保存时调整图像大小

Question

如何在将图像上传到Django后轻松调整图像大小？我正在使用Django 1.0.2，我已经安装了PIL。

我正在考虑覆盖模型的save（）方法来调整它的大小，但我真的不知道如何开始并覆盖它。

有人能指出我正确的方向吗？谢谢： - ）

@GuðmundurH： 这不起作用，因为django-stdimage包在Windows上不起作用： - （

Answer 1

我建议使用django-stdimage中的StdImageField，它应该为您处理所有脏工作。它易于使用，您只需在字段定义中指定已调整大小的图像的尺寸：

class MyModel(models.Model):
    image = StdImageField(upload_to='path/to/img',  size=(640, 480))

查看文档 - 它也可以缩略图。

Answer 2

您应该使用方法来处理上传的文件，如Django documentation。

中所示

在此方法中，您可以连接变量中的块（而不是直接将它们写入磁盘），从该变量创建PIL图像，调整图像大小并将其保存到磁盘。

在PIL中，您应该查看Image.fromstring和Image.resize。

Answer 3

我使用此代码处理上传的图像，在内存上调整它们的大小（不将它们永久保存在磁盘上），然后将拇指保存在Django ImageField上。 希望可以帮助。

    def handle_uploaded_image(i):
        import StringIO
        from PIL import Image, ImageOps
        import os
        from django.core.files import File
        # read image from InMemoryUploadedFile
        image_str = “”
        for c in i.chunks():
            image_str += c

        # create PIL Image instance
        imagefile  = StringIO.StringIO(image_str)
        image = Image.open(imagefile)

        # if not RGB, convert
        if image.mode not in (“L”, “RGB”):
            image = image.convert(“RGB”)

        #define file output dimensions (ex 60x60)
        x = 130
        y = 130

        #get orginal image ratio
        img_ratio = float(image.size[0]) / image.size[1]

        # resize but constrain proportions?
        if x==0.0:
            x = y * img_ratio
        elif y==0.0:
            y = x / img_ratio

        # output file ratio
        resize_ratio = float(x) / y
        x = int(x); y = int(y)

        # get output with and height to do the first crop
        if(img_ratio > resize_ratio):
            output_width = x * image.size[1] / y
            output_height = image.size[1]
            originX = image.size[0] / 2 - output_width / 2
            originY = 0
        else:
            output_width = image.size[0]
            output_height = y * image.size[0] / x
            originX = 0
            originY = image.size[1] / 2 - output_height / 2

        #crop
        cropBox = (originX, originY, originX + output_width, originY + output_height)
        image = image.crop(cropBox)

        # resize (doing a thumb)
        image.thumbnail([x, y], Image.ANTIALIAS)

        # re-initialize imageFile and set a hash (unique filename)
        imagefile = StringIO.StringIO()
        filename = hashlib.md5(imagefile.getvalue()).hexdigest()+’.jpg’

        #save to disk
        imagefile = open(os.path.join(‘/tmp’,filename), ‘w’)
        image.save(imagefile,’JPEG’, quality=90)
        imagefile = open(os.path.join(‘/tmp’,filename), ‘r’)
        content = File(imagefile)

        return (filename, content)

#views.py

    form = YourModelForm(request.POST, request.FILES, instance=profile)
        if form.is_valid():
            ob = form.save(commit=False)
            try:
                t = handle_uploaded_image(request.FILES[‘icon’])
                ob.image.save(t[0],t[1])
            except KeyError:
                ob.save()

Answer 4

我强烈建议sorl-thumbnail应用程序轻松，透明地处理图像大小调整。它出现在我开始的每一个Django项目中。

Answer 5

我知道这已经过时了，但对于任何绊倒它的人来说，Django-thumbs - Easy powerful thumbnails for Django integrated with StorageBackend处有一个包django-thumbs，它会自动生成您指定大小的缩略图，如果不这样，则不会生成缩略图。然后，使用所需的尺寸调用所需的缩略图。

例如，如果您希望图片的缩略图为64x64和128x128，则只需导入thumbs.models.ImageWithThumbsField，然后使用它代替ImageField。将参数sizes=((64,64),(128,128))添加到字段定义中，然后从模板中调用：

{{ ClassName.field_name.url_64x64 }}

和

{{ ClassName.field_name.url_128x128 }}

显示缩略图。瞧！所有工作都在这个包中完成。

Answer 6

以下是使用表单的完整解决方案。我使用了管理员视图：

class MyInventoryItemForm(forms.ModelForm):

    class Meta:
        model = InventoryItem
        exclude = ['thumbnail', 'price', 'active']

    def clean_photo(self):
        import StringIO
        image_field = self.cleaned_data['photo']
        photo_new = StringIO.StringIO(image_field.read())

        try:
            from PIL import Image, ImageOps

        except ImportError:
            import Image
            import ImageOps

        image = Image.open(photo_new)

        # ImageOps compatible mode
        if image.mode not in ("L", "RGB"):
            image = image.convert("RGB")

        image.thumbnail((200, 200), Image.ANTIALIAS)

        image_file = StringIO.StringIO()
        image.save(image_file, 'png')

        image_field.file = image_file

        return image_field

我的库存模型如下所示：

class InventoryItem(models.Model):

    class Meta:
        ordering = ['name']
        verbose_name_plural = "Items"

    def get_absolute_url(self):
        return "/products/{0}/".format(self.slug)

    def get_file_path(instance, filename):

        if InventoryItem.objects.filter(pk=instance.pk):
            cur_inventory = InventoryItem.objects.get(pk=instance.pk)
            if cur_inventory.photo:
                old_filename = str(cur_inventory.photo)
                os.remove(os.path.join(MEDIA_ROOT, old_filename))

        ext = filename.split('.')[-1]
        filename = "{0}.{1}".format(uuid.uuid4(), ext)
        return os.path.join('inventory', filename)
        #return os.path.join(filename)

    def admin_image(self):
        return '<img height="50px" src="{0}/{1}"/>'.format(MEDIA_URL, self.photo)
    admin_image.allow_tags = True

    photo = models.ImageField(_('Image'), upload_to=get_file_path, storage=fs, blank=False, null=False)
    thumbnail = models.ImageField(_('Thumbnail'), upload_to="thumbnails/", storage=fs,     blank=True, null=True)

...

我结束了覆盖模特的保存功能而不是保存照片和拇指而不只是调整照片大小：

def save(self):

    # Save this photo instance first
    super(InventoryItem, self).save()

    from PIL import Image
    from cStringIO import StringIO
    from django.core.files.uploadedfile import SimpleUploadedFile

    # Set our max thumbnail size in a tuple (max width, max height)
    THUMBNAIL_SIZE = (200, 200)

    # Open original photo which we want to thumbnail using PIL's Image object
    image = Image.open(os.path.join(MEDIA_ROOT, self.photo.name))

    if image.mode not in ('L', 'RGB'):
        image = image.convert('RGB')

    image.thumbnail(THUMBNAIL_SIZE, Image.ANTIALIAS)

    # Save the thumbnail
    temp_handle = StringIO()
    image.save(temp_handle, 'png')  # image stored to stringIO

    temp_handle.seek(0)  # sets position of file to 0

     # Save to the thumbnail field
     suf = SimpleUploadedFile(os.path.split(self.photo.name)[-1],
        temp_handle.read(), content_type='image/png')  # reads in the file to save it

    self.thumbnail.save(suf.name+'.png', suf, save=False)

    #Save this photo instance again to save the thumbnail
    super(InventoryItem, self).save()

虽然取决于你想做什么，但两者都很有效：）

Answer 7

如果您使用的是Django Rest Framework，则可能会使用：

第一个定义函数来压缩和调整图像大小

def compress_image(photo):
# start compressing image
image_temporary = Image.open(photo)
output_io_stream = BytesIO()
image_temporary.thumbnail((1250, 1250), Image.ANTIALIAS)

# change orientation if necessary
for orientation in ExifTags.TAGS.keys():
    if ExifTags.TAGS[orientation] == 'Orientation':
        break
exif = dict(image_temporary._getexif().items())
# noinspection PyUnboundLocalVariable
if exif.get(orientation) == 3:
    image_temporary = image_temporary.rotate(180, expand=True)
elif exif.get(orientation) == 6:
    image_temporary = image_temporary.rotate(270, expand=True)
elif exif.get(orientation) == 8:
    image_temporary = image_temporary.rotate(90, expand=True)

# saving output
image_temporary.save(output_io_stream, format='JPEG', quality=75, optimize=True, progressive=True)
output_io_stream.seek(0)
photo = InMemoryUploadedFile(output_io_stream, 'ImageField', "%s.jpg" % photo.name.split('.')[0],
                             'image/jpeg', getsizeof(output_io_stream), None)
return photo

第二，现在您可以在序列化器中使用该功能：

class SomeSerializer(serializers.ModelSerializer):
def update(self, instance, validated_data):
    # сжимаем рисунок
    if 'photo' in validated_data:           
        validated_data.update({'photo': compress_image(validated_data['photo'])})

    return super(SomeSerializer, self).update(instance, validated_data)

def create(self, validated_data):
    # сжимаем рисунок
    if 'photo' in validated_data:
        validated_data.update({'photo': compress_image(validated_data['photo'])})

    return super(SomeSerializer, self).create(validated_data)