[英]Converting a PIL.Image to wagtailimages.Image
我正在使用枕頭為圖像創建縮略圖,但是我無法將它們存儲在字段image_thumbnail中,因為該字段的類型為Image,並且我遇到了一個例外:ValueError:無法分配“”:“ GalleryItem.image_thumbnail”必須為一個“圖像”實例。
g已經在使用枕頭,但我找不到簡單的方法來做...
class GalleryItem(models.Model):
image = models.ForeignKey(
'wagtailimages.Image',
null=True,
blank=True,
on_delete=models.SET_NULL,
related_name='+',
help_text='Image size must be 1440 x 961 px.'
)
image_thumbnail = models.ForeignKey(
'wagtailimages.Image',
null=True,
blank=True,
on_delete=models.SET_NULL,
related_name='+',
)
category = models.ForeignKey(
'ImageCategorie',
null=True,
blank=True,
on_delete=models.SET_NULL,
related_name='+'
)
def createThumbnails(self):
size = (300, 300)
outfile = self.image.title.split('.')[0] + ".thumbnail.jpg"
try:
im = Image.open(self.image.file)
im.thumbnail(size)
im.save(outfile, format="jpeg")
return im
except IOError:
print("cannot create thumbnail for", self.image.file)
def save(self, *args, **kwargs):
self.image_thumbnail = self.createThumbnails()
import ipdb; ipdb.set_trace()
super(GalleryItem, self).save(*args, **kwargs)
def __str__(self):
return self.image.title
從概念上講,PIL.Image和wagtailimages.Image是兩個不同的東西:PIL.Image表示一個圖像文件(即一堆特定的像素),而wagtailimages.Image是一個“圖片”的數據庫記錄,可以選擇並重用。編輯內容,並帶有支持的元數據(通常僅是標題,但其他字段也是可能的),並且能夠以任意大小重新呈現它。 使用wagtailimages.Image存儲現有圖像的縮略圖版本是矯枉過正,你很可能推遲作出更好的image_thumbnail
領域的Django ImageField
(這在“組像素”感存儲的圖像)。
如果您確實想在這里使用wagtailimages.Image,可以,但是您需要為該圖像創建數據庫記錄, 然后將其附加到GalleryItem對象。 該代碼將類似於:
from io import BytesIO
from PIL import Image as PILImage
from django.core.files.images import ImageFile
from wagtail.images.models import Image as WagtailImage
...
pil_image = PILImage.open(self.image.file)
pil_image.thumbnail(size)
f = BytesIO()
pil_image.save(f, 'JPEG')
wagtail_image = WagtailImage.objects.create(
title=('thumbnail of %s' % self.image.title),
file=ImageFile(f, name=outfile)
)
self.image_thumbnail = wagtail_image
在看到加斯曼的答案之前,我成功完成了以下代碼:
def createThumbnails(self):
# Set our max thumbnail size in a tuple (max width, max height)
THUMBNAIL_SIZE = (200, 200)
outfile = self.image.title.split('.')[0] + ".thumbnail.jpg"
extention = self.image.filename.split('.')[1]
img_io = BytesIO()
PIL_TYPE = 'jpeg'
try:
# Open original photo which we want to thumbnail using PIL's Image
im = PILImage.open(BytesIO(self.image.file.read()))
im.thumbnail(THUMBNAIL_SIZE, PILImage.ANTIALIAS)
im.save(img_io, PIL_TYPE)
img_io.seek(0)
# Save image to a SimpleUploadedFile which can be saved into
# ImageField
suf = SimpleUploadedFile(outfile, img_io.read())
self.screenshot.save(outfile, suf, save=False)
except IOError:
print("cannot create thumbnail for", self.image.file)
def save(self, *args, **kwargs):
self.createThumbnails()
super(GalleryItem, self).save(force_update=False)
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