GTK4: gtk_style_context_get replacement

Platform
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1

For rendering a custom widget I’ve used the above in GTK3 to retrieve e.g. the font to use from CSS. This allowed to keep the styling information out of the code. How would I do the same in GTK4? (I’ve also used gtk_style_context_set_{path,parent} but I think I can emulate that with gtk_widget_add_css_class() sufficiently well).

The purpose here is not to support external themes (I only care about Adwaita and HC) but rather to not have those things hardcoded in C.

2

There are quite a number of examples on Stackoverflow.

Just look for something.

3

Thanks for the answer but how does that apply to custom widgets where I want to retrieve the style properties to do custom rendering in the snapshot vfunc and therefore e.g. get the font via

  gtk_style_context_get (context, state, "font", &font, NULL);
4

The documentation says:

"Do not use widget style properties

Style properties do not exist in GTK 4. You should stop using them in your custom CSS and in your code."

So I conclude, that it is no longer possible to query the StyleContext of a widget hierarchy.

If necessary, you can manually create a corresponding resource, as shown in the examples given above.

5

"Do not use widget style properties

I’ve read the documentation and I think I have some idea how to apply CSS to widgets in general. My question is how I can query e.g. the effective pango font description that applies to a widget in a hierarchy for custom rendering. Can you point me where the examples you refer to do this?

GtkInspector can do it but uses GtkCssNode which is private.

6

“My question is how I can query e.g. the effective pango font description that applies to a widget…”

My proposal is to:

#include"pango-widget.h"


void activate (GtkApplication *app, gpointer data)
{
  GtkWidget *window;

  window =gtk_application_window_new(app);
  gtk_widget_set_size_request(window,50,50);

  PangoContext* pcontext = gtk_widget_get_pango_context (window);

  PangoFontDescription* description = pango_context_get_font_description (pcontext);

  const char* family = pango_font_description_get_family (description);

  g_print("family: %s \n",family);

 gtk_widget_set_visible(window,TRUE);
}

Further necessary information should also be extracted.

7

You don’t: you’re supposed to use GtkLabel (or GtkInscription).

“Custom rendering” and “styling” are orthogonal: either you render custom content, or you get CSS integration by using widgets.

8

…ahh missed that one. Thanks!

9

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