set extra glyph scale factor from freetype font metrics

src/fontstash.h

@@ -378,6 +378,7 @@ struct FONSfont
 	float ascender;
 	float descender;
 	float lineh;
+	float scaleFactor;
 	FONSglyph* glyphs;
 	int cglyphs;
 	int nglyphs;
@@ -938,6 +939,11 @@ int fonsAddFontMem(FONScontext* stash, const char* name, unsigned char* data, in
 	font->ascender = (float)ascent / (float)fh;
 	font->descender = (float)descent / (float)fh;
 	font->lineh = (float)(fh + lineGap) / (float)fh;
+#ifdef FONS_USE_FREETYPE
+	font->scaleFactor = (float)(font->font.font->height) / (float)(font->font.font->units_per_EM);
+#else
+	font->scaleFactor = 1.0f;
+#endif
 
 	return idx;
 
@@ -1042,7 +1048,7 @@ static FONSglyph* fons__getGlyph(FONScontext* stash, FONSfont* font, unsigned in
 	float scale;
 	FONSglyph* glyph = NULL;
 	unsigned int h;
-	float size = isize/10.0f;
+	float size = isize/10.0f * font->scaleFactor;
 	int pad, added;
 	unsigned char* bdst;
 	unsigned char* dst;