将使用魔杖生成的图像保存到django ImageField

时间：2015-01-30 23:59:32

标签： python django imagemagick django-models wand

我试图为＆＃34;叠加＆＃34;生成预览配置存储在django模型中，而不是稍后应用于其他模型。我没有太多使用python操作文件的经验... =（

这是我的代码：

import io
from django.conf import settings
from django.db import models
from wand.image import Image
from PIL.ImageFile import ImageFile, Parser, Image as PilImage

class Overlay(models.Model):
    RELATIVE_POSITIONS = (...)
    SIZE_MODES = (...)

    name = models.CharField(max_length=50)
    source = models.FileField(upload_to='overlays/%Y/%m/%d')
    sample = models.ImageField(upload_to='overlay_samples/%Y/%m/%d', blank=True)
    px = models.SmallIntegerField(default=0)
    py = models.SmallIntegerField(default=0)
    position = models.CharField(max_length=2, choices=RELATIVE_POSITIONS)
    width = models.SmallIntegerField(default=0)
    height = models.SmallIntegerField(default=0)
    size_mode = models.CharField(max_length=1, choices=SIZE_MODES, default='B')
    last_edit = models.DateTimeField(auto_now=True)

    def generate_sample(self):
        """
        Generates the sample image and saves it in the "sample" field model
        :return: void
        """
        base_pic = Image(filename=os.path.join(settings.BASE_DIR, 'girl.jpg'))
        overlay_pic = Image(file=self.source)
        result_pic = io.BytesIO()
        pil_parser = Parser()

        if self.width or self.height:
            resize_args = {}
            if self.width:
                resize_args['width'] = self.width
            if self.height:
                resize_args['height'] = self.height
            overlay_pic.resize(**resize_args)
            base_pic.composite(overlay_pic, self.px, self.py)
            base_pic.save(file=result_pic)

        result_pic.seek(0)
        while True:
            s = result_pic.read(1024)
            if not s:
                break
            pil_parser.feed(s)

        pil_result_pic = pil_parser.close()
        self.sample.save(self.name, pil_result_pic, False)

    def save(self, force_insert=False, force_update=False, using=None, update_fields=None):
        self.generate_sample()
        super(Overlay, self).save(force_insert, force_update, using, update_fields)

但我在这里读取AttributeError是我的django调试数据的一部分：

 /usr/local/lib/python2.7/dist-packages/django/core/files/utils.py in <lambda>

    """
    encoding = property(lambda self: self.file.encoding)
    fileno = property(lambda self: self.file.fileno)
    flush = property(lambda self: self.file.flush)
    isatty = property(lambda self: self.file.isatty)
    newlines = property(lambda self: self.file.newlines)
    read = property(lambda self: self.file.read)
    readinto = property(lambda self: self.file.readinto)
    readline = property(lambda self: self.file.readline)
    readlines = property(lambda self: self.file.readlines)
    seek = property(lambda self: self.file.seek)
    softspace = property(lambda self: self.file.softspace)
    tell = property(lambda self: self.file.tell)

▼本地变种 变量值

self    <File: None>



/usr/local/lib/python2.7/dist-packages/PIL/Image.py in __getattr__

        # numpy array interface support
        new = {}
        shape, typestr = _conv_type_shape(self)
        new['shape'] = shape
        new['typestr'] = typestr
        new['data'] = self.tobytes()
        return new
    raise AttributeError(name)

def __getstate__(self):
    return [
        self.info,
        self.mode,
        self.size,

▼本地变种 变量值

self    <PIL.JpegImagePlugin.JpegImageFile image mode=RGB size=1080x1618 at 0x7F1429291248>
name    'read'

出了什么问题？

3 个答案:

答案 0 :(得分：2)

解决！

例如@Alexey Kuleshevich说django FileField需要文件objeto，但缺少的是我们必须先将图像保存到磁盘或内存中的文件中，因为它会更好记忆......所以这是最终的解决方案。我认为可以改进不使用两步“转换”

from django.core.files.base import ContentFile

并在方法中：

    result_pic = io.BytesIO()
    pil_parser = Parser()

    ...
    overlay_pic.resize(**resize_args)
    base_pic.composite(overlay_pic, self.px, self.py)
    base_pic.save(file=result_pic)

    result_pic.seek(0)
    while True:
        s = result_pic.read(1024)
        if not s:
            break
        pil_parser.feed(s)

    result_pic = io.BytesIO()
    pil_result_pic = pil_parser.close()
    pil_result_pic.save(result_pic, format='JPEG')
    django_file = ContentFile(result_pic.getvalue())
    self.sample.save(self.name, django_file, False)

感谢这个答案： How do you convert a PIL Image to a Django File?

答案 1 :(得分：1)

以防万一，这是一个更优雅（在我看来）的实现。首先，它需要这个应用程序：django-smartfields。这个解决方案如何更好：

  • 仅在sample字段更改时更新source字段，并且仅在保存模型之前更新。
  • 如果省略keep_orphans，则会清除旧的source文件。

实际代码：

import os
from django.conf import settings
from django.db import models
from django.utils import six

from smartfields import fields
from smartfields.dependencies import FileDependency
from smartfields.processors import WandImageProcessor
from wand.image import Image

class CustomImageProcessor(WandImageProcessor):

    def resize(self, image, scale=None, instance=None, **kwargs):
        scale = {'width': instance.width, 'height': instance.height}
        return super(CustomImageProcessor, self).resize(
            image, scale=scale, instance=instance, **kwargs)

    def convert(self, image, instance=None, **kwargs):
        base_pic = Image(filename=os.path.join(settings.BASE_DIR, 'girl.jpg'))
        base_pic.composite(image, instance.px, instance.py)
        stream_out = super(CustomImageProcessor, self).convert(
            image, instance=instance, **kwargs):
        if stream_out is None:
            stream_out = six.BytesIO()
            base_pic.save(file=stream_out)
        return stream_out        


class Overlay(models.Model):
    RELATIVE_POSITIONS = (...)
    SIZE_MODES = (...)

    name = models.CharField(max_length=50)
    source = fields.ImageField(upload_to='overlays/%Y/%m/%d', dependencies=[
        FileDependency(attname='sample', processor=CustomImageProcessor())
    ], keep_orphans=True)
    sample = models.ImageField(upload_to='overlay_samples/%Y/%m/%d', blank=True)
    px = models.SmallIntegerField(default=0)
    py = models.SmallIntegerField(default=0)
    position = models.CharField(max_length=2, choices=RELATIVE_POSITIONS)
    width = models.SmallIntegerField(default=0)
    height = models.SmallIntegerField(default=0)
    size_mode = models.CharField(max_length=1, choices=SIZE_MODES, default='B')
    last_edit = models.DateTimeField(auto_now=True)

答案 2 :(得分：0)

每当您将文件保存到ImageField或FileField时，您需要确保它是Django的File对象。这里是对文档的引用：https://docs.djangoproject.com/en/1.7/ref/models/fields/#filefield-and-fieldfile 

from django.core.files import File

并在方法中：

def generate_sample(self):
    ...
    pil_result_pic = pil_parser.close()
    self.sample.save(self.name, File(pil_result_pic), False)

否则它看起来不错，虽然我可能错过了一些东西。尝试一下，看看它是否解决了问题，如果没有，我会更多地了解它。

修改

您实际上不需要解析器。我认为应该解决它：

from django.core.files import ContentFile

class Overlay(models.Model):
    ...

    def generate_sample(self):
        base_pic = Image(filename=os.path.join(settings.BASE_DIR, 'girl.jpg'))
        overlay_pic = Image(file=self.source)
        result_pic = io.BytesIO()

        if self.width or self.height:
            resize_args = {}
            if self.width:
                resize_args['width'] = self.width
            if self.height:
                resize_args['height'] = self.height
            overlay_pic.resize(**resize_args)
        base_pic.composite(overlay_pic, self.px, self.py)
        base_pic.save(file=result_pic)

        content = result_pic.getvalue()
        self.sample.save(self.name, ContentFile(content), False)
        result_pic.close()
        base_pic.close()
        overlay_pic.close()

有一件事可能是一个潜在的问题，它会在每次保存Overlay模型时执行此操作，即使原始图像是相同的。但如果很少保存，那应该不是问题。

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