django-assetkit/assetkit/models/assets.py

# -*- coding: utf-8 -*-
from __future__ import unicode_literals
# Erik Stein <code@classlibrary.net>, 2016

from django.db import models
from django.utils.translation import ugexttext_lazy as _

from imagekit.models import ImageSpecField
from imagekit.processors import Adjust, Thumbnail, ResizeToFit

from ..exceptions import ConversionNotApplicable
from ..processors import Noop, Placeholder

from .fields import MediaAssetFileField


MEDIA_TYPE_CHOICES = (
        (UNKNOWN,  _("unknown")),
        (IMAGE,    _("image")),
        (MOVIE,    _("movie")),
        (AUDIO,    _("audio")),
        (PDF,      _("pdf")),
        (SVG,      _("svg")),
        (VECTOR,   _("eps")),
        (DOCUMENT, _("document")),
    )


class ImageMediaHandler(object):
    # thumbnail = ImageSpecField(ThumbnailSpec)

    thumbnail = ImageSpecField(source='file',
            processors=[Adjust(contrast=1.2, sharpness=1.1),
                        Thumbnail(100, 50)],
            format='JPEG', options={'quality': 90})


# class PDFFile(object)
#     def get_page(self, num):
#     def get_page_count(self):


class PDFMediaHandler(object):
    # thumbnail = ImageSpec
    # small_downloadable = PDFSpecField

    def page_count(self):
        # self.original_file = PDFFile()
        return count(self.original_file.pages)


class MovieMediaHandler(object):
    # thumbnail = ImageSpec
    # desktop_webm = MovieSpecField
    # desktop_mp4 = MovieSpecField
    pass


class MediaAsset(models.Model):
    """
    TODO Django should have a internal=True parameter on FileFields, preventing URL based access to the files

    Depending on the type the Asset might have different
    """
    # TODO Added uuid field
    original_file = MediaAssetFileField(_("original file"), metadata_field='metadata')
    original_mimetype = models.CharField(_("mimetype"), blank=True, max_length=50)
    metadata = models.JSONField()
    media_type = models.ChoiceField(_("media type"), blank=True, choices=MEDIA_TYPE_CHOICES, default=MEDIA_TYPE_CHOICES[0][0])
    description = models.TextField(_("internal description"), null=True, blank=True)
    slug = SlugField(help_text=_("should contain only the most specific part of the description, e.g.\"poster\"; the whole filename will be automatically build from the object the asset is attached and "))
    # copyright = models.TextField(_("copyright"), null=True, blank=True)
    # author = models.TextField(_("author"), null=True, blank=True)

    def save(self, *args, **kwargs):
        # TODO Fill media_type field
        # TODO Fill mimetype field
        super(MediaAsset, self).save(*args, **kwargs)

    @property
    def media_handler(self):
        """
        Returns a media_handler instance depending on the type
        of the original file.

        >>> m = MediaAsset.objects.first()
        >>> m.original_file
        'media/0/reference.png'
        >>> m.media_handler.thumbnail
        """
        pass