Pass buttons state in scroll events

A scroll event might be produced when a mouse button is pressed (for
example when scrolling while selecting a text). For consistency, pass
the actual buttons state (instead of 0).

In practice, it seems that this use case does not work properly with
Android event injection, but it will work with HID mouse.

app/src/control_msg.c

@@ -119,7 +119,8 @@ control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
                              (uint32_t) msg->inject_scroll_event.hscroll);
             buffer_write32be(&buf[17],
                              (uint32_t) msg->inject_scroll_event.vscroll);
-            return 21;
+            buffer_write32be(&buf[21], msg->inject_scroll_event.buttons);
+            return 25;
         case CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON:
             buf[1] = msg->inject_keycode.action;
             return 2;
@@ -192,11 +193,12 @@ control_msg_log(const struct control_msg *msg) {
         }
         case CONTROL_MSG_TYPE_INJECT_SCROLL_EVENT:
             LOG_CMSG("scroll position=%" PRIi32 ",%" PRIi32 " hscroll=%" PRIi32
-                         " vscroll=%" PRIi32,
+                         " vscroll=%" PRIi32 " buttons=%06lx",
                      msg->inject_scroll_event.position.point.x,
                      msg->inject_scroll_event.position.point.y,
                      msg->inject_scroll_event.hscroll,
-                     msg->inject_scroll_event.vscroll);
+                     msg->inject_scroll_event.vscroll,
+                     (long) msg->inject_scroll_event.buttons);
             break;
         case CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON:
             LOG_CMSG("back-or-screen-on %s",

app/src/control_msg.h

@@ -70,6 +70,7 @@ struct control_msg {
             struct sc_position position;
             int32_t hscroll;
             int32_t vscroll;
+            enum android_motionevent_buttons buttons;
         } inject_scroll_event;
         struct {
             enum android_keyevent_action action; // action for the BACK key

app/src/input_events.h

@@ -360,6 +360,7 @@ struct sc_mouse_scroll_event {
     struct sc_position position;
     int32_t hscroll;
     int32_t vscroll;
+    uint8_t buttons_state; // bitwise-OR of sc_mouse_button values
 };
 
 struct sc_mouse_motion_event {

app/src/input_manager.c

@@ -810,7 +810,7 @@ input_manager_process_mouse_wheel(struct input_manager *im,
     // mouse_x and mouse_y are expressed in pixels relative to the window
     int mouse_x;
     int mouse_y;
-    SDL_GetMouseState(&mouse_x, &mouse_y);
+    uint32_t buttons = SDL_GetMouseState(&mouse_x, &mouse_y);
 
     struct sc_mouse_scroll_event evt = {
         .position = {
@@ -820,6 +820,8 @@ input_manager_process_mouse_wheel(struct input_manager *im,
         },
         .hscroll = event->x,
         .vscroll = event->y,
+        .buttons_state =
+            sc_mouse_buttons_state_from_sdl(buttons, im->forward_all_clicks),
     };
 
     im->mp->ops->process_mouse_scroll(im->mp, &evt);

app/src/mouse_inject.c

@@ -108,6 +108,7 @@ sc_mouse_processor_process_mouse_scroll(struct sc_mouse_processor *mp,
             .position = event->position,
             .hscroll = event->hscroll,
             .vscroll = event->vscroll,
+            .buttons = convert_mouse_buttons(event->buttons_state),
         },
     };
 

app/tests/test_control_msg_serialize.c

@@ -126,12 +126,13 @@ static void test_serialize_inject_scroll_event(void) {
             },
             .hscroll = 1,
             .vscroll = -1,
+            .buttons = 1,
         },
     };
 
     unsigned char buf[CONTROL_MSG_MAX_SIZE];
     size_t size = control_msg_serialize(&msg, buf);
-    assert(size == 21);
+    assert(size == 25);
 
     const unsigned char expected[] = {
         CONTROL_MSG_TYPE_INJECT_SCROLL_EVENT,
@@ -139,6 +140,7 @@ static void test_serialize_inject_scroll_event(void) {
         0x04, 0x38, 0x07, 0x80, // 1080 1920
         0x00, 0x00, 0x00, 0x01, // 1
         0xFF, 0xFF, 0xFF, 0xFF, // -1
+        0x00, 0x00, 0x00, 0x01, // 1
     };
     assert(!memcmp(buf, expected, sizeof(expected)));
 }

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

@@ -71,12 +71,13 @@ public final class ControlMessage {
         return msg;
     }
 
-    public static ControlMessage createInjectScrollEvent(Position position, int hScroll, int vScroll) {
+    public static ControlMessage createInjectScrollEvent(Position position, int hScroll, int vScroll, int buttons) {
         ControlMessage msg = new ControlMessage();
         msg.type = TYPE_INJECT_SCROLL_EVENT;
         msg.position = position;
         msg.hScroll = hScroll;
         msg.vScroll = vScroll;
+        msg.buttons = buttons;
         return msg;
     }
 

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

@@ -10,7 +10,7 @@ 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 INJECT_SCROLL_EVENT_PAYLOAD_LENGTH = 24;
     static final int BACK_OR_SCREEN_ON_LENGTH = 1;
     static final int SET_SCREEN_POWER_MODE_PAYLOAD_LENGTH = 1;
     static final int GET_CLIPBOARD_LENGTH = 1;
@@ -154,7 +154,8 @@ public class ControlMessageReader {
         Position position = readPosition(buffer);
         int hScroll = buffer.getInt();
         int vScroll = buffer.getInt();
-        return ControlMessage.createInjectScrollEvent(position, hScroll, vScroll);
+        int buttons = buffer.getInt();
+        return ControlMessage.createInjectScrollEvent(position, hScroll, vScroll, buttons);
     }
 
     private ControlMessage parseBackOrScreenOnEvent() {

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

@@ -98,7 +98,7 @@ public class Controller {
                 break;
             case ControlMessage.TYPE_INJECT_SCROLL_EVENT:
                 if (device.supportsInputEvents()) {
-                    injectScroll(msg.getPosition(), msg.getHScroll(), msg.getVScroll());
+                    injectScroll(msg.getPosition(), msg.getHScroll(), msg.getVScroll(), msg.getButtons());
                 }
                 break;
             case ControlMessage.TYPE_BACK_OR_SCREEN_ON:
@@ -221,7 +221,7 @@ public class Controller {
         return device.injectEvent(event, Device.INJECT_MODE_ASYNC);
     }
 
-    private boolean injectScroll(Position position, int hScroll, int vScroll) {
+    private boolean injectScroll(Position position, int hScroll, int vScroll, int buttons) {
         long now = SystemClock.uptimeMillis();
         Point point = device.getPhysicalPoint(position);
         if (point == null) {
@@ -239,7 +239,7 @@ public class Controller {
         coords.setAxisValue(MotionEvent.AXIS_VSCROLL, vScroll);
 
         MotionEvent event = MotionEvent
-                .obtain(lastTouchDown, now, MotionEvent.ACTION_SCROLL, 1, pointerProperties, pointerCoords, 0, 0, 1f, 1f, DEFAULT_DEVICE_ID, 0,
+                .obtain(lastTouchDown, now, MotionEvent.ACTION_SCROLL, 1, pointerProperties, pointerCoords, 0, buttons, 1f, 1f, DEFAULT_DEVICE_ID, 0,
                         InputDevice.SOURCE_MOUSE, 0);
         return device.injectEvent(event, Device.INJECT_MODE_ASYNC);
     }

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

@@ -128,6 +128,7 @@ public class ControlMessageReaderTest {
         dos.writeShort(1920);
         dos.writeInt(1);
         dos.writeInt(-1);
+        dos.writeInt(1);
 
         byte[] packet = bos.toByteArray();
 
@@ -144,6 +145,7 @@ public class ControlMessageReaderTest {
         Assert.assertEquals(1920, event.getPosition().getScreenSize().getHeight());
         Assert.assertEquals(1, event.getHScroll());
         Assert.assertEquals(-1, event.getVScroll());
+        Assert.assertEquals(1, event.getButtons());
     }
 
     @Test