[instaviz-users] How do I move boxes?

[Glen Low]

All

On 26/12/2008, at 5:27 AM, Ryan Schmidt wrote:

>
> On Dec 25, 2008, at 12:13, Randy Kaempen wrote:
>
>> One feature I really think is missing is the ability to rearrange
>> objects.  Right now, if you click and drag, it assumes you are  
>> drawing
>> a line.  This should only be the case if nothing is selected.  If you
>> click and select a box, you should then be able to drag it to a new
>> position.  The default positions that the program chooses don't  
>> always
>> make the most sense for a diagram.
>
> I don't think Graphviz, the library Instaviz uses, is designed for
> arbitrary positions of nodes; it's designed for automatic positions.

Ryan is correct, Graphviz is for automated layout and not manual  
layout. This is actually a feature and not a bug :-) -- on a device  
like the iPhone, you don't necessarily devote the same amount of  
attention to a graph as you would on a desktop or even a laptop  
machine. You might be in the middle of doing something else or jumping  
from task to task, and carrying much less "mental context" with you  
than switching between multiple windows on a desktop. So with  
Instaviz, you concentrate on what's important -- what connects with  
what -- and let the program figure out how to best represent it on  
screen.

There is also the problem of figuring out the right user interface for  
arbitrary placement of nodes, and not having that conflict with the  
existing node drawing, linking and scrolling. I suspect that adding  
arbitrary placement of nodes would make Instaviz harder and not easier  
to use.

But... I'm willing to be devil's advocate against myself, for at least  
a couple of entries in an email thread...

We need to address these two separate issues:

1.	Graphviz layout. As Stephen said privately, most users would only  
be interested in node placement and not edge placement. And I know  
he's talked about the path planning part of the library before... how  
easy or difficult would it be to come out with a new layout engine,  
largely based on "dot", that eliminated the node rearrangement step  
but still kept the path planning part? Or maybe even a graph flag to  
stop the node rearrangement step within "dot"?

2.	User interface. How to express arbitrary node placement? Given that  
"dragging between nodes" means "link the nodes with an edge", what  
gesture should represent "drag this node to a new position"? I'm  
thinking tap + hold could be it, but it may conflict with the need to  
use the gesture for "pop up some info about this node" I'm planning  
for 2.0. I'm still not in favor of any modal solutions i.e. a button  
which toggles between automatic and manual placement.

If together we can come up with good answers to the above, we may see  
this feature happen in time for 2.0.




Cheers, Glen Low


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