Implement device screen off while mirroring

Add two shortcuts:
 - Ctrl+o to turn the device screen off while mirroring
 - Ctrl+Shift+o to turn it back on

On power on (either via the POWER key or BACK while screen is off), both
the device screen and the mirror are turned on.

<https://github.com/Genymobile/scrcpy/issues/175>

README.md

@@ -284,7 +284,9 @@ you are interested, see [issue 14].
  | click on `VOLUME_UP`                   | `Ctrl`+`↑` _(up)_   (`Cmd`+`↑` on MacOS) |
  | click on `VOLUME_DOWN`                 | `Ctrl`+`↓` _(down)_ (`Cmd`+`↓` on MacOS) |
  | click on `POWER`                       | `Ctrl`+`p`                    |
- | turn screen on                         | _Right-click²_                |
+ | power on                               | _Right-click²_                |
+ | turn device screen off (keep mirroring)| `Ctrl`+`o`                    |
+ | turn device screen on                  | `Ctrl`+`Shift`+`o`            |
  | expand notification panel              | `Ctrl`+`n`                    |
  | collapse notification panel            | `Ctrl`+`Shift`+`n`            |
  | copy device clipboard to computer      | `Ctrl`+`c`                    |

app/src/control_msg.c

@@ -55,6 +55,9 @@ control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
                                       &buf[1]);
             return 1 + len;
         }
+        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:

app/src/control_msg.h

@@ -24,6 +24,13 @@ enum control_msg_type {
     CONTROL_MSG_TYPE_COLLAPSE_NOTIFICATION_PANEL,
     CONTROL_MSG_TYPE_GET_CLIPBOARD,
     CONTROL_MSG_TYPE_SET_CLIPBOARD,
+    CONTROL_MSG_TYPE_SET_SCREEN_POWER_MODE,
+};
+
+enum screen_power_mode {
+    // see <https://android.googlesource.com/platform/frameworks/base.git/+/pie-release-2/core/java/android/view/SurfaceControl.java#305>
+    SCREEN_POWER_MODE_OFF = 0,
+    SCREEN_POWER_MODE_NORMAL = 2,
 };
 
 struct control_msg {
@@ -50,6 +57,9 @@ struct control_msg {
         struct {
             char *text; // owned, to be freed by SDL_free()
         } set_clipboard;
+        struct {
+            enum screen_power_mode mode;
+        } set_screen_power_mode;
     };
 };
 

app/src/input_manager.c

@@ -159,6 +159,18 @@ set_device_clipboard(struct controller *controller) {
     }
 }
 
+static void
+set_screen_power_mode(struct controller *controller,
+                      enum screen_power_mode mode) {
+    struct control_msg msg;
+    msg.type = CONTROL_MSG_TYPE_SET_SCREEN_POWER_MODE;
+    msg.set_screen_power_mode.mode = mode;
+
+    if (!controller_push_msg(controller, &msg)) {
+        LOGW("Cannot request 'set screen power mode'");
+    }
+}
+
 static void
 switch_fps_counter_state(struct video_buffer *vb) {
     mutex_lock(vb->mutex);
@@ -263,6 +275,14 @@ input_manager_process_key(struct input_manager *input_manager,
                     action_power(input_manager->controller, action);
                 }
                 return;
+            case SDLK_o:
+                if (control && ctrl && !meta && event->type == SDL_KEYDOWN) {
+                    enum screen_power_mode mode = shift
+                                                ? SCREEN_POWER_MODE_NORMAL
+                                                : SCREEN_POWER_MODE_OFF;
+                    set_screen_power_mode(input_manager->controller, mode);
+                }
+                return;
             case SDLK_DOWN:
 #ifdef __APPLE__
                 if (control && !ctrl && meta && !shift) {

app/src/main.c

@@ -129,7 +129,13 @@ static void usage(const char *arg0) {
         "        click on POWER (turn screen on/off)\n"
         "\n"
         "    Right-click (when screen is off)\n"
-        "        turn screen on\n"
+        "        power on\n"
+        "\n"
+        "    Ctrl+o\n"
+        "        turn device screen off (keep mirroring)\n"
+        "\n"
+        "    Ctrl+Shift+o\n"
+        "        turn device screen on\n"
         "\n"
         "    Ctrl+n\n"
         "       expand notification panel\n"

app/tests/test_control_msg_serialize.c

@@ -213,6 +213,25 @@ static void test_serialize_set_clipboard(void) {
     assert(!memcmp(buf, expected, sizeof(expected)));
 }
 
+static void test_serialize_set_screen_power_mode(void) {
+    struct control_msg msg = {
+        .type = CONTROL_MSG_TYPE_SET_SCREEN_POWER_MODE,
+        .set_screen_power_mode = {
+            .mode = SCREEN_POWER_MODE_NORMAL,
+        },
+    };
+
+    unsigned char buf[CONTROL_MSG_SERIALIZED_MAX_SIZE];
+    int size = control_msg_serialize(&msg, buf);
+    assert(size == 2);
+
+    const unsigned char expected[] = {
+        CONTROL_MSG_TYPE_SET_SCREEN_POWER_MODE,
+        0x02, // SCREEN_POWER_MODE_NORMAL
+    };
+    assert(!memcmp(buf, expected, sizeof(expected)));
+}
+
 int main(void) {
     test_serialize_inject_keycode();
     test_serialize_inject_text();
@@ -224,5 +243,6 @@ int main(void) {
     test_serialize_collapse_notification_panel();
     test_serialize_get_clipboard();
     test_serialize_set_clipboard();
+    test_serialize_set_screen_power_mode();
     return 0;
 }

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

@@ -1,5 +1,7 @@
 package com.genymobile.scrcpy;
 
+import com.genymobile.scrcpy.wrappers.SurfaceControl;
+
 /**
  * Union of all supported event types, identified by their {@code type}.
  */
@@ -14,11 +16,12 @@ public final class ControlMessage {
     public static final int TYPE_COLLAPSE_NOTIFICATION_PANEL = 6;
     public static final int TYPE_GET_CLIPBOARD = 7;
     public static final int TYPE_SET_CLIPBOARD = 8;
+    public static final int TYPE_SET_SCREEN_POWER_MODE = 9;
 
     private int type;
     private String text;
     private int metaState; // KeyEvent.META_*
-    private int action; // KeyEvent.ACTION_* or MotionEvent.ACTION_*
+    private int action; // KeyEvent.ACTION_* or MotionEvent.ACTION_* or POWER_MODE_*
     private int keycode; // KeyEvent.KEYCODE_*
     private int buttons; // MotionEvent.BUTTON_*
     private Position position;
@@ -69,6 +72,16 @@ public final class ControlMessage {
         return event;
     }
 
+    /**
+     * @param mode one of the {@code Device.SCREEN_POWER_MODE_*} constants
+     */
+    public static ControlMessage createSetScreenPowerMode(int mode) {
+        ControlMessage event = new ControlMessage();
+        event.type = TYPE_SET_SCREEN_POWER_MODE;
+        event.action = mode;
+        return event;
+    }
+
     public static ControlMessage createEmpty(int type) {
         ControlMessage event = new ControlMessage();
         event.type = type;

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

@@ -11,6 +11,7 @@ public class ControlMessageReader {
     private static final int INJECT_KEYCODE_PAYLOAD_LENGTH = 9;
     private static final int INJECT_MOUSE_EVENT_PAYLOAD_LENGTH = 17;
     private static final int INJECT_SCROLL_EVENT_PAYLOAD_LENGTH = 20;
+    private static final int SET_SCREEN_POWER_MODE_PAYLOAD_LENGTH = 1;
 
     public static final int TEXT_MAX_LENGTH = 300;
     public static final int CLIPBOARD_TEXT_MAX_LENGTH = 4093;
@@ -67,6 +68,9 @@ public class ControlMessageReader {
             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:
@@ -144,6 +148,14 @@ public class ControlMessageReader {
         return ControlMessage.createSetClipboard(text);
     }
 
+    private ControlMessage parseSetScreenPowerMode() {
+        if (buffer.remaining() < SET_SCREEN_POWER_MODE_PAYLOAD_LENGTH) {
+            return null;
+        }
+        int mode = buffer.get();
+        return ControlMessage.createSetScreenPowerMode(mode);
+    }
+
     private static Position readPosition(ByteBuffer buffer) {
         int x = buffer.getInt();
         int y = buffer.getInt();

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

@@ -97,6 +97,9 @@ public class Controller {
             case ControlMessage.TYPE_SET_CLIPBOARD:
                 device.setClipboardText(msg.getText());
                 break;
+            case ControlMessage.TYPE_SET_SCREEN_POWER_MODE:
+                device.setScreenPowerMode(msg.getAction());
+                break;
             default:
                 // do nothing
         }

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

@@ -1,15 +1,20 @@
 package com.genymobile.scrcpy;
 
 import com.genymobile.scrcpy.wrappers.ServiceManager;
+import com.genymobile.scrcpy.wrappers.SurfaceControl;
 
 import android.graphics.Rect;
 import android.os.Build;
+import android.os.IBinder;
 import android.os.RemoteException;
 import android.view.IRotationWatcher;
 import android.view.InputEvent;
 
 public final class Device {
 
+    public static final int POWER_MODE_OFF = SurfaceControl.POWER_MODE_OFF;
+    public static final int POWER_MODE_NORMAL = SurfaceControl.POWER_MODE_NORMAL;
+
     public interface RotationListener {
         void onRotationChanged(int rotation);
     }
@@ -152,6 +157,15 @@ public final class Device {
         Ln.i("Device clipboard set");
     }
 
+    /**
+     * @param mode one of the {@code SCREEN_POWER_MODE_*} constants
+     */
+    public void setScreenPowerMode(int mode) {
+        IBinder d = SurfaceControl.getBuiltInDisplay(0);
+        SurfaceControl.setDisplayPowerMode(d, mode);
+        Ln.i("Device screen turned " + (mode == Device.POWER_MODE_OFF ? "off" : "on"));
+    }
+
     static Rect flipRect(Rect crop) {
         return new Rect(crop.top, crop.left, crop.bottom, crop.right);
     }

server/src/main/java/com/genymobile/scrcpy/wrappers/SurfaceControl.java

@@ -10,6 +10,10 @@ public final class SurfaceControl {
 
     private static final Class<?> CLASS;
 
+    // see <https://android.googlesource.com/platform/frameworks/base.git/+/pie-release-2/core/java/android/view/SurfaceControl.java#305>
+    public static final int POWER_MODE_OFF = 0;
+    public static final int POWER_MODE_NORMAL = 2;
+
     static {
         try {
             CLASS = Class.forName("android.view.SurfaceControl");
@@ -71,6 +75,22 @@ public final class SurfaceControl {
         }
     }
 
+    public static IBinder getBuiltInDisplay(int builtInDisplayId) {
+        try {
+            return (IBinder) CLASS.getMethod("getBuiltInDisplay", int.class).invoke(null, builtInDisplayId);
+        } catch (Exception e) {
+            throw new AssertionError(e);
+        }
+    }
+
+    public static void setDisplayPowerMode(IBinder displayToken, int mode) {
+        try {
+            CLASS.getMethod("setDisplayPowerMode", IBinder.class, int.class).invoke(null, displayToken, mode);
+        } catch (Exception e) {
+            throw new AssertionError(e);
+        }
+    }
+
     public static void destroyDisplay(IBinder displayToken) {
         try {
             CLASS.getMethod("destroyDisplay", IBinder.class).invoke(null, displayToken);

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

@@ -210,6 +210,24 @@ public class ControlMessageReaderTest {
         Assert.assertEquals("testé", event.getText());
     }
 
+    @Test
+    public void testParseSetScreenPowerMode() throws IOException {
+        ControlMessageReader reader = new ControlMessageReader();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+        dos.writeByte(ControlMessage.TYPE_SET_SCREEN_POWER_MODE);
+        dos.writeByte(Device.POWER_MODE_NORMAL);
+
+        byte[] packet = bos.toByteArray();
+
+        reader.readFrom(new ByteArrayInputStream(packet));
+        ControlMessage event = reader.next();
+
+        Assert.assertEquals(ControlMessage.TYPE_SET_SCREEN_POWER_MODE, event.getType());
+        Assert.assertEquals(Device.POWER_MODE_NORMAL, event.getAction());
+    }
+
     @Test
     public void testMultiEvents() throws IOException {
         ControlMessageReader reader = new ControlMessageReader();