Drawing children widgets in a Gtk::Layout

Desktop Ruby-Gnome 2
1

Hello ! I’m dealing with a problem that I can’t find any solution on the
net.
I got a Gtk::Layout where I load multiples Gtk::Image created with .png
images files.
I stock each of those Image in a Gtk::EventBox to capture mouse clicks
and drag them everywhere on the Layout, and use
event_box.set_visble_window(false) cause I need the background of images
to be transparent.
Until there, all works fine. The problems comes when I want to implement
a system of rubberbanding selection of the images. As soon as I use
Cairo to draw my dashed rectangle unvisible windowed images aren’t drawn
anymore (although, there are if i set their window visible, but that’s
not what I want). I assume I have to add in my ‘draw’ method line(s)
that tell the program to (re)draw children widget of the layout. But I
can’t find in the documentation (even in other languages than Ruby) how
to achieve that.

Can someone help me, please ?

NB : I’m using cairo1.12.6, gtk2-2.0.2 and Ruby1.9.3 on Windows7 if that
could be of some help

EDIT : Found a way to achieve that :
while dealing with the expose_event of the layout, I used
img.event_box.send_expose(event) to propagate the expose_event.
That works quite well.
Next step, would be to show when an Image is selected. For that, i
implement two methods select and unselect to switch the visibility of
their even_box.window.
I then get another problem, not really important but still…; When the
rubberband selection rectangle moves fast in and out of images, it
causes sometimes a little glitch where the image is visible in the
upper-left corner of the Gtk::Layout instead of its x, y position for a
fraction of second.

So if someone can figure a way to improve that, it will be great.

2

Hi,

In [email protected]
“[ruby-gnome2-devel-en] drawing children widgets in a Gtk::Layout” on
Thu, 05 Dec 2013 16:10:24 +0100,
“67Daidalos …” [email protected] wrote:

Cairo to draw my dashed rectangle unvisible windowed images aren’t drawn
anymore (although, there are if i set their window visible, but that’s
not what I want). I assume I have to add in my ‘draw’ method line(s)
that tell the program to (re)draw children widget of the layout. But I
can’t find in the documentation (even in other languages than Ruby) how
to achieve that.

Can someone help me, please ?

Could you show a sample program that can be ran by us? If
you provide it, we can try to tackle your problem easily. :slight_smile:

Thanks,

kou

3

Here you have a sample program showing the problem, and two PNG I used
to do this little test.

I commented the main aspects, especially those related to the two
problem I mentioned above.
If you run it and move the rubberband fast in and out of the two images,
you should occasionnaly see them appear for a split second in the
upper-left corner of the layout

4

Hi,

In [email protected]
“Re: [ruby-gnome2-devel-en] drawing children widgets in a Gtk::Layout”
on Fri, 06 Dec 2013 15:59:19 +0100,
“67Daidalos …” [email protected] wrote:

Here you have a sample program showing the problem, and two PNG I used
to do this little test.

Thanks!

You don’t need to call send_expose. You just return “false”
from expose-event callback. If you don’t return not “false”
value, other expose callbacks are not called. They will be
have image draw callbacks.

See also:
https://developer.gnome.org/gtk2/2.24/GtkWidget.html#GtkWidget-expose-event

— essai2.0.rb.orig 2013-12-06 23:52:54.000000000 +0900
+++ essai2.0.rb 2013-12-07 12:11:49.902475686 +0900
@@ -146,14 +146,14 @@
cr = widget.bin_window.create_cairo_context
draw(cr, widget, select_rect)
[@spr1, @spr2].each do |spr|

  • spr.e_box.send_expose(event) #before posting yesterday, I didn’t
    have thought to add this line… as people say, sleep on first ! That
    resolve
  •                # the visibility problem I had.
    if select_rect.intersect(spr.rectangle)
    spr.select
    else
    spr.unselect
    end
    end
  • stop_propagation = false
  • stop_propagation
    end

scwin = ScrolledWindow.new

I commented the main aspects, especially those related to the two
problem I mentioned above.
If you run it and move the rubberband fast in and out of the two images,
you should occasionnaly see them appear for a split second in the
upper-left corner of the layout

It is reproduced on my environment too.
Umm, why…

Thanks,

kou

5

Can you post the fixed, working version of your program?

It looks like it works to me.

Thanks,
Eric

6

Thank you Kou-san, I didn’t knew about the return value for signals.

Kouhei S. wrote in post #1129960:

I commented the main aspects, especially those related to the two
problem I mentioned above.
If you run it and move the rubberband fast in and out of the two images,
you should occasionnaly see them appear for a split second in the
upper-left corner of the layout

It is reproduced on my environment too.
Umm, why…

I thought I have a beginning of explanation. As I tried to start
dragging a rubberbanding rectangle from inside one of the images, I saw
it draws on the upper-left corner too… I assume the events that
occurs in EventBoxes are passed somehow to the parent container (i.e.
the Gtk::Layout) but with coordinates relative to the EventBox.