Call Looper.prepareMainLooper() to avoid exception

Some devices internally create a Handler when creating an input Surface,
causing an exception:

> Surface: java.lang.RuntimeException: Can't create handler inside
> thread that has not called Looper.prepare()

As a workaround, call Looper.prepareMainLooper() beforehand.

Fixes:
 - <https://github.com/Genymobile/scrcpy/issues/240>
 - <https://github.com/Genymobile/scrcpy/issues/921>

Signed-off-by: Romain Vimont <rom@rom1v.com>

README.md

@@ -143,7 +143,6 @@ This is useful for example to mirror only one eye of the Oculus Go:
 
 ```bash
 scrcpy --crop 1224:1440:0:0   # 1224x1440 at offset (0,0)
-scrcpy -c 1224:1440:0:0       # short version
 ```
 
 If `--max-size` is also specified, resizing is applied after cropping.
@@ -226,7 +225,6 @@ The window of app can always be above others by:
 
 ```bash
 scrcpy --always-on-top
-scrcpy -T  # short version
 ```
 
 

app/scrcpy.1

@@ -61,6 +61,13 @@ Set the TCP port the client listens on.
 
 Default is 27183.
 
+.TP
+.B \-\-prefer\-text
+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
 .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/event_converter.c

@@ -75,7 +75,8 @@ convert_meta_state(SDL_Keymod mod) {
 }
 
 bool
-convert_keycode(SDL_Keycode from, enum android_keycode *to, uint16_t mod) {
+convert_keycode(SDL_Keycode from, enum android_keycode *to, uint16_t mod,
+                bool prefer_text) {
     switch (from) {
         MAP(SDLK_RETURN,       AKEYCODE_ENTER);
         MAP(SDLK_KP_ENTER,     AKEYCODE_NUMPAD_ENTER);
@@ -92,6 +93,12 @@ convert_keycode(SDL_Keycode from, enum android_keycode *to, uint16_t mod) {
         MAP(SDLK_DOWN,         AKEYCODE_DPAD_DOWN);
         MAP(SDLK_UP,           AKEYCODE_DPAD_UP);
     }
+
+    if (prefer_text) {
+        // do not forward alpha and space key events
+        return false;
+    }
+
     if (mod & (KMOD_LALT | KMOD_RALT | KMOD_LGUI | KMOD_RGUI)) {
         return false;
     }

app/src/event_converter.h

@@ -14,7 +14,8 @@ enum android_metastate
 convert_meta_state(SDL_Keymod mod);
 
 bool
-convert_keycode(SDL_Keycode from, enum android_keycode *to, uint16_t mod);
+convert_keycode(SDL_Keycode from, enum android_keycode *to, uint16_t mod,
+                bool prefer_text);
 
 enum android_motionevent_buttons
 convert_mouse_buttons(uint32_t state);

app/src/input_manager.c

@@ -214,12 +214,15 @@ clipboard_paste(struct controller *controller) {
 void
 input_manager_process_text_input(struct input_manager *im,
                                  const SDL_TextInputEvent *event) {
+    if (!im->prefer_text) {
         char c = event->text[0];
         if (isalpha(c) || c == ' ') {
             SDL_assert(event->text[1] == '\0');
             // letters and space are handled as raw key event
             return;
         }
+    }
+
     struct control_msg msg;
     msg.type = CONTROL_MSG_TYPE_INJECT_TEXT;
     msg.inject_text.text = SDL_strdup(event->text);
@@ -234,7 +237,8 @@ input_manager_process_text_input(struct input_manager *im,
 }
 
 static bool
-convert_input_key(const SDL_KeyboardEvent *from, struct control_msg *to) {
+convert_input_key(const SDL_KeyboardEvent *from, struct control_msg *to,
+                  bool prefer_text) {
     to->type = CONTROL_MSG_TYPE_INJECT_KEYCODE;
 
     if (!convert_keycode_action(from->type, &to->inject_keycode.action)) {
@@ -242,7 +246,8 @@ convert_input_key(const SDL_KeyboardEvent *from, struct control_msg *to) {
     }
 
     uint16_t mod = from->keysym.mod;
-    if (!convert_keycode(from->keysym.sym, &to->inject_keycode.keycode, mod)) {
+    if (!convert_keycode(from->keysym.sym, &to->inject_keycode.keycode, mod,
+                         prefer_text)) {
         return false;
     }
 
@@ -393,7 +398,7 @@ input_manager_process_key(struct input_manager *im,
     }
 
     struct control_msg msg;
-    if (convert_input_key(event, &msg)) {
+    if (convert_input_key(event, &msg, im->prefer_text)) {
         if (!controller_push_msg(controller, &msg)) {
             LOGW("Could not request 'inject keycode'");
         }

app/src/input_manager.h

@@ -14,6 +14,7 @@ struct input_manager {
     struct controller *controller;
     struct video_buffer *video_buffer;
     struct screen *screen;
+    bool prefer_text;
 };
 
 void

app/src/main.c

@@ -67,6 +67,13 @@ static void usage(const char *arg0) {
         "        Set the TCP port the client listens on.\n"
         "        Default is %d.\n"
         "\n"
+        "    --prefer-text\n"
+        "        Inject alpha characters and space as text events instead of\n"
+        "        key events.\n"
+        "        This avoids issues when combining multiple keys to enter a\n"
+        "        special character, but breaks the expected behavior of alpha\n"
+        "        keys in games (typically WASD).\n"
+        "\n"
         "    --push-target path\n"
         "        Set the target directory for pushing files to the device by\n"
         "        drag & drop. It is passed as-is to \"adb push\".\n"
@@ -297,28 +304,32 @@ guess_record_format(const char *filename) {
 #define OPT_RENDER_EXPIRED_FRAMES 1000
 #define OPT_WINDOW_TITLE          1001
 #define OPT_PUSH_TARGET           1002
+#define OPT_ALWAYS_ON_TOP         1003
+#define OPT_CROP                  1004
+#define OPT_RECORD_FORMAT         1005
+#define OPT_PREFER_TEXT           1006
 
 static bool
 parse_args(struct args *args, int argc, char *argv[]) {
     static const struct option long_options[] = {
-        {"always-on-top",         no_argument,       NULL, 'T'},
+        {"always-on-top",         no_argument,       NULL, OPT_ALWAYS_ON_TOP},
         {"bit-rate",              required_argument, NULL, 'b'},
-        {"crop",                  required_argument, NULL, 'c'},
+        {"crop",                  required_argument, NULL, OPT_CROP},
         {"fullscreen",            no_argument,       NULL, 'f'},
         {"help",                  no_argument,       NULL, 'h'},
         {"max-size",              required_argument, NULL, 'm'},
         {"no-control",            no_argument,       NULL, 'n'},
         {"no-display",            no_argument,       NULL, 'N'},
         {"port",                  required_argument, NULL, 'p'},
-        {"push-target",           required_argument, NULL,
+        {"push-target",           required_argument, NULL, OPT_PUSH_TARGET},
-                                                 OPT_PUSH_TARGET},
         {"record",                required_argument, NULL, 'r'},
-        {"record-format",         required_argument, NULL, 'F'},
+        {"record-format",         required_argument, NULL, OPT_RECORD_FORMAT},
         {"render-expired-frames", no_argument,       NULL,
                                                      OPT_RENDER_EXPIRED_FRAMES},
         {"serial",                required_argument, NULL, 's'},
         {"show-touches",          no_argument,       NULL, 't'},
         {"turn-screen-off",       no_argument,       NULL, 'S'},
+        {"prefer-text",           no_argument,       NULL, OPT_PREFER_TEXT},
         {"version",               no_argument,       NULL, 'v'},
         {"window-title",          required_argument, NULL,
                                                      OPT_WINDOW_TITLE},
@@ -337,12 +348,18 @@ parse_args(struct args *args, int argc, char *argv[]) {
                 }
                 break;
             case 'c':
+                LOGW("Deprecated option -c. Use --crop instead.");
+                // fall through
+            case OPT_CROP:
                 opts->crop = optarg;
                 break;
             case 'f':
                 opts->fullscreen = true;
                 break;
             case 'F':
+                LOGW("Deprecated option -F. Use --record-format instead.");
+                // fall through
+            case OPT_RECORD_FORMAT:
                 if (!parse_record_format(optarg, &opts->record_format)) {
                     return false;
                 }
@@ -379,6 +396,9 @@ parse_args(struct args *args, int argc, char *argv[]) {
                 opts->show_touches = true;
                 break;
             case 'T':
+                LOGW("Deprecated option -T. Use --always-on-top instead.");
+                // fall through
+            case OPT_ALWAYS_ON_TOP:
                 opts->always_on_top = true;
                 break;
             case 'v':
@@ -393,6 +413,9 @@ parse_args(struct args *args, int argc, char *argv[]) {
             case OPT_PUSH_TARGET:
                 opts->push_target = optarg;
                 break;
+            case OPT_PREFER_TEXT:
+                opts->prefer_text = true;
+                break;
             default:
                 // getopt prints the error message on stderr
                 return false;

app/src/recorder.c

@@ -174,11 +174,16 @@ recorder_open(struct recorder *recorder, const AVCodec *input_codec) {
 
 void
 recorder_close(struct recorder *recorder) {
+    if (recorder->header_written) {
         int ret = av_write_trailer(recorder->ctx);
         if (ret < 0) {
             LOGE("Failed to write trailer to %s", recorder->filename);
             recorder->failed = true;
         }
+    } else {
+        // the recorded file is empty
+        recorder->failed = true;
+    }
     avio_close(recorder->ctx->pb);
     avformat_free_context(recorder->ctx);
 

app/src/scrcpy.c

@@ -42,6 +42,7 @@ static struct input_manager input_manager = {
     .controller = &controller,
     .video_buffer = &video_buffer,
     .screen = &screen,
+    .prefer_text = false, // initialized later
 };
 
 // init SDL and set appropriate hints
@@ -414,6 +415,8 @@ scrcpy(const struct scrcpy_options *options) {
         show_touches_waited = true;
     }
 
+    input_manager.prefer_text = options->prefer_text;
+
     ret = event_loop(options->display, options->control);
     LOGD("quit...");
 

app/src/scrcpy.h

@@ -5,6 +5,7 @@
 #include <stdint.h>
 
 #include "config.h"
+#include "input_manager.h"
 #include "recorder.h"
 
 struct scrcpy_options {
@@ -24,6 +25,7 @@ struct scrcpy_options {
     bool display;
     bool turn_screen_off;
     bool render_expired_frames;
+    bool prefer_text;
 };
 
 #define SCRCPY_OPTIONS_DEFAULT { \
@@ -43,6 +45,7 @@ struct scrcpy_options {
     .display = true, \
     .turn_screen_off = false, \
     .render_expired_frames = false, \
+    .prefer_text = false, \
 }
 
 bool

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

@@ -7,6 +7,7 @@ import android.media.MediaCodec;
 import android.media.MediaCodecInfo;
 import android.media.MediaFormat;
 import android.os.IBinder;
+import android.os.Looper;
 import android.view.Surface;
 
 import java.io.FileDescriptor;
@@ -54,6 +55,11 @@ public class ScreenEncoder implements Device.RotationListener {
     }
 
     public void streamScreen(Device device, FileDescriptor fd) throws IOException {
+        // Some devices internally create a Handler when creating an input Surface, causing an exception:
+        // "Can't create handler inside thread that has not called Looper.prepare()"
+        // <https://github.com/Genymobile/scrcpy/issues/240>
+        Looper.prepareMainLooper();
+
         MediaFormat format = createFormat(bitRate, frameRate, iFrameInterval);
         device.setRotationListener(this);
         boolean alive;