Django 圖片上傳和調整大小

Question

我有一個帶有圖像字段的標准 Django 表單。 上傳圖片時，我想確保圖片不大於 300 像素 x 300 像素。 這是我的代碼：

def post(request):
    if request.method == 'POST':
        instance = Product(posted_by=request.user)
        form = ProductModelForm(request.POST or None, request.FILES or None)
        if form.is_valid():
           new_product = form.save(commit=False)
           if 'image' in request.FILES:
              img = Image.open(form.cleaned_data['image'])
              img.thumbnail((300, 300), Image.ANTIALIAS)

              # this doesnt save the contents here...
              img.save(new_product.image)

              # ..because this prints the original width (2830px in my case)
              print new_product.image.width

我面臨的問題是，我不清楚如何將Image類型轉換為 ImageField 類型。

Answer 1

從 ImageField 的保存方法的文檔中：

注意內容參數應該是 django.core.files.File 的實例，而不是 Python 的內置文件 object。

This means you would need to convert the PIL.Image ( img ) to a Python file object, and then convert the Python object to a django.core.files.File object. 像這樣的東西（我沒有測試過這段代碼）可能會起作用：

img.thumbnail((300, 300), Image.ANTIALIAS)

# Convert PIL.Image to a string, and then to a Django file
# object. We use ContentFile instead of File because the
# former can operate on strings.
from django.core.files.base import ContentFile
djangofile = ContentFile(img.tostring())
new_product.image.save(filename, djangofile)

Answer 2

那里有 go，只需更改一點以滿足您的需要：

class PhotoField(forms.FileField, object):

    def __init__(self, *args, **kwargs):
        super(PhotoField, self).__init__(*args, **kwargs)
        self.help_text = "Images over 500kb will be resized to keep under 500kb limit, which may result in some loss of quality"

    def validate(self,image):
        if not str(image).split('.')[-1].lower() in ["jpg","jpeg","png","gif"]:
            raise ValidationError("File format not supported, please try again and upload a JPG/PNG/GIF file")

    def to_python(self, image):
        try:
            limit = 500000
            num_of_tries = 10
            img = Image.open(image.file)
            width, height = img.size
            ratio = float(width) / float(height)

            upload_dir = settings.FILE_UPLOAD_TEMP_DIR if settings.FILE_UPLOAD_TEMP_DIR else '/tmp'
            tmp_file = open(os.path.join(upload_dir, str(uuid.uuid1())), "w")
            tmp_file.write(image.file.read())
            tmp_file.close()

            while os.path.getsize(tmp_file.name) > limit:
                num_of_tries -= 1
                width = 900 if num_of_tries == 0 else width - 100
                height = int(width / ratio)
                img.thumbnail((width, height), Image.ANTIALIAS)
                img.save(tmp_file.name, img.format)
                image.file = open(tmp_file.name)
                if num_of_tries == 0:
                    break                    
        except:
            pass
        return image

來源： http://james.lin.net.nz/2012/11/19/django-snippet-reduce-image-size-during-upload/

Answer 3

這是一個可以解決這個問題的應用程序： django-smartfields

from django.db import models

from smartfields import fields
from smartfields.dependencies import FileDependency
from smartfields.processors import ImageProcessor

class Product(models.Model):
    image = fields.ImageField(dependencies=[
        FileDependency(processor=ImageProcessor(
            scale={'max_width': 300, 'max_height': 300}))
    ])

Answer 4

如何使用標准圖像場https://github.com/humanfromearth/django-stdimage

Answer 5

在這里嘗試我的解決方案： https://stackoverflow.com/a/25222000/3731039

強調

• 使用 Pillow 進行圖像處理（需要兩個包：libjpeg-dev、zlib1g-dev）
• 使用 Model 和 ImageField 作為存儲
• 使用 HTTP POST 或 PUT 與 multipart/form
• 無需手動將文件保存到磁盤。
• 創建多個分辨率並存儲它們的尺寸。

Answer 6

你可以使用我的庫django-sizedimagefield ，它沒有額外的依賴並且使用起來非常簡單。