Refresh Gtk::Image (newb question)

lljk · May 25, 2010, 9:17pm

hello all,
first let me say that i’m a complete programming and ruby newbie -
haven’t done any programming since writing stuff in basic on my TI99-4a,
circa 1984 - so please forgive any questions or code (!) that seem
ridiculous.
here’s my story/questions…
i’m working on a simple mp3 player written in ruby, using gstreamer
and gtk+… really pretty straightforward - not supposed to do much
except load and save a playlist, and show some playback controls and the
cover art. i’ve got it doing all of that alright, only problem is i
can’t figure out for the life of me how to update the album art when the
song changes, either from a ‘next’ button click, or reaching the end of
the song. i’ve googled the b-jaysus out of refreshing gtk images, and
come up with some different ideas (event boxes, drawing areas…) but i
can’t seem to get anything to work.
i imagine this is something really simple that for some reason i just
can’t figure out. it seems that i have to jump out of the gtk.main loop
in order to update the cover. i know that a Gdk (that’s “d,” not “t,”)
window has an invalidate method, and a queue method, and it seems like
that could be a solution - or maybe through triggering an eventBox…
or through some other blatently obvious solution that i have no idea
about.
here’s a look at what i think should be the relevant code… thanks in
advance for any and all help.

everything is inside a Gtk::Window - here’s the bit about the album
art…

code snippet:
…

“player.img” is dynamic, based on the current song

coverpix = Gdk::Pixbuf.new(player.img, 196, 196)
cover = Gtk::Image.new(coverpix)
cover.show
artBox = Gtk::EventBox.new.add(cover)
artBox.show

box = Gtk::VBox.new(false,0)
box.pack_start(artBox,true,true,2)
box.pack_start(bbox,false,false,2)
box.show

window.add box
window.show

Gtk.main
…

i’ve tried using this bit of code as a ‘refresh’ method, and also
inside the next button’s EventBox block - when i add a “puts player.img”
in there to see what’s happening under the hood, i don’t see anything
until i stop the program (breaking the gtk main loop,) at which point
any and all of the correct image filenames appear for the songs played.

again, sorry if this is a boneheaded question, but i’ve been up high
down and low searching and experimenting with no luck - any ideas would
be appreciated…

-jk

lljk · May 25, 2010, 11:20pm

Hello

I suspect that the issue you are experiencing stems from Gtk::Image
widget not updating on changes to the Gdk::Image it is displaying.

The simplest way to work around this is to create a new Gdk::Image
when the cover art changes and assign it to the Gtk::Image widget.

The other way would be to invalidete the widget so that it gets
repainted eventually or force it to repaint even.

If your problem is not solved by this then I suggest you post the
exact code which demonstrates it.

HTH

Michal

lljk · May 25, 2010, 11:34pm

Hi.

I have had the same issue with my music player. You just call the
Gtk::Image#show each time the image is updated.

Vincent

P.S.: on your snippet, you don’t have to call the show method on all
Gtk widgets instead you can call show_all on the main container once
other widgets have been added (i.e. window.show_all instead of all the
show methods)

2010/5/25, Michal S. [email protected]:

lljk · May 26, 2010, 12:45pm

hi folks -

thank you all very much indeed - now i’ve got some things to play
with! going to fiddle around some with all of your suggestions and see
what i can come up with. if i can’t get things working i’ll post back
with more complete code, and when i do get it working i’ll make sure to
post the solution that worked for me.

thanks again,
viva the ruby forum!

jk

lljk · May 26, 2010, 12:48am

Hello!

Take a look at:
http://www.raditex.nu//websvn/listing.php?repname=kurssrc.Exempel&path=%2FRubyStateMachine%2F#_RubyStateMachine_

First start “ruby ./DoorServer.rb” And then “ruby ./GtkDoorClient.rb”

This implement a simple state machine
- It shows how you should switch images upon state changes
I demonstrate how you could split your applications in client
server…
- Your userinterface could be the client and the player could be the
  server

GÃ¶ran

2010/5/25 Jake K. [email protected]

lljk · May 26, 2010, 11:55pm

…the eagle has landed.

thanks all…

j

lljk · May 26, 2010, 8:26pm

hello again,

first let me thank you all for your suggestions, they got me thinking
and experimenting, and i’ve now got some code working in an example
program that i think will solve my problem. i ended up clearing the
EventBox with the #remove method, then recreating the Gtk::Image as
suggested, and then adding this to the now empty EventBox. not sure how
‘elegant’ it is, but it works!
i’ve included the code to the sample program - feel free to let me
know if you think something looks just plain dumb! i’ll give a quick
shout back when i get this worked into the mp3 player.

thanks again for the ideas…

peace, love, rock and roll -

jk

########## CODE #######################################

require ‘gtk2’

class Pics
attr_accessor :pile, :picindex, :atBat, :image, :box, :window

def initialize
@window = Gtk::Window.new()
@window.signal_connect(“destroy”){Gtk.main_quit}
pic1 = “TradyBlix.png”
pic2 = “ride.png”
pic3 = “konichiwa.jpeg”
@pile = [pic1, pic2, pic3]
@picindex = 0
self.getImage
@box = Gtk::EventBox.new.add(@image)
end

def batterUp
@box.remove(@image)
@picindex = @picindex + 1
@picindex = 0 if @picindex == @pile.length
self.getImage
@box.add(@image)
@box.show
end

def getImage
@atBat = @pile[@picindex]
img = Gdk::Pixbuf.new(@atBat, 200, 200)
@image = Gtk::Image.new(img)
@image.show
end

end # class Pics

pics = Pics.new
pics.box.signal_connect(“button_press_event”){pics.batterUp}
pics.window.set_default_size(200, 250)
pics.window.add(pics.box)
pics.window.show_all

Gtk.main

############ EOF ##############################

lljk · May 27, 2010, 9:43am

On 26 May 2010 20:26, jake kaiden [email protected]
wrote:

hello again,

Â first let me thank you all for your suggestions, they got me thinking
and experimenting, and i’ve now got some code working in an example
program that i think will solve my problem. Â i ended up clearing the
EventBox with the #remove method, then recreating the Gtk::Image as
suggested, and then adding this to the now empty EventBox. Â not sure how
‘elegant’ it is, but it works!
Â i’ve included the code to the sample program - feel free to let me
know if you think something looks just plain dumb! Â i’ll give a quick

As I wrote earlier it suffices to replace the Gdk::Pixbuf, the
GtkImage can stay:

@@ -7,11 +7,9 @@
def initialize
@window = Gtk::Window.new()
@window.signal_connect(“destroy”){Gtk.main_quit}

pic1 = “TradyBlix.png”
pic2 = “ride.png”
pic3 = “konichiwa.jpeg”
@pile = [pic1, pic2, pic3]

@pile = Dir::glob(“104*”) + Dir::glob(“2003*”)
@picindex = 0
@image = Gtk::Image.new
self.getImage
@box = Gtk::EventBox.new.add(@image)
end
@@ -28,8 +26,7 @@
def getImage
@atBat = @pile[@picindex]
img = Gdk::Pixbuf.new(@atBat, 200, 200)

@image = Gtk::Image.new(img)
@image.show

@image.pixbuf = img
end

end # class Pics

HTH

Michal