################################################################################
# Program:          fontmerger.py
#
# Description:      This program merges all the font files in current directory
#                   and merged font file is saved as mergedfont.ttf. Note that
#                   only files with .ttf extention are considered for now.
#
# Author:           Mohsin Shafeeque Hijazee (m_hijazee@yahoo.com)
#                   This program written for Grand Nastaleeq Project at
#                   UrduWeb.Org (http://www.urduweb.org).
#                   The aim of the project to create an everlasting Nastaleeq
#                   font for Urdu utilizing ligature and character based 
#                   paradimgs of the Nastaleeq font development.
#                   You can join the development fourms 
#                   at http://www.urduweb.org/mehfil
#
# RevisionLog:     22 June, 2008:   (Mohsin)
#                     * Initial testing of idea
#
#                  24 June, 2008:   (Mohsin)
#                     * Moved merging of two fonts to mergeFont()
#                     * mergeFont() improved to take either TTFont object, a
#                       File object or a string object containing path as args.
#                       This is done by addding function getFontObject()
#                     * Added fucntion mergeAllFonts()
#                     * Program can be used as reuseable module
#
# TODO: User should be able to specify output directory and file name
# TODO: User should be able to mention the source directory for fonts to be merged.


import types
import sys
import glob

try:
    from fontTools.ttLib import TTFont
except ImportError:
    print 'fontmerger requires fontTools to be installed. Google fontTools for more information.'
    exit()


def getFontObject(file_or_path):
    """ Given a file object or path, returns TTFont object"""
    
    # If its a file object or a path string, return font object
    # Otherwise chances are that its already a TTFont object
    if type(file_or_path) == types.StringType or type(file_or_path) == types.FileType:
        return TTFont(file_or_path)
    else:
        return file_or_path

    
def mergeFonts(font1, font2):
    """ Merges second font into first font.
        Both arguments can be either
            * File objects
            * String mentioning absolute/relative path
            * TTFont objects.
        Returns merged TTFont object.
    """

    # Get the font objects
    firstFont = getFontObject(font1)
    secondFont = getFontObject(font2)

    # Get the 'glyf' table of each
    first_glyf = firstFont['glyf']
    second_glyf = secondFont['glyf']

    # Get 'hmtx' tables of each to merge horizontal metrics
    first_hmtx = firstFont['hmtx']
    second_hmtx = secondFont['hmtx']

    # For each of the glyphs in 'glyf' table of second font
    for glyphName in second_glyf.keys():
        
        # If first font already has this glyph
        if first_glyf.glyphs.has_key(glyphName):
            print "WARNING: font already contains glyph named '%s'" % glyphName
            continue

        # 1... Merge glph in 'glyf' table
        # 2... Record horizontal metrices in 'hmtx'
        # 3... Record order in 'loca' table
        first_glyf.glyphs[glyphName] = second_glyf[glyphName]
        first_hmtx.metrics[glyphName] = second_hmtx.metrics[glyphName]
        firstFont.glyphOrder.append(glyphName)

    return firstFont

def mergeAllFonts():
    """Merges all the fonts in current directory to single font mergedfont.ttf"""

    # Get all the .ttf files in current director
    fontFiles = glob.glob('*.ttf')

    # Pick the first file
    firstFile = fontFiles[0]
    # All fonts will be merged into this
    mergedFont = TTFont(firstFile)
    
    for index in range(1, len(fontFiles)):
        print "Merging '%s' with '%s'" % (fontFiles[index], firstFile)
        mergeFonts(mergedFont, fontFiles[index])

    mergedFont.save('mergedfont.ttf')
    print "Merged font is saved as 'mergedfont.ttf'"
    
    

# If not being used as module, merge all fonts in current directory    
if __name__ == '__main__':
    mergeAllFonts()