[tepl] utils: add override_font()

[Sébastien Wilmet <swilmet src gnome org>]

commit a075e2a79320b42fe3f6626dc2479b0d13cf401c
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Tue Nov 24 01:58:00 2020 +0100

    utils: add override_font()

 docs/reference/tepl-sections.txt |  1 +
 tepl/tepl-utils.c                | 73 ++++++++++++++++++++++++++++++++++++++++
 tepl/tepl-utils.h                |  4 +++
 3 files changed, 78 insertions(+)
---
diff --git a/docs/reference/tepl-sections.txt b/docs/reference/tepl-sections.txt
index eb695ef..cc0b1c2 100644
--- a/docs/reference/tepl-sections.txt
+++ b/docs/reference/tepl-sections.txt
@@ -578,6 +578,7 @@ tepl_utils_list_box_scroll_to_row
 tepl_utils_list_box_scroll_to_selected_row
 tepl_utils_list_box_get_row_at_index_with_filter
 tepl_utils_list_box_get_filtered_children
+tepl_utils_override_font
 tepl_utils_binding_transform_func_smart_bool
 </SECTION>
 
diff --git a/tepl/tepl-utils.c b/tepl/tepl-utils.c
index d8e69cd..ca01eae 100644
--- a/tepl/tepl-utils.c
+++ b/tepl/tepl-utils.c
@@ -11,6 +11,7 @@
 #include <string.h>
 #include "tepl-application-window.h"
 #include "tepl-icu.h"
+#include "tepl-pango.h"
 
 /**
  * SECTION:utils
@@ -1014,6 +1015,78 @@ tepl_utils_list_box_get_filtered_children (GtkListBox           *list_box,
        return (GtkListBoxRow **) g_ptr_array_free (filtered_rows, FALSE);
 }
 
+/**
+ * tepl_utils_override_font:
+ * @widget: a #GtkWidget.
+ * @font_str: (nullable): a string representation of a #PangoFontDescription, or
+ *   %NULL to undo the effect of previous calls to this function on @widget.
+ *
+ * A replacement for gtk_widget_override_font(). Because
+ * gtk_widget_override_font() is deprecated but was useful.
+ *
+ * See pango_font_description_from_string() for a description of the format of
+ * the string representation for @font_str.
+ *
+ * This function uses tepl_pango_font_description_to_css() and applies the CSS
+ * to the #GtkStyleContext of @widget.
+ *
+ * Since: 6.0
+ */
+void
+tepl_utils_override_font (GtkWidget   *widget,
+                         const gchar *font_str)
+{
+       GtkStyleContext *style_context;
+       GtkCssProvider *css_provider;
+       PangoFontDescription *font_description;
+       gchar *css_declarations;
+       gchar *css_rule_set;
+
+#define FONT_CSS_PROVIDER_KEY "tepl-utils-override-font-css-provider-key"
+
+       g_return_if_fail (GTK_IS_WIDGET (widget));
+
+       style_context = gtk_widget_get_style_context (widget);
+       css_provider = g_object_get_data (G_OBJECT (widget), FONT_CSS_PROVIDER_KEY);
+
+       if (css_provider != NULL)
+       {
+               gtk_style_context_remove_provider (style_context, GTK_STYLE_PROVIDER (css_provider));
+               g_object_set_data (G_OBJECT (widget), FONT_CSS_PROVIDER_KEY, NULL);
+               css_provider = NULL;
+       }
+
+       if (font_str == NULL)
+       {
+               return;
+       }
+
+       font_description = pango_font_description_from_string (font_str);
+       g_return_if_fail (font_description != NULL);
+
+       css_declarations = tepl_pango_font_description_to_css (font_description);
+       css_rule_set = g_strdup_printf ("* {\n"
+                                       "    %s\n"
+                                       "}\n",
+                                       css_declarations);
+
+       css_provider = gtk_css_provider_new ();
+       g_object_set_data_full (G_OBJECT (widget),
+                               FONT_CSS_PROVIDER_KEY,
+                               css_provider,
+                               g_object_unref);
+
+       gtk_css_provider_load_from_data (css_provider, css_rule_set, -1, NULL);
+       gtk_style_context_add_provider (style_context,
+                                       GTK_STYLE_PROVIDER (css_provider),
+                                       /* Priority "library". */
+                                       GTK_STYLE_PROVIDER_PRIORITY_APPLICATION - 1);
+
+       pango_font_description_free (font_description);
+       g_free (css_declarations);
+       g_free (css_rule_set);
+}
+
 /**
  * tepl_utils_binding_transform_func_smart_bool:
  * @binding: a #GBinding.
diff --git a/tepl/tepl-utils.h b/tepl/tepl-utils.h
index 4c313ee..f7ea05d 100644
--- a/tepl/tepl-utils.h
+++ b/tepl/tepl-utils.h
@@ -109,6 +109,10 @@ GtkListBoxRow **tepl_utils_list_box_get_filtered_children  (GtkListBox
                                                                 gpointer              user_data,
                                                                 gint                 *n_filtered_children);
 
+_TEPL_EXTERN
+void           tepl_utils_override_font                        (GtkWidget   *widget,
+                                                                const gchar *font_str);
+
 /* Other */
 
 _TEPL_EXTERN