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.

As a consequence of this change, the BACK button is now handled by
Android on mouse released. This is consistent with the keyboard shortcut
(Mod+b) behavior.

PR #2259 <https://github.com/Genymobile/scrcpy/pull/2259>
Refs #2258 <https://github.com/Genymobile/scrcpy/pull/2258>

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_UP, event.getAction());
     }
 
     @Test