Add font dumping command

cmd/dumpfont/dumpfont.go

@@ -0,0 +1,38 @@
+// Copyright 2010-2017 The Freetype-Go Authors. All rights reserved.
+// Use of this source code is governed by your choice of either the
+// FreeType License or the GNU General Public License version 2 (or
+// any later version), both of which can be found in the LICENSE file.
+package main
+
+import (
+	"flag"
+	"io/ioutil"
+
+	"fmt"
+	"os"
+
+	"github.com/golang/freetype"
+)
+
+var fontfile = flag.String("font", "", "filename of font to dump")
+
+func main() {
+	flag.Parse()
+
+	// Load the raw data from disk
+	fontData, err := ioutil.ReadFile(*fontfile)
+	if err != nil {
+		fmt.Printf("Failed to load font from %s: %+v\n", *fontfile, err)
+		os.Exit(1)
+	}
+
+	// Parse the font data
+	font, err := freetype.ParseFont(fontData)
+	if err != nil {
+		fmt.Printf("Failed to parse font from %s: %+v\n", *fontfile, err)
+		os.Exit(1)
+	}
+
+	// Dump summary info
+	font.Dump()
+}

truetype/truetype.go

@@ -641,3 +641,26 @@ func parse(ttf []byte, offset int) (font *Font, err error) {
 	font = f
 	return
 }
+
+// Dump prints internal details about the font to stdout
+func (f *Font) Dump() {
+	fmt.Printf("Name: %s\n", f.Name(NameIDFontFullName))
+	fmt.Printf(" Glyphs: %d\n HMetrics: %d\n Kerns: %d\n", f.nGlyph, f.nHMetric, f.nKern)
+	fmt.Printf(" FUnits-per-em: %d\n", f.fUnitsPerEm)
+	fmt.Printf(" Bounds: %+v\n", f.bounds)
+	fmt.Printf(" Ascent: %d\tDescent: %d\n", f.ascent, f.descent)
+
+	// Build a mapping of glyph indices to characters
+	glyphToChar := make([]uint32, f.nGlyph)
+	for _, cm := range f.cm {
+		for i := cm.start; i <= cm.end; i++ {
+			glyphToChar[f.Index(rune(i))] = i
+		}
+	}
+
+	// Dump the cmap in glyph index order
+	fmt.Printf("cmap:\n")
+	for i, val := range glyphToChar {
+		fmt.Printf(" Glyph %d -> %+q\n", i, val)
+	}
+}