Prevent auto-layout of Graph[] objects in Mathematica 8

Question

Some types of objects have special input/output formatting in Mathematica. This includes Graphics, raster images, and, as of Mathematica 8, graphs (Graph[]). Unfortunately large graphs may take a very long time to visualize, much longer than most other operations I'm doing on them during interactive work.

How can I prevent auto-layout of Graph[] objects in StandardForm and TraditionalForm, and have them displayed as e.g. -Graph-, preferably preserving the interpretability of the output (perhaps using Interpretation?). I think this will involve changing Format and/or MakeBoxes in some way, but I was unsuccessful in getting this to work.

I would like to do this in a reversible way, and preferably define a function that will return the original interactive graph display when applied to a Graph object (not the same as GraphPlot, which is not interactive).

On a related note, is there a way to retrieve Format/MakeBoxes definitions associated with certain symbols? FormatValues is one relevant function, but it is empty for Graph.

Sample session:

In[1]:= Graph[{1->2, 2->3, 3->1}]
Out[1]= -Graph-

In[2]:= interactiveGraphPlot[%] (* note that % works *)
Out[2]= (the usual interactive graph plot should be shown here)

Answer 1

Though I do not have Mathematica 8 to try this in, one possibility is to use this construct:

Unprotect[Graph]

MakeBoxes[g_Graph, StandardForm] /; TrueQ[$short] ^:= 
 ToBoxes@Interpretation[Skeleton["Graph"], g]

$short = True;

Afterward, a Graph object should display in Skeleton form, and setting $short = False should restore default behavior.

Hopefully this works to automate the switching:

interactiveGraphPlot[g_Graph] := Block[{$short}, Print[g]]

---

Mark's concern about modifying Graph caused me to consider the option of using $PrePrint. I think this should also prevent the slow layout step from taking place. It may be more desirable, assuming you are not already using $PrePrint for something else.

$PrePrint = 
  If[TrueQ[$short], # /. _Graph -> Skeleton["Graph"], #] &;

$short = True

Also conveniently, at least with Graphics (again I cannot test with Graph in v7) you can get the graphic with simply Print. Here, shown with Graphics:

g = Plot[Sin[x], {x, 0, 2 Pi}]

(*  Out =  <<"Graphics">>  *)

Then

Print[g]

I left the $short test in place for easy switching via a global symbol, but one could leave it out and use:

    $PrePrint = # /. _Graph -> Skeleton["Graph"] &;

And then use $PrePrint = . to reset the default functionality.