Re: "changed" signal

[Ari Jolma <ari jolma tkk fi>]

muppet wrote:

> > In my custom widget I have an image, which I make on the fly. I also 
> > can't seem to make the widget support flexible resizing of the 
> > window, this also works in ScrolledWindow.
>
>
> "flexible resizing"?


I mean basically the widget is an image viewer. The use has to be able to

zoom in - I can do this with a VScale widget (external) or keypress 
(+/-) within the widget

pan - works with the Scrollbars of the ScrolledWindow or keypress (arrow 
keys), should work also with drag and drop, but I have not implemented 
that yet

resize the window which contains the image viewer - I respond to this 
with hooking to changed signals of the adjustments of the ScrolledWindow

The custom widget inherits from ScrolledWindow and contains an EventBox, 
which contains the Image. A strange thing is that I can hook up to 
button_press-event and motion_notify_event of the EventBox, but I need 
to connect the key_press_event to $self (ScrolledWindow) to catch it.

> do you mean scaling the image to whatever size the window is?  hook 
> into the size-allocate signal and use Gtk2::Gdk::Pixbuf::scale_simple 
> and Gtk2::Gtk::Image::set_from_pixbuf to show the image at the size of 
> the window.


I'm making the pixbuf myself from a raster data maintained by another 
perl object but yes. The pixbuf I put into a pixmap because I want to be 
able to draw on the image.

> do you mean shrink the widget below the size of the image?  in 
> size-allocate, set the size request to be something small, e.g. 0,0.


I do this initially when I create the Image but in my render method 
(when the image is done by set_from_pixmap) I say 
set_size_request(zoom*native_size) otherwise the scrollbars do not show 
correctly and set_alignment(value/(upper-page_size)) (value, upper and 
page_size are from the adjustments).

Anyway the widget seems to work now. The code is public (it is already 
now in cvs.sourceforge.net:/cvsroot/libral as Gtk2-Geo-Raster) it could 
be of interest also outside my use with Geo-Raster (which is also in 
sourceforge and in CPAN), with normal image files. Maybe such widget 
already exists, I did not check, I have to admit.

Ari

> --
> If I lived in Teletubby Land, the homicide rate would be four.
>   -- elysse