Re: canvas coordinates in guile-gnome-platform 2.7.96

[Greg Troxel]

  Try the patch below.  You should be able run this wtw.scm

With the patch I can use world-to-window.  Thanks for sending it, and
I hope it gets in the real sources once the annual arch archive
confusion subsides :-)

I think my real problem is that canvas won't do quite what I want.
I'd like to set a more complex transform matrix for world-to-canvas
than scale + translate.  It seems I can do that for a group, and I did
this for the root group:

    (affine-absolute canvas-root 1 0 .1 1 0 0)

which skewed my vertical column out nicely, and more aggressive
transform worked too:

    (affine-absolute canvas-root 0 4 4 0 0 0)

But window-to-world seems to work on canvas, and not canvas groups, so
it isn't immediately apparent how to go from world to canvas
coordinates for this item.

Is there a way to set the matrix for the whole canvas?  In C one get
get an array with 6 values, and it's not the least bit clear from the
developer api docs if those are r/w or read-only values.

Other random observations:

It seems that gnome_canvas_get_item_at was not wrapped, but I can't
figure out why.   It's not in the override list to ignore, and
arguments are pretty vanilla.  I would like to get a buttonpress event
(which I have), and a) interpret that in my coordinate system (set
above in root group, since I apparently can't set a matrix for canvas
itself) and b) find which item was clicked.

The delete event doesn't seem to get mapped to a symbol by
gdk-event:type.  I see the debug message pointing me to
gtk/gnome/gw/gdk-support.c..

gdk-event-button:x fails on a 2button-press event, but thre is no
gdk-event-2button:x

I can't set tooltips on canvas items.  The set-tip function seems to
want a GtkWidget, and canvas items aren't widgets.  I think this is a
missing feature in gnomecanvas, not a wrapper deficiency.


-- 
        Greg Troxel <address@hidden>