From 31db7e468e628aba0f15956630a0ab1f019e9ea9 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 22 Jul 2016 21:59:57 +0300
Subject: [PATCH] Add cap height and x height metrics to Font

Since FreeType (and consequently ttf2png) doesn't provide these metrics,
they are estimated by the makefont script.
---
 scripts/makefont.py | 25 +++++++++++++++++++++----
 source/font.cpp     |  6 +++++-
 source/font.h       |  4 ++++
 3 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/scripts/makefont.py b/scripts/makefont.py
index 64c8e684..1d7a4332 100755
--- a/scripts/makefont.py
+++ b/scripts/makefont.py
@@ -1,8 +1,15 @@
 #!/usr/bin/python
 
+caps = list(range(ord("A"), ord("Z")+1))
+xchars = [ord(c) for c in "acemnorsuvwxz"]
+
 def convert_def(fn):
 	src = file(fn)
 
+	result = ""
+	header = ""
+	cap_height = []
+	x_height = []
 	for line in src.readlines():
 		line = line.strip()
 		if not line or line[0]=='#':
@@ -12,9 +19,9 @@ def convert_def(fn):
 
 		if parts[0]=="font":
 			tw, th, fh, fa, fd = map(int, parts[1:])
-			result = "native_size %d;\n"%fh
-			result += "ascent %.3f;\n"%(float(fa)/fh)
-			result += "descent %.3f;\n"%(float(fd)/fh)
+			header += "native_size %d;\n"%fh
+			header += "ascent %.3f;\n"%(float(fa)/fh)
+			header += "descent %.3f;\n"%(float(fd)/fh)
 		elif parts[0]=="glyph":
 			g, x, y, w, h, ox, oy, a = map(int, parts[1:])
 			result += "glyph %d\n{\n"%g
@@ -23,11 +30,21 @@ def convert_def(fn):
 			result += "\toffset %.3f %.3f;\n"%(float(ox)/fh, float(oy)/fh)
 			result += "\tadvance %.3f;\n"%(float(a)/fh)
 			result += "};\n"
+
+			if g in caps:
+				cap_height.append(h)
+			elif g in xchars:
+				x_height.append(h)
 		elif parts[0]=="kern":
 			l, r, d = map(int, parts[1:])
 			result += "kerning %d %d %.3f;\n"%(l, r, float(d)/fh)
 
-	return result
+	if cap_height:
+		header += "cap_height %.3f;\n"%(float(cap_height[len(cap_height)*2/3])/fh)
+	if x_height:
+		header += "x_height %.3f;\n"%(float(x_height[len(x_height)*2/3])/fh)
+
+	return header+result
 
 def make_font(fn, size, ch_range, autohinter, margin, padding):
 	import maketex
diff --git a/source/font.cpp b/source/font.cpp
index 6780f5fa..54631926 100644
--- a/source/font.cpp
+++ b/source/font.cpp
@@ -15,7 +15,9 @@ namespace GL {
 Font::Font():
 	native_size(1),
 	ascent(1),
-	descent(0)
+	descent(0),
+	cap_height(1),
+	x_height(0.5)
 { }
 
 // Avoid synthesizing ~RefPtr in files including font.h
@@ -139,11 +141,13 @@ void Font::Loader::init()
 {
 	add("native_size", &Font::native_size);
 	add("ascent",      &Font::ascent);
+	add("cap_height",  &Font::cap_height);
 	add("descent",     &Font::descent);
 	add("texture",     &Loader::texture);
 	add("texture",     &Loader::texture_ref);
 	add("glyph",       &Loader::glyph);
 	add("kerning",     &Loader::kerning);
+	add("x_height",    &Font::x_height);
 }
 
 void Font::Loader::glyph(unsigned c)
diff --git a/source/font.h b/source/font.h
index efef8351..4eaed963 100644
--- a/source/font.h
+++ b/source/font.h
@@ -60,6 +60,8 @@ private:
 	float native_size;
 	float ascent;
 	float descent;
+	float cap_height;
+	float x_height;
 	GlyphMap glyphs;
 	KerningMap kerning;
 
@@ -81,6 +83,8 @@ public:
 
 	float get_ascent() const { return ascent; }
 	float get_descent() const { return descent; }
+	float get_cap_height() const { return cap_height; }
+	float get_x_height() const { return x_height; }
 
 	/** Returns the width of a string, in multiples of the font size.  Scale the
 	result according to the size used in rendering. */
-- 
2.45.2