[gimp] app: undeprecate some Pango/Harfbuzz calls.

[Jehan <jehanp src gnome org>]

commit 7a50b0940ea8f4ea38b631cc278ca889a9689b91
Author: Jehan <jehan girinstud io>
Date:   Sun Nov 15 15:45:20 2020 +0100

    app: undeprecate some Pango/Harfbuzz calls.
    
    pango_fc_font_lock_face() is deprecated since Pango 1.44.
    
    This may hopefully also fix #5922 as I completely changed the code where
    the CRITICAL happened. Yet I left g_return_val_if_fail() to check if the
    Harfbuzz font and FreeType face variables are not NULL (because looking
    at the code, it looks like these functions returning NULL actually means
    there is a bug in the code).
    
    Nevertheless if it turned out that there are non-bug cases where these
    could return NULL (for instance a broken font file?), then probably we
    should not use g_return_val_if_fail(), but instead address the data
    issue in a nicer way.
    
    Bumping harfbuzz dependency to 1.0.5 for hb_ft_font_set_funcs(). Without
    configuring the Harfbuzz font with it, hb_ft_font_get_face() always
    returns NULL.
    Note that it looks like hb_ft_font_lock_face() would actually be better,
    but this requires harfbuzz 2.6.5 from last April which is quite recent.
    So let's just use the get_face() variant for now.

 app/text/gimpfont.c | 26 +++++++++++++++++++++++---
 configure.ac        |  2 +-
 2 files changed, 24 insertions(+), 4 deletions(-)
---
diff --git a/app/text/gimpfont.c b/app/text/gimpfont.c
index 5d39391bd4..cb4db309fc 100644
--- a/app/text/gimpfont.c
+++ b/app/text/gimpfont.c
@@ -389,6 +389,7 @@ gimp_font_get_sample_string (PangoContext         *context,
 {
   PangoFont        *font;
   hb_face_t        *hb_face;
+  hb_font_t        *hb_font;
   FT_Face           face;
   TT_OS2           *os2;
   PangoOTTableType  tt;
@@ -672,8 +673,28 @@ gimp_font_get_sample_string (PangoContext         *context,
 
   g_return_val_if_fail (PANGO_IS_FC_FONT (font), "Aa");
 
-  face = pango_fc_font_lock_face (PANGO_FC_FONT (font));
+  hb_font = pango_font_get_hb_font (font);
+  g_return_val_if_fail (hb_font != NULL, "Aa");
+
+  /* These are needed to set hb_font to the right internal format, which
+   * can only work if the font is not immutable. Hence we make a copy.
+   */
+  hb_font = hb_font_create_sub_font (hb_font);
+  hb_ft_font_set_funcs (hb_font);
+  /* TODO: use hb_ft_font_lock_face/hb_ft_font_unlock_face() when we
+   * bump to harfbuzz >= 2.6.5.
+   */
+  face = hb_ft_font_get_face (hb_font);
+
+  /* Are there actual cases where this function could return NULL while
+   * it's not a bug in the code?
+   * For instance if the font file is broken, we don't want to return a
+   * CRITICAL, but properly address the issue (removing the font with a
+   * warning or whatnot).
+   * See #5922.
+   */
   g_return_val_if_fail (face != NULL, "Aa");
+
   hb_face = hb_ft_face_create (face, NULL);
 
   /* First check what script(s), if any, the font has GSUB or GPOS
@@ -753,8 +774,7 @@ gimp_font_get_sample_string (PangoContext         *context,
         }
     }
 
-  pango_fc_font_unlock_face (PANGO_FC_FONT (font));
-
+  hb_font_destroy (hb_font);
   g_object_unref (font);
 
   if (n_ot_alts > 2)
diff --git a/configure.ac b/configure.ac
index 63b85be07a..ae780a72c8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -68,7 +68,7 @@ m4_define([glib_required_version], [2.56.2])
 m4_define([gtk_mac_integration_required_version], [2.0.0])
 m4_define([gtk_required_version], [3.22.29])
 m4_define([gtkdoc_required_version], [1.0])
-m4_define([harfbuzz_required_version], [0.9.19])
+m4_define([harfbuzz_required_version], [1.0.5])
 m4_define([intltool_required_version], [0.40.1])
 m4_define([introspection_required_version], [1.32.0])
 m4_define([json_glib_required_version], [1.2.6])