kai.pet...@gmail.com wrote: > I just wrote this bit (coming from Pascal)
> if (((xdim / 8) * ydim) + header) <> filesize: Yeah, either Pascal or Barry Warsaw is your uncle ;) https://www.python.org/dev/peps/pep-0401/ > and am wondering how seasoned > Python programmers would have done the same? Anything terribly non-python? > def RenderByte(draw, byte, x, y): Please read PEP 8 for naming conventions etc. The function at the core of your code > def RenderByte(draw, byte, x, y): > > blist = list(bin(byte).lstrip('0b')) # turn byte into list with 8 > elements, > c = 0 # each representing one bit > for bit in blist: > if bit: > draw.point((x + c, y), fcolor) > > c += 1 > return can be fixed/micro-optimised, and if I were to do that I'd precreate a lookup table that maps every byte (i. e. value in the range 0...255) to a sequence of offsets lookup = [ (), # for b"\x00" the inner loop is empty (0), (1), (0, 1), ... (0, 1, 2, 3, 4, 5, 6, 7), # for b"\xFF" the inner loop comprises # all 8 bits ] or to a 8x1 image, but my idea of a "seasoned Python programmer" will try to keep the big picture in mind -- and that is that handling individual bits/pixels in Python is inefficient. Therefore many libraries tend to offer an alternative that is both easier to use and faster. In this case that's img = Image.frombytes("1", (width, height), data) and with the extra comfort of reading the size from the EPD file from PIL import Image import struct EPDFILE = "tmp.epd" PNGFILE = "tmp.png" class EPDError(Exception): pass with open(EPDFILE, "rb") as f: header = f.read(16) width, height, colordepth = struct.unpack("<HHb", header[1:6]) if colordepth != 1: raise EPDError("Unsupported color depth {}".format(colordepth)) data = f.read() datasize = width // 8 * height if len(data) != datasize: raise EPDError( "Inconsistent pixel data size. " "Expected {} but got {} bytes".format( datasize, len(data))) img = Image.frombytes("1", (width, height), data) img.save(PNGFILE) I'm assuming the header follows the format spec given in this PDF: http://www.pervasivedisplays.com/_literature_112691/Developer_Guide_for_Demo_Kit PS: I thought that Image.frombytes() was already pointed out to you, but I failed to find it in the archives. So there. -- https://mail.python.org/mailman/listinfo/python-list
