Forward DOWN and UP separately for right-click

The shortcut "back on screen on" is a bit special: the control is
requested by the client, but the actual event injection (POWER or BACK)
is determined on the device.

To properly inject DOWN and UP events for BACK, transmit the action as
a control parameter.

If the screen is off:
 - on DOWN, inject POWER (DOWN and UP) (wake up the device immediately)
 - on UP, do nothing
If the screen is on:
 - on DOWN, inject BACK DOWN
 - on UP, inject BACK UP

A corner case is when the screen turns off between the DOWN and UP
event. In that case, a BACK UP event will be injected, so it's harmless.

With this change, the actual BACK is handled by Android on UP on the
device (instead of DOWN). This is consistent with the keyboard shortcut
(Mod+b) behavior.

app/scrcpy.1

@@ -187,16 +187,16 @@ Enable "show touches" on start, restore the initial value on exit.
 
 It only shows physical touches (not clicks from scrcpy).
 
-.TP
-.B \-v, \-\-version
-Print the version of scrcpy.
-
 .TP
 .BI "\-V, \-\-verbosity " value
 Set the log level ("debug", "info", "warn" or "error").
 
 Default is "info" for release builds, "debug" for debug builds.
 
+.TP
+.B \-v, \-\-version
+Print the version of scrcpy.
+
 .TP
 .B \-w, \-\-stay-awake
 Keep the device on while scrcpy is running, when the device is plugged in.

app/src/cli.c

@@ -179,9 +179,6 @@ scrcpy_print_usage(const char *arg0) {
         "        on exit.\n"
         "        It only shows physical touches (not clicks from scrcpy).\n"
         "\n"
-        "    -v, --version\n"
-        "        Print the version of scrcpy.\n"
-        "\n"
         "    -V, --verbosity value\n"
         "        Set the log level (debug, info, warn or error).\n"
 #ifndef NDEBUG
@@ -189,6 +186,9 @@ scrcpy_print_usage(const char *arg0) {
 #else
         "        Default is info.\n"
 #endif
+        "\n"
+        "    -v, --version\n"
+        "        Print the version of scrcpy.\n"
         "\n"
         "    -w, --stay-awake\n"
         "        Keep the device on while scrcpy is running, when the device\n"

app/src/control_msg.c

@@ -67,6 +67,9 @@ control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
             buffer_write32be(&buf[17],
                              (uint32_t) msg->inject_scroll_event.vscroll);
             return 21;
+        case CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON:
+            buf[1] = msg->inject_keycode.action;
+            return 2;
         case CONTROL_MSG_TYPE_SET_CLIPBOARD: {
             buf[1] = !!msg->set_clipboard.paste;
             size_t len = write_string(msg->set_clipboard.text,
@@ -77,7 +80,6 @@ control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
         case CONTROL_MSG_TYPE_SET_SCREEN_POWER_MODE:
             buf[1] = msg->set_screen_power_mode.mode;
             return 2;
-        case CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON:
         case CONTROL_MSG_TYPE_EXPAND_NOTIFICATION_PANEL:
         case CONTROL_MSG_TYPE_COLLAPSE_NOTIFICATION_PANEL:
         case CONTROL_MSG_TYPE_GET_CLIPBOARD:

app/src/control_msg.h

@@ -64,6 +64,10 @@ struct control_msg {
             int32_t hscroll;
             int32_t vscroll;
         } inject_scroll_event;
+        struct {
+            enum android_keyevent_action action; // action for the BACK key
+            // screen may only be turned on on ACTION_DOWN
+        } back_or_screen_on;
         struct {
             char *text; // owned, to be freed by free()
             bool paste;

app/src/input_manager.c

@@ -146,13 +146,25 @@ action_cut(struct controller *controller, int actions) {
 }
 
 // turn the screen on if it was off, press BACK otherwise
+// If the screen is off, it is turned on only on ACTION_DOWN
 static void
-press_back_or_turn_screen_on(struct controller *controller) {
+press_back_or_turn_screen_on(struct controller *controller, int actions) {
     struct control_msg msg;
     msg.type = CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON;
 
-    if (!controller_push_msg(controller, &msg)) {
-        LOGW("Could not request 'press back or turn screen on'");
+    if (actions & ACTION_DOWN) {
+        msg.back_or_screen_on.action = AKEY_EVENT_ACTION_DOWN;
+        if (!controller_push_msg(controller, &msg)) {
+            LOGW("Could not request 'press back or turn screen on'");
+            return;
+        }
+    }
+
+    if (actions & ACTION_UP) {
+        msg.back_or_screen_on.action = AKEY_EVENT_ACTION_UP;
+        if (!controller_push_msg(controller, &msg)) {
+            LOGW("Could not request 'press back or turn screen on'");
+        }
     }
 }
 
@@ -646,13 +658,15 @@ input_manager_process_mouse_button(struct input_manager *im,
     }
 
     bool down = event->type == SDL_MOUSEBUTTONDOWN;
-    if (!im->forward_all_clicks && down) {
+    if (!im->forward_all_clicks) {
+        int action = down ? ACTION_DOWN : ACTION_UP;
+
         if (control && event->button == SDL_BUTTON_RIGHT) {
-            press_back_or_turn_screen_on(im->controller);
+            press_back_or_turn_screen_on(im->controller, action);
             return;
         }
         if (control && event->button == SDL_BUTTON_MIDDLE) {
-            action_home(im->controller, ACTION_DOWN | ACTION_UP);
+            action_home(im->controller, action);
             return;
         }
 
@@ -665,7 +679,9 @@ input_manager_process_mouse_button(struct input_manager *im,
             bool outside = x < r->x || x >= r->x + r->w
                         || y < r->y || y >= r->y + r->h;
             if (outside) {
-                screen_resize_to_fit(im->screen);
+                if (down) {
+                    screen_resize_to_fit(im->screen);
+                }
                 return;
             }
         }

app/src/scrcpy.c

@@ -128,30 +128,6 @@ sdl_init_and_configure(bool display, const char *render_driver,
     return true;
 }
 
-
-#if defined(__APPLE__) || defined(__WINDOWS__)
-# define CONTINUOUS_RESIZING_WORKAROUND
-#endif
-
-#ifdef CONTINUOUS_RESIZING_WORKAROUND
-// On Windows and MacOS, resizing blocks the event loop, so resizing events are
-// not triggered. As a workaround, handle them in an event handler.
-//
-// <https://bugzilla.libsdl.org/show_bug.cgi?id=2077>
-// <https://stackoverflow.com/a/40693139/1987178>
-static int
-event_watcher(void *data, SDL_Event *event) {
-    (void) data;
-    if (event->type == SDL_WINDOWEVENT
-            && event->window.event == SDL_WINDOWEVENT_RESIZED) {
-        // In practice, it seems to always be called from the same thread in
-        // that specific case. Anyway, it's just a workaround.
-        screen_render(&screen, true);
-    }
-    return 0;
-}
-#endif
-
 static bool
 is_apk(const char *file) {
     const char *ext = strrchr(file, '.');
@@ -191,7 +167,7 @@ handle_event(SDL_Event *event, const struct scrcpy_options *options) {
                 action = ACTION_PUSH_FILE;
             }
             file_handler_request(&file_handler, action, file);
-            break;
+            goto end;
         }
     }
 
@@ -209,11 +185,6 @@ end:
 
 static bool
 event_loop(const struct scrcpy_options *options) {
-#ifdef CONTINUOUS_RESIZING_WORKAROUND
-    if (options->display) {
-        SDL_AddEventWatch(event_watcher, NULL);
-    }
-#endif
     SDL_Event event;
     while (SDL_WaitEvent(&event)) {
         enum event_result result = handle_event(&event, options);
@@ -394,6 +365,7 @@ scrcpy(const struct scrcpy_options *options) {
             .window_borderless = options->window_borderless,
             .rotation = options->rotation,
             .mipmaps = options->mipmaps,
+            .fullscreen = options->fullscreen,
         };
 
         if (!screen_init(&screen, &video_buffer, &fps_counter,
@@ -411,10 +383,6 @@ scrcpy(const struct scrcpy_options *options) {
                 LOGW("Could not request 'set screen power mode'");
             }
         }
-
-        if (options->fullscreen) {
-            screen_switch_fullscreen(&screen);
-        }
     }
 
     // now we consumed the header values, the socket receives the video stream

app/src/screen.c

@@ -239,6 +239,29 @@ create_texture(struct screen *screen) {
     return texture;
 }
 
+#if defined(__APPLE__) || defined(__WINDOWS__)
+# define CONTINUOUS_RESIZING_WORKAROUND
+#endif
+
+#ifdef CONTINUOUS_RESIZING_WORKAROUND
+// On Windows and MacOS, resizing blocks the event loop, so resizing events are
+// not triggered. As a workaround, handle them in an event handler.
+//
+// <https://bugzilla.libsdl.org/show_bug.cgi?id=2077>
+// <https://stackoverflow.com/a/40693139/1987178>
+static int
+event_watcher(void *data, SDL_Event *event) {
+    struct screen *screen = data;
+    if (event->type == SDL_WINDOWEVENT
+            && event->window.event == SDL_WINDOWEVENT_RESIZED) {
+        // In practice, it seems to always be called from the same thread in
+        // that specific case. Anyway, it's just a workaround.
+        screen_render(screen, true);
+    }
+    return 0;
+}
+#endif
+
 bool
 screen_init(struct screen *screen, struct video_buffer *vb,
             struct fps_counter *fps_counter,
@@ -362,10 +385,18 @@ screen_init(struct screen *screen, struct video_buffer *vb,
 
     screen_update_content_rect(screen);
 
+    if (params->fullscreen) {
+        screen_switch_fullscreen(screen);
+    }
+
+#ifdef CONTINUOUS_RESIZING_WORKAROUND
+    SDL_AddEventWatch(event_watcher, screen);
+#endif
+
     return true;
 }
 
-void
+static void
 screen_show_window(struct screen *screen) {
     SDL_ShowWindow(screen->window);
 }

app/src/screen.h

@@ -52,6 +52,8 @@ struct screen_params {
 
     uint8_t rotation;
     bool mipmaps;
+
+    bool fullscreen;
 };
 
 // initialize screen, create window, renderer and texture (window is hidden)
@@ -60,10 +62,6 @@ screen_init(struct screen *screen, struct video_buffer *vb,
             struct fps_counter *fps_counter,
             const struct screen_params *params);
 
-// show the window
-void
-screen_show_window(struct screen *screen);
-
 // destroy window, renderer and texture (if any)
 void
 screen_destroy(struct screen *screen);

app/tests/test_control_msg_serialize.c

@@ -146,14 +146,18 @@ static void test_serialize_inject_scroll_event(void) {
 static void test_serialize_back_or_screen_on(void) {
     struct control_msg msg = {
         .type = CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON,
+        .back_or_screen_on = {
+            .action = AKEY_EVENT_ACTION_UP,
+        },
     };
 
     unsigned char buf[CONTROL_MSG_MAX_SIZE];
     size_t size = control_msg_serialize(&msg, buf);
-    assert(size == 1);
+    assert(size == 2);
 
     const unsigned char expected[] = {
         CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON,
+        0x01, // AKEY_EVENT_ACTION_UP
     };
     assert(!memcmp(buf, expected, sizeof(expected)));
 }

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

@@ -71,6 +71,13 @@ public final class ControlMessage {
         return msg;
     }
 
+    public static ControlMessage createBackOrScreenOn(int action) {
+        ControlMessage msg = new ControlMessage();
+        msg.type = TYPE_BACK_OR_SCREEN_ON;
+        msg.action = action;
+        return msg;
+    }
+
     public static ControlMessage createSetClipboard(String text, boolean paste) {
         ControlMessage msg = new ControlMessage();
         msg.type = TYPE_SET_CLIPBOARD;

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

@@ -11,6 +11,7 @@ public class ControlMessageReader {
     static final int INJECT_KEYCODE_PAYLOAD_LENGTH = 13;
     static final int INJECT_TOUCH_EVENT_PAYLOAD_LENGTH = 27;
     static final int INJECT_SCROLL_EVENT_PAYLOAD_LENGTH = 20;
+    static final int BACK_OR_SCREEN_ON_LENGTH = 1;
     static final int SET_SCREEN_POWER_MODE_PAYLOAD_LENGTH = 1;
     static final int SET_CLIPBOARD_FIXED_PAYLOAD_LENGTH = 1;
 
@@ -66,13 +67,15 @@ public class ControlMessageReader {
             case ControlMessage.TYPE_INJECT_SCROLL_EVENT:
                 msg = parseInjectScrollEvent();
                 break;
+            case ControlMessage.TYPE_BACK_OR_SCREEN_ON:
+                msg = parseBackOrScreenOnEvent();
+                break;
             case ControlMessage.TYPE_SET_CLIPBOARD:
                 msg = parseSetClipboard();
                 break;
             case ControlMessage.TYPE_SET_SCREEN_POWER_MODE:
                 msg = parseSetScreenPowerMode();
                 break;
-            case ControlMessage.TYPE_BACK_OR_SCREEN_ON:
             case ControlMessage.TYPE_EXPAND_NOTIFICATION_PANEL:
             case ControlMessage.TYPE_COLLAPSE_NOTIFICATION_PANEL:
             case ControlMessage.TYPE_GET_CLIPBOARD:
@@ -150,6 +153,14 @@ public class ControlMessageReader {
         return ControlMessage.createInjectScrollEvent(position, hScroll, vScroll);
     }
 
+    private ControlMessage parseBackOrScreenOnEvent() {
+        if (buffer.remaining() < BACK_OR_SCREEN_ON_LENGTH) {
+            return null;
+        }
+        int action = toUnsigned(buffer.get());
+        return ControlMessage.createBackOrScreenOn(action);
+    }
+
     private ControlMessage parseSetClipboard() {
         if (buffer.remaining() < SET_CLIPBOARD_FIXED_PAYLOAD_LENGTH) {
             return null;

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

@@ -101,7 +101,7 @@ public class Controller {
                 break;
             case ControlMessage.TYPE_BACK_OR_SCREEN_ON:
                 if (device.supportsInputEvents()) {
-                    pressBackOrTurnScreenOn();
+                    pressBackOrTurnScreenOn(msg.getAction());
                 }
                 break;
             case ControlMessage.TYPE_EXPAND_NOTIFICATION_PANEL:
@@ -255,12 +255,22 @@ public class Controller {
         }, 200, TimeUnit.MILLISECONDS);
     }
 
-    private boolean pressBackOrTurnScreenOn() {
-        int keycode = Device.isScreenOn() ? KeyEvent.KEYCODE_BACK : KeyEvent.KEYCODE_POWER;
-        if (keepPowerModeOff && keycode == KeyEvent.KEYCODE_POWER) {
+    private boolean pressBackOrTurnScreenOn(int action) {
+        if (Device.isScreenOn()) {
+            return device.injectKeyEvent(action, KeyEvent.KEYCODE_BACK, 0, 0);
+        }
+
+        // Screen is off
+        // Only press POWER on ACTION_DOWN
+        if (action != KeyEvent.ACTION_DOWN) {
+            // do nothing,
+            return true;
+        }
+
+        if (keepPowerModeOff) {
             schedulePowerModeOff();
         }
-        return device.injectKeycode(keycode);
+        return device.injectKeycode(KeyEvent.KEYCODE_POWER);
     }
 
     private boolean setClipboard(String text, boolean paste) {

server/src/test/java/com/genymobile/scrcpy/ControlMessageReaderTest.java

@@ -154,6 +154,7 @@ public class ControlMessageReaderTest {
         ByteArrayOutputStream bos = new ByteArrayOutputStream();
         DataOutputStream dos = new DataOutputStream(bos);
         dos.writeByte(ControlMessage.TYPE_BACK_OR_SCREEN_ON);
+        dos.writeByte(KeyEvent.ACTION_UP);
 
         byte[] packet = bos.toByteArray();
 
@@ -161,6 +162,7 @@ public class ControlMessageReaderTest {
         ControlMessage event = reader.next();
 
         Assert.assertEquals(ControlMessage.TYPE_BACK_OR_SCREEN_ON, event.getType());
+        Assert.assertEquals(KeyEvent.ACTION_DOWN, event.getAction());
     }
 
     @Test