Map right-click to BACK if screen is on

Right-click was used to turn the screen on. It did nothing when the
screen was already on.

Instead, in that case, press BACK (like Vysor).

Suggested by: <https://www.reddit.com/r/Android/comments/834zmr/introducing_scrcpy_an_app_to_display_and_control/dvfueft/>

README.md

@@ -199,10 +199,12 @@ To run without installing:
  | click on `VOLUME_UP`                   | `Ctrl`+`+`    |
  | click on `VOLUME_DOWN`                 | `Ctrl`+`-`    |
  | click on `POWER`                       | `Ctrl`+`p`    |
- | turn screen on                         | _Right-click_ |
+ | turn screen on or press BACK¹          | _Right-click_ |
  | paste computer clipboard to device     | `Ctrl`+`v`    |
  | enable/disable FPS counter (on stdout) | `Ctrl`+`i`    |
 
+_¹ Press BACK if the screen is already on._
+
 
 ## Why _scrcpy_?
 

app/src/controlevent.h

@@ -20,7 +20,7 @@ enum control_event_type {
     CONTROL_EVENT_TYPE_COMMAND,
 };
 
-#define CONTROL_EVENT_COMMAND_SCREEN_ON 0
+#define CONTROL_EVENT_COMMAND_BACK_OR_SCREEN_ON 0
 
 struct control_event {
     enum control_event_type type;

app/src/inputmanager.c

@@ -78,10 +78,11 @@ static inline void action_volume_down(struct controller *controller) {
     send_keycode(controller, AKEYCODE_VOLUME_DOWN, "VOLUME_DOWN");
 }
 
-static void turn_screen_on(struct controller *controller) {
+// turn the screen on if it was off, press BACK otherwise
+static void press_back_or_turn_screen_on(struct controller *controller) {
     struct control_event control_event;
     control_event.type = CONTROL_EVENT_TYPE_COMMAND;
-    control_event.command_event.action = CONTROL_EVENT_COMMAND_SCREEN_ON;
+    control_event.command_event.action = CONTROL_EVENT_COMMAND_BACK_OR_SCREEN_ON;
 
     if (!controller_push_event(controller, &control_event)) {
         LOGW("Cannot turn screen on");
@@ -226,7 +227,7 @@ void input_manager_process_mouse_motion(struct input_manager *input_manager,
 void input_manager_process_mouse_button(struct input_manager *input_manager,
                                         const SDL_MouseButtonEvent *event) {
     if (event->button == SDL_BUTTON_RIGHT && event->type == SDL_MOUSEBUTTONDOWN) {
-        turn_screen_on(input_manager->controller);
+        press_back_or_turn_screen_on(input_manager->controller);
         return;
     };
     struct control_event control_event;

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

@@ -11,7 +11,7 @@ public final class ControlEvent {
     public static final int TYPE_SCROLL = 3;
     public static final int TYPE_COMMAND = 4;
 
-    public static final int COMMAND_SCREEN_ON = 0;
+    public static final int COMMAND_BACK_OR_SCREEN_ON = 0;
 
     private int type;
     private String text;

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

@@ -167,10 +167,15 @@ public class EventController {
         return device.isScreenOn() || injectKeycode(KeyEvent.KEYCODE_POWER);
     }
 
+    private boolean pressBackOrTurnScreenOn() {
+        int keycode = device.isScreenOn() ? KeyEvent.KEYCODE_BACK : KeyEvent.KEYCODE_POWER;
+        return injectKeycode(keycode);
+    }
+
     private boolean executeCommand(int action) {
         switch (action) {
-            case ControlEvent.COMMAND_SCREEN_ON:
-                return turnScreenOn();
+            case ControlEvent.COMMAND_BACK_OR_SCREEN_ON:
+                return pressBackOrTurnScreenOn();
             default:
                 Ln.w("Unsupported command: " + action);
         }