[instaviz-users] Opinions wanted: sketching vs scrolling

[Glen Low]

Hi All

I hope you've all had a chance to play with Instaviz and are settling  
into the group nicely. Special thanks to Richard, Jeremy, Thomas,  
David and Juan for taking the time and effort to submit bug tickets  
for Instaviz -- I'll be attending to some of them this week.

I need your opinion on how scrolling and sketching should interact.

In a typical iPhone app, you can scroll the screen by dragging,  
swiping or flicking with your fingers. In a drawing app like Instaviz,  
we have to support drawing with similar sorts of finger gestures. The  
question is: how to get Instaviz to distinguish between a drag to  
scroll and a drag to sketch?

As I see it, there are three broad ways to do it:

1.	SKETCH: with one finger only, drag immediately.
	SCROLL: with two fingers only, drag immediately.
	(This was how it worked in 0.1.)

2.	SKETCH: with one finger only, wait a short while before dragging.
	SCROLL: with one or two fingers, drag immediately.
	(This is how it works in 0.1.1.)

3.	Use a slider to choose between SKETCH mode and SCROLL mode. New  
graph default is SKETCH, old graph default is SCROLL.
	SKETCH or SCROLL: with one finger, drag immediately.
	a.	One variation is to use orientation to choose e.g. SKETCH when the  
iPhone is horizontal, and SCROLL when the iPhone is vertical.

These are some of the pro's and con's bouncing around in my head:

1.	SKETCH with one finger, SCROLL with two.
	Pro's
	*	Doesn't get in the way of sketching, since there's no need for a  
delay.
	*	Scrolling with two fingers extends to pinch zooming naturally.
	Con's
	*	Most users are more familiar with using ONE finger to scroll, not  
two.
	*	Sometimes when you end a scroll by lifting one finger off before  
the other, the graph "bounces" back.

2.	SKETCH after a delay, SCROLL immediately.
	Pro's
	*	Users will be used to using one finger to scroll immediately.
	*	The stuff you do often is the easiest i.e. browsing a graph rather  
than creating/editing a graph.
	Con's
	*	Different interaction when graph is small (can sketch immediately,  
no scrolling) and when graph is big (cannot sketch immediately,  
scrolling allowed).
	*	Can't sketch quickly since you're forced to pause between each  
stroke. Feels much like writing on a slippery surface.

3.	Use a slider to choose between SKETCH and SCROLL.
	Pro's
	*	Explicitly tells the user what he can do.
	Con's
	*	If you choose SKETCH or SCROLL and get distracted or come back to  
the app after doing something else, it may be easy to forget which  
mode you're in.
	*	Harder to switch quickly between sketching and scrolling.

What do you think?




Cheers, Glen Low


---
pixelglow software | simply brilliant stuff
www.pixelglow.com
aim: pixglen

P.S. I moved from option 1 to 2 in 0.1.1 mainly because of technical  
limitations, so even if you think 1 is the right way, I may not be  
able to coerce the iPhone to do that...