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126 lines
4.2 KiB
Python
126 lines
4.2 KiB
Python
from pathlib import Path
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from django.core.exceptions import FieldError
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from django.db import models
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from django.db.models.fields.files import ImageFieldFile
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from PIL import Image
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from core.utils import resize_image_explicit
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class ResizedImageFieldFile(ImageFieldFile):
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def get_resized_dimensions(self, image: Image.Image) -> tuple[int, int]:
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"""Get the dimensions of the resized image.
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If the width and height are given, they are used.
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If only one is given, the other is calculated to keep the same ratio.
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Returns:
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Tuple of width and height
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"""
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width = self.field.width
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height = self.field.height
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if width is not None and height is not None:
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return self.field.width, self.field.height
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if width is None:
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width = int(image.width * height / image.height)
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elif height is None:
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height = int(image.height * width / image.width)
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return width, height
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def get_name(self) -> str:
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"""Get the name of the resized image.
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If the field has a force_format attribute,
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the extension of the file will be changed to match it.
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Otherwise, the name is left unchanged.
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Raises:
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ValueError: If the image format is unknown
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"""
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if not self.field.force_format:
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return self.name
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formats = {val: key for key, val in Image.registered_extensions().items()}
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new_format = self.field.force_format
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if new_format in formats:
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extension = formats[new_format]
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else:
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raise ValueError(f"Unknown format {new_format}")
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return str(Path(self.file.name).with_suffix(extension))
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def save(self, name, content, save=True): # noqa FBT002
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content.file.seek(0)
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img = Image.open(content.file)
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width, height = self.get_resized_dimensions(img)
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img_format = self.field.force_format or img.format
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new_content = resize_image_explicit(img, (width, height), img_format)
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name = self.get_name()
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return super().save(name, new_content, save)
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class ResizedImageField(models.ImageField):
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"""A field that automatically resizes images to a given size.
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This field is useful for profile pictures or product icons, for example.
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The final size of the image is determined by the width and height parameters :
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- If both are given, the image will be resized
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to fit in a rectangle of width x height
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- If only one is given, the other will be calculated to keep the same ratio
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If the force_format parameter is given, the image will be converted to this format.
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Examples:
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To resize an image with a height of 100px, without changing the ratio,
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and a format of WEBP :
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```python
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class Product(models.Model):
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icon = ResizedImageField(height=100, force_format="WEBP")
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```
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To explicitly resize an image to 100x100px (but possibly change the ratio) :
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```python
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class Product(models.Model):
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icon = ResizedImageField(width=100, height=100)
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```
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Raises:
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FieldError: If neither width nor height is given
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Args:
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width: If given, the width of the resized image
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height: If given, the height of the resized image
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force_format: If given, the image will be converted to this format
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"""
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attr_class = ResizedImageFieldFile
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def __init__(
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self,
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width: int | None = None,
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height: int | None = None,
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force_format: str | None = None,
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**kwargs,
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):
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if width is None and height is None:
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raise FieldError(
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f"{self.__class__.__name__} requires "
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"width, height or both, but got neither"
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)
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self.width = width
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self.height = height
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self.force_format = force_format
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super().__init__(**kwargs)
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def deconstruct(self):
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name, path, args, kwargs = super().deconstruct()
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if self.width is not None:
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kwargs["width"] = self.width
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if self.height is not None:
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kwargs["height"] = self.height
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kwargs["force_format"] = self.force_format
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return name, path, args, kwargs
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