Pango loads Tux Paint-supplied fonts on macOS.

Previously Pango loaded system-supplied fonts instead, which could lead
to fonts not rendering in a human-readable text.  This change fixes
https://sourceforge.net/p/tuxpaint/bugs/265/

src/debug.h

@@ -1,6 +1,32 @@
 //#define DEBUG
 //#define VERBOSE
 
+/*
+  Enable fontconfig debugging.  The value of this variable, which must be a
+  string, but is interpreted as a number, and each bit within that value
+  controls different debugging messages.  (from
+  https://www.freedesktop.org/software/fontconfig/fontconfig-user.html#DEBUG)
+
+  Name         Value    Meaning
+  ---------------------------------------------------------
+  MATCH            1    Brief information about font matching
+  MATCHV           2    Extensive font matching information
+  EDIT             4    Monitor match/test/edit execution
+  FONTSET          8    Track loading of font information at startup
+  CACHE           16    Watch cache files being written
+  CACHEV          32    Extensive cache file writing information
+  PARSE           64    (no longer in use)
+  SCAN           128    Watch font files being scanned to build caches
+  SCANV          256    Verbose font file scanning information
+  MEMORY         512    Monitor fontconfig memory usage
+  CONFIG        1024    Monitor which config files are loaded
+  LANGSET       2048    Dump char sets used to construct lang values
+  MATCH2        4096    Display font-matching transformation in patterns
+*/
+#if defined(DEBUG) && defined(VERBOSE)
+#define FC_DEBUG "1025"
+#endif
+
 /*
 * Enable verbose logging if requested on platforms that support it.
 *

src/fonts.c

@@ -286,6 +286,16 @@ TuxPaint_Font *TuxPaint_Font_OpenFont(const char *pangodesc,
            desc);
 #endif
 
+#ifdef __APPLE__
+    /*
+    * SDLPango_CreateContext_GivenFontDesc() defaults to ASCII character set
+    * (at least on the macOS) unless the CHARSET environment varaible is set.
+    * May also want to set on non-macOS platforms, also.
+    */
+
+    mysetenv("CHARSET", "UTF-8");
+#endif
+
     tpf->pango_context = SDLPango_CreateContext_GivenFontDesc(desc);
     if (tpf->pango_context == NULL)
     {

src/i18n.c

@@ -1064,7 +1064,7 @@ static void set_langint_from_locale_string(const char *restrict loc)
  * @param name Variable to set
  * @param value Value to set the variable to
  */
-static void mysetenv(const char *name, const char *value)
+void mysetenv(const char *name, const char *value)
 {
 #ifndef HAVE_SETENV
   int len;

src/i18n.h

@@ -208,6 +208,7 @@ extern w_langs wished_langs[255];
 int get_current_language(void);
 int setup_i18n(const char *restrict lang, const char *restrict locale,
                int *ptr_num_wished_languages) MUST_CHECK;
+void mysetenv(const char *name, const char *value);
 
 #ifdef NO_SDLPANGO
      int smash_i18n(void) MUST_CHECK;

src/tuxpaint.c

@@ -450,8 +450,12 @@ int iswprint(wchar_t wc)
 #error "---------------------------------------------------"
 #endif
 
+#ifdef DEBUG
+/* These are required to display pango debugging information later in this file */
+#include <pango/pango.h>
+#include <pango/pangoft2.h>
 #endif
-
+#endif /* !defined(NO_SDLPANGO) */
 
 #ifndef NOSOUND
 
@@ -30999,6 +31003,13 @@ int main(int argc, char *argv[])
   putenv((char *) "FONTCONFIG_PATH=Resources/etc");
 #endif
 
+#if defined(FC_DEBUG)
+  /*
+  * Enable fontconfig debugging. See "debug.h"
+  */
+  mysetenv("FC_DEBUG", FC_DEBUG);
+#endif
+
 #ifdef FORKED_FONTS
   /* must start ASAP, but depends on locale which in turn needs the config */
 #ifdef NO_SDLPANGO
@@ -31044,6 +31055,31 @@ int main(int argc, char *argv[])
 #endif
 
 
+#if defined(DEBUG) && !defined(NO_SDLPANGO)
+  /* Confirm pango's character set */
+  if(1) {
+    const char* charset;
+
+    g_get_charset(&charset);
+    printf("pango charset: %s\n", charset);
+  }
+
+  /* Display fonts available to pango */
+  if(1) {
+    PangoFontMap* fontmap;
+    PangoFontFamily** families;
+    int n_families;
+
+    fontmap = pango_ft2_font_map_new();
+    pango_font_map_list_families(fontmap, &families, &n_families);
+
+    for(int i=0; i < n_families; i++) {
+      const char* family_name = pango_font_family_get_name(families[i]);
+
+      printf("pango ft2 fontmap[%d] = '%s'\n", i, family_name);
+    }
+  }
+#endif
 
   claim_to_be_ready();