Add auto-panning when pointer goes beyond viewport edge with Select tool

[elbertronnie]

Partly closes #1527

Notes:

• This PR adds code for shifting viewport when using the select tool when it is in Dragging, DrawingBox, ResizingBounds or DraggingPivot state.
• The only major difference in this implementation from the given reference video in the issue is that the shift only occurs on mouse movement. Keeping the mouse stationary beyond the edge will not shift the viewport.

[0HyperCube]

Looks good so far - although it would be nice if this updated when there was no mouse motion.

To implement this I think we could probably send a message on each animation frame which is received in the init_after_frontend_ready so that as well as calling poll_node_graph_evaluation we could also do something like:

call_closure_with_editor_and_handle(|editor, handle| {
	for message in editor.handle_message(BroadcastMessage::TriggerEvent(BroadcastEvent::AnimationFrame)) {
		handle.send_frontend_message_to_js(message);
	}
});

Then subscribe to the broadcast event so that we can update the viewport position.

[elbertronnie]

I have made the changes so that the viewport shifts when there is no mouse motion.
A new Message is created in SelectToolMessage named as PointerOutsideViewport. When the mouse moves outside the viewport, it subscribes to AnimationFrame broadcast message. After coming inside the viewport, it unsubscribes.
The logic of shifting viewport runs when a PointerOutsideViewport message is recieved.

• Is the approach used correct?
• Should I create a new struct SelectToolPointerKeys to manage axis_align, snap_angle, center and duplicate with a single name? It was getting cluttered very easily since all these parameters had to be passed often.

[0HyperCube]

@elbertronnie thanks for this change. The approach seems reasonable, and I think that it would be good to have a struct to group the select tool modifier keys.

[elbertronnie]

I have grouped all modifier keys into SelectToolPointerKeys and cleaned up the code

[Keavon]

!build

[github-actions]

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[Keavon]

Great work! Could you slow it down by about 50? It goes really fast right now.

Could you also please add it to these tools?:

[list moved to #1527]

Please try to structure it so as much code as possible can be reused across the implementations.

[0HyperCube]

@elbertronnie thanks for these changes - it feels much smoother now with the animation frame callback.

I fixed a small bug whereby during the dragging of the bounding box, the shape would shift around (due to the message ordering - the modification to original_bound_transform happens immediately, whereas the messages are handled later, but putting all of the modifications in messages allows for this to be resolved).

[Keavon]

!build

[elbertronnie]

Could you also please add it to these tools?

@Keavon I will do it but I won't be able to contribute for a week since my college exams are going on.

[Keavon]

Ok, let's merge this one today and then do the other tools as a followup PR once you're done with exams!

[github-actions]

📦 Build Complete for c7358fb
https://8de5d82d.graphite.pages.dev

[Keavon]

This works nicely, thanks! I capped the speed with an overextension of 50px beyond the viewport bounds so it doesn't fly off uncontrollably. I love how fluid this feels, much better than a lot of other apps I've tried!