From 17b0cca50de329d1897b245a0a3b077609570730 Mon Sep 17 00:00:00 2001
From: kraus <olikraus@gmail.com>
Date: Mon, 27 May 2024 21:43:16 +0200
Subject: [PATCH] issue #2406

---
 tools/font/bdfconv/Makefile  |  8 ++++++++
 tools/font/otf2bdf/otf2bdf.c | 14 ++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/tools/font/bdfconv/Makefile b/tools/font/bdfconv/Makefile
index c8d7c5bd..edcc30d7 100644
--- a/tools/font/bdfconv/Makefile
+++ b/tools/font/bdfconv/Makefile
@@ -92,6 +92,14 @@ issue1769: bdfconv
 	./bdfconv -v -f 1 -b 2 -m '32-128' 3x7_Multi_V7.bdf -o u8g2_font_3x7_multi.c  -n u8g2_font_3x7_multi -d ../bdf/helvR12.bdf 
 	convert bdf.tga -trim u8g2_font_3x7_multi.png
 
+issue2406: bdfconv
+	-../otf2bdf/otf2bdf -y -v -r 72 -p 16 -o tmp.bdf ../tmp/zfull/zfull-regular.ttf
+	#-../otf2bdf/otf2bdf -v -r 72 -p 16 -o tmp.bdf ../ttf/Logisoso.ttf
+	#-../otf2bdf/otf2bdf -v -r 72 -p 16 -o tmp.bdf ../ttf/PressStart2P.ttf
+	#-../otf2bdf/otf2bdf -v -r 72 -p 16 -o tmp.bdf ../ttf/Wizzard.ttf
+	./bdfconv -v -f 1 -b 2 -m '32-128' tmp.bdf -o u8g2_zfull.c  -n u8g2_zfull -d ../bdf/helvR12.bdf 
+	convert bdf.tga -trim u8g2_zfull.png
+
 
 emoticons21: bdfconv
 	./bdfconv -v -f 1 -m '32-64' ../emoticons/emoticons21.bdf -o emoticons21.c  -n u8g2_font_emoticons21_tn -d ../bdf/helvB18.bdf 
diff --git a/tools/font/otf2bdf/otf2bdf.c b/tools/font/otf2bdf/otf2bdf.c
index 940fd9e8..61c7e9b7 100644
--- a/tools/font/otf2bdf/otf2bdf.c
+++ b/tools/font/otf2bdf/otf2bdf.c
@@ -135,6 +135,8 @@ static char *prog;
  */
 static int verbose = 0;
 
+static int alternate_y_offset_calculation = 0;  // u8g2 issue 2406 https://github.com/olikraus/u8g2/issues/2406 
+
 /*
  * Flags used when loading glyphs.
  */
@@ -880,6 +882,10 @@ generate_font(FILE *out, char *iname, char *oname)
         ht = ey - sy;
         x_off = sx + face->glyph->bitmap_left;
         y_off = sy + face->glyph->bitmap_top - face->glyph->bitmap.rows;
+        // u8g2 issue 2406
+        // the above calculation seems to be wrong, this should be: 
+        if ( alternate_y_offset_calculation )
+          y_off = face->glyph->bitmap_top - ey;
 
         bbx.maxas = MAX(bbx.maxas, ht + y_off);
         bbx.maxds = MAX(bbx.maxds, -y_off);
@@ -902,6 +908,10 @@ generate_font(FILE *out, char *iname, char *oname)
         fprintf(tmp, "DWIDTH %hd 0\n", dwidth);
         fprintf(tmp, "BBX %ld %ld %hd %hd\n", wd, ht, x_off, y_off);
 
+        // debug output (u8g2 issue 2406)
+        //if ( remapped_code >= 96 && remapped_code <= 103 )
+        //   fprintf(stderr, "%05ld BBX %ld %ld %hd %hd sy=%d, ey=%d bitmap_top=%d bitmap.rows=%d\n", (long) remapped_code, wd, ht, x_off, y_off, (int)sy, (int)ey, face->glyph->bitmap_top, face->glyph->bitmap.rows);
+
         /*
          * Check for an error return here in case the temporary file system
          * fills up or the file is deleted while it is being used.
@@ -1242,6 +1252,7 @@ usage(int eval)
     printf("-m mapfile\tGlyph reencoding file.\n");
     printf("-n\t\tTurn off glyph hinting.\n");
     printf("-a\t\tForce auto hinting.\n");
+    printf("-y\t\tApply bugfix for the bbx y offset calculation (u8g2 issue 2406).\n");
     printf("-g\t\tOutput raw glyphs instead of unicode chars.\n");
     printf("-et\t\tDisplay the encoding tables available in the font.\n");
     printf("-c c\t\tSet the character spacing (default: from font).\n");
@@ -1310,6 +1321,9 @@ main(int argc, char *argv[])
               case 'a': case 'A':
                 load_flags |= FT_LOAD_FORCE_AUTOHINT;
                 break;
+              case 'y': case 'Y':
+                alternate_y_offset_calculation = 1;
+                break;
               case 'g': case 'G':              
                 forcenocmap = 1;
                 break;