Inject touch events on the server

On receiving an "inject touch" control message, update the local
pointers state and inject touches.

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

@@ -23,10 +23,18 @@ public class Controller {
     private final MotionEvent.PointerProperties[] mousePointerProperties = {new MotionEvent.PointerProperties()};
     private final MotionEvent.PointerCoords[] mousePointerCoords = {new MotionEvent.PointerCoords()};
 
+    private long lastTouchDown;
+    private final PointersState pointersState = new PointersState();
+    private final MotionEvent.PointerProperties[] touchPointerProperties =
+            new MotionEvent.PointerProperties[PointersState.MAX_POINTERS];
+    private final MotionEvent.PointerCoords[] touchPointerCoords =
+            new MotionEvent.PointerCoords[PointersState.MAX_POINTERS];
+
     public Controller(Device device, DesktopConnection connection) {
         this.device = device;
         this.connection = connection;
         initMousePointer();
+        initTouchPointers();
         sender = new DeviceMessageSender(connection);
     }
 
@@ -41,6 +49,20 @@ public class Controller {
         coords.size = 1;
     }
 
+    private void initTouchPointers() {
+        for (int i = 0; i < PointersState.MAX_POINTERS; ++i) {
+            MotionEvent.PointerProperties props = new MotionEvent.PointerProperties();
+            props.toolType = MotionEvent.TOOL_TYPE_FINGER;
+
+            MotionEvent.PointerCoords coords = new MotionEvent.PointerCoords();
+            coords.orientation = 0;
+            coords.size = 1;
+
+            touchPointerProperties[i] = props;
+            touchPointerCoords[i] = coords;
+        }
+    }
+
     private void setMousePointerCoords(Point point) {
         MotionEvent.PointerCoords coords = mousePointerCoords[0];
         coords.x = point.getX();
@@ -90,6 +112,9 @@ public class Controller {
             case ControlMessage.TYPE_INJECT_MOUSE_EVENT:
                 injectMouse(msg.getAction(), msg.getButtons(), msg.getPosition());
                 break;
+            case ControlMessage.TYPE_INJECT_TOUCH_EVENT:
+                injectTouch(msg.getAction(), msg.getPointerId(), msg.getPosition(), msg.getPressure());
+                break;
             case ControlMessage.TYPE_INJECT_SCROLL_EVENT:
                 injectScroll(msg.getPosition(), msg.getHScroll(), msg.getVScroll());
                 break;
@@ -164,6 +189,45 @@ public class Controller {
         return injectEvent(event);
     }
 
+    private boolean injectTouch(int action, long pointerId, Position position, float pressure) {
+        long now = SystemClock.uptimeMillis();
+
+        Point point = device.getPhysicalPoint(position);
+        if (point == null) {
+            // ignore event
+            return false;
+        }
+
+        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(touchPointerProperties, touchPointerCoords);
+
+        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, touchPointerProperties,
+                touchPointerCoords, 0, 0, 1f, 1f, 0, 0, InputDevice.SOURCE_TOUCHSCREEN, 0);
+        return injectEvent(event);
+    }
+
     private boolean injectScroll(Position position, int hScroll, int vScroll) {
         long now = SystemClock.uptimeMillis();
         Point point = device.getPhysicalPoint(position);

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);
+            }
+        }
+    }
+}