我试图将一个UploadedFile
对象转换为PIL Image
对象进行缩略图处理,然后将我的缩略图函数返回的PIL Image
对象转换回File
对象。如何实现这一操作?
我试图将一个UploadedFile
对象转换为PIL Image
对象进行缩略图处理,然后将我的缩略图函数返回的PIL Image
对象转换回File
对象。如何实现这一操作?
不必写回到文件系统,再通过打开调用将文件带回内存,可以使用StringIO和Django InMemoryUploadedFile来实现。以下是一个示例,演示如何完成这一操作。假设您已经有一个名为“thumb”的缩略图像:
import StringIO
from django.core.files.uploadedfile import InMemoryUploadedFile
# Create a file-like object to write thumb data (thumb data previously created
# using PIL, and stored in variable 'thumb')
thumb_io = StringIO.StringIO()
thumb.save(thumb_io, format='JPEG')
# Create a new Django file-like object to be used in models as ImageField using
# InMemoryUploadedFile. If you look at the source in Django, a
# SimpleUploadedFile is essentially instantiated similarly to what is shown here
thumb_file = InMemoryUploadedFile(thumb_io, None, 'foo.jpg', 'image/jpeg',
thumb_io.len, None)
# Once you have a Django file-like object, you may assign it to your ImageField
# and save.
...
如果需要更多解释,请告诉我。 我现在已经在我的项目中使用django-storages将文件上传到S3,这花费了我大部分时间来正确地找到解决方案。
StringIO
的?我不得不使用BytesIO
(由于它没有_len()_函数,所以必须使用_tell()_来确定其长度)。 - John CBytesIO
。请尝试使用我在这里提供的答案:https://dev59.com/uYvda4cB1Zd3GeqPWjlV#30435175。顺便说一句,之前的评论已经过时并被删除了。 - madzohan我不得不分几步来完成这个过程,因为在PHP中使用imagejpeg()需要类似的过程。并不是说没有办法将所有东西都保存在内存中,但是这种方法可以为原始图片和缩略图(如果您必须返回更改缩略图大小)提供文件引用。
模型:
class YourModel(Model):
img = models.ImageField(upload_to='photos')
thumb = models.ImageField(upload_to='thumbs')
使用方法:
#in upload code
uploaded = request.FILES['photo']
from django.core.files.base import ContentFile
file_content = ContentFile(uploaded.read())
new_file = YourModel()
#1 - get it into the DB and file system so we know the real path
new_file.img.save(str(new_file.id) + '.jpg', file_content)
new_file.save()
from PIL import Image
import os.path
#2, open it from the location django stuck it
thumb = Image.open(new_file.img.path)
thumb.thumbnail(100, 100)
#make tmp filename based on id of the model
filename = str(new_file.id)
#3. save the thumbnail to a temp dir
temp_image = open(os.path.join('/tmp',filename), 'w')
thumb.save(temp_image, 'JPEG')
#4. read the temp file back into a File
from django.core.files import File
thumb_data = open(os.path.join('/tmp',filename), 'r')
thumb_file = File(thumb_data)
new_file.thumb.save(str(new_file.id) + '.jpg', thumb_file)
这是一个实际工作的示例,使用的是Python 3.5和Django 1.10。
在views.py文件中:
from io import BytesIO
from django.core.files.base import ContentFile
from django.core.files.uploadedfile import InMemoryUploadedFile
def pill(image_io):
im = Image.open(image_io)
ltrb_border = (0, 0, 0, 10)
im_with_border = ImageOps.expand(im, border=ltrb_border, fill='white')
buffer = BytesIO()
im_with_border.save(fp=buffer, format='JPEG')
buff_val = buffer.getvalue()
return ContentFile(buff_val)
def save_img(request)
if request.POST:
new_record = AddNewRecordForm(request.POST, request.FILES)
pillow_image = pill(request.FILES['image'])
image_file = InMemoryUploadedFile(pillow_image, None, 'foo.jpg', 'image/jpeg', pillow_image.tell, None)
request.FILES['image'] = image_file # really need rewrite img in POST for success form validation
new_record.image = request.FILES['image']
new_record.save()
return redirect(...)
def resize_and_save(file):
size = 1024, 1024
thumbnail_size = 300, 300
uploaded_file_url = getURLforFile(file, size, MEDIA_ROOT)
uploaded_thumbnail_url = getURLforFile(file, thumbnail_size, THUMBNAIL_ROOT)
return [uploaded_file_url, uploaded_thumbnail_url]
def getURLforFile(file, size, location):
img = Image.open(file)
img.thumbnail(size, Image.ANTIALIAS)
thumb_io = BytesIO()
img.save(thumb_io, format='JPEG')
thumb_file = InMemoryUploadedFile(thumb_io, None, file.name, 'image/jpeg', thumb_io.tell, None)
fs = FileSystemStorage(location=location)
filename = fs.save(file.name, thumb_file)
return fs.url(filename)
if request.FILES:
fl, thumbnail = resize_and_save(request.FILES['avatar'])
#delete old profile picture before saving new one
try:
os.remove(BASE_DIR + user.userprofile.avatarURL)
except Exception as e:
pass
user.userprofile.avatarURL = fl
user.userprofile.thumbnailURL = thumbnail
user.userprofile.save()
from io import BytesIO
from django.core.files.base import ContentFile
import requests
# Read a file in
r = request.get(image_url)
image = r.content
scr = Image.open(BytesIO(image))
# Perform an image operation like resize:
width, height = scr.size
new_width = 320
new_height = int(new_width * height / width)
img = scr.resize((new_width, new_height))
# Get the Django file object
thumb_io = BytesIO()
img.save(thumb_io, format='JPEG')
photo_smaller = ContentFile(thumb_io.getvalue())
对于那些使用django-storages/-redux
将图像文件存储在S3上的人,这是我采取的路径(下面的示例创建了现有图像的缩略图):
from PIL import Image
import StringIO
from django.core.files.storage import default_storage
try:
# example 1: use a local file
image = Image.open('my_image.jpg')
# example 2: use a model's ImageField
image = Image.open(my_model_instance.image_field)
image.thumbnail((300, 200))
except IOError:
pass # handle exception
thumb_buffer = StringIO.StringIO()
image.save(thumb_buffer, format=image.format)
s3_thumb = default_storage.open('my_new_300x200_image.jpg', 'w')
s3_thumb.write(thumb_buffer.getvalue())
s3_thumb.close()
这里有一个可以实现此功能的应用程序:django-smartfields
from django.db import models
from smartfields import fields
from smartfields.dependencies import FileDependency
from smartfields.processors import ImageProcessor
class ImageModel(models.Model):
image = fields.ImageField(dependencies=[
FileDependency(processor=ImageProcessor(
scale={'max_width': 150, 'max_height': 150}))
])
如果您想保留旧文件,请确保将keep_orphans=True
传递给该字段,否则在替换时它们将被清理。