Support trackpad scroll with InputEventPanGesture

[jmoon1506]

Enable two finger scrolling on MacBooks with InputEventPanGesture events.

[SpyrexDE]

I just added basic support, however, this will need more work for it to feel not as spongy as it is right now:

SmoothScroll/addons/SmoothScroll/SmoothScrollContainer.gd

Lines 240 to 244 in 2759650

	if event is InputEventPanGesture:
	if should_scroll_horizontal():
	velocity.x = -event.delta.x * speed
	if should_scroll_vertical():
	velocity.y = -event.delta.y * speed

The current implementation ignores overdrag and relies on the scroll wheel speed variable which is not optimal.

[HaroldLever]

Probably considering pan gesture as dragging would be a better way? But I don't know there is any way to know when gesture starts or ends. Another way is to calculate velocity that is needed to scroll to specific destination.

[SpyrexDE]

Probably considering pan gesture as dragging would be a better way? But I don't know there is any way to know when gesture starts or ends.

I thought about that as well, however, it is exactly as you say. Reading the pan gesture is quite different to reading dragging. The pan gesture only provides a delta (how much the value changed) whereas when reading dragging we know when it starts and when it ends.