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from io import BytesIO
from django.db import models
import logging
from django.core.files.uploadedfile import SimpleUploadedFile
class ExtendedImageField(models.ImageField):
"""Extended ImageField that can resize image before saving it."""
def __init__(self, *args, **kwargs):
self.width = kwargs.pop('width', None)
self.height = kwargs.pop('height', None)
super(ExtendedImageField, self).__init__(*args, **kwargs)
def save_form_data(self, instance, data):
if data is not None and data != self.default:
if not data:
data = self.default
if instance.avatar != self.default:
instance.avatar.delete()
else:
if hasattr(data, 'read') and self.width and self.height:
content = self.resize_image(
data.read(), width=self.width, height=self.height)
data = SimpleUploadedFile(
instance.user.username + '.png', content, 'image/png')
super(ExtendedImageField, self).save_form_data(instance, data)
def resize_image(self, rawdata, width, height):
"""Resize image to fit it into (width, height) box."""
from PIL import Image
image = Image.open(BytesIO(rawdata))
try:
oldw, oldh = image.size
if oldw > width or oldh > height:
if oldw >= oldh:
x = int(round((oldw - oldh) / 2.0))
image = image.crop((x, 0, (x + oldh) - 1, oldh - 1))
else:
y = int(round((oldh - oldw) / 2.0))
image = image.crop((0, y, oldw - 1, (y + oldw) - 1))
image = image.resize((width, height), resample=Image.ANTIALIAS)
except Exception as err:
logging.error(err)
return ''
string = BytesIO()
image.save(string, format='PNG')
return string.getvalue()
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