def write( filename, width, height, data ):
"""
Writes data out to a windows bitmap file.
:Parameters:
filename : string
The name of the file to write to.
width : int
The width of the image in pixels
height : int
The height of the image in pixels
data : string
The data as a binary string.
:rtype: boolean
:returns: True on success
"""
bpp = 24
if bpp == 4:
# 16 colors are reserved for this depth of images.
colors = { "\x00\x00\x00": 0, "\x80\x00\x00": 1, "\x00\x80\x00": 2, "\x80\x80\x00": 3,
"\x00\x00\x80": 4, "\x80\x00\x80": 5, "\x00\x80\x80": 6, "\xc0\xc0\xc0": 7,
"\x80\x80\x80": 8, "\xff\x00\x00": 9, "\x00\xff\x00":10, "\xff\xff\x00":11,
"\x00\x00\xff":12, "\x00\xff\xff":13, "\x00\xff\xff":14, "\xff\xff\xff":15 }
data = [ data[ i*width*3 : (i+1)*width*3 ] for i in range( height ) ]
data.reverse( ) #reverse the bytes ( they are stored this way in bmp format )
rawdata = ''.join( data )
# I'm not sure of the easiest way to transform the raw data into the format I need here.
# Color #7 is causing the problem, otherwise I could just bitmask it with 0xc0.
# If I do that, I won't be able to tell the difference between 0xff and 0xc0.
if bpp == 24:
#swap the red and blue channels to make it easier to write this format
data = swapChannels( width, height, data, 0, 2 )[ 2 ]
# split data into a list of rows
data = [ data[ i*width*3 : (i+1)*width*3 ] for i in range( height ) ]
padding = "\x00" * ( ( -width * 3 ) % 4 ) # make each row an even multiple of 4.
data.reverse( ) #reverse the bytes ( they are stored this way in bmp format )
bmpdata = padding.join( data )
# create the header (Windows V3)
filesize = len( bmpdata ) + 54
header = "BM"
header += struct.pack( "IHHI", filesize, 0, 0, 54 ) # The main file header
header += struct.pack( "IIIHHIIIIII", 40, width, height, 1, bpp, 0, len( bmpdata ), 3937, 3937, 0, 0 ) # Windows V3 header
imageFile = open( filename, 'wb' )
imageFile.write( header + bmpdata )
imageFile.close( )
return True
def execute( width, height, data ):
"""
Swaps the red and blue channels in an image.
:Parameters:
width : int
The width of the image being converted
height : int
The height of the image being converted
data : string
A string containing the data for the image
:rtype: tuple
:returns: a tuple containing a width, height, and data as a binary string.
"""
channels = len( data ) // ( width * height )
if channels in ( 3, 4 ):
return swapChannels( width, height, data, 0, 2 )
def read( filename ):
"""
Reads a windows bitmap file.
:Parameters:
filename : string
the name of the file to be read.
:rtype: tuple
:returns: A tuple ( width, height, data ). Width and height are in pixels, data is a string containing chr(red) + chr(green) + chr(blue) for each pixel.
"""
imageData = str( )
imageFile = open( filename, 'rb' )
#=========================== READ THE FILE HEADER ========================================
fileHeader = imageFile.read( 14 )
if ( fileHeader[ :2 ] != 'BM' ):
log( "Warning: Incorrectly formatted bitmap file" )
dataAddress = struct.unpack( 'I', fileHeader[ 10: ] )[ 0 ]
infoHeader = imageFile.read( dataAddress - 14 )
infoHeaderSize = struct.unpack( 'I', infoHeader[ :4 ] )[ 0 ]
#============================ READ THE INFOHEADER ==========================================
if ( infoHeaderSize == 24 ): # OS/2 V1 Header
width, height, colorPlanes, bpp = struct.unpack( "HHHH", infoHeader[ 4:12 ] )
elif ( infoHeaderSize == 40 ): # Windows V3 Header
width, height, colorPlanes, bpp, compression = struct.unpack( 'IIHHI', infoHeader[ 4:20 ] )
else:
imageFile.close( )
raise ImageFormatError( "Unable to parse header information" )
#========================================================================================
if compression:
imageFile.close( )
raise ImageReadError( "Compressed bitmap images are not currently supported" )
if bpp == 4:
# 16 colors are reserved for this depth of images. The following are the 20 reserved
# Windows colors. The 4 commented out are omitted from this palette.
colors = { 0: "\x00\x00\x00", 1: "\x80\x00\x00", 2: "\x00\x80\x00", 3: "\x80\x80\x00",
4: "\x00\x00\x80", 5: "\x80\x00\x80", 6: "\x00\x80\x80", 7: "\xc0\xc0\xc0",
#8: "\xc0\xdc\xc0", 9: "\xa6\xca\xf0", 246: "\xff\xfb\xf0", 247: "\xa0\xa0\xa4",
248: "\x80\x80\x80", 249: "\xff\x00\x00", 250: "\x00\xff\x00", 251: "\xff\xff\x00",
252: "\x00\x00\xff", 253: "\x00\xff\xff", 254: "\x00\xff\xff", 255: "\xff\xff\xff" }
palette = colors.values( )
data = imageFile.read( )
try:
translatedData = str( )
for i in range( len( data ) ):
pixels = ord( data[ i ] )
translatedData += palette[ pixels >> 4 ] + palette[ pixels & 0xf ]
imageData = [ translatedData[ i*width*3 : (i+1)*width*3 ] for i in range( height ) ]
imageData.reverse( )
imageData = ''.join( imageData )
except IndexError:
raise ImageReadError( "This image appears to be corrupted." )
elif bpp == 24:
eof = width * height * 3
while ( len( imageData ) < eof ):
data = imageFile.read( width * 3 )
#throw away the extra \0 padding at the end of a line (if any)
padding = ( -width * 3 ) % 4
if padding:
imageFile.seek( imageFile.tell( ) + padding )
imageData = data + imageData
# swap the red and blue channels, the channels are stored in reverse order
# from what we need in the file
imageData = swapChannels( width, height, imageData, 0, 2 )[ 2 ]
else:
imageFile.close( )
raise ImageFormatError( "Images of %d bpp are not supported" % depth )
imageFile.close( )
return ( width, height, imageData )
