From 9580908b4c206675f912c0639d8f450bc42c504b Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 21 Nov 2015 11:58:39 +0200
Subject: [PATCH] Implement additional two-finger gestures

---
 source/input/gesturedetector.cpp | 35 +++++++++++++++++++++++++++-----
 source/input/gesturedetector.h   |  4 +++-
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/source/input/gesturedetector.cpp b/source/input/gesturedetector.cpp
index cc02797..aecfa81 100644
--- a/source/input/gesturedetector.cpp
+++ b/source/input/gesturedetector.cpp
@@ -28,8 +28,12 @@ string GestureDetector::get_button_name(unsigned btn) const
 {
 	if(btn==GESTURE_DRAG)
 		return "Drag";
+	else if(btn==GESTURE_DRAG_2)
+		return "Two-finger drag";
 	else if(btn==GESTURE_PINCH)
 		return "Pinch";
+	else if(btn==GESTURE_ROTATE)
+		return "Rotate";
 	else
 		return Device::get_button_name(btn);
 }
@@ -135,8 +139,13 @@ void GestureDetector::start_gesture()
 			/* If the points moved away from or towards each other without rotating
 			significantly, it's a pinch gesture. */
 			current_gesture = GESTURE_PINCH;
-		else
-			invalid_gesture = true;
+		else if(turn*turn2>0 && abs(turn)>abs(away) && abs(turn2)>abs(away2))
+			/* If the points both turned in the same direction without significant
+			changes in distance, it's a rotate gesture. */
+			current_gesture = GESTURE_ROTATE;
+		else if((p.x*p2.x+p.y*p2.y)>2*abs(p.x*p2.y-p.y*p2.x))
+			// If both points moved in the same direction, it's a two-finger drag.
+			current_gesture = GESTURE_DRAG_2;
 
 		if(current_gesture!=GESTURE_NONE)
 		{
@@ -157,6 +166,8 @@ void GestureDetector::start_gesture()
 
 	if(current_gesture!=GESTURE_NONE)
 		set_button_state(current_gesture, true, true);
+	else
+		invalid_gesture = true;
 }
 
 void GestureDetector::update_progress()
@@ -168,7 +179,13 @@ void GestureDetector::update_progress()
 		set_axis_value(2, p.x, true);
 		set_axis_value(3, p.y, true);
 	}
-	else if(current_gesture==GESTURE_PINCH)
+	else if(current_gesture==GESTURE_DRAG_2)
+	{
+		TouchPoint &p2 = points[1];
+		set_axis_value(2, (p.x+p2.x)/2, true);
+		set_axis_value(3, (p.y+p2.y)/2, true);
+	}
+	else if(current_gesture==GESTURE_PINCH || current_gesture==GESTURE_ROTATE)
 	{
 		TouchPoint &p2 = points[1];
 		/* Pinch progress is the ratio between the current distance of the points
@@ -177,8 +194,16 @@ void GestureDetector::update_progress()
 		float ddy = p.down_y-p2.down_y;
 		float dx = ddx+p.x-p2.x;
 		float dy = ddy+p.y-p2.y;
-		set_axis_value(2, sqrt(dx*dx+dy*dy)/sqrt(ddx*ddx+ddy*ddy)-1, true);
-		set_axis_value(3, 0, true);
+		if(current_gesture==GESTURE_PINCH)
+		{
+			set_axis_value(2, sqrt(dx*dx+dy*dy)/sqrt(ddx*ddx+ddy*ddy)-1, true);
+			set_axis_value(3, 0, true);
+		}
+		else if(current_gesture==GESTURE_ROTATE)
+		{
+			set_axis_value(2, atan2(dy*ddx-dx*ddy, dx*ddx+dy*ddy)/M_PI/2, true);
+			set_axis_value(3, 0, true);
+		}
 	}
 }
 
diff --git a/source/input/gesturedetector.h b/source/input/gesturedetector.h
index fdd083d..ccccc88 100644
--- a/source/input/gesturedetector.h
+++ b/source/input/gesturedetector.h
@@ -12,7 +12,9 @@ enum Gesture
 {
 	GESTURE_NONE,
 	GESTURE_DRAG,
-	GESTURE_PINCH
+	GESTURE_DRAG_2,
+	GESTURE_PINCH,
+	GESTURE_ROTATE
 };
 
 /**
-- 
2.45.2