id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
233	Using ImageField without PIL	nesh <nesh [at] studioquattro [dot] co [dot] yu>	Adrian Holovaty	"Using PIL to extract width and height of the image is not necessary. For that I'm using handy function that I got from draco [http://draco.boskant.nl/]:

Works for GIF, PNG and JPEG formats.

Also, maybe is useful to cache results of function to avoid accessing to file system frequently.

Another good idea from draco is the IMG tag rewriter which automatically adds image width and height to img tags. Can this be added to template system?

{{{
def _imageInfo(fhandle):
    """"""
    Determine the image type of fhandle and return its size.
    from draco
    """"""

    head = fhandle.read(24)
    if len(head) != 24:
        return
    if head[:4] == '\x89PNG':
        # PNG
        check = struct.unpack('>i', head[4:8])[0]
        if check != 0x0d0a1a0a:
            return
        width, height = struct.unpack('>ii', head[16:24])
        img_type = 'PNG'
    elif head[:6] in ('GIF87a', 'GIF89a'):
        # GIF
        width, height = struct.unpack('<HH', head[6:10])
        img_type = 'GIF'
    elif head[:4] == '\xff\xd8\xff\xe0' and head[6:10] == 'JFIF':
        # JPEG
        img_type = 'JPEG'
        try:
            fhandle.seek(0)  # Read 0xff next
            size = 2
            ftype = 0
            while not 0xc0 <= ftype <= 0xcf:
                fhandle.seek(size, 1)
                byte = fhandle.read(1)
                while ord(byte) == 0xff: 
                    byte = fhandle.read(1)
                ftype = ord(byte)
                size = struct.unpack('>H', fhandle.read(2))[0] - 2
            # We are at a SOFn block
            fhandle.seek(1, 1)  # Skip `precision' byte.
            height, width = struct.unpack('>HH', fhandle.read(4))
        except Exception: #IGNORE:W0703
            return
    else:
        return
    return img_type, width, height
# imageSize
}}}"		closed	Core (Other)		normal	invalid			Unreviewed	0	0	0	0	0	0