misc/scripts/png2c.py

   1 #!/usr/bin/python
   2
   3 # This script is a slightly modified version of the original found at
   4 #
   5 #       http://wiki.wxwidgets.org/Embedding_PNG_Images-Bin2c_In_Python
   6 #
   7 # without any copyright attribution so it is assumed it can be used under
   8 # wxWindows licence as the rest of the wiki material.
   9
  10 import sys
  11 import os
  12 import os.path
  13 import re
  14 import array
  15
  16 USAGE = """Usage: png2c [-s] [file...]
  17 Output input PNG files as C arrays to standard output. Used to embed PNG images
  18 in C code (like XPM but with full alpha channel support).
  19
  20   -s    embed the image size in the image names in generated code."""
  21
  22 if len(sys.argv) < 2:
  23         print USAGE
  24         sys.exit(1)
  25
  26 r = re.compile("^([a-zA-Z._][a-zA-Z._0-9]*)[.][pP][nN][gG]$")
  27
  28 with_size = 0
  29 size_suffix = ''
  30 for path in sys.argv[1:]:
  31         if path == '-s':
  32             with_size = 1
  33             continue
  34
  35         filename = os.path.basename(path).replace('-','_')
  36         m = r.match(filename)
  37
  38         # Allow only filenames that make sense as C variable names
  39         if not(m):
  40                 print "Skipped file (unsuitable filename): " + filename
  41                 continue
  42
  43         # Read PNG file as character array
  44         bytes = array.array('B', open(path, "rb").read())
  45         count = len(bytes)
  46
  47         # Check that it's actually a PNG to avoid problems when loading it
  48         # later.
  49         #
  50         # Each PNG file starts with a 8 byte signature that should be followed
  51         # by IHDR chunk which is always 13 bytes in length so the first 16
  52         # bytes are fixed (or at least we expect them to be).
  53         if bytes[0:16].tostring() != '\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR':
  54                 print '"%s" doesn\'t seem to be a valid PNG file.' % filename
  55                 continue
  56
  57         # Try to naively get its size if necessary
  58         if with_size:
  59                 def getInt(start):
  60                         """ Convert 4 bytes in network byte order to an integer. """
  61                         return 16777216*bytes[start]   + \
  62                                   65536*bytes[start+1] + \
  63                                     256*bytes[start+2] + \
  64                                         bytes[start+3];
  65
  66                 size_suffix = "_%dx%d" % (getInt(16), getInt(20))
  67
  68         # Create the C header
  69         text = "/* %s - %d bytes */\n" \
  70                "static const unsigned char %s%s_png[] = {\n" % (
  71                     filename, count, m.group(1), size_suffix)
  72
  73         # Iterate the characters, we want
  74         # lines like:
  75         #   0x01, 0x02, .... (8 values per line maximum)
  76         i = 0
  77         count = len(bytes)
  78         for byte in bytes:
  79                 # Every new line starts with two whitespaces
  80                 if (i % 8) == 0:
  81                         text += "  "
  82                 # Then the hex data (up to 8 values per line)
  83                 text += "0x%02x" % (byte)
  84                 # Separate all but the last values
  85                 if (i % 8) == 7:
  86                         text += ',\n'
  87                 elif (i + 1) < count:
  88                         text += ", "
  89                 i += 1
  90
  91         # Now conclude the C source
  92         text += "};\n\n"
  93
  94         print text