[gnome-software/155-allow-some-markup-in-release-notes-in-appdata] gs-description-box: Use markup for the description text

[Milan Crha <mcrha src gnome org>]

commit 86b4e9d3cbb62b99db6ee6e301c7cf99d4632f25
Author: Milan Crha <mcrha redhat com>
Date:   Thu Nov 4 09:54:50 2021 +0100

    gs-description-box: Use markup for the description text
    
    Use the markup for the description text, instead of the plain text.
    The apps are supposed to set the text markup-escaped.
    
    Closes https://gitlab.gnome.org/GNOME/gnome-software/-/issues/155

 src/gs-description-box.c | 44 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)
---
diff --git a/src/gs-description-box.c b/src/gs-description-box.c
index 23fb09dba..b8bdf4bd0 100644
--- a/src/gs-description-box.c
+++ b/src/gs-description-box.c
@@ -70,7 +70,7 @@ gs_description_box_update_content (GsDescriptionBox *box)
        if (g_strcmp0 (text, gtk_button_get_label (box->button)) != 0)
                gtk_button_set_label (box->button, text);
 
-       gtk_label_set_text (box->label, box->text);
+       gtk_label_set_markup (box->label, box->text);
        gtk_label_set_lines (box->label, -1);
        gtk_label_set_ellipsize (box->label, PANGO_ELLIPSIZE_NONE);
 
@@ -82,11 +82,40 @@ gs_description_box_update_content (GsDescriptionBox *box)
        if (box->is_collapsed && n_lines > MAX_COLLAPSED_LINES) {
                PangoLayoutLine *line;
                GString *str;
+               GSList *opened_markup = NULL;
+               gint start_index, line_index, in_markup = 0;
 
                line = pango_layout_get_line_readonly (layout, MAX_COLLAPSED_LINES);
 
-               str = g_string_sized_new (line->start_index);
-               g_string_append_len (str, box->text, line->start_index);
+               line_index = line->start_index;
+
+               /* Pango does not count markup in the text, thus calculate the position manually */
+               for (start_index = 0; box->text[start_index] && line_index > 0; start_index++) {
+                       if (box->text[start_index] == '<') {
+                               if (box->text[start_index + 1] == '/') {
+                                       g_free (opened_markup->data);
+                                       opened_markup = g_slist_remove (opened_markup, opened_markup->data);
+                               } else {
+                                       const gchar *end = strchr (box->text + start_index, '>');
+                                       opened_markup = g_slist_prepend (opened_markup, g_strndup (box->text 
+ start_index + 1, end - (box->text + start_index) - 1));
+                               }
+                               in_markup++;
+                       } else if (box->text[start_index] == '>') {
+                               g_warn_if_fail (in_markup > 0);
+                               in_markup--;
+                       } else if (!in_markup) {
+                               /* Encoded characters count as one */
+                               if (box->text[start_index] == '&') {
+                                       const gchar *end = strchr (box->text + start_index, ';');
+                                       if (end)
+                                               start_index += end - box->text - start_index;
+                               }
+
+                               line_index--;
+                       }
+               }
+               str = g_string_sized_new (start_index);
+               g_string_append_len (str, box->text, start_index);
 
                /* Cut white spaces from the end of the string, thus it doesn't look bad when it's 
ellipsized. */
                while (str->len > 0 && strchr ("\r\n\t ", str->str[str->len - 1])) {
@@ -95,10 +124,17 @@ gs_description_box_update_content (GsDescriptionBox *box)
 
                str->str[str->len] = '\0';
 
+               /* Close any opened tags after cutting the text */
+               for (GSList *link = opened_markup; link; link = g_slist_next (link)) {
+                       const gchar *tag = link->data;
+                       g_string_append_printf (str, "</%s>", tag);
+               }
+
                gtk_label_set_lines (box->label, MAX_COLLAPSED_LINES);
                gtk_label_set_ellipsize (box->label, PANGO_ELLIPSIZE_END);
-               gtk_label_set_text (box->label, str->str);
+               gtk_label_set_markup (box->label, str->str);
 
+               g_slist_free_full (opened_markup, g_free);
                g_string_free (str, TRUE);
        }
 }