Add "inject touch" control message

Add a control message type in the protocol to forward touch events to
the device.

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;
@@ -43,6 +54,14 @@ control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
             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);
+            return 24;
         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

@@ -19,6 +19,7 @@ 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,
@@ -50,6 +51,12 @@ struct control_msg {
             enum android_motionevent_buttons buttons;
             struct position position;
         } inject_mouse_event;
+        struct {
+            enum android_motionevent_action action;
+            uint64_t pointer_id;
+            struct position position;
+            float pressure;
+        } inject_touch_event;
         struct {
             struct position position;
             int32_t hscroll;

app/tests/test_control_msg_serialize.c

@@ -100,6 +100,41 @@ static void test_serialize_inject_mouse_event(void) {
     assert(!memcmp(buf, expected, sizeof(expected)));
 }
 
+static void test_serialize_inject_touch_event(void) {
+    struct control_msg msg = {
+        .type = CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT,
+        .inject_touch_event = {
+            .action = AMOTION_EVENT_ACTION_DOWN,
+            .pointer_id = 0x1234567887654321L,
+            .position = {
+                .point = {
+                    .x = 100,
+                    .y = 200,
+                },
+                .screen_size = {
+                    .width = 1080,
+                    .height = 1920,
+                },
+            },
+            .pressure = 1.0f,
+        },
+    };
+
+    unsigned char buf[CONTROL_MSG_SERIALIZED_MAX_SIZE];
+    int size = control_msg_serialize(&msg, buf);
+    assert(size == 24);
+
+    const unsigned char expected[] = {
+        CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT,
+        0x00, // AKEY_EVENT_ACTION_DOWN
+        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
+    };
+    assert(!memcmp(buf, expected, sizeof(expected)));
+}
+
 static void test_serialize_inject_scroll_event(void) {
     struct control_msg msg = {
         .type = CONTROL_MSG_TYPE_INJECT_SCROLL_EVENT,
@@ -237,6 +272,7 @@ int main(void) {
     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

@@ -8,13 +8,14 @@ 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_SCROLL_EVENT = 3;
-    public static final int TYPE_BACK_OR_SCREEN_ON = 4;
-    public static final int TYPE_EXPAND_NOTIFICATION_PANEL = 5;
-    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;
+    public static final int TYPE_INJECT_TOUCH_EVENT = 3;
+    public static final int TYPE_INJECT_SCROLL_EVENT = 4;
+    public static final int TYPE_BACK_OR_SCREEN_ON = 5;
+    public static final int TYPE_EXPAND_NOTIFICATION_PANEL = 6;
+    public static final int TYPE_COLLAPSE_NOTIFICATION_PANEL = 7;
+    public static final int TYPE_GET_CLIPBOARD = 8;
+    public static final int TYPE_SET_CLIPBOARD = 9;
+    public static final int TYPE_SET_SCREEN_POWER_MODE = 10;
 
     private int type;
     private String text;
@@ -22,6 +23,8 @@ 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;
@@ -54,6 +57,16 @@ public final class ControlMessage {
         return msg;
     }
 
+    public static ControlMessage createInjectTouchEvent(int action, long pointerId, Position position, float pressure) {
+        ControlMessage msg = new ControlMessage();
+        msg.type = TYPE_INJECT_TOUCH_EVENT;
+        msg.action = action;
+        msg.pointerId = pointerId;
+        msg.pressure = pressure;
+        msg.position = position;
+        return msg;
+    }
+
     public static ControlMessage createInjectScrollEvent(Position position, int hScroll, int vScroll) {
         ControlMessage msg = new ControlMessage();
         msg.type = TYPE_INJECT_SCROLL_EVENT;
@@ -110,6 +123,14 @@ 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;
 
@@ -62,6 +63,9 @@ public class ControlMessageReader {
             case ControlMessage.TYPE_INJECT_MOUSE_EVENT:
                 msg = parseInjectMouseEvent();
                 break;
+            case ControlMessage.TYPE_INJECT_TOUCH_EVENT:
+                msg = parseInjectTouchEvent();
+                break;
             case ControlMessage.TYPE_INJECT_SCROLL_EVENT:
                 msg = parseInjectScrollEvent();
                 break;
@@ -130,6 +134,21 @@ public class ControlMessageReader {
         return ControlMessage.createInjectMouseEvent(action, buttons, position);
     }
 
+    @SuppressWarnings("checkstyle:MagicNumber")
+    private ControlMessage parseInjectTouchEvent() {
+        if (buffer.remaining() < INJECT_TOUCH_EVENT_PAYLOAD_LENGTH) {
+            return null;
+        }
+        int action = toUnsigned(buffer.get());
+        long pointerId = buffer.getLong();
+        Position position = readPosition(buffer);
+        // 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);
+        return ControlMessage.createInjectTouchEvent(action, pointerId, position, pressure);
+    }
+
     private ControlMessage parseInjectScrollEvent() {
         if (buffer.remaining() < INJECT_SCROLL_EVENT_PAYLOAD_LENGTH) {
             return null;

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

@@ -105,6 +105,37 @@ public class ControlMessageReaderTest {
         Assert.assertEquals(1920, event.getPosition().getScreenSize().getHeight());
     }
 
+    @Test
+    @SuppressWarnings("checkstyle:MagicNumber")
+    public void testParseTouchEvent() throws IOException {
+        ControlMessageReader reader = new ControlMessageReader();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+        dos.writeByte(ControlMessage.TYPE_INJECT_TOUCH_EVENT);
+        dos.writeByte(MotionEvent.ACTION_DOWN);
+        dos.writeLong(-42); // pointerId
+        dos.writeInt(100);
+        dos.writeInt(200);
+        dos.writeShort(1080);
+        dos.writeShort(1920);
+        dos.writeShort(0xffff); // pressure
+
+        byte[] packet = bos.toByteArray();
+
+        reader.readFrom(new ByteArrayInputStream(packet));
+        ControlMessage event = reader.next();
+
+        Assert.assertEquals(ControlMessage.TYPE_INJECT_TOUCH_EVENT, event.getType());
+        Assert.assertEquals(MotionEvent.ACTION_DOWN, event.getAction());
+        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
+    }
+
     @Test
     @SuppressWarnings("checkstyle:MagicNumber")
     public void testParseScrollEvent() throws IOException {