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jhass / crystal-gobject

gobject-introspection for Crystal

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How can I use Glade templates?

n-rodriguez opened this issue · comments

commented

Hi there!

I'd like to use Glade templates in my Gtk application but I'm stuck with Error: undefined method 'set_template_from_resource' for Gtk::Widget.class.

It seems that Gtk::Widget.class should implement set_template_from_resource or set_template https://lazka.github.io/pgi-docs/Gtk-3.0/classes/WidgetClass.html#Gtk.WidgetClass.set_template_from_resource to get it work.

To give you more context I'm rewriting a Ruby/Gtk3 application to Crystal/Gtk3 (https://github.com/jbox-web/ssh-tunnel) so I'm already using this technique and it works pretty well : https://github.com/jbox-web/ssh-tunnel/blob/master/lib/ssh-tunnel/ui/windows/application_window.rb

commented

Hey!

First of all crystal-gobject rewrites set_foo to foo=, so you'd be looking for template= or template_from_resource= here.

Now we probably should map those Class stuff (I guess it's returned by g_object_info_get_class_struct) into class methods on the wrapper classes somehow. But I'm not sure how to get the particular instance inside those functions at runtime. It would be interesting to see a corresponding C example.

commented

Hi @jhass! Thanks for your quick answer :)

First of all crystal-gobject rewrites set_foo to foo=, so you'd be looking for template= or template_from_resource= here.

good to know 👍

It would be interesting to see a corresponding C example.

There is some code examples here : https://developer.gnome.org/gtk3/stable/ch01s04.html

commented

From Gtk3 doc : (important things are in bold)

To make use of this file in our application, we revisit our GtkApplicationWindow subclass, and call gtk_widget_class_set_template_from_resource() from the class init function to set the ui file as template for this class. We also add a call to gtk_widget_init_template() in the instance init function to instantiate the template for each instance of our class.

That's what you see in Ruby/Gtk3 implementation : https://github.com/jbox-web/ssh-tunnel/blob/master/lib/ssh-tunnel/ui/windows/application_window.rb#L11

Here the workflow in Ruby :

  1. Gtk3 (or something) calls Class.init
  2. Class.init sets the template by calling set_template
  3. set_template calls the C method (https://github.com/ruby-gnome/ruby-gnome/blob/dde8c4fdabeadc6d9c8e4ca345aace535853deb6/gtk3/lib/gtk3/widget.rb#L33)
  4. the object is instantiated with Class.new and initialize_post is called (https://github.com/ruby-gnome/ruby-gnome/blob/dde8c4fdabeadc6d9c8e4ca345aace535853deb6/gtk3/lib/gtk3/widget.rb#L148)
  5. initialize_post calls the C method init_template
commented

Here some Crystal code : https://github.com/jbox-web/ssh-tunnel.cr

To run the app :

  • make ssh-tunnel
  • ./bin/ssh-tunnel
commented

I tried your suggestion but it doesn't work so you will have an error on compilation :

In src/ssh-tunnel/ui/windows/application_window.cr:5:14

 5 | self.template_from_resource = "/com/jbox-web/ssh-tunnel/ui/application_window.glade"
          ^---------------------
Error: undefined method 'template_from_resource=' for SSHTunnel::UI::Windows::ApplicationWindow.class
make: *** [Makefile:18 : ssh-tunnel] Erreur 1

Just comment the line and it will work.

commented

Sorry, I cannot promise I'll find time to look into this myself this year :)

The code that's generating the wrapper classes for objects is at https://github.com/jhass/crystal-gobject/tree/main/src/g_i_repository/info/object_info.cr

commented

Hi there! Any news? 😃

commented

Hey,
I embed glade templates in my application like that:

require "gobject/gtk"

template = {{ `cat #{__DIR__}/window.glade`.stringify }}

builder = Gtk::Builder.new_from_string template, template.bytesize
builder.connect_signals
@window = window = Gtk::Window.cast builder["window"]

That works pretty good, but it's not using GResources. You try to fetch the template from a resource, did you find a way to link your resource file into the executable? I would like to use icons through a GResource file, but found no way to link that into the executable.

commented

Not directly related to the issue, but you must use template.bytesize instead of template.size, since due to UTF-8 encoding these are not always the same.

commented

Not directly related to the issue, but you must use template.bytesize instead of template.size, since due to UTF-8 encoding these are not always the same.

Good catch, thanks! I changed it above for reference.

commented

FYI: Almost 1.5 years later, in a different shard but it's finally possible to use glade template in Crystal-GTK 😃

hugopl/gtk4.cr@c93354e

sorry for the cross-repo post, but I'm very happy it worked and remembered this issue that basically made me knew this feature existed in GTK, otherwise I would still be using Gtk::Builder forever.