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>

README.md

@@ -137,12 +137,14 @@ scrcpy -b 2M  # short version
 
 #### Limit frame rate
 
-On devices with Android >= 10, the capture frame rate can be limited:
+The capture frame rate can be limited:
 
 ```bash
 scrcpy --max-fps 15
 ```
 
+This is officially supported since Android 10, but may work on earlier versions.
+
 #### Crop
 
 The device screen may be cropped to mirror only part of the screen.

app/meson.build

@@ -76,11 +76,9 @@ cc = meson.get_compiler('c')
 
 if host_machine.system() == 'windows'
     src += [ 'src/sys/win/command.c' ]
-    src += [ 'src/sys/win/net.c' ]
     dependencies += cc.find_library('ws2_32')
 else
     src += [ 'src/sys/unix/command.c' ]
-    src += [ 'src/sys/unix/net.c' ]
 endif
 
 conf = configuration_data()

app/scrcpy.1

@@ -43,7 +43,7 @@ Print this help.
 
 .TP
 .BI "\-\-max\-fps " value
-Limit the framerate of screen capture (only supported on devices with Android >= 10).
+Limit the framerate of screen capture (officially supported since Android 10, but may work on earlier versions).
 
 .TP
 .BI "\-m, \-\-max\-size " value

app/src/cli.c

@@ -42,8 +42,8 @@ scrcpy_print_usage(const char *arg0) {
         "        Print this help.\n"
         "\n"
         "    --max-fps value\n"
-        "        Limit the frame rate of screen capture (only supported on\n"
-        "        devices with Android >= 10).\n"
+        "        Limit the frame rate of screen capture (officially supported\n"
+        "        since Android 10, but may work on earlier versions).\n"
         "\n"
         "    -m, --max-size value\n"
         "        Limit both the width and height of the video to value. The\n"

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/src/sys/unix/net.c

@@ -1,21 +0,0 @@
-#include "util/net.h"
-
-#include <unistd.h>
-
-#include "config.h"
-
-bool
-net_init(void) {
-    // do nothing
-    return true;
-}
-
-void
-net_cleanup(void) {
-    // do nothing
-}
-
-bool
-net_close(socket_t socket) {
-    return !close(socket);
-}

app/src/sys/win/net.c

@@ -1,25 +0,0 @@
-#include "util/net.h"
-
-#include "config.h"
-#include "util/log.h"
-
-bool
-net_init(void) {
-    WSADATA wsa;
-    int res = WSAStartup(MAKEWORD(2, 2), &wsa) < 0;
-    if (res < 0) {
-        LOGC("WSAStartup failed with error %d", res);
-        return false;
-    }
-    return true;
-}
-
-void
-net_cleanup(void) {
-    WSACleanup();
-}
-
-bool
-net_close(socket_t socket) {
-    return !closesocket(socket);
-}

app/src/util/net.c

@@ -1,6 +1,7 @@
 #include "net.h"
 
 #include <stdio.h>
+#include <SDL2/SDL_platform.h>
 
 #include "config.h"
 #include "log.h"
@@ -115,3 +116,32 @@ bool
 net_shutdown(socket_t socket, int how) {
     return !shutdown(socket, how);
 }
+
+bool
+net_init(void) {
+#ifdef __WINDOWS__
+    WSADATA wsa;
+    int res = WSAStartup(MAKEWORD(2, 2), &wsa) < 0;
+    if (res < 0) {
+        LOGC("WSAStartup failed with error %d", res);
+        return false;
+    }
+#endif
+    return true;
+}
+
+void
+net_cleanup(void) {
+#ifdef __WINDOWS__
+    WSACleanup();
+#endif
+}
+
+bool
+net_close(socket_t socket) {
+#ifdef __WINDOWS__
+    return !closesocket(socket);
+#else
+    return !close(socket);
+#endif
+}

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

@@ -19,6 +19,7 @@ public class ScreenEncoder implements Device.RotationListener {
 
     private static final int DEFAULT_I_FRAME_INTERVAL = 10; // seconds
     private static final int REPEAT_FRAME_DELAY_US = 100_000; // repeat after 100ms
+    private static final String KEY_MAX_FPS_TO_ENCODER = "max-fps-to-encoder";
 
     private static final int NO_PTS = -1;
 
@@ -150,11 +151,10 @@ public class ScreenEncoder implements Device.RotationListener {
         // display the very first frame, and recover from bad quality when no new frames
         format.setLong(MediaFormat.KEY_REPEAT_PREVIOUS_FRAME_AFTER, REPEAT_FRAME_DELAY_US); // µs
         if (maxFps > 0) {
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
-                format.setFloat(MediaFormat.KEY_MAX_FPS_TO_ENCODER, maxFps);
-            } else {
-                Ln.w("Max FPS is only supported since Android 10, the option has been ignored");
-            }
+            // The key existed privately before Android 10:
+            // <https://android.googlesource.com/platform/frameworks/base/+/625f0aad9f7a259b6881006ad8710adce57d1384%5E%21/>
+            // <https://github.com/Genymobile/scrcpy/issues/488#issuecomment-567321437>
+            format.setFloat(KEY_MAX_FPS_TO_ENCODER, maxFps);
         }
         return format;
     }

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