Add multitouch simulation

While the Ctrl key is held, the first left-click adds an immobile
"virtual finger" at this position.

Moving the mouse moves another cursor. The left click may be released
and pressed as necessary to control the second finger.

Releasing Ctrl releases the virtual finger.

app/src/buffer_util.h

@@ -20,6 +20,12 @@ buffer_write32be(uint8_t *buf, uint32_t value) {
     buf[3] = value;
 }
 
+static inline void
+buffer_write64be(uint8_t *buf, uint64_t value) {
+    buffer_write32be(buf, value >> 32);
+    buffer_write32be(&buf[4], (uint32_t) value);
+}
+
 static inline uint16_t
 buffer_read16be(const uint8_t *buf) {
     return (buf[0] << 8) | buf[1];

app/src/control_msg.c

@@ -1,6 +1,7 @@
 #include "control_msg.h"
 
 #include <string.h>
+#include <SDL2/SDL_assert.h>
 
 #include "config.h"
 #include "buffer_util.h"
@@ -24,6 +25,16 @@ write_string(const char *utf8, size_t max_len, unsigned char *buf) {
     return 2 + len;
 }
 
+static uint16_t
+to_fixed_point_16(float f) {
+    SDL_assert(f >= 0.0f && f <= 1.0f);
+    uint32_t u = f * 0x1p16f; // 2^16
+    if (u >= 0xffff) {
+        u = 0xffff;
+    }
+    return (uint16_t) u;
+}
+
 size_t
 control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
     buf[0] = msg->type;
@@ -38,11 +49,15 @@ control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
                                       CONTROL_MSG_TEXT_MAX_LENGTH, &buf[1]);
             return 1 + len;
         }
-        case CONTROL_MSG_TYPE_INJECT_MOUSE_EVENT:
-            buf[1] = msg->inject_mouse_event.action;
-            buffer_write32be(&buf[2], msg->inject_mouse_event.buttons);
-            write_position(&buf[6], &msg->inject_mouse_event.position);
-            return 18;
+        case CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT:
+            buf[1] = msg->inject_touch_event.action;
+            buffer_write64be(&buf[2], msg->inject_touch_event.pointer_id);
+            write_position(&buf[10], &msg->inject_touch_event.position);
+            uint16_t pressure =
+                to_fixed_point_16(msg->inject_touch_event.pressure);
+            buffer_write16be(&buf[22], pressure);
+            buffer_write32be(&buf[24], msg->inject_touch_event.buttons);
+            return 28;
         case CONTROL_MSG_TYPE_INJECT_SCROLL_EVENT:
             write_position(&buf[1], &msg->inject_scroll_event.position);
             buffer_write32be(&buf[13],

app/src/control_msg.h

@@ -15,10 +15,13 @@
 #define CONTROL_MSG_SERIALIZED_MAX_SIZE \
     (3 + CONTROL_MSG_CLIPBOARD_TEXT_MAX_LENGTH)
 
+#define POINTER_ID_MOUSE UINT64_C(-1);
+#define POINTER_ID_VIRTUAL_FINGER UINT64_C(-2);
+
 enum control_msg_type {
     CONTROL_MSG_TYPE_INJECT_KEYCODE,
     CONTROL_MSG_TYPE_INJECT_TEXT,
-    CONTROL_MSG_TYPE_INJECT_MOUSE_EVENT,
+    CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT,
     CONTROL_MSG_TYPE_INJECT_SCROLL_EVENT,
     CONTROL_MSG_TYPE_BACK_OR_SCREEN_ON,
     CONTROL_MSG_TYPE_EXPAND_NOTIFICATION_PANEL,
@@ -48,8 +51,10 @@ struct control_msg {
         struct {
             enum android_motionevent_action action;
             enum android_motionevent_buttons buttons;
+            uint64_t pointer_id;
             struct position position;
-        } inject_mouse_event;
+            float pressure;
+        } inject_touch_event;
         struct {
             struct position position;
             int32_t hscroll;

app/src/event_converter.c

@@ -128,15 +128,6 @@ convert_keycode(SDL_Keycode from, enum android_keycode *to, uint16_t mod) {
     }
 }
 
-static bool
-convert_mouse_action(SDL_EventType from, enum android_motionevent_action *to) {
-    switch (from) {
-        MAP(SDL_MOUSEBUTTONDOWN, AMOTION_EVENT_ACTION_DOWN);
-        MAP(SDL_MOUSEBUTTONUP,   AMOTION_EVENT_ACTION_UP);
-        FAIL;
-    }
-}
-
 static enum android_motionevent_buttons
 convert_mouse_buttons(uint32_t state) {
     enum android_motionevent_buttons buttons = 0;
@@ -176,20 +167,31 @@ convert_input_key(const SDL_KeyboardEvent *from, struct control_msg *to) {
     return true;
 }
 
+static bool
+convert_mouse_action(SDL_EventType from, enum android_motionevent_action *to) {
+    switch (from) {
+        MAP(SDL_MOUSEBUTTONDOWN, AMOTION_EVENT_ACTION_DOWN);
+        MAP(SDL_MOUSEBUTTONUP,   AMOTION_EVENT_ACTION_UP);
+        FAIL;
+    }
+}
+
 bool
 convert_mouse_button(const SDL_MouseButtonEvent *from, struct size screen_size,
                      struct control_msg *to) {
-    to->type = CONTROL_MSG_TYPE_INJECT_MOUSE_EVENT;
+    to->type = CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT;
 
-    if (!convert_mouse_action(from->type, &to->inject_mouse_event.action)) {
+    if (!convert_mouse_action(from->type, &to->inject_touch_event.action)) {
         return false;
     }
 
-    to->inject_mouse_event.buttons =
+    to->inject_touch_event.pointer_id = POINTER_ID_MOUSE;
+    to->inject_touch_event.position.screen_size = screen_size;
+    to->inject_touch_event.position.point.x = from->x;
+    to->inject_touch_event.position.point.y = from->y;
+    to->inject_touch_event.pressure = 1.f;
+    to->inject_touch_event.buttons =
         convert_mouse_buttons(SDL_BUTTON(from->button));
-    to->inject_mouse_event.position.screen_size = screen_size;
-    to->inject_mouse_event.position.point.x = from->x;
-    to->inject_mouse_event.position.point.y = from->y;
 
     return true;
 }
@@ -197,16 +199,47 @@ convert_mouse_button(const SDL_MouseButtonEvent *from, struct size screen_size,
 bool
 convert_mouse_motion(const SDL_MouseMotionEvent *from, struct size screen_size,
                      struct control_msg *to) {
-    to->type = CONTROL_MSG_TYPE_INJECT_MOUSE_EVENT;
-    to->inject_mouse_event.action = AMOTION_EVENT_ACTION_MOVE;
-    to->inject_mouse_event.buttons = convert_mouse_buttons(from->state);
-    to->inject_mouse_event.position.screen_size = screen_size;
-    to->inject_mouse_event.position.point.x = from->x;
-    to->inject_mouse_event.position.point.y = from->y;
+    to->type = CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT;
+    to->inject_touch_event.action = AMOTION_EVENT_ACTION_MOVE;
+    to->inject_touch_event.pointer_id = POINTER_ID_MOUSE;
+    to->inject_touch_event.position.screen_size = screen_size;
+    to->inject_touch_event.position.point.x = from->x;
+    to->inject_touch_event.position.point.y = from->y;
+    to->inject_touch_event.pressure = 1.f;
+    to->inject_touch_event.buttons = convert_mouse_buttons(from->state);
 
     return true;
 }
 
+static bool
+convert_touch_action(SDL_EventType from, enum android_motionevent_action *to) {
+    switch (from) {
+        MAP(SDL_FINGERMOTION, AMOTION_EVENT_ACTION_MOVE);
+        MAP(SDL_FINGERDOWN,   AMOTION_EVENT_ACTION_DOWN);
+        MAP(SDL_FINGERUP,     AMOTION_EVENT_ACTION_UP);
+        FAIL;
+    }
+}
+
+bool
+convert_touch(const SDL_TouchFingerEvent *from, struct size screen_size,
+              struct control_msg *to) {
+    to->type = CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT;
+
+    if (!convert_touch_action(from->type, &to->inject_touch_event.action)) {
+        return false;
+    }
+
+    to->inject_touch_event.pointer_id = from->fingerId;
+    to->inject_touch_event.position.screen_size = screen_size;
+    // SDL touch event coordinates are normalized in the range [0; 1]
+    to->inject_touch_event.position.point.x = from->x * screen_size.width;
+    to->inject_touch_event.position.point.y = from->y * screen_size.height;
+    to->inject_touch_event.pressure = from->pressure;
+    to->inject_touch_event.buttons = 0;
+    return true;
+}
+
 bool
 convert_mouse_wheel(const SDL_MouseWheelEvent *from, struct position position,
                     struct control_msg *to) {

app/src/event_converter.h

@@ -30,6 +30,10 @@ bool
 convert_mouse_motion(const SDL_MouseMotionEvent *from, struct size screen_size,
                      struct control_msg *to);
 
+bool
+convert_touch(const SDL_TouchFingerEvent *from, struct size screen_size,
+              struct control_msg *to);
+
 // on Android, a scroll event requires the current mouse position
 bool
 convert_mouse_wheel(const SDL_MouseWheelEvent *from, struct position position,

app/src/input_manager.c

@@ -7,6 +7,19 @@
 #include "lock_util.h"
 #include "log.h"
 
+void
+input_manager_init(struct input_manager *input_manager,
+                   struct controller *controller,
+                   struct video_buffer *video_buffer,
+                   struct screen *screen) {
+    input_manager->controller = controller;
+    input_manager->video_buffer = video_buffer;
+    input_manager->screen = screen;
+
+    input_manager->ctrl_down = false;
+    input_manager->vfinger.down = false;
+}
+
 // Convert window coordinates (as provided by SDL_GetMouseState() to renderer
 // coordinates (as provided in SDL mouse events)
 //
@@ -211,6 +224,26 @@ clipboard_paste(struct controller *controller) {
     }
 }
 
+static void
+simulate_virtual_finger(struct input_manager *input_manager, bool down,
+                        struct position *position) {
+    SDL_assert(input_manager->vfinger.down != down);
+    input_manager->vfinger.down = down;
+
+    struct control_msg msg;
+    msg.type = CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT;
+    msg.inject_touch_event.action = down ? AMOTION_EVENT_ACTION_DOWN
+                                         : AMOTION_EVENT_ACTION_UP;
+    msg.inject_touch_event.pointer_id = POINTER_ID_VIRTUAL_FINGER;
+    msg.inject_touch_event.position = *position;
+    msg.inject_touch_event.pressure = 1.f;
+    msg.inject_touch_event.buttons = 0;
+
+    if (!controller_push_msg(input_manager->controller, &msg)) {
+        LOGW("Could not request 'inject virtual finger event'");
+    }
+}
+
 void
 input_manager_process_text_input(struct input_manager *input_manager,
                                  const SDL_TextInputEvent *event) {
@@ -244,6 +277,14 @@ input_manager_process_key(struct input_manager *input_manager,
     bool alt = event->keysym.mod & (KMOD_LALT | KMOD_RALT);
     bool meta = event->keysym.mod & (KMOD_LGUI | KMOD_RGUI);
 
+    // store the Ctrl state to modify mouse events
+    input_manager->ctrl_down = ctrl;
+
+    if (input_manager->vfinger.down && !ctrl) {
+        simulate_virtual_finger(input_manager, false,
+                                &input_manager->vfinger.position);
+    }
+
     // use Cmd on macOS, Ctrl on other platforms
 #ifdef __APPLE__
     bool cmd = !ctrl && meta;
@@ -389,6 +430,10 @@ input_manager_process_mouse_motion(struct input_manager *input_manager,
         // do not send motion events when no button is pressed
         return;
     }
+    if (event->which == SDL_TOUCH_MOUSEID) {
+        // simulated from touch events, so it's a duplicate
+        return;
+    }
     struct control_msg msg;
     if (convert_mouse_motion(event, input_manager->screen->frame_size, &msg)) {
         if (!controller_push_msg(input_manager->controller, &msg)) {
@@ -397,6 +442,17 @@ input_manager_process_mouse_motion(struct input_manager *input_manager,
     }
 }
 
+void
+input_manager_process_touch(struct input_manager *input_manager,
+                            const SDL_TouchFingerEvent *event) {
+    struct control_msg msg;
+    if (convert_touch(event, input_manager->screen->frame_size, &msg)) {
+        if (!controller_push_msg(input_manager->controller, &msg)) {
+            LOGW("Could not request 'inject touch event'");
+        }
+    }
+}
+
 static bool
 is_outside_device_screen(struct input_manager *input_manager, int x, int y)
 {
@@ -408,6 +464,11 @@ void
 input_manager_process_mouse_button(struct input_manager *input_manager,
                                    const SDL_MouseButtonEvent *event,
                                    bool control) {
+    if (event->which == SDL_TOUCH_MOUSEID) {
+        // 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(input_manager->controller);
@@ -418,12 +479,24 @@ input_manager_process_mouse_button(struct input_manager *input_manager,
             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(input_manager, event->x, event->y);
-            if (outside) {
-                screen_resize_to_fit(input_manager->screen);
-                return;
+        if (event->button == SDL_BUTTON_LEFT) {
+            if (event->clicks >= 2) {
+                bool outside =
+                    is_outside_device_screen(input_manager, event->x, event->y);
+                if (outside) {
+                    screen_resize_to_fit(input_manager->screen);
+                    return;
+                }
+            }
+
+            struct virtual_finger *vfinger = &input_manager->vfinger;
+            if (input_manager->ctrl_down && !vfinger->down) {
+                vfinger->position.point.x = event->x;
+                vfinger->position.point.y = event->y;
+                vfinger->position.screen_size =
+                    input_manager->screen->frame_size,
+                simulate_virtual_finger(input_manager, true,
+                                        &vfinger->position);
             }
         }
         // otherwise, send the click event to the device

app/src/input_manager.h

@@ -14,8 +14,21 @@ struct input_manager {
     struct controller *controller;
     struct video_buffer *video_buffer;
     struct screen *screen;
+
+    bool ctrl_down;
+
+    struct virtual_finger {
+        bool down;
+        struct position position;
+    } vfinger;
 };
 
+void
+input_manager_init(struct input_manager *input_manager,
+                   struct controller *controller,
+                   struct video_buffer *video_buffer,
+                   struct screen *screen);
+
 void
 input_manager_process_text_input(struct input_manager *input_manager,
                                  const SDL_TextInputEvent *event);
@@ -29,6 +42,10 @@ void
 input_manager_process_mouse_motion(struct input_manager *input_manager,
                                    const SDL_MouseMotionEvent *event);
 
+void
+input_manager_process_touch(struct input_manager *input_manager,
+                            const SDL_TouchFingerEvent *event);
+
 void
 input_manager_process_mouse_button(struct input_manager *input_manager,
                                    const SDL_MouseButtonEvent *event,

app/src/scrcpy.c

@@ -37,12 +37,7 @@ static struct decoder decoder;
 static struct recorder recorder;
 static struct controller controller;
 static struct file_handler file_handler;
-
-static struct input_manager input_manager = {
-    .controller = &controller,
-    .video_buffer = &video_buffer,
-    .screen = &screen,
-};
+static struct input_manager input_manager;
 
 // init SDL and set appropriate hints
 static bool
@@ -181,6 +176,11 @@ handle_event(SDL_Event *event, bool control) {
             input_manager_process_mouse_button(&input_manager, &event->button,
                                                control);
             break;
+        case SDL_FINGERMOTION:
+        case SDL_FINGERDOWN:
+        case SDL_FINGERUP:
+            input_manager_process_touch(&input_manager, &event->tfinger);
+            break;
         case SDL_DROPFILE: {
             if (!control) {
                 break;
@@ -306,6 +306,8 @@ scrcpy(const struct scrcpy_options *options) {
         goto end;
     }
 
+    input_manager_init(&input_manager, &controller, &video_buffer, &screen);
+
     if (!server_connect_to(&server)) {
         goto end;
     }

app/tests/test_control_msg_serialize.c

@@ -67,35 +67,39 @@ static void test_serialize_inject_text_long(void) {
     assert(!memcmp(buf, expected, sizeof(expected)));
 }
 
-static void test_serialize_inject_mouse_event(void) {
+static void test_serialize_inject_touch_event(void) {
     struct control_msg msg = {
-        .type = CONTROL_MSG_TYPE_INJECT_MOUSE_EVENT,
-        .inject_mouse_event = {
+        .type = CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT,
+        .inject_touch_event = {
             .action = AMOTION_EVENT_ACTION_DOWN,
-            .buttons = AMOTION_EVENT_BUTTON_PRIMARY,
+            .pointer_id = 0x1234567887654321L,
             .position = {
                 .point = {
-                    .x = 260,
-                    .y = 1026,
+                    .x = 100,
+                    .y = 200,
                 },
                 .screen_size = {
                     .width = 1080,
                     .height = 1920,
                 },
             },
+            .pressure = 1.0f,
+            .buttons = AMOTION_EVENT_BUTTON_PRIMARY,
         },
     };
 
     unsigned char buf[CONTROL_MSG_SERIALIZED_MAX_SIZE];
     int size = control_msg_serialize(&msg, buf);
-    assert(size == 18);
+    assert(size == 28);
 
     const unsigned char expected[] = {
-        CONTROL_MSG_TYPE_INJECT_MOUSE_EVENT,
+        CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT,
         0x00, // AKEY_EVENT_ACTION_DOWN
-        0x00, 0x00, 0x00, 0x01, // AMOTION_EVENT_BUTTON_PRIMARY
-        0x00, 0x00, 0x01, 0x04, 0x00, 0x00, 0x04, 0x02, // 260 1026
+        0x12, 0x34, 0x56, 0x78, 0x87, 0x65, 0x43, 0x21, // pointer id
+        0x00, 0x00, 0x00, 0x64, 0x00, 0x00, 0x00, 0xc8, // 100 200
         0x04, 0x38, 0x07, 0x80, // 1080 1920
+        0xff, 0xff, // pressure
+        0x00, 0x00, 0x00, 0x01 // AMOTION_EVENT_BUTTON_PRIMARY
     };
     assert(!memcmp(buf, expected, sizeof(expected)));
 }
@@ -236,7 +240,7 @@ int main(void) {
     test_serialize_inject_keycode();
     test_serialize_inject_text();
     test_serialize_inject_text_long();
-    test_serialize_inject_mouse_event();
+    test_serialize_inject_touch_event();
     test_serialize_inject_scroll_event();
     test_serialize_back_or_screen_on();
     test_serialize_expand_notification_panel();

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

@@ -7,7 +7,7 @@ public final class ControlMessage {
 
     public static final int TYPE_INJECT_KEYCODE = 0;
     public static final int TYPE_INJECT_TEXT = 1;
-    public static final int TYPE_INJECT_MOUSE_EVENT = 2;
+    public static final int TYPE_INJECT_TOUCH_EVENT = 2;
     public static final int TYPE_INJECT_SCROLL_EVENT = 3;
     public static final int TYPE_BACK_OR_SCREEN_ON = 4;
     public static final int TYPE_EXPAND_NOTIFICATION_PANEL = 5;
@@ -22,6 +22,8 @@ public final class ControlMessage {
     private int action; // KeyEvent.ACTION_* or MotionEvent.ACTION_* or POWER_MODE_*
     private int keycode; // KeyEvent.KEYCODE_*
     private int buttons; // MotionEvent.BUTTON_*
+    private long pointerId;
+    private float pressure;
     private Position position;
     private int hScroll;
     private int vScroll;
@@ -45,12 +47,15 @@ public final class ControlMessage {
         return msg;
     }
 
-    public static ControlMessage createInjectMouseEvent(int action, int buttons, Position position) {
+    public static ControlMessage createInjectTouchEvent(int action, long pointerId, Position position, float pressure,
+            int buttons) {
         ControlMessage msg = new ControlMessage();
-        msg.type = TYPE_INJECT_MOUSE_EVENT;
+        msg.type = TYPE_INJECT_TOUCH_EVENT;
         msg.action = action;
-        msg.buttons = buttons;
+        msg.pointerId = pointerId;
+        msg.pressure = pressure;
         msg.position = position;
+        msg.buttons = buttons;
         return msg;
     }
 
@@ -110,6 +115,14 @@ public final class ControlMessage {
         return buttons;
     }
 
+    public long getPointerId() {
+        return pointerId;
+    }
+
+    public float getPressure() {
+        return pressure;
+    }
+
     public Position getPosition() {
         return position;
     }

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

@@ -10,6 +10,7 @@ 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_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;
 
@@ -59,8 +60,8 @@ public class ControlMessageReader {
             case ControlMessage.TYPE_INJECT_TEXT:
                 msg = parseInjectText();
                 break;
-            case ControlMessage.TYPE_INJECT_MOUSE_EVENT:
-                msg = parseInjectMouseEvent();
+            case ControlMessage.TYPE_INJECT_TOUCH_EVENT:
+                msg = parseInjectTouchEvent();
                 break;
             case ControlMessage.TYPE_INJECT_SCROLL_EVENT:
                 msg = parseInjectScrollEvent();
@@ -120,14 +121,20 @@ public class ControlMessageReader {
         return ControlMessage.createInjectText(text);
     }
 
-    private ControlMessage parseInjectMouseEvent() {
-        if (buffer.remaining() < INJECT_MOUSE_EVENT_PAYLOAD_LENGTH) {
+    @SuppressWarnings("checkstyle:MagicNumber")
+    private ControlMessage parseInjectTouchEvent() {
+        if (buffer.remaining() < INJECT_TOUCH_EVENT_PAYLOAD_LENGTH) {
             return null;
         }
         int action = toUnsigned(buffer.get());
-        int buttons = buffer.getInt();
+        long pointerId = buffer.getLong();
         Position position = readPosition(buffer);
-        return ControlMessage.createInjectMouseEvent(action, buttons, position);
+        // 16 bits fixed-point
+        int pressureInt = toUnsigned(buffer.getShort());
+        // convert it to a float between 0 and 1 (0x1p16f is 2^16 as float)
+        float pressure = pressureInt == 0xffff ? 1f : (pressureInt / 0x1p16f);
+        int buttons = buffer.getInt();
+        return ControlMessage.createInjectTouchEvent(action, pointerId, position, pressure, buttons);
     }
 
     private ControlMessage parseInjectScrollEvent() {

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

@@ -19,38 +19,32 @@ public class Controller {
 
     private final KeyCharacterMap charMap = KeyCharacterMap.load(KeyCharacterMap.VIRTUAL_KEYBOARD);
 
-    private long lastMouseDown;
-    private final MotionEvent.PointerProperties[] pointerProperties = {new MotionEvent.PointerProperties()};
-    private final MotionEvent.PointerCoords[] pointerCoords = {new MotionEvent.PointerCoords()};
+    private long lastTouchDown;
+    private final PointersState pointersState = new PointersState();
+    private final MotionEvent.PointerProperties[] pointerProperties =
+            new MotionEvent.PointerProperties[PointersState.MAX_POINTERS];
+    private final MotionEvent.PointerCoords[] pointerCoords =
+            new MotionEvent.PointerCoords[PointersState.MAX_POINTERS];
 
     public Controller(Device device, DesktopConnection connection) {
         this.device = device;
         this.connection = connection;
-        initPointer();
+        initPointers();
         sender = new DeviceMessageSender(connection);
     }
 
-    private void initPointer() {
-        MotionEvent.PointerProperties props = pointerProperties[0];
-        props.id = 0;
-        props.toolType = MotionEvent.TOOL_TYPE_FINGER;
+    private void initPointers() {
+        for (int i = 0; i < PointersState.MAX_POINTERS; ++i) {
+            MotionEvent.PointerProperties props = new MotionEvent.PointerProperties();
+            props.toolType = MotionEvent.TOOL_TYPE_FINGER;
 
-        MotionEvent.PointerCoords coords = pointerCoords[0];
-        coords.orientation = 0;
-        coords.pressure = 1;
-        coords.size = 1;
-    }
+            MotionEvent.PointerCoords coords = new MotionEvent.PointerCoords();
+            coords.orientation = 0;
+            coords.size = 1;
 
-    private void setPointerCoords(Point point) {
-        MotionEvent.PointerCoords coords = pointerCoords[0];
-        coords.x = point.getX();
-        coords.y = point.getY();
-    }
-
-    private void setScroll(int hScroll, int vScroll) {
-        MotionEvent.PointerCoords coords = pointerCoords[0];
-        coords.setAxisValue(MotionEvent.AXIS_HSCROLL, hScroll);
-        coords.setAxisValue(MotionEvent.AXIS_VSCROLL, vScroll);
+            pointerProperties[i] = props;
+            pointerCoords[i] = coords;
+        }
     }
 
     @SuppressWarnings("checkstyle:MagicNumber")
@@ -87,8 +81,8 @@ public class Controller {
             case ControlMessage.TYPE_INJECT_TEXT:
                 injectText(msg.getText());
                 break;
-            case ControlMessage.TYPE_INJECT_MOUSE_EVENT:
-                injectMouse(msg.getAction(), msg.getButtons(), msg.getPosition());
+            case ControlMessage.TYPE_INJECT_TOUCH_EVENT:
+                injectTouch(msg.getAction(), msg.getPointerId(), msg.getPosition(), msg.getPressure(), 0);
                 break;
             case ControlMessage.TYPE_INJECT_SCROLL_EVENT:
                 injectScroll(msg.getPosition(), msg.getHScroll(), msg.getVScroll());
@@ -148,19 +142,42 @@ public class Controller {
         return successCount;
     }
 
-    private boolean injectMouse(int action, int buttons, Position position) {
+    private boolean injectTouch(int action, long pointerId, Position position, float pressure, int buttons) {
         long now = SystemClock.uptimeMillis();
-        if (action == MotionEvent.ACTION_DOWN) {
-            lastMouseDown = now;
-        }
+
         Point point = device.getPhysicalPoint(position);
         if (point == null) {
             // ignore event
             return false;
         }
-        setPointerCoords(point);
-        MotionEvent event = MotionEvent.obtain(lastMouseDown, now, action, 1, pointerProperties, pointerCoords, 0, buttons, 1f, 1f, 0, 0,
-                InputDevice.SOURCE_TOUCHSCREEN, 0);
+
+        int pointerIndex = pointersState.getPointerIndex(pointerId);
+        if (pointerIndex == -1) {
+            Ln.w("Too many pointers for touch event");
+            return false;
+        }
+        Pointer pointer = pointersState.get(pointerIndex);
+        pointer.setPoint(point);
+        pointer.setPressure(pressure);
+        pointer.setUp(action == MotionEvent.ACTION_UP);
+
+        int pointerCount = pointersState.update(pointerProperties, pointerCoords);
+
+        if (pointerCount == 1) {
+            if (action == MotionEvent.ACTION_DOWN) {
+                lastTouchDown = now;
+            }
+        } else {
+            // secondary pointers must use ACTION_POINTER_* ORed with the pointerIndex
+            if (action == MotionEvent.ACTION_UP) {
+                action = MotionEvent.ACTION_POINTER_UP | (pointerIndex << MotionEvent.ACTION_POINTER_INDEX_SHIFT);
+            } else if (action == MotionEvent.ACTION_DOWN) {
+                action = MotionEvent.ACTION_POINTER_DOWN | (pointerIndex << MotionEvent.ACTION_POINTER_INDEX_SHIFT);
+            }
+        }
+
+        MotionEvent event = MotionEvent.obtain(lastTouchDown, now, action, pointerCount, pointerProperties,
+                pointerCoords, 0, 0, 1f, 1f, 0, 0, InputDevice.SOURCE_TOUCHSCREEN, 0);
         return injectEvent(event);
     }
 
@@ -171,23 +188,30 @@ public class Controller {
             // ignore event
             return false;
         }
-        setPointerCoords(point);
-        setScroll(hScroll, vScroll);
-        MotionEvent event = MotionEvent.obtain(lastMouseDown, now, MotionEvent.ACTION_SCROLL, 1, pointerProperties, pointerCoords, 0, 0, 1f, 1f, 0,
-                0, InputDevice.SOURCE_MOUSE, 0);
+
+        MotionEvent.PointerProperties props = pointerProperties[0];
+        props.id = 0;
+
+        MotionEvent.PointerCoords coords = pointerCoords[0];
+        coords.x = point.getX();
+        coords.y = point.getY();
+        coords.setAxisValue(MotionEvent.AXIS_HSCROLL, hScroll);
+        coords.setAxisValue(MotionEvent.AXIS_VSCROLL, vScroll);
+
+        MotionEvent event = MotionEvent.obtain(lastTouchDown, now, MotionEvent.ACTION_SCROLL, 1, pointerProperties,
+                pointerCoords, 0, 0, 1f, 1f, 0, 0, InputDevice.SOURCE_MOUSE, 0);
         return injectEvent(event);
     }
 
     private boolean injectKeyEvent(int action, int keyCode, int repeat, int metaState) {
         long now = SystemClock.uptimeMillis();
-        KeyEvent event = new KeyEvent(now, now, action, keyCode, repeat, metaState, KeyCharacterMap.VIRTUAL_KEYBOARD, 0, 0,
-                InputDevice.SOURCE_KEYBOARD);
+        KeyEvent event = new KeyEvent(now, now, action, keyCode, repeat, metaState, KeyCharacterMap.VIRTUAL_KEYBOARD,
+                0, 0, InputDevice.SOURCE_KEYBOARD);
         return injectEvent(event);
     }
 
     private boolean injectKeycode(int keyCode) {
-        return injectKeyEvent(KeyEvent.ACTION_DOWN, keyCode, 0, 0)
-                && injectKeyEvent(KeyEvent.ACTION_UP, keyCode, 0, 0);
+        return injectKeyEvent(KeyEvent.ACTION_DOWN, keyCode, 0, 0) && injectKeyEvent(KeyEvent.ACTION_UP, keyCode, 0, 0);
     }
 
     private boolean injectEvent(InputEvent event) {

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

@@ -0,0 +1,55 @@
+package com.genymobile.scrcpy;
+
+public class Pointer {
+
+    /**
+     * Pointer id as received from the client.
+     */
+    private final long id;
+
+    /**
+     * Local pointer id, using the lowest possible values to fill the {@link android.view.MotionEvent.PointerProperties PointerProperties}.
+     */
+    private final int localId;
+
+    private Point point;
+    private float pressure;
+    private boolean up;
+
+    public Pointer(long id, int localId) {
+        this.id = id;
+        this.localId = localId;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public int getLocalId() {
+        return localId;
+    }
+
+    public Point getPoint() {
+        return point;
+    }
+
+    public void setPoint(Point point) {
+        this.point = point;
+    }
+
+    public float getPressure() {
+        return pressure;
+    }
+
+    public void setPressure(float pressure) {
+        this.pressure = pressure;
+    }
+
+    public boolean isUp() {
+        return up;
+    }
+
+    public void setUp(boolean up) {
+        this.up = up;
+    }
+}

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

@@ -0,0 +1,103 @@
+package com.genymobile.scrcpy;
+
+import android.view.MotionEvent;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class PointersState {
+
+    public static final int MAX_POINTERS = 10;
+
+    private final List<Pointer> pointers = new ArrayList<>();
+
+    private int indexOf(long id) {
+        for (int i = 0; i < pointers.size(); ++i) {
+            Pointer pointer = pointers.get(i);
+            if (pointer.getId() == id) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    private boolean isLocalIdAvailable(int localId) {
+        for (int i = 0; i < pointers.size(); ++i) {
+            Pointer pointer = pointers.get(i);
+            if (pointer.getLocalId() == localId) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private int nextUnusedLocalId() {
+        for (int localId = 0; localId < MAX_POINTERS; ++localId) {
+            if (isLocalIdAvailable(localId)) {
+                return localId;
+            }
+        }
+        return -1;
+    }
+
+    public Pointer get(int index) {
+        return pointers.get(index);
+    }
+
+    public int getPointerIndex(long id) {
+        int index = indexOf(id);
+        if (index != -1) {
+            // already exists, return it
+            return index;
+        }
+        if (pointers.size() >= MAX_POINTERS) {
+            // it's full
+            return -1;
+        }
+        // id 0 is reserved for mouse events
+        int localId = nextUnusedLocalId();
+        if (localId == -1) {
+            throw new AssertionError("pointers.size() < maxFingers implies that a local id is available");
+        }
+        Pointer pointer = new Pointer(id, localId);
+        pointers.add(pointer);
+        // return the index of the pointer
+        return pointers.size() - 1;
+    }
+
+    /**
+     * Initialize the motion event parameters.
+     *
+     * @param props  the pointer properties
+     * @param coords the pointer coordinates
+     * @return The number of items initialized (the number of pointers).
+     */
+    public int update(MotionEvent.PointerProperties[] props, MotionEvent.PointerCoords[] coords) {
+        int count = pointers.size();
+        for (int i = 0; i < count; ++i) {
+            Pointer pointer = pointers.get(i);
+
+            // id 0 is reserved for mouse events
+            props[i].id = pointer.getLocalId();
+
+            Point point = pointer.getPoint();
+            coords[i].x = point.getX();
+            coords[i].y = point.getY();
+            coords[i].pressure = pointer.getPressure();
+        }
+        cleanUp();
+        return count;
+    }
+
+    /**
+     * Remove all pointers which are UP.
+     */
+    private void cleanUp() {
+        for (int i = pointers.size() - 1; i >= 0; --i) {
+            Pointer pointer = pointers.get(i);
+            if (pointer.isUp()) {
+                pointers.remove(i);
+            }
+        }
+    }
+}

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

@@ -78,31 +78,35 @@ public class ControlMessageReaderTest {
 
     @Test
     @SuppressWarnings("checkstyle:MagicNumber")
-    public void testParseMouseEvent() throws IOException {
+    public void testParseTouchEvent() throws IOException {
         ControlMessageReader reader = new ControlMessageReader();
 
         ByteArrayOutputStream bos = new ByteArrayOutputStream();
         DataOutputStream dos = new DataOutputStream(bos);
-        dos.writeByte(ControlMessage.TYPE_INJECT_MOUSE_EVENT);
+        dos.writeByte(ControlMessage.TYPE_INJECT_TOUCH_EVENT);
         dos.writeByte(MotionEvent.ACTION_DOWN);
-        dos.writeInt(MotionEvent.BUTTON_PRIMARY);
+        dos.writeLong(-42); // pointerId
         dos.writeInt(100);
         dos.writeInt(200);
         dos.writeShort(1080);
         dos.writeShort(1920);
+        dos.writeShort(0xffff); // pressure
+        dos.writeInt(MotionEvent.BUTTON_PRIMARY);
 
         byte[] packet = bos.toByteArray();
 
         reader.readFrom(new ByteArrayInputStream(packet));
         ControlMessage event = reader.next();
 
-        Assert.assertEquals(ControlMessage.TYPE_INJECT_MOUSE_EVENT, event.getType());
+        Assert.assertEquals(ControlMessage.TYPE_INJECT_TOUCH_EVENT, event.getType());
         Assert.assertEquals(MotionEvent.ACTION_DOWN, event.getAction());
-        Assert.assertEquals(MotionEvent.BUTTON_PRIMARY, event.getButtons());
+        Assert.assertEquals(-42, event.getPointerId());
         Assert.assertEquals(100, event.getPosition().getPoint().getX());
         Assert.assertEquals(200, event.getPosition().getPoint().getY());
         Assert.assertEquals(1080, event.getPosition().getScreenSize().getWidth());
         Assert.assertEquals(1920, event.getPosition().getScreenSize().getHeight());
+        Assert.assertEquals(1f, event.getPressure(), 0f); // must be exact
+        Assert.assertEquals(MotionEvent.BUTTON_PRIMARY, event.getButtons());
     }
 
     @Test