Remove broken scroll gesture on Android

[madmiraal]

Detecting an Android scroll gesture and using it to create a InputEventPanGesture was added as part of #33630, which aimed to address #8151, i.e. it had nothing to do with scrolling. Unfortunately, the implementation of the creation of the InputEventPanGesture was deeply flawed and broke everything that used the InputEventPanGesture on Android; most notably ScrollContainers, but also GraphEdit and possibly others.

This PR removes the flawed implementation of InputEventPanGesture on Android.

Fixes #36312
Fixes #45402
Fixes #53619
Fixes #60600
Fixes #61816

[m4gr3d]

Unfortunately, the implementation of the creation of the InputEventPanGesture was deeply flawed and broke everything that used the InputEventPanGesture on Android; most notably ScrollContainers, but also GraphEdit and possibly others.

Can you provide more context? Do you know what in the implementation caused the breakage?

This PR removes the flawed implementation of InputEventPanGesture on Android.

Are scroll gestures still properly handled after the removal of this logic?

[madmiraal]

Can you provide more context? Do you know what in the implementation caused the breakage?

The only data extracted from the GestureDetector.SimpleOnGestureListener.onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) call are the distanceX and distanceY values:

godot/platform/android/java/lib/src/org/godotengine/godot/input/GodotGestureHandler.java

Lines 83 to 89 in 21b51fd

	public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
	//Log.i("GodotGesture", "onScroll");
	final int x = Math.round(distanceX);
	final int y = Math.round(distanceY);
	GodotLib.scroll(x, y);
	return true;
	}

Therefore, only the amount moved since the last MotionEvent is being used.

Furthermore, these movement values are then used as position values, from which a new movement values is calculated:

godot/platform/android/android_input_handler.cpp

Lines 385 to 393 in 21b51fd

	void AndroidInputHandler::process_scroll(Point2 p_pos) {
	Ref<InputEventPanGesture> ev;
	ev.instantiate();
	_set_key_modifier_state(ev);
	ev->set_position(p_pos);
	ev->set_delta(p_pos - scroll_prev_pos);
	Input::get_singleton()->parse_input_event(ev);
	scroll_prev_pos = p_pos;
	}

The result is an InputEventPanGesture with a position that is always around (0, 0) (the amount moved since the last MotionEvent) and a nonsense delta that is the difference between the last two amounts moved!

Since the position is always around (0, 0), these nonsense events are only picked up by Control elements that use InputEventPanGestures that are located in the top left corner of the screen (or full screen elements) as seen in all the bugs.

Are scroll gestures still properly handled after the removal of this logic?

Yes, the functional scrolling that uses the emulate_mouse_from_touch is unaffected by this removal.

[m4gr3d]

Thanks for providing additional context and catching that implementation error!