Notes regarding GFig

Bill Skaggs, July 3, 2004


Most importantly: this version of Gfig has been massively revised.  It
is very unstable.  It is likely to crash at any moment.  It is full of
bugs.  Many things are incompletely implemented, and others do not
work yet.  Play with it at your own risk.

(If it does crash, though, it is not likely to corrupt the image, so
in most cases you should be able to Exit the plug-in and continue
working.) 

A quick summary of recent changes:

Gfig now works somewhat like the text tool.  It uses special dedicated
"Gfig" layers.  A Gfig layer is defined by the presence of a parasite
called "Gfig", which contains a representation of the figure.  (It is
actually a Gfig file whose contents are attached to the layer as a
parasite.) 

If Gfig is run when the active layer is a Gfig layer, then it loads
the figure that is stored there, so that it can be modified.  If the
active layer is not a Gfig layer, then a new layer is created, and
initialized to transparent.  

The figure that you create is saved to the layer when you hit the
Close button.  If you hit the Cancel button, the results of your work
are not saved.  The GFig data parasite is not overwritten until you
hit Close, so you can always revert to the previous version of the
figure by hitting Cancel and then re-running GFig.

Each object that you create in Gfig can have its own style.  Currently
the only style attributes that work are foreground color and brush
shape; others will be added shortly.

When you start Gfig, and the dialog comes up, the background of the
preview shows a representation of the image you are working on.  Each
time you do something in GFig, the result is reflected by a change in
both the Pika image and the GFig preview, so you can see in real time
the results of everything that you do.  (The rendering could stand to
be speeded up, though.)  You can turn the background display in the
preview on or off by toggling Edit->Options->Show image.

PLEASE NOTE: The Gfig file format has not yet stabilized.  Until it
does, the parasite used to store the layer data is marked
non-persistent, meaning it will not be stored in XCF files.  This will
be trivial to change when the time comes.  The ordinary pixel data
*is* stored in XCF files, though.  This means that if you save the
image as XCF and re-open it, the GFig layers will be there but you
will not be able to use GFig to modify them.

ALSO NOTE: When GFig loads a GFig layer, it begins by clearing the
layer to transparent and redrawing it as stored in the GFig parasite.
This means that any changes you have made in the layer in the meantime
will be lost.  It would be nice if GFig could give a warning that this
is about to happen, but it is difficult to implement, because Gimp
does not yet provide an easy way to tell whether a layer has been
modified (as far as I know).