALT | KMOD_GUI)
 
 static inline uint16_t
-to_sdl_mod(unsigned shortcut_mod) {
+to_sdl_mod(uint8_t shortcut_mod) {
     uint16_t sdl_mod = 0;
     if (shortcut_mod & SC_SHORTCUT_MOD_LCTRL) {
         sdl_mod |= KMOD_LCTRL;
@@ -38,15 +38,18 @@ is_shortcut_mod(struct sc_input_manager *im, uint16_t sdl_mod) {
     // keep only the relevant modifier keys
     sdl_mod &= SC_SDL_SHORTCUT_MODS_MASK;
 
-    assert(im->sdl_shortcut_mods.count);
-    assert(im->sdl_shortcut_mods.count < SC_MAX_SHORTCUT_MODS);
-    for (unsigned i = 0; i < im->sdl_shortcut_mods.count; ++i) {
-        if (im->sdl_shortcut_mods.data[i] == sdl_mod) {
-            return true;
-        }
-    }
+    // at least one shortcut mod pressed?
+    return sdl_mod & im->sdl_shortcut_mods;
+}
 
-    return false;
+static bool
+is_shortcut_key(struct sc_input_manager *im, SDL_Keycode keycode) {
+    return (im->sdl_shortcut_mods & KMOD_LCTRL && keycode == SDLK_LCTRL)
+        || (im->sdl_shortcut_mods & KMOD_RCTRL && keycode == SDLK_RCTRL)
+        || (im->sdl_shortcut_mods & KMOD_LALT  && keycode == SDLK_LALT)
+        || (im->sdl_shortcut_mods & KMOD_RALT  && keycode == SDLK_RALT)
+        || (im->sdl_shortcut_mods & KMOD_LGUI  && keycode == SDLK_LGUI)
+        || (im->sdl_shortcut_mods & KMOD_RGUI  && keycode == SDLK_RGUI);
 }
 
 void
@@ -68,15 +71,7 @@ sc_input_manager_init(struct sc_input_manager *im,
     im->legacy_paste = params->legacy_paste;
     im->clipboard_autosync = params->clipboard_autosync;
 
-    const struct sc_shortcut_mods *shortcut_mods = params->shortcut_mods;
-    assert(shortcut_mods->count);
-    assert(shortcut_mods->count < SC_MAX_SHORTCUT_MODS);
-    for (unsigned i = 0; i < shortcut_mods->count; ++i) {
-        uint16_t sdl_mod = to_sdl_mod(shortcut_mods->data[i]);
-        assert(sdl_mod);
-        im->sdl_shortcut_mods.data[i] = sdl_mod;
-    }
-    im->sdl_shortcut_mods.count = shortcut_mods->count;
+    im->sdl_shortcut_mods = to_sdl_mod(params->shortcut_mods);
 
     im->vfinger_down = false;
     im->vfinger_invert_x = false;
@@ -403,6 +398,7 @@ sc_input_manager_process_key(struct sc_input_manager *im,
     // controller is NULL if --no-control is requested
     bool control = im->controller;
     bool paused = im->screen->paused;
+    bool video = im->screen->video;
 
     SDL_Keycode keycode = event->keysym.sym;
     uint16_t mod = event->keysym.mod;
@@ -411,7 +407,12 @@ sc_input_manager_process_key(struct sc_input_manager *im,
     bool shift = event->keysym.mod & KMOD_SHIFT;
     bool repeat = event->repeat;
 
-    bool smod = is_shortcut_mod(im, mod);
+    // Either the modifier includes a shortcut modifier, or the key
+    // press/release is a modifier key.
+    // The second condition is necessary to ignore the release of the modifier
+    // key (because in this case mod is 0).
+    bool is_shortcut = is_shortcut_mod(im, mod)
+                    || is_shortcut_key(im, keycode);
 
     if (down && !repeat) {
         if (keycode == im->last_keycode && mod == im->last_mod) {
@@ -423,8 +424,7 @@ sc_input_manager_process_key(struct sc_input_manager *im,
         }
     }
 
-    // The shortcut modifier is pressed
-    if (smod) {
+    if (is_shortcut) {
         enum sc_action action = down ? SC_ACTION_DOWN : SC_ACTION_UP;
         switch (keycode) {
             case SDLK_h:
@@ -462,13 +462,13 @@ sc_input_manager_process_key(struct sc_input_manager *im,
                 }
                 return;
             case SDLK_z:
-                if (down && !repeat) {
+                if (video && down && !repeat) {
                     sc_screen_set_paused(im->screen, !shift);
                 }
                 return;
             case SDLK_DOWN:
                 if (shift) {
-                    if (!repeat && down) {
+                    if (video && !repeat && down) {
                         apply_orientation_transform(im,
                                                     SC_ORIENTATION_FLIP_180);
                     }
@@ -479,7 +479,7 @@ sc_input_manager_process_key(struct sc_input_manager *im,
                 return;
             case SDLK_UP:
                 if (shift) {
-                    if (!repeat && down) {
+                    if (video && !repeat && down) {
                         apply_orientation_transform(im,
                                                     SC_ORIENTATION_FLIP_180);
                     }
@@ -489,7 +489,7 @@ sc_input_manager_process_key(struct sc_input_manager *im,
                 }
                 return;
             case SDLK_LEFT:
-                if (!repeat && down) {
+                if (video && !repeat && down) {
                     if (shift) {
                         apply_orientation_transform(im,
                                                     SC_ORIENTATION_FLIP_0);
@@ -500,7 +500,7 @@ sc_input_manager_process_key(struct sc_input_manager *im,
                 }
                 return;
             case SDLK_RIGHT:
-                if (!repeat && down) {
+                if (video && !repeat && down) {
                     if (shift) {
                         apply_orientation_transform(im,
                                                     SC_ORIENTATION_FLIP_0);
@@ -533,22 +533,22 @@ sc_input_manager_process_key(struct sc_input_manager *im,
                 }
                 return;
             case SDLK_f:
-                if (!shift && !repeat && down) {
+                if (video && !shift && !repeat && down) {
                     sc_screen_switch_fullscreen(im->screen);
                 }
                 return;
             case SDLK_w:
-                if (!shift && !repeat && down) {
+                if (video && !shift && !repeat && down) {
                     sc_screen_resize_to_fit(im->screen);
                 }
                 return;
             case SDLK_g:
-                if (!shift && !repeat && down) {
+                if (video && !shift && !repeat && down) {
                     sc_screen_resize_to_pixel_perfect(im->screen);
                 }
                 return;
             case SDLK_i:
-                if (!shift && !repeat && down) {
+                if (video && !shift && !repeat && down) {
                     switch_fps_counter_state(im);
                 }
                 return;
@@ -625,6 +625,23 @@ sc_input_manager_process_key(struct sc_input_manager *im,
     im->kp->ops->process_key(im->kp, &evt, ack_to_wait);
 }
 
+static struct sc_position
+sc_input_manager_get_position(struct sc_input_manager *im, int32_t x,
+                                                           int32_t y) {
+    if (im->mp->relative_mode) {
+        // No absolute position
+        return (struct sc_position) {
+            .screen_size = {0, 0},
+            .point = {0, 0},
+        };
+    }
+
+    return (struct sc_position) {
+        .screen_size = im->screen->frame_size,
+        .point = sc_screen_convert_window_to_frame_coords(im->screen, x, y),
+    };
+}
+
 static void
 sc_input_manager_process_mouse_motion(struct sc_input_manager *im,
                                       const SDL_MouseMotionEvent *event) {
@@ -634,12 +651,7 @@ sc_input_manager_process_mouse_motion(struct sc_input_manager *im,
     }
 
     struct sc_mouse_motion_event evt = {
-        .position = {
-            .screen_size = im->screen->frame_size,
-            .point = sc_screen_convert_window_to_frame_coords(im->screen,
-                                                              event->x,
-                                                              event->y),
-        },
+        .position = sc_input_manager_get_position(im, event->x, event->y),
         .pointer_id = im->forward_all_clicks ? POINTER_ID_MOUSE
                                              : POINTER_ID_GENERIC_FINGER,
         .xrel = event->xrel,
@@ -735,7 +747,8 @@ sc_input_manager_process_mouse_button(struct sc_input_manager *im,
         }
 
         // double-click on black borders resize to fit the device screen
-        if (event->button == SDL_BUTTON_LEFT && event->clicks == 2) {
+        bool video = im->screen->video;
+        if (video && event->button == SDL_BUTTON_LEFT && event->clicks == 2) {
             int32_t x = event->x;
             int32_t y = event->y;
             sc_screen_hidpi_scale_coords(im->screen, &x, &y);
@@ -759,12 +772,7 @@ sc_input_manager_process_mouse_button(struct sc_input_manager *im,
     uint32_t sdl_buttons_state = SDL_GetMouseState(NULL, NULL);
 
     struct sc_mouse_click_event evt = {
-        .position = {
-            .screen_size = im->screen->frame_size,
-            .point = sc_screen_convert_window_to_frame_coords(im->screen,
-                                                              event->x,
-                                                              event->y),
-        },
+        .position = sc_input_manager_get_position(im, event->x, event->y),
         .action = sc_action_from_sdl_mousebutton_type(event->type),
         .button = sc_mouse_button_from_sdl(event->button),
         .pointer_id = im->forward_all_clicks ? POINTER_ID_MOUSE
@@ -839,11 +847,7 @@ sc_input_manager_process_mouse_wheel(struct sc_input_manager *im,
     uint32_t buttons = SDL_GetMouseState(&mouse_x, &mouse_y);
 
     struct sc_mouse_scroll_event evt = {
-        .position = {
-            .screen_size = im->screen->frame_size,
-            .point = sc_screen_convert_window_to_frame_coords(im->screen,
-                                                              mouse_x, mouse_y),
-        },
+        .position = sc_input_manager_get_position(im, mouse_x, mouse_y),
 #if SDL_VERSION_ATLEAST(2, 0, 18)
         .hscroll = CLAMP(event->preciseX, -1.0f, 1.0f),
         .vscroll = CLAMP(event->preciseY, -1.0f, 1.0f),

app/src/input_manager.h

@@ -26,10 +26,7 @@ struct sc_input_manager {
     bool legacy_paste;
     bool clipboard_autosync;
 
-    struct {
-        unsigned data[SC_MAX_SHORTCUT_MODS];
-        unsigned count;
-    } sdl_shortcut_mods;
+    uint16_t sdl_shortcut_mods;
 
     bool vfinger_down;
     bool vfinger_invert_x;
@@ -55,7 +52,7 @@ struct sc_input_manager_params {
     bool forward_all_clicks;
     bool legacy_paste;
     bool clipboard_autosync;
-    const struct sc_shortcut_mods *shortcut_mods;
+    uint8_t shortcut_mods; // OR of enum sc_shortcut_mod values
 };
 
 void

app/src/options.c

@@ -30,10 +30,7 @@ const struct scrcpy_options scrcpy_options_default = {
     },
     .tunnel_host = 0,
     .tunnel_port = 0,
-    .shortcut_mods = {
-        .data = {SC_SHORTCUT_MOD_LALT, SC_SHORTCUT_MOD_LSUPER},
-        .count = 2,
-    },
+    .shortcut_mods = SC_SHORTCUT_MOD_LALT | SC_SHORTCUT_MOD_LSUPER,
     .max_size = 0,
     .video_bit_rate = 0,
     .audio_bit_rate = 0,
@@ -71,7 +68,7 @@ const struct scrcpy_options scrcpy_options_default = {
     .force_adb_forward = false,
     .disable_screensaver = false,
     .forward_key_repeat = true,
-    .forward_all_clicks = false,
+    .forward_all_clicks = SC_FORWARD_ALL_CLICKS_AUTO,
     .legacy_paste = false,
     .power_off_on_close = false,
     .clipboard_autosync = true,
@@ -89,6 +86,7 @@ const struct scrcpy_options scrcpy_options_default = {
     .kill_adb_on_close = false,
     .camera_high_speed = false,
     .list = 0,
+    .window = true,
 };
 
 enum sc_orientation

app/src/options.h

@@ -83,6 +83,12 @@ enum sc_orientation {         // v v v
     SC_ORIENTATION_FLIP_270,  // 1 1 1
 };
 
+enum sc_forward_all_clicks {
+    SC_FORWARD_ALL_CLICKS_AUTO,
+    SC_FORWARD_ALL_CLICKS_TRUE,
+    SC_FORWARD_ALL_CLICKS_FALSE,
+};
+
 static inline bool
 sc_orientation_is_mirror(enum sc_orientation orientation) {
     assert(!(orientation & ~7));
@@ -169,8 +175,6 @@ enum sc_key_inject_mode {
     SC_KEY_INJECT_MODE_RAW,
 };
 
-#define SC_MAX_SHORTCUT_MODS 8
-
 enum sc_shortcut_mod {
     SC_SHORTCUT_MOD_LCTRL = 1 << 0,
     SC_SHORTCUT_MOD_RCTRL = 1 << 1,
@@ -180,11 +184,6 @@ enum sc_shortcut_mod {
     SC_SHORTCUT_MOD_RSUPER = 1 << 5,
 };
 
-struct sc_shortcut_mods {
-    unsigned data[SC_MAX_SHORTCUT_MODS];
-    unsigned count;
-};
-
 struct sc_port_range {
     uint16_t first;
     uint16_t last;
@@ -219,7 +218,7 @@ struct scrcpy_options {
     struct sc_port_range port_range;
     uint32_t tunnel_host;
     uint16_t tunnel_port;
-    struct sc_shortcut_mods shortcut_mods;
+    uint8_t shortcut_mods; // OR of enum sc_shortcut_mod values
     uint16_t max_size;
     uint32_t video_bit_rate;
     uint32_t audio_bit_rate;
@@ -257,7 +256,7 @@ struct scrcpy_options {
     bool force_adb_forward;
     bool disable_screensaver;
     bool forward_key_repeat;
-    bool forward_all_clicks;
+    enum sc_forward_all_clicks forward_all_clicks;
     bool legacy_paste;
     bool power_off_on_close;
     bool clipboard_autosync;
@@ -279,6 +278,7 @@ struct scrcpy_options {
 #define SC_OPTION_LIST_CAMERAS 0x4
 #define SC_OPTION_LIST_CAMERA_SIZES 0x8
     uint8_t list;
+    bool window;
 };
 
 extern const struct scrcpy_options scrcpy_options_default;

app/src/receiver.c

@@ -10,7 +10,8 @@
 #include "util/str.h"
 
 bool
-sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket) {
+sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket,
+                 const struct sc_receiver_callbacks *cbs, void *cbs_userdata) {
     bool ok = sc_mutex_init(&receiver->mutex);
     if (!ok) {
         return false;
@@ -20,6 +21,10 @@ sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket) {
     receiver->acksync = NULL;
     receiver->uhid_devices = NULL;
 
+    assert(cbs && cbs->on_error);
+    receiver->cbs = cbs;
+    receiver->cbs_userdata = cbs_userdata;
+
     return true;
 }
 
@@ -152,6 +157,8 @@ run_receiver(void *data) {
         }
     }
 
+    receiver->cbs->on_error(receiver, receiver->cbs_userdata);
+
     return 0;
 }
 

app/src/receiver.h

@@ -19,10 +19,18 @@ struct sc_receiver {
 
     struct sc_acksync *acksync;
     struct sc_uhid_devices *uhid_devices;
+
+    const struct sc_receiver_callbacks *cbs;
+    void *cbs_userdata;
+};
+
+struct sc_receiver_callbacks {
+    void (*on_error)(struct sc_receiver *receiver, void *userdata);
 };
 
 bool
-sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket);
+sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket,
+                 const struct sc_receiver_callbacks *cbs, void *cbs_userdata);
 
 void
 sc_receiver_destroy(struct sc_receiver *receiver);

app/src/scrcpy.c

@@ -174,6 +174,9 @@ event_loop(struct scrcpy *s) {
             case SC_EVENT_DEMUXER_ERROR:
                 LOGE("Demuxer error");
                 return SCRCPY_EXIT_FAILURE;
+            case SC_EVENT_CONTROLLER_ERROR:
+                LOGE("Controller error");
+                return SCRCPY_EXIT_FAILURE;
             case SC_EVENT_RECORDER_ERROR:
                 LOGE("Recorder error");
                 return SCRCPY_EXIT_FAILURE;
@@ -265,6 +268,16 @@ sc_audio_demuxer_on_ended(struct sc_demuxer *demuxer,
     }
 }
 
+static void
+sc_controller_on_error(struct sc_controller *controller, void *userdata) {
+    // Note: this function may be called twice, once from the controller thread
+    // and once from the receiver thread
+    (void) controller;
+    (void) userdata;
+
+    PUSH_EVENT(SC_EVENT_CONTROLLER_ERROR);
+}
+
 static void
 sc_server_on_connection_failed(struct sc_server *server, void *userdata) {
     (void) server;
@@ -408,7 +421,7 @@ scrcpy(struct scrcpy_options *options) {
         return SCRCPY_EXIT_FAILURE;
     }
 
-    if (options->video_playback) {
+    if (options->window) {
         // Set hints before starting the server thread to avoid race conditions
         // in SDL
         sdl_set_hints(options->render_driver);
@@ -430,7 +443,7 @@ scrcpy(struct scrcpy_options *options) {
     assert(!options->video_playback || options->video);
     assert(!options->audio_playback || options->audio);
 
-    if (options->video_playback ||
+    if (options->window ||
             (options->control && options->clipboard_autosync)) {
         // Initialize the video subsystem even if --no-video or
         // --no-video-playback is passed so that clipboard synchronization
@@ -553,7 +566,12 @@ scrcpy(struct scrcpy_options *options) {
     struct sc_mouse_processor *mp = NULL;
 
     if (options->control) {
-        if (!sc_controller_init(&s->controller, s->server.control_socket)) {
+        static const struct sc_controller_callbacks controller_cbs = {
+            .on_error = sc_controller_on_error,
+        };
+
+        if (!sc_controller_init(&s->controller, s->server.control_socket,
+            &controller_cbs, NULL)) {
             goto end;
         }
         controller_initialized = true;
@@ -684,19 +702,25 @@ scrcpy(struct scrcpy_options *options) {
     // There is a controller if and only if control is enabled
     assert(options->control == !!controller);
 
-    if (options->video_playback) {
+    if (options->window) {
         const char *window_title =
             options->window_title ? options->window_title : info->device_name;
 
+        // The option forward_all_clicks must have been resolved at this point
+        assert(options->forward_all_clicks != SC_FORWARD_ALL_CLICKS_AUTO);
+        bool forward_all_clicks =
+            options->forward_all_clicks == SC_FORWARD_ALL_CLICKS_TRUE;
+
         struct sc_screen_params screen_params = {
+            .video = options->video_playback,
             .controller = controller,
             .fp = fp,
             .kp = kp,
             .mp = mp,
-            .forward_all_clicks = options->forward_all_clicks,
+            .forward_all_clicks = forward_all_clicks,
             .legacy_paste = options->legacy_paste,
             .clipboard_autosync = options->clipboard_autosync,
-            .shortcut_mods = &options->shortcut_mods,
+            .shortcut_mods = options->shortcut_mods,
             .window_title = window_title,
             .always_on_top = options->always_on_top,
             .window_x = options->window_x,
@@ -710,12 +734,15 @@ scrcpy(struct scrcpy_options *options) {
             .start_fps_counter = options->start_fps_counter,
         };
 
-        struct sc_frame_source *src = &s->video_decoder.frame_source;
-        if (options->display_buffer) {
-            sc_delay_buffer_init(&s->display_buffer, options->display_buffer,
-                                 true);
-            sc_frame_source_add_sink(src, &s->display_buffer.frame_sink);
-            src = &s->display_buffer.frame_source;
+        struct sc_frame_source *src;
+        if (options->video_playback) {
+            src = &s->video_decoder.frame_source;
+            if (options->display_buffer) {
+                sc_delay_buffer_init(&s->display_buffer,
+                                     options->display_buffer, true);
+                sc_frame_source_add_sink(src, &s->display_buffer.frame_sink);
+                src = &s->display_buffer.frame_source;
+            }
         }
 
         if (!sc_screen_init(&s->screen, &screen_params)) {
@@ -723,7 +750,9 @@ scrcpy(struct scrcpy_options *options) {
         }
         screen_initialized = true;
 
-        sc_frame_source_add_sink(src, &s->screen.frame_sink);
+        if (options->video_playback) {
+            sc_frame_source_add_sink(src, &s->screen.frame_sink);
+        }
     }
 
     if (options->audio_playback) {

app/src/screen.c

@@ -205,6 +205,8 @@ sc_screen_toggle_mouse_capture(struct sc_screen *screen) {
 
 static void
 sc_screen_update_content_rect(struct sc_screen *screen) {
+    assert(screen->video);
+
     int dw;
     int dh;
     SDL_GL_GetDrawableSize(screen->window, &dw, &dh);
@@ -246,6 +248,8 @@ sc_screen_update_content_rect(struct sc_screen *screen) {
 // changed, so that the content rectangle is recomputed
 static void
 sc_screen_render(struct sc_screen *screen, bool update_content_rect) {
+    assert(screen->video);
+
     if (update_content_rect) {
         sc_screen_update_content_rect(screen);
     }
@@ -255,6 +259,13 @@ sc_screen_render(struct sc_screen *screen, bool update_content_rect) {
     (void) res; // any error already logged
 }
 
+static void
+sc_screen_render_novideo(struct sc_screen *screen) {
+    enum sc_display_result res =
+        sc_display_render(&screen->display, NULL, SC_ORIENTATION_0);
+    (void) res; // any error already logged
+}
+
 #if defined(__APPLE__) || defined(__WINDOWS__)
 # define CONTINUOUS_RESIZING_WORKAROUND
 #endif
@@ -268,6 +279,8 @@ sc_screen_render(struct sc_screen *screen, bool update_content_rect) {
 static int
 event_watcher(void *data, SDL_Event *event) {
     struct sc_screen *screen = data;
+    assert(screen->video);
+
     if (event->type == SDL_WINDOWEVENT
             && event->window.event == SDL_WINDOWEVENT_RESIZED) {
         // In practice, it seems to always be called from the same thread in
@@ -326,6 +339,7 @@ sc_screen_frame_sink_close(struct sc_frame_sink *sink) {
 static bool
 sc_screen_frame_sink_push(struct sc_frame_sink *sink, const AVFrame *frame) {
     struct sc_screen *screen = DOWNCAST(sink);
+    assert(screen->video);
 
     bool previous_skipped;
     bool ok = sc_frame_buffer_push(&screen->fb, frame, &previous_skipped);
@@ -364,6 +378,9 @@ sc_screen_init(struct sc_screen *screen,
     screen->mouse_capture_key_pressed = 0;
     screen->paused = false;
     screen->resume_frame = NULL;
+    screen->orientation = SC_ORIENTATION_0;
+
+    screen->video = params->video;
 
     screen->req.x = params->window_x;
     screen->req.y = params->window_y;
@@ -381,41 +398,75 @@ sc_screen_init(struct sc_screen *screen,
         goto error_destroy_frame_buffer;
     }
 
-    screen->orientation = params->orientation;
-    if (screen->orientation != SC_ORIENTATION_0) {
-        LOGI("Initial display orientation set to %s",
-             sc_orientation_get_name(screen->orientation));
+    if (screen->video) {
+        screen->orientation = params->orientation;
+        if (screen->orientation != SC_ORIENTATION_0) {
+            LOGI("Initial display orientation set to %s",
+                 sc_orientation_get_name(screen->orientation));
+        }
     }
 
-    uint32_t window_flags = SDL_WINDOW_HIDDEN
-                          | SDL_WINDOW_RESIZABLE
-                          | SDL_WINDOW_ALLOW_HIGHDPI;
+    uint32_t window_flags = SDL_WINDOW_ALLOW_HIGHDPI;
     if (params->always_on_top) {
         window_flags |= SDL_WINDOW_ALWAYS_ON_TOP;
     }
     if (params->window_borderless) {
         window_flags |= SDL_WINDOW_BORDERLESS;
     }
+    if (params->video) {
+        // The window will be shown on first frame
+        window_flags |= SDL_WINDOW_HIDDEN
+                      | SDL_WINDOW_RESIZABLE;
+    }
+
+    const char *title = params->window_title;
+    assert(title);
+
+    int x = SDL_WINDOWPOS_UNDEFINED;
+    int y = SDL_WINDOWPOS_UNDEFINED;
+    int width = 256;
+    int height = 256;
+    if (params->window_x != SC_WINDOW_POSITION_UNDEFINED) {
+        x = params->window_x;
+    }
+    if (params->window_y != SC_WINDOW_POSITION_UNDEFINED) {
+        y = params->window_y;
+    }
+    if (params->window_width) {
+        width = params->window_width;
+    }
+    if (params->window_height) {
+        height = params->window_height;
+    }
 
     // The window will be positioned and sized on first video frame
-    screen->window =
-        SDL_CreateWindow(params->window_title, 0, 0, 0, 0, window_flags);
+    screen->window = SDL_CreateWindow(title, x, y, width, height, window_flags);
     if (!screen->window) {
         LOGE("Could not create window: %s", SDL_GetError());
         goto error_destroy_fps_counter;
     }
 
-    ok = sc_display_init(&screen->display, screen->window, params->mipmaps);
-    if (!ok) {
-        goto error_destroy_window;
-    }
-
     SDL_Surface *icon = scrcpy_icon_load();
     if (icon) {
         SDL_SetWindowIcon(screen->window, icon);
-        scrcpy_icon_destroy(icon);
-    } else {
+    } else if (params->video) {
+        // just a warning
         LOGW("Could not load icon");
+    } else {
+        // without video, the icon is used as window content, it must be present
+        LOGE("Could not load icon");
+        goto error_destroy_fps_counter;
+    }
+
+    SDL_Surface *icon_novideo = params->video ? NULL : icon;
+    bool mipmaps = params->video && params->mipmaps;
+    ok = sc_display_init(&screen->display, screen->window, icon_novideo,
+                         mipmaps);
+    if (icon) {
+        scrcpy_icon_destroy(icon);
+    }
+    if (!ok) {
+        goto error_destroy_window;
     }
 
     screen->frame = av_frame_alloc();
@@ -439,7 +490,9 @@ sc_screen_init(struct sc_screen *screen,
     sc_input_manager_init(&screen->im, &im_params);
 
 #ifdef CONTINUOUS_RESIZING_WORKAROUND
-    SDL_AddEventWatch(event_watcher, screen);
+    if (screen->video) {
+        SDL_AddEventWatch(event_watcher, screen);
+    }
 #endif
 
     static const struct sc_frame_sink_ops ops = {
@@ -454,6 +507,11 @@ sc_screen_init(struct sc_screen *screen,
     screen->open = false;
 #endif
 
+    if (!screen->video && sc_screen_is_relative_mode(screen)) {
+        // Capture mouse immediately if video mirroring is disabled
+        sc_screen_set_mouse_capture(screen, true);
+    }
+
     return true;
 
 error_destroy_display:
@@ -524,6 +582,8 @@ sc_screen_destroy(struct sc_screen *screen) {
 static void
 resize_for_content(struct sc_screen *screen, struct sc_size old_content_size,
                    struct sc_size new_content_size) {
+    assert(screen->video);
+
     struct sc_size window_size = get_window_size(screen);
     struct sc_size target_size = {
         .width = (uint32_t) window_size.width * new_content_size.width
@@ -537,6 +597,8 @@ resize_for_content(struct sc_screen *screen, struct sc_size old_content_size,
 
 static void
 set_content_size(struct sc_screen *screen, struct sc_size new_content_size) {
+    assert(screen->video);
+
     if (!screen->fullscreen && !screen->maximized && !screen->minimized) {
         resize_for_content(screen, screen->content_size, new_content_size);
     } else if (!screen->resize_pending) {
@@ -551,6 +613,8 @@ set_content_size(struct sc_screen *screen, struct sc_size new_content_size) {
 
 static void
 apply_pending_resize(struct sc_screen *screen) {
+    assert(screen->video);
+
     assert(!screen->fullscreen);
     assert(!screen->maximized);
     assert(!screen->minimized);
@@ -564,6 +628,8 @@ apply_pending_resize(struct sc_screen *screen) {
 void
 sc_screen_set_orientation(struct sc_screen *screen,
                           enum sc_orientation orientation) {
+    assert(screen->video);
+
     if (orientation == screen->orientation) {
         return;
     }
@@ -598,6 +664,8 @@ sc_screen_init_size(struct sc_screen *screen) {
 // recreate the texture and resize the window if the frame size has changed
 static enum sc_display_result
 prepare_for_frame(struct sc_screen *screen, struct sc_size new_frame_size) {
+    assert(screen->video);
+
     if (screen->frame_size.width == new_frame_size.width
             && screen->frame_size.height == new_frame_size.height) {
         return SC_DISPLAY_RESULT_OK;
@@ -617,6 +685,8 @@ prepare_for_frame(struct sc_screen *screen, struct sc_size new_frame_size) {
 
 static bool
 sc_screen_apply_frame(struct sc_screen *screen) {
+    assert(screen->video);
+
     sc_fps_counter_add_rendered_frame(&screen->fps_counter);
 
     AVFrame *frame = screen->frame;
@@ -656,6 +726,8 @@ sc_screen_apply_frame(struct sc_screen *screen) {
 
 static bool
 sc_screen_update_frame(struct sc_screen *screen) {
+    assert(screen->video);
+
     if (screen->paused) {
         if (!screen->resume_frame) {
             screen->resume_frame = av_frame_alloc();
@@ -677,6 +749,8 @@ sc_screen_update_frame(struct sc_screen *screen) {
 
 void
 sc_screen_set_paused(struct sc_screen *screen, bool paused) {
+    assert(screen->video);
+
     if (!paused && !screen->paused) {
         // nothing to do
         return;
@@ -704,6 +778,8 @@ sc_screen_set_paused(struct sc_screen *screen, bool paused) {
 
 void
 sc_screen_switch_fullscreen(struct sc_screen *screen) {
+    assert(screen->video);
+
     uint32_t new_mode = screen->fullscreen ? 0 : SDL_WINDOW_FULLSCREEN_DESKTOP;
     if (SDL_SetWindowFullscreen(screen->window, new_mode)) {
         LOGW("Could not switch fullscreen mode: %s", SDL_GetError());
@@ -721,6 +797,8 @@ sc_screen_switch_fullscreen(struct sc_screen *screen) {
 
 void
 sc_screen_resize_to_fit(struct sc_screen *screen) {
+    assert(screen->video);
+
     if (screen->fullscreen || screen->maximized || screen->minimized) {
         return;
     }
@@ -745,6 +823,8 @@ sc_screen_resize_to_fit(struct sc_screen *screen) {
 
 void
 sc_screen_resize_to_pixel_perfect(struct sc_screen *screen) {
+    assert(screen->video);
+
     if (screen->fullscreen || screen->minimized) {
         return;
     }
@@ -788,6 +868,13 @@ sc_screen_handle_event(struct sc_screen *screen, const SDL_Event *event) {
             return true;
         }
         case SDL_WINDOWEVENT:
+            if (!screen->video
+                    && event->window.event == SDL_WINDOWEVENT_EXPOSED) {
+                sc_screen_render_novideo(screen);
+            }
+
+            // !video implies !has_frame
+            assert(screen->video || !screen->has_frame);
             if (!screen->has_frame) {
                 // Do nothing
                 return true;
@@ -891,6 +978,8 @@ sc_screen_handle_event(struct sc_screen *screen, const SDL_Event *event) {
 struct sc_point
 sc_screen_convert_drawable_to_frame_coords(struct sc_screen *screen,
                                            int32_t x, int32_t y) {
+    assert(screen->video);
+
     enum sc_orientation orientation = screen->orientation;
 
     int32_t w = screen->content_size.width;

app/src/screen.h

@@ -26,6 +26,8 @@ struct sc_screen {
     bool open; // track the open/close state to assert correct behavior
 #endif
 
+    bool video;
+
     struct sc_display display;
     struct sc_input_manager im;
     struct sc_frame_buffer fb;
@@ -70,6 +72,8 @@ struct sc_screen {
 };
 
 struct sc_screen_params {
+    bool video;
+
     struct sc_controller *controller;
     struct sc_file_pusher *fp;
     struct sc_key_processor *kp;
@@ -78,7 +82,7 @@ struct sc_screen_params {
     bool forward_all_clicks;
     bool legacy_paste;
     bool clipboard_autosync;
-    const struct sc_shortcut_mods *shortcut_mods;
+    uint8_t shortcut_mods; // OR of enum sc_shortcut_mod values
 
     const char *window_title;
     bool always_on_top;

app/src/sys/win/process.c

@@ -176,6 +176,8 @@ sc_process_execute_p(const char *const argv[], HANDLE *handle, unsigned flags,
         free(lpAttributeList);
     }
 
+    CloseHandle(pi.hThread);
+
     // These handles are used by the child process, close them for this process
     if (pin) {
         CloseHandle(stdin_read_handle);

app/src/util/audiobuf.c

@@ -46,6 +46,9 @@ sc_audiobuf_read(struct sc_audiobuf *buf, void *to_, uint32_t samples_count) {
     uint32_t head = atomic_load_explicit(&buf->head, memory_order_acquire);
 
     uint32_t can_read = (buf->alloc_size + head - tail) % buf->alloc_size;
+    if (!can_read) {
+        return 0;
+    }
     if (samples_count > can_read) {
         samples_count = can_read;
     }
@@ -86,6 +89,9 @@ sc_audiobuf_write(struct sc_audiobuf *buf, const void *from_,
     uint32_t tail = atomic_load_explicit(&buf->tail, memory_order_acquire);
 
     uint32_t can_write = (buf->alloc_size + tail - head - 1) % buf->alloc_size;
+    if (!can_write) {
+        return 0;
+    }
     if (samples_count > can_write) {
         samples_count = can_write;
     }

app/tests/test_cli.c

@@ -124,32 +124,22 @@ static void test_options2(void) {
 }
 
 static void test_parse_shortcut_mods(void) {
-    struct sc_shortcut_mods mods;
+    uint8_t mods;
     bool ok;
 
     ok = sc_parse_shortcut_mods("lctrl", &mods);
     assert(ok);
-    assert(mods.count == 1);
-    assert(mods.data[0] == SC_SHORTCUT_MOD_LCTRL);
-
-    ok = sc_parse_shortcut_mods("lctrl+lalt", &mods);
-    assert(ok);
-    assert(mods.count == 1);
-    assert(mods.data[0] == (SC_SHORTCUT_MOD_LCTRL | SC_SHORTCUT_MOD_LALT));
+    assert(mods == SC_SHORTCUT_MOD_LCTRL);
 
     ok = sc_parse_shortcut_mods("rctrl,lalt", &mods);
     assert(ok);
-    assert(mods.count == 2);
-    assert(mods.data[0] == SC_SHORTCUT_MOD_RCTRL);
-    assert(mods.data[1] == SC_SHORTCUT_MOD_LALT);
+    assert(mods == (SC_SHORTCUT_MOD_RCTRL | SC_SHORTCUT_MOD_LALT));
 
-    ok = sc_parse_shortcut_mods("lsuper,rsuper+lalt,lctrl+rctrl+ralt", &mods);
+    ok = sc_parse_shortcut_mods("lsuper,rsuper,lctrl", &mods);
     assert(ok);
-    assert(mods.count == 3);
-    assert(mods.data[0] == SC_SHORTCUT_MOD_LSUPER);
-    assert(mods.data[1] == (SC_SHORTCUT_MOD_RSUPER | SC_SHORTCUT_MOD_LALT));
-    assert(mods.data[2] == (SC_SHORTCUT_MOD_LCTRL | SC_SHORTCUT_MOD_RCTRL |
-                            SC_SHORTCUT_MOD_RALT));
+    assert(mods == (SC_SHORTCUT_MOD_LSUPER
+                  | SC_SHORTCUT_MOD_RSUPER
+                  | SC_SHORTCUT_MOD_LCTRL));
 
     ok = sc_parse_shortcut_mods("", &mods);
     assert(!ok);

build.gradle

@@ -7,7 +7,7 @@ buildscript {
         mavenCentral()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:8.1.3'
+        classpath 'com.android.tools.build:gradle:8.3.0'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files

doc/audio.md

@@ -28,10 +28,17 @@ To disable only the audio playback, see [no playback](video.md#no-playback).
 
 ## Audio only
 
-To play audio only, disable the video:
+To play audio only, disable video and control:
 
 ```bash
-scrcpy --no-video
+scrcpy --no-video --no-control
+```
+
+To play audio without a window:
+
+```bash
+# --no-video and --no-control are implied by --no-window
+scrcpy --no-window
 # interrupt with Ctrl+C
 ```
 

doc/control.md

@@ -15,6 +15,31 @@ scrcpy -n   # short version
 Read [keyboard](keyboard.md) and [mouse](mouse.md).
 
 
+## Control only
+
+To control the device without mirroring:
+
+```bash
+scrcpy --no-video --no-audio
+```
+
+By default, mouse mode is switched to UHID if video mirroring is disabled (a
+relative mouse mode is required).
+
+To also use a UHID keyboard, set it explicitly:
+
+```bash
+scrcpy --no-video --no-audio --keyboard=uhid
+scrcpy --no-video --no-audio -K  # short version
+```
+
+To use AOA instead (over USB only):
+
+```bash
+scrcpy --no-video --no-audio --keyboard=aoa --mouse=aoa
+```
+
+
 ## Copy-paste
 
 Any time the Android clipboard changes, it is automatically synchronized to the
@@ -83,11 +108,20 @@ This only works for the default mouse mode (`--mouse=sdk`).
 
 ## Right-click and middle-click
 
-By default, right-click triggers BACK (or POWER on) and middle-click triggers
-HOME. To disable these shortcuts and forward the clicks to the device instead:
+Two behaviors are possible:
+
+ - either right-click triggers BACK (or POWER on) and middle-click triggers
+   HOME, or
+ - these shortcuts are disabled and the clicks are forwarded to the device.
+
+By default, the clicks are forwarded only for UHID and AOA [mouse
+modes](mouse.md).
 
 ```bash
-scrcpy --forward-all-clicks
+scrcpy --forward-all-clicks        # enable
+scrcpy --forward-all-clicks=auto   # enable only for UHID and AOA (default)
+scrcpy --forward-all-clicks=true   # enable (equivalent to no argument)
+scrcpy --forward-all-clicks=false  # disable
 ```
 
 ## File drop

doc/otg.md

@@ -1,19 +1,21 @@
 # OTG
 
 By default, _scrcpy_ injects input events at the Android API level. As an
-alternative, when connected over USB, it is possible to send HID events, so that
-scrcpy behaves as if it was a physical keyboard and/or mouse connected to the
-Android device.
+alternative, it is possible to send HID events, so that scrcpy behaves as if it
+was a [physical keyboard] and/or a [physical mouse] connected to the Android
+device (see [keyboard](keyboard.md) and [mouse](mouse.md)).
 
-A special mode allows to control the device without mirroring, using AOA
-[keyboard](keyboard.md#aoa) and [mouse](mouse.md#aoa). Therefore, it is possible
-to run _scrcpy_ with only physical keyboard and mouse simulation (HID), as if
-the computer keyboard and mouse were plugged directly to the device via an OTG
-cable.
+[physical keyboard]: keyboard.md#physical-keyboard-simulation
+[physical mouse]: physical-keyboard-simulation
 
-In this mode, `adb` (USB debugging) is not necessary, and mirroring is disabled.
+A special mode (OTG) allows to control the device using AOA
+[keyboard](keyboard.md#aoa) and [mouse](mouse.md#aoa), without using _adb_ at
+all (so USB debugging is not necessary). In this mode, video and audio are
+disabled, and `--keyboard=aoa and `--mouse=aoa` are implicitly set.
 
-This is similar to `--keyboard=aoa --mouse=aoa`, but without mirroring.
+Therefore, it is possible to run _scrcpy_ with only physical keyboard and mouse
+simulation, as if the computer keyboard and mouse were plugged directly to the
+device via an OTG cable.
 
 To enable OTG mode:
 
@@ -23,7 +25,7 @@ scrcpy --otg
 scrcpy --otg -s 0123456789abcdef
 ```
 
-It is possible to disable HID keyboard or HID mouse:
+It is possible to disable keyboard or mouse:
 
 ```bash
 scrcpy --otg --keyboard=disabled
@@ -35,3 +37,22 @@ It only works if the device is connected over USB.
 ## OTG issues on Windows
 
 See [FAQ](/FAQ.md#otg-issues-on-windows).
+
+
+## Control only
+
+Note that the purpose of OTG is to control the device without USB debugging
+(adb).
+
+If you want to solely control the device without mirroring while USB debugging
+is enabled, then OTG mode is not necessary.
+
+Instead, disable video and audio, and select UHID (or AOA):
+
+```bash
+scrcpy --no-video --no-audio --keyboard=uhid --mouse=uhid
+scrcpy --no-video --no-audio -KM  # short version
+scrcpy --no-video --no-audio --keyboard=aoa --mouse=aoa
+```
+
+One benefit of UHID is that it also works wirelessly.

doc/recording.md

@@ -58,12 +58,10 @@ orientation](video.md#orientation).
 
 ## No playback
 
-To disable playback while recording:
+To disable playback and control while recording:
 
 ```bash
-scrcpy --no-playback --record=file.mp4
-scrcpy -Nr file.mkv
-# interrupt recording with Ctrl+C
+scrcpy --no-playback --no-control --record=file.mp4
 ```
 
 It is also possible to disable video and audio playback separately:
@@ -73,6 +71,13 @@ It is also possible to disable video and audio playback separately:
 scrcpy --record=file.mkv --no-audio-playback
 ```
 
+To also disable the window:
+
+```bash
+scrcpy --no-playback --no-window --record=file.mp4
+# interrupt recording with Ctrl+C
+```
+
 ## Time limit
 
 To limit the recording time:

doc/shortcuts.md

@@ -13,8 +13,8 @@ It can be changed using `--shortcut-mod`. Possible keys are `lctrl`, `rctrl`,
 # use RCtrl for shortcuts
 scrcpy --shortcut-mod=rctrl
 
-# use either LCtrl+LAlt or LSuper for shortcuts
-scrcpy --shortcut-mod=lctrl+lalt,lsuper
+# use either LCtrl or LSuper for shortcuts
+scrcpy --shortcut-mod=lctrl,lsuper
 ```
 
 _<kbd>[Super]</kbd> is typically the <kbd>Windows</kbd> or <kbd>Cmd</kbd> key._

doc/window.md

@@ -1,5 +1,14 @@
 # Window
 
+## Disable window
+
+To disable window (may be useful for recording or for playing audio only):
+
+```bash
+scrcpy --no-window --record=file.mp4
+# Ctrl+C to interrupt
+```
+
 ## Title
 
 By default, the window title is the device model. It can be changed:

server/src/main/java/com/genymobile/scrcpy/ScreenCapture.java

@@ -45,18 +45,18 @@ public class ScreenCapture extends SurfaceCapture implements Device.RotationList
         }
 
         try {
-            display = createDisplay();
-            setDisplaySurface(display, surface, videoRotation, contentRect, unlockedVideoRect, layerStack);
-            Ln.d("Display: using SurfaceControl API");
-        } catch (Exception surfaceControlException) {
             Rect videoRect = screenInfo.getVideoSize().toRect();
+            virtualDisplay = ServiceManager.getDisplayManager()
+                    .createVirtualDisplay("scrcpy", videoRect.width(), videoRect.height(), device.getDisplayId(), surface);
+            Ln.d("Display: using DisplayManager API");
+        } catch (Exception displayManagerException) {
             try {
-                virtualDisplay = ServiceManager.getDisplayManager()
-                        .createVirtualDisplay("scrcpy", videoRect.width(), videoRect.height(), device.getDisplayId(), surface);
-                Ln.d("Display: using DisplayManager API");
-            } catch (Exception displayManagerException) {
-                Ln.e("Could not create display using SurfaceControl", surfaceControlException);
+                display = createDisplay();
+                setDisplaySurface(display, surface, videoRotation, contentRect, unlockedVideoRect, layerStack);
+                Ln.d("Display: using SurfaceControl API");
+            } catch (Exception surfaceControlException) {
                 Ln.e("Could not create display using DisplayManager", displayManagerException);
+                Ln.e("Could not create display using SurfaceControl", surfaceControlException);
                 throw new AssertionError("Could not create display");
             }
         }
@@ -68,6 +68,11 @@ public class ScreenCapture extends SurfaceCapture implements Device.RotationList
         device.setFoldListener(null);
         if (display != null) {
             SurfaceControl.destroyDisplay(display);
+            display = null;
+        }
+        if (virtualDisplay != null) {
+            virtualDisplay.release();
+            virtualDisplay = null;
         }
     }
 

server/src/main/java/com/genymobile/scrcpy/SurfaceEncoder.java

@@ -48,7 +48,7 @@ public class SurfaceEncoder implements AsyncProcessor {
         this.downsizeOnError = downsizeOnError;
     }
 
-    private void streamScreen() throws IOException, ConfigurationException {
+    private void streamCapture() throws IOException, ConfigurationException {
         Codec codec = streamer.getCodec();
         MediaCodec mediaCodec = createMediaCodec(codec, encoderName);
         MediaFormat format = createFormat(codec.getMimeType(), videoBitRate, maxFps, codecOptions);
@@ -254,7 +254,7 @@ public class SurfaceEncoder implements AsyncProcessor {
             Looper.prepare();
 
             try {
-                streamScreen();
+                streamCapture();
             } catch (ConfigurationException e) {
                 // Do not print stack trace, a user-friendly error-message has already been logged
             } catch (IOException e) {