Handle down/up actions for BACK or POWER ON

Pressing right-click generates either BACK or POWER ON, depending on the
current screen state.

Forward DOWN and UP events separately to the device, to generate key
events accordingly.

Ref #1062 <https://github.com/Genymobile/scrcpy/issues/1062>

app/src/control_msg.c

@@ -75,6 +75,8 @@ control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
             buf[1] = msg->set_screen_power_mode.mode;
             return 2;
         case CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON:
+            buf[1] = msg->back_or_screen_on.action;
+            return 2;
         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

@@ -66,6 +66,9 @@ struct control_msg {
         struct {
             enum screen_power_mode mode;
         } set_screen_power_mode;
+        struct {
+            enum android_keyevent_action action;
+        } back_or_screen_on;
     };
 };
 

app/src/input_manager.c

@@ -99,9 +99,14 @@ action_menu(struct controller *controller, int actions) {
 
 // turn the screen on if it was off, press BACK otherwise
 static void
-press_back_or_turn_screen_on(struct controller *controller) {
+press_back_or_turn_screen_on(struct controller *controller, int action) {
+    assert(action == ACTION_DOWN || action == ACTION_UP);
+
     struct control_msg msg;
     msg.type = CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON;
+    msg.back_or_screen_on.action = action == ACTION_DOWN
+                                 ? AKEY_EVENT_ACTION_DOWN
+                                 : AKEY_EVENT_ACTION_UP;
 
     if (!controller_push_msg(controller, &msg)) {
         LOGW("Could not request 'press back or turn screen on'");
@@ -521,31 +526,36 @@ input_manager_process_mouse_button(struct input_manager *im,
         // simulated from touch events, so it's a duplicate
         return;
     }
-    if (event->type == SDL_MOUSEBUTTONDOWN) {
-        if (control && event->button == SDL_BUTTON_RIGHT) {
-            press_back_or_turn_screen_on(im->controller);
+
+    // double-click on black borders resize to fit the device screen
+    if (event->type == SDL_MOUSEBUTTONDOWN
+            && event->button == SDL_BUTTON_LEFT
+            && event->clicks == 2) {
+        bool outside = is_outside_device_screen(im, event->x, event->y);
+        if (outside) {
+            screen_resize_to_fit(im->screen);
             return;
         }
-        if (control && event->button == SDL_BUTTON_MIDDLE) {
-            action_home(im->controller, ACTION_DOWN | ACTION_UP);
-            return;
-        }
-        // double-click on black borders resize to fit the device screen
-        if (event->button == SDL_BUTTON_LEFT && event->clicks == 2) {
-            bool outside =
-                is_outside_device_screen(im, event->x, event->y);
-            if (outside) {
-                screen_resize_to_fit(im->screen);
-                return;
-            }
-        }
-        // otherwise, send the click event to the device
     }
 
     if (!control) {
         return;
     }
 
+    if (event->button == SDL_BUTTON_MIDDLE) {
+        int action = event->type == SDL_MOUSEBUTTONDOWN ? ACTION_DOWN
+                                                        : ACTION_UP;
+        action_home(im->controller, action);
+        return;
+    }
+
+    if (event->button == SDL_BUTTON_RIGHT) {
+        int action = event->type == SDL_MOUSEBUTTONDOWN ? ACTION_DOWN
+                                                        : ACTION_UP;
+        press_back_or_turn_screen_on(im->controller, action);
+        return;
+    }
+
     struct control_msg msg;
     if (convert_mouse_button(event, im->screen, &msg)) {
         if (!controller_push_msg(im->controller, &msg)) {

app/tests/test_control_msg_serialize.c

@@ -140,14 +140,18 @@ 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_SERIALIZED_MAX_SIZE];
     int size = control_msg_serialize(&msg, buf);
-    assert(size == 1);
+    assert(size == 2);
 
     const unsigned char expected[] = {
         CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON,
+        AKEY_EVENT_ACTION_UP,
     };
     assert(!memcmp(buf, expected, sizeof(expected)));
 }

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

@@ -85,6 +85,13 @@ 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 createEmpty(int type) {
         ControlMessage msg = new ControlMessage();
         msg.type = type;

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

@@ -13,6 +13,7 @@ public class ControlMessageReader {
     private static final int INJECT_TOUCH_EVENT_PAYLOAD_LENGTH = 21;
     private static final int INJECT_SCROLL_EVENT_PAYLOAD_LENGTH = 20;
     private static final int SET_SCREEN_POWER_MODE_PAYLOAD_LENGTH = 1;
+    private static final int BACK_OR_SCREEN_ON_PAYLOAD_LENGTH = 1;
 
     public static final int TEXT_MAX_LENGTH = 300;
     public static final int CLIPBOARD_TEXT_MAX_LENGTH = 4093;
@@ -73,6 +74,8 @@ public class ControlMessageReader {
                 msg = parseSetScreenPowerMode();
                 break;
             case ControlMessage.TYPE_BACK_OR_SCREEN_ON:
+                msg = parseBackOrScreenOn();
+                break;
             case ControlMessage.TYPE_EXPAND_NOTIFICATION_PANEL:
             case ControlMessage.TYPE_COLLAPSE_NOTIFICATION_PANEL:
             case ControlMessage.TYPE_GET_CLIPBOARD:
@@ -164,6 +167,14 @@ public class ControlMessageReader {
         return ControlMessage.createSetScreenPowerMode(mode);
     }
 
+    private ControlMessage parseBackOrScreenOn() {
+        if (buffer.remaining() < BACK_OR_SCREEN_ON_PAYLOAD_LENGTH) {
+            return null;
+        }
+        int action = toUnsigned(buffer.get());
+        return ControlMessage.createBackOrScreenOn(action);
+    }
+
     private static Position readPosition(ByteBuffer buffer) {
         int x = buffer.getInt();
         int y = buffer.getInt();

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

@@ -26,6 +26,9 @@ public class Controller {
     private final MotionEvent.PointerProperties[] pointerProperties = new MotionEvent.PointerProperties[PointersState.MAX_POINTERS];
     private final MotionEvent.PointerCoords[] pointerCoords = new MotionEvent.PointerCoords[PointersState.MAX_POINTERS];
 
+    private boolean backPressed;
+    private boolean powerPressed;
+
     public Controller(Device device, DesktopConnection connection) {
         this.device = device;
         this.connection = connection;
@@ -88,7 +91,7 @@ public class Controller {
                 injectScroll(msg.getPosition(), msg.getHScroll(), msg.getVScroll());
                 break;
             case ControlMessage.TYPE_BACK_OR_SCREEN_ON:
-                pressBackOrTurnScreenOn();
+                pressBackOrTurnScreenOn(msg.getAction());
                 break;
             case ControlMessage.TYPE_EXPAND_NOTIFICATION_PANEL:
                 device.expandNotificationPanel();
@@ -223,8 +226,33 @@ public class Controller {
         return device.injectInputEvent(event, InputManager.INJECT_INPUT_EVENT_MODE_ASYNC);
     }
 
-    private boolean pressBackOrTurnScreenOn() {
-        int keycode = device.isScreenOn() ? KeyEvent.KEYCODE_BACK : KeyEvent.KEYCODE_POWER;
-        return injectKeycode(keycode);
+    private boolean pressBackOrTurnScreenOn(int action) {
+        int keycode = -1;
+        if (action == KeyEvent.ACTION_UP) {
+            // if BACK or POWER were pressed, this action is the corresponding release event (regardless of the screen state)
+            if (backPressed) {
+                keycode = KeyEvent.KEYCODE_BACK;
+                backPressed = false;
+            } else if (powerPressed) {
+                keycode = KeyEvent.KEYCODE_POWER;
+                powerPressed = false;
+            }
+        }
+
+        if (keycode == -1) {
+            keycode = device.isScreenOn() ? KeyEvent.KEYCODE_BACK : KeyEvent.KEYCODE_POWER;
+        }
+
+        if (action == KeyEvent.ACTION_DOWN) {
+            if (keycode == KeyEvent.KEYCODE_BACK) {
+                backPressed = true;
+                powerPressed = false;
+            } else {
+                backPressed = false;
+                powerPressed = true;
+            }
+        }
+
+        return injectKeyEvent(action, keycode, 0, 0);
     }
 }

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

@@ -145,6 +145,7 @@ 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();
 
@@ -152,6 +153,7 @@ public class ControlMessageReaderTest {
         ControlMessage event = reader.next();
 
         Assert.assertEquals(ControlMessage.TYPE_BACK_OR_SCREEN_ON, event.getType());
+        Assert.assertEquals(KeyEvent.ACTION_UP, event.getAction());
     }
 
     @Test