保存时调整图像大小

Question

在Django上传图像后如何轻松调整图像大小？我正在使用Django 1.0.2,我已经安装了PIL.

我正在考虑重写模型的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:这不行,因为django-stdimage包在Windows上不起作用:-(

Answer 1

我建议使用django-stdimage中的StdImageField,它应该为你处理所有脏工作.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 - 它也可以做缩略图.

Answer 2

您应该使用一种方法来处理上传的文件,如Django文档中所示.

在此方法中,您可以在变量中连接块(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,你应该看看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

我强烈推荐使用sorl-thumbnail应用程序轻松,透明地处理图像大小调整.它开始于我开始的每一个Django项目.