Implement universal translation of touch to mouse

Now generating mouse events from touch is optional (on by default) and it's performed by `InputDefault` instead of having each OS abstraction doing it. (*)

The translation algorithm waits for a touch index to be pressed and tracks it translating its events to mouse events until it is raised, while ignoring other pointers.

Furthermore, to avoid an stuck "touch mouse", since not all platforms may report touches raised when the window is unfocused, it checks if touches are still down by the time it's focused again and if so it resets the state of the emulated mouse.

*: In the case of Windows, since it already provides touch-to-mouse translation by itself, "echo" mouse events are filtered out to have it working like the rest.

On X11 a little hack has been needed to avoid a case of a spurious mouse motion event that is generated during touch interaction.

Plus: Improve/fix tracking of current mouse position.

** Summary of changes to settings: **

- `display/window/handheld/emulate_touchscreen` becomes `input/pointing_devices/emulate_touch_from_mouse`
- New setting: `input/pointing_devices/emulate_mouse_from_touch`

2 files changed, 38 insertions, 46 deletions

diff --git a/platform/uwp/app.cpp b/platform/uwp/app.cpp
index 5ff62b38f9..c18aa36402 100644
--- a/platform/uwp/app.cpp
+++ b/platform/uwp/app.cpp
@@ -85,8 +85,7 @@ App::App() :
 		mWindowHeight(0),
 		mEglDisplay(EGL_NO_DISPLAY),
 		mEglContext(EGL_NO_CONTEXT),
-		mEglSurface(EGL_NO_SURFACE),
-		number_of_contacts(0) {
+		mEglSurface(EGL_NO_SURFACE) {
 }
 
 // The first method called when the IFrameworkView is being created.
@@ -271,48 +270,44 @@ void App::pointer_event(Windows::UI::Core::CoreWindow ^ sender, Windows::UI::Cor
 		last_touch_y[screen_touch->get_index()] = pos.Y;
 
 		os->input_event(screen_touch);
-		if (number_of_contacts > 1)
-			return;
+	} else {
 
-	}; // fallthrought of sorts
-
-	Ref<InputEventMouseButton> mouse_button;
-	mouse_button.instance();
-	mouse_button->set_device(0);
-	mouse_button->set_pressed(p_pressed);
-	mouse_button->set_button_index(but);
-	mouse_button->set_position(Vector2(pos.X, pos.Y));
-	mouse_button->set_global_position(Vector2(pos.X, pos.Y));
-
-	if (p_is_wheel) {
-		if (point->Properties->MouseWheelDelta > 0) {
-			mouse_button->set_button_index(point->Properties->IsHorizontalMouseWheel ? BUTTON_WHEEL_RIGHT : BUTTON_WHEEL_UP);
-		} else if (point->Properties->MouseWheelDelta < 0) {
-			mouse_button->set_button_index(point->Properties->IsHorizontalMouseWheel ? BUTTON_WHEEL_LEFT : BUTTON_WHEEL_DOWN);
+		Ref<InputEventMouseButton> mouse_button;
+		mouse_button.instance();
+		mouse_button->set_device(0);
+		mouse_button->set_pressed(p_pressed);
+		mouse_button->set_button_index(but);
+		mouse_button->set_position(Vector2(pos.X, pos.Y));
+		mouse_button->set_global_position(Vector2(pos.X, pos.Y));
+
+		if (p_is_wheel) {
+			if (point->Properties->MouseWheelDelta > 0) {
+				mouse_button->set_button_index(point->Properties->IsHorizontalMouseWheel ? BUTTON_WHEEL_RIGHT : BUTTON_WHEEL_UP);
+			} else if (point->Properties->MouseWheelDelta < 0) {
+				mouse_button->set_button_index(point->Properties->IsHorizontalMouseWheel ? BUTTON_WHEEL_LEFT : BUTTON_WHEEL_DOWN);
+			}
 		}
-	}
 
-	last_touch_x[31] = pos.X;
-	last_touch_y[31] = pos.Y;
+		last_touch_x[31] = pos.X;
+		last_touch_y[31] = pos.Y;
 
-	os->input_event(mouse_button);
-
-	if (p_is_wheel) {
-		// Send release for mouse wheel
-		mouse_button->set_pressed(false);
 		os->input_event(mouse_button);
+
+		if (p_is_wheel) {
+			// Send release for mouse wheel
+			mouse_button->set_pressed(false);
+			os->input_event(mouse_button);
+		}
 	}
 };
 
 void App::OnPointerPressed(Windows::UI::Core::CoreWindow ^ sender, Windows::UI::Core::PointerEventArgs ^ args) {
 
-	number_of_contacts++;
 	pointer_event(sender, args, true);
 };
 
 void App::OnPointerReleased(Windows::UI::Core::CoreWindow ^ sender, Windows::UI::Core::PointerEventArgs ^ args) {
 
-	number_of_contacts--;
 	pointer_event(sender, args, false);
 };
 
@@ -351,7 +346,7 @@ void App::OnPointerMoved(Windows::UI::Core::CoreWindow ^ sender, Windows::UI::Co
 	Windows::UI::Input::PointerPoint ^ point = args->CurrentPoint;
 	Windows::Foundation::Point pos = _get_pixel_position(window, point->Position, os);
 
-	if (point->IsInContact && _is_touch(point)) {
+	if (_is_touch(point)) {
 
 		Ref<InputEventScreenDrag> screen_drag;
 		screen_drag.instance();
@@ -361,25 +356,23 @@ void App::OnPointerMoved(Windows::UI::Core::CoreWindow ^ sender, Windows::UI::Co
 		screen_drag->set_relative(Vector2(screen_drag->get_position().x - last_touch_x[screen_drag->get_index()], screen_drag->get_position().y - last_touch_y[screen_drag->get_index()]));
 
 		os->input_event(screen_drag);
-		if (number_of_contacts > 1)
-			return;
-
-	}; // fallthrought of sorts
+	} else {
 
-	// In case the mouse grabbed, MouseMoved will handle this
-	if (os->get_mouse_mode() == OS::MouseMode::MOUSE_MODE_CAPTURED)
-		return;
+		// In case the mouse grabbed, MouseMoved will handle this
+		if (os->get_mouse_mode() == OS::MouseMode::MOUSE_MODE_CAPTURED)
+			return;
 
-	Ref<InputEventMouseMotion> mouse_motion;
-	mouse_motion.instance();
-	mouse_motion->set_device(0);
-	mouse_motion->set_position(Vector2(pos.X, pos.Y));
-	mouse_motion->set_global_position(Vector2(pos.X, pos.Y));
-	mouse_motion->set_relative(Vector2(pos.X - last_touch_x[31], pos.Y - last_touch_y[31]));
+		Ref<InputEventMouseMotion> mouse_motion;
+		mouse_motion.instance();
+		mouse_motion->set_device(0);
+		mouse_motion->set_position(Vector2(pos.X, pos.Y));
+		mouse_motion->set_global_position(Vector2(pos.X, pos.Y));
+		mouse_motion->set_relative(Vector2(pos.X - last_touch_x[31], pos.Y - last_touch_y[31]));
 
-	last_mouse_pos = pos;
+		last_mouse_pos = pos;
 
-	os->input_event(mouse_motion);
+		os->input_event(mouse_motion);
+	}
 }
 
 void App::OnMouseMoved(MouseDevice ^ mouse_device, MouseEventArgs ^ args) {
diff --git a/platform/uwp/app.h b/platform/uwp/app.h
index c23270b8ba..5f69f2cb0e 100644
--- a/platform/uwp/app.h
+++ b/platform/uwp/app.h
@@ -107,7 +107,6 @@ namespace GodotUWP
 
 		int last_touch_x[32]; // 20 fingers, index 31 reserved for the mouse
 		int last_touch_y[32];
-		int number_of_contacts;
 		Windows::Foundation::Point last_mouse_pos;
 	};
 }