A URL field specifically for images, which can validate details about the filesize, dimensions and format of an image at a given URL, without having to read the entire image into memory.
Requires Python Imaging Library.
4th October, 2008 - updated for 1.0 compatibility.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 | import urllib
from django import forms
from django.template.defaultfilters import filesizeformat
from django.utils.text import get_text_list
from PIL import ImageFile
class ImageURLField(forms.URLField):
"""
A URL field specifically for images, which can validate details
about the filesize, dimensions and format of an image at a given
URL.
Specifying any of the following arguments will result in the
appropriate validation of image details, retrieved from the URL
specified in this field:
max/min_filesize
An integer specifying an image filesize limit, in bytes.
max/min_width
An integer specifying an image width limit, in pixels.
max/min_height
An integer specifying an image height limit, in pixels.
image_formats
A list of image formats to be accepted, specified as uppercase
strings.
For a list of valid image formats, see the "Image File Formats"
section of the `Python Imaging Library Handbook`_.
.. _`Python Imaging Library Handbook`: http://www.pythonware.com/library/pil/handbook/
"""
def __init__(self, max_filesize=None, min_filesize=None, max_width=None,
min_width=None, max_height=None, min_height=None, image_formats=None,
*args, **kwargs):
super(ImageURLField, self).__init__(*args, **kwargs)
self.max_filesize, self.min_filesize = max_filesize, min_filesize
self.max_width, self.min_width = max_width, min_width
self.max_height, self.min_height = max_height, min_height
self.image_formats = image_formats
self.validate_image = \
max_filesize is not None or min_filesize is not None or \
max_width is not None or min_width is not None or \
max_height is not None or min_height is not None or \
image_formats is not None
def clean(self, value):
value = super(ImageURLField, self).clean(value)
if value == u'' or not self.validate_image:
return value
try:
filesize, dimensions, format = self._get_image_details(value)
if dimensions is None or format is None:
raise forms.ValidationError(
'Could not retrieve image details from this URL.')
if self.max_filesize is not None and filesize > self.max_filesize:
raise forms.ValidationError(
u'The image at this URL is %s large - it must be at most %s.' % (
filesizeformat(filesize), filesizeformat(self.max_filesize)))
if self.min_filesize is not None and filesize < self.min_filesize:
raise forms.ValidationError(
u'The image at this URL is %s large - it must be at least %s.' % (
filesizeformat(filesize), filesizeformat(self.min_filesize)))
if self.max_width is not None and dimensions[0] > self.max_width:
raise forms.ValidationError(
u'The image at this URL is %s pixels wide - it must be at most %s pixels.' % (
dimensions[0], self.max_width))
if self.min_width is not None and dimensions[0] < self.min_width:
raise forms.ValidationError(
u'The image at this URL is %s pixels wide - it must be at least %s pixels.' % (
dimensions[0], self.min_width))
if self.max_height is not None and dimensions[1] > self.max_height:
raise forms.ValidationError(
u'The image at this URL is %s pixels high - it must be at most %s pixels.' % (
dimensions[1], self.max_height))
if self.min_height is not None and dimensions[1] < self.min_height:
raise forms.ValidationError(
u'The image at this URL is %s pixels high - it must be at least %s pixels.' % (
dimensions[1], self.min_height))
if self.image_formats is not None and format not in self.image_formats:
raise forms.ValidationError(
u'The image at this URL is in %s format - %s %s.' % (
format,
len(self.image_formats) == 1 and u'the only accepted format is' or 'accepted formats are',
get_text_list(self.image_formats)))
except IOError:
raise forms.ValidationError(u'Could not load an image from this URL.')
return value
def _get_image_details(self, url):
"""
Retrieves details about the image accessible at the given URL,
returning a 3-tuple of (filesize, image dimensions (width,
height) and image format), or (filesize, ``None``, ``None``) if
image details could not be determined.
The Python Imaging Library is used to parse the image in chunks
in order to determine its dimension and format details without
having to load the entire image into memory.
Adapted from http://effbot.org/zone/pil-image-size.htm
"""
file = urllib.urlopen(url)
filesize = file.headers.get('content-length')
if filesize: filesize = int(filesize)
p = ImageFile.Parser()
while 1:
data = file.read(1024)
if not data:
break
p.feed(data)
if p.image:
return filesize, p.image.size, p.image.format
break
file.close()
return filesize, None, None
|
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Comments
Cool, I'll use this code in my photoblog! Did you read all image by chunks or header only, using
data = file.read(1024)
andp.feed(data)
? Why do not callfile.read()
instead?And, probably, you dont need
try: except:
statement around of all theseifs
, you need this around_get_image_details
call, only, isnt it?#
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