constants/base.py

@@ -100,3 +100,10 @@ ABUSE_TYPE = Choices(
     ('ABUSE_USER', ABUSE_TYPE_USER, "User"),
     ('ABUSE_RATING', ABUSE_TYPE_RATING, "Rating"),
 )
+
+# **N.B.**: thumbnail sizes are not intended to be changed on the fly:
+# thumbnails of existing images must exist in MEDIA_ROOT before
+# the code expecting thumbnails of new dimensions can be deployed!
+THUMBNAIL_SIZES = {'1080p': [1920, 1080], '360p': [640, 360]}
+THUMBNAIL_FORMAT = 'PNG'
+THUMBNAIL_QUALITY = 83

extensions/templates/extensions/components/card.html

@@ -1,13 +1,13 @@
 {% load common filters %}
-{% with latest=extension.latest_version %}
+{% with latest=extension.latest_version thumbnail_360p_url=extension.previews.listed.first.thumbnail_360p_url %}
 
 <div class="ext-card {% if blur %}is-background-blur{% endif %}">
   {% if blur %}
-  <div class="ext-card-thumbnail-blur" style="background-image: url({{ extension.previews.listed.first.source.url }});"></div>
+  <div class="ext-card-thumbnail-blur" style="background-image: url({{ thumbnail_360p_url }});"></div>
   {% endif %}
 
   <a class="ext-card-thumbnail" href="{{ extension.get_absolute_url }}">
-    <div class="ext-card-thumbnail-img" style="background-image: url({{ extension.previews.listed.first.source.url }});" title="{{ extension.name }}"></div>
+    <div class="ext-card-thumbnail-img" style="background-image: url({{ thumbnail_360p_url }});" title="{{ extension.name }}"></div>
   </a>
 
   <div class="ext-card-body">

extensions/templates/extensions/components/galleria.html

@@ -3,19 +3,17 @@
   {% if previews %}
   <div class="galleria-items{% if previews.count > 5 %} is-many{% endif %}{% if previews.count == 1 %} is-single{% endif %}" id="galleria-items">
     {% for preview in previews %}
+      {% with thumbnail_1080p_url=preview.thumbnail_1080p_url %}
       <a
         class="galleria-item js-galleria-item-preview galleria-item-type-{{ preview.content_type|slugify|slice:5 }}{% if forloop.first %} is-active{% endif %}"
-      href="{{ preview.source.url }}"
+        href="{{ thumbnail_1080p_url }}"
         {% if 'video' in preview.content_type %}data-galleria-video-url="{{ preview.source.url }}"{% endif %}
         data-galleria-content-type="{{ preview.content_type }}"
         data-galleria-index="{{ forloop.counter }}">
 
-        {% if 'video' in preview.content_type and preview.thumbnail %}
+        <img src="{{ thumbnail_1080p_url }}" alt="{{ preview.preview.caption }}">
-        <img src="{{ preview.thumbnail.url }}" alt="{{ preview.preview.caption }}">
-        {% else %}
-        <img src="{{ preview.source.url }}" alt="{{ preview.preview.caption }}">
-        {% endif %}
         </a>
+      {% endwith %}
     {% endfor %}
   </div>
   {% else %}

files/admin.py

@@ -1,10 +1,16 @@
+import logging
+
+from django.conf import settings
 from django.contrib import admin
+from django.template.loader import render_to_string
 import background_task.admin
 import background_task.models
 
 from .models import File, FileValidation
 import files.signals
 
+logger = logging.getLogger(__name__)
+
 
 def scan_selected_files(self, request, queryset):
     """Scan selected files."""
@@ -12,6 +18,12 @@ def scan_selected_files(self, request, queryset):
         files.signals.schedule_scan(instance)
 
 
+def make_thumbnails(self, request, queryset):
+    """Schedule thumbnails generation for selected files."""
+    for instance in queryset.filter(type__in=(File.TYPES.IMAGE, File.TYPES.VIDEO)):
+        files.tasks.make_thumbnails(file_id=instance.pk)
+
+
 class FileValidationInlineAdmin(admin.StackedInline):
     model = FileValidation
     readonly_fields = ('date_created', 'date_modified', 'is_ok', 'results')
@@ -27,6 +39,28 @@ class FileValidationInlineAdmin(admin.StackedInline):
 
 @admin.register(File)
 class FileAdmin(admin.ModelAdmin):
+    class Media:
+        css = {'all': ('files/admin/file.css',)}
+
+    def thumbnails(self, obj):
+        if not obj or not (obj.is_image or obj.is_video):
+            return ''
+        try:
+            context = {'file': obj, 'MEDIA_URL': settings.MEDIA_URL}
+            return render_to_string('files/admin/thumbnails.html', context)
+        except Exception:
+            # Make sure any exception happening here is always logged
+            # (e.g. admin eats exceptions in ModelAdmin properties, making it hard to debug)
+            logger.exception('Failed to render thumbnails')
+            raise
+
+    def get_form(self, request, obj=None, **kwargs):
+        """Override metadata help text depending on file type."""
+        if obj and (obj.is_image or obj.is_video):
+            help_text = 'Additional information about the file, e.g. existing thumbnails.'
+            kwargs.update({'help_texts': {'metadata': help_text}})
+        return super().get_form(request, obj, **kwargs)
+
     view_on_site = False
     save_on_top = True
 
@@ -48,6 +82,9 @@ class FileAdmin(admin.ModelAdmin):
         'date_approved',
         'date_status_changed',
         'size_bytes',
+        'thumbnails',
+        'thumbnail',
+        'type',
         'user',
         'original_hash',
         'original_name',
@@ -67,9 +104,8 @@ class FileAdmin(admin.ModelAdmin):
             {
                 'fields': (
                     'id',
-                    ('source', 'thumbnail'),
+                    ('source', 'thumbnails', 'thumbnail'),
-                    ('original_name', 'content_type'),
+                    ('type', 'content_type', 'original_name'),
-                    'type',
                     'status',
                 )
             },
@@ -99,7 +135,7 @@ class FileAdmin(admin.ModelAdmin):
     )
 
     inlines = [FileValidationInlineAdmin]
-    actions = [scan_selected_files]
+    actions = [scan_selected_files, make_thumbnails]
 
     def is_ok(self, obj):
         return obj.validation.is_ok if hasattr(obj, 'validation') else None

files/migrations/0008_alter_file_thumbnail.py

@@ -0,0 +1,19 @@
+# Generated by Django 4.2.11 on 2024-04-23 10:31
+
+from django.db import migrations, models
+import files.models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('files', '0007_alter_file_status'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='file',
+            name='thumbnail',
+            field=models.ImageField(blank=True, editable=False, help_text='Thumbnail generated from uploaded image or video source file', max_length=256, null=True, upload_to=files.models.thumbnail_upload_to),
+        ),
+    ]

files/models.py

@@ -6,11 +6,8 @@ from django.contrib.auth import get_user_model
 from django.db import models
 
 from common.model_mixins import CreatedModifiedMixin, TrackChangesMixin
-from files.utils import get_sha256, guess_mimetype_from_ext
+from files.utils import get_sha256, guess_mimetype_from_ext, get_thumbnail_upload_to
-from constants.base import (
+from constants.base import FILE_STATUS_CHOICES, FILE_TYPE_CHOICES
-    FILE_STATUS_CHOICES,
-    FILE_TYPE_CHOICES,
-)
 import utils
 
 User = get_user_model()
@@ -41,15 +38,11 @@ def file_upload_to(instance, filename):
 
 
 def thumbnail_upload_to(instance, filename):
-    prefix = 'thumbnails/'
+    return get_thumbnail_upload_to(instance.hash)
-    _hash = instance.hash.split(':')[-1]
-    extension = Path(filename).suffix
-    path = Path(prefix, _hash[:2], _hash).with_suffix(extension)
-    return path
 
 
 class File(CreatedModifiedMixin, TrackChangesMixin, models.Model):
-    track_changes_to_fields = {'status', 'size_bytes', 'hash'}
+    track_changes_to_fields = {'status', 'size_bytes', 'hash', 'thumbnail', 'metadata'}
 
     TYPES = FILE_TYPE_CHOICES
     STATUSES = FILE_STATUS_CHOICES
@@ -63,7 +56,8 @@ class File(CreatedModifiedMixin, TrackChangesMixin, models.Model):
         null=True,
         blank=True,
         max_length=256,
-        help_text='Image thumbnail in case file is a video',
+        help_text='Thumbnail generated from uploaded image or video source file',
+        editable=False,
     )
     content_type = models.CharField(max_length=256, null=True, blank=True)
     type = models.PositiveSmallIntegerField(
@@ -203,6 +197,30 @@ class File(CreatedModifiedMixin, TrackChangesMixin, models.Model):
     def get_submit_url(self) -> str:
         return self.extension.get_draft_url()
 
+    def get_thumbnail_of_size(self, size_key: str) -> str:
+        """Return absolute path portion of the URL of a thumbnail of this file.
+
+        Fall back to the source file, if no thumbnail is stored.
+        Log absence of the thumbnail file instead of exploding somewhere in the templates.
+        """
+        # We don't (yet?) have thumbnails for anything other than images and videos.
+        assert self.is_image or self.is_video, f'File pk={self.pk} is neither image nor video'
+
+        try:
+            path = self.metadata['thumbnails'][size_key]['path']
+            return self.thumbnail.storage.url(path)
+        except (KeyError, TypeError):
+            log.exception(f'File pk={self.pk} is missing thumbnail "{size_key}": {self.metadata}')
+        return self.source.url
+
+    @property
+    def thumbnail_1080p_url(self) -> str:
+        return self.get_thumbnail_of_size('1080p')
+
+    @property
+    def thumbnail_360p_url(self) -> str:
+        return self.get_thumbnail_of_size('360p')
+
 
 class FileValidation(CreatedModifiedMixin, TrackChangesMixin, models.Model):
     track_changes_to_fields = {'is_ok', 'results'}

files/signals.py

@@ -5,6 +5,7 @@ from django.dispatch import receiver
 
 import files.models
 import files.tasks
+import files.utils
 
 logger = logging.getLogger(__name__)
 
@@ -35,6 +36,30 @@ def _scan_new_file(
     schedule_scan(instance)
 
 
+def schedule_thumbnails(file: files.models.File) -> None:
+    """Schedule thumbnail generation for a given file."""
+    args = {'pk': file.pk, 'type': file.get_type_display()}
+    logger.info('Scheduling thumbnail generation for file pk=%(pk)s type=%(type)s', args)
+    verbose_name = f'make thumbnails for "{file.source.name}"'
+    files.tasks.make_thumbnails(file_id=file.pk, creator=file, verbose_name=verbose_name)
+
+
+@receiver(post_save, sender=files.models.FileValidation)
+def _schedule_thumbnails(
+    sender: object, instance: files.models.FileValidation, created: bool, **kwargs: object
+) -> None:
+    if not created:
+        return
+
+    if not instance.is_ok:
+        return
+
+    file = instance.file
+    # Generate thumbnails if initial scan found no issues
+    if file.is_image or file.is_video:
+        schedule_thumbnails(file)
+
+
 @receiver(pre_delete, sender=files.models.File)
 @receiver(pre_delete, sender=files.models.FileValidation)
 def _log_deletion(sender: object, instance: files.models.File, **kwargs: object) -> None:
@@ -46,3 +71,4 @@ def delete_orphaned_files(sender: object, instance: files.models.File, **kwargs:
     """Delete source and thumbnail files from storage when File record is deleted."""
     files.utils.delete_file_in_storage(instance.source.name)
     files.utils.delete_file_in_storage(instance.thumbnail.name)
+    files.utils.delete_thumbnails(instance.metadata)

files/static/files/admin/file.css

@@ -0,0 +1,11 @@
+.file-thumbnail {
+    display: inline-block;
+    border: grey solid 1px;
+    margin-left: 0.5rem;
+}
+.file-thumbnail-size {
+    position: absolute;
+    background: rgba(255, 255, 255, 0.5);
+    padding-right: 0.5rem;
+    padding-left: 0.5rem;
+}

files/tasks.py

@@ -27,3 +27,45 @@ def clamdscan(file_id: int):
         file_validation.results = scan_result
         file_validation.is_ok = is_ok
         file_validation.save(update_fields={'results', 'is_ok', 'date_modified'})
+
+
+@background(schedule={'action': TaskSchedule.RESCHEDULE_EXISTING})
+def make_thumbnails(file_id: int) -> None:
+    """Generate thumbnails for a given file, store them in thumbnail and metadata columns."""
+    file = files.models.File.objects.get(pk=file_id)
+    args = {'pk': file_id, 'type': file.get_type_display()}
+
+    if not file.is_image and not file.is_video:
+        logger.error('File pk=%(pk)s of type "%(type)s" is neither an image nor a video', args)
+        return
+    if not file.validation.is_ok:
+        logger.error("File pk={pk} is flagged, won't make thumbnails".format(**args))
+        return
+
+    # For an image, source of the thumbnails is the original image
+    source_path = file.source.path
+    thumbnail_field = file.thumbnail
+    unchanged_thumbnail = thumbnail_field.name
+
+    if file.is_video:
+        frame_path = files.utils.get_thumbnail_upload_to(file.hash)
+        # For a video, source of the thumbnails is a frame extracted with ffpeg
+        files.utils.extract_frame(source_path, frame_path)
+        thumbnail_field.name = frame_path
+        source_path = frame_path
+
+    thumbnails = files.utils.make_thumbnails(source_path, file.hash)
+
+    if not thumbnail_field.name:
+        thumbnail_field.name = thumbnails['1080p']['path']
+
+    update_fields = set()
+    if thumbnail_field.name != unchanged_thumbnail:
+        update_fields.add('thumbnail')
+    if file.metadata.get('thumbnails') != thumbnails:
+        file.metadata.update({'thumbnails': thumbnails})
+        update_fields.add('metadata')
+    if update_fields:
+        args['update_fields'] = update_fields
+        logger.info('Made thumbnails for file pk=%(pk)s, updating %(update_fields)s', args)
+        file.save(update_fields=update_fields)

files/templates/files/admin/thumbnails.html

@@ -0,0 +1,8 @@
+<div class="file-thumbnails">
+  {% for size_key, thumb in file.metadata.thumbnails.items %}
+    <div class="file-thumbnail">
+      <span class="file-thumbnail-size">{{ thumb.size.0 }}x{{ thumb.size.1 }}px</span>
+      <img height="{% widthratio thumb.size.1 10 1 %}" src="{{ MEDIA_URL }}{{ thumb.path }}" title={{ thumb.path }}>
+    </div>
+  {% endfor %}
+</div>

files/tests/test_models.py

@@ -42,9 +42,11 @@ class FileTest(TestCase):
                     'new_state': {'status': 'Approved'},
                     'object': '<File: test.zip (Approved)>',
                     'old_state': {
-                        'status': 2,
                         'hash': 'foobar',
+                        'metadata': {},
                         'size_bytes': 7149,
+                        'status': 2,
+                        'thumbnail': '',
                     },
                 }
             },

files/tests/test_tasks.py

@@ -0,0 +1,112 @@
+from pathlib import Path
+from unittest.mock import patch
+import logging
+
+from django.test import TestCase, override_settings
+
+from common.tests.factories.files import FileFactory
+from files.tasks import make_thumbnails
+import files.models
+
+TEST_MEDIA_DIR = Path(__file__).resolve().parent / 'media'
+
+
+@override_settings(MEDIA_ROOT=TEST_MEDIA_DIR)
+class TasksTest(TestCase):
+    def test_make_thumbnails_fails_when_no_validation(self):
+        file = FileFactory(original_hash='foobar', source='file/original_image_source.jpg')
+
+        with self.assertRaises(files.models.File.validation.RelatedObjectDoesNotExist):
+            make_thumbnails.task_function(file_id=file.pk)
+
+    @patch('files.utils.make_thumbnails')
+    def test_make_thumbnails_fails_when_validation_not_ok(self, mock_make_thumbnails):
+        file = FileFactory(original_hash='foobar', source='file/original_image_source.jpg')
+        files.models.FileValidation.objects.create(file=file, is_ok=False, results={})
+
+        with self.assertLogs(level=logging.ERROR) as logs:
+            make_thumbnails.task_function(file_id=file.pk)
+
+        self.maxDiff = None
+        self.assertEqual(
+            logs.output[0], f"ERROR:files.tasks:File pk={file.pk} is flagged, won't make thumbnails"
+        )
+
+        mock_make_thumbnails.assert_not_called()
+
+    @patch('files.utils.make_thumbnails')
+    def test_make_thumbnails_fails_when_not_image_or_video(self, mock_make_thumbnails):
+        file = FileFactory(
+            original_hash='foobar', source='file/source.zip', type=files.models.File.TYPES.THEME
+        )
+
+        with self.assertLogs(level=logging.ERROR) as logs:
+            make_thumbnails.task_function(file_id=file.pk)
+
+        self.maxDiff = None
+        self.assertEqual(
+            logs.output[0],
+            f'ERROR:files.tasks:File pk={file.pk} of type "Theme" is neither an image nor a video',
+        )
+
+        mock_make_thumbnails.assert_not_called()
+
+    @patch('files.utils.resize_image')
+    @patch('files.utils.Image')
+    def test_make_thumbnails_for_image(self, mock_image, mock_resize_image):
+        file = FileFactory(original_hash='foobar', source='file/original_image_source.jpg')
+        files.models.FileValidation.objects.create(file=file, is_ok=True, results={})
+        self.assertIsNone(file.thumbnail.name)
+        self.assertEqual(file.metadata, {})
+
+        make_thumbnails.task_function(file_id=file.pk)
+
+        mock_image.open.assert_called_once_with(
+            str(TEST_MEDIA_DIR / 'file' / 'original_image_source.jpg')
+        )
+        mock_image.open.return_value.close.assert_called_once()
+
+        file.refresh_from_db()
+        self.assertEqual(file.thumbnail.name, 'thumbnails/fo/foobar_1920x1080.png')
+        self.assertEqual(
+            file.metadata,
+            {
+                'thumbnails': {
+                    '1080p': {'path': 'thumbnails/fo/foobar_1920x1080.png', 'size': [1920, 1080]},
+                    '360p': {'path': 'thumbnails/fo/foobar_640x360.png', 'size': [640, 360]},
+                },
+            },
+        )
+
+    @patch('files.utils.resize_image')
+    @patch('files.utils.Image')
+    @patch('files.utils.FFmpeg')
+    def test_make_thumbnails_for_video(self, mock_ffmpeg, mock_image, mock_resize_image):
+        file = FileFactory(
+            original_hash='deadbeef', source='file/path.mp4', type=files.models.File.TYPES.VIDEO
+        )
+        files.models.FileValidation.objects.create(file=file, is_ok=True, results={})
+        self.assertIsNone(file.thumbnail.name)
+        self.assertEqual(file.metadata, {})
+
+        make_thumbnails.task_function(file_id=file.pk)
+
+        mock_ffmpeg.assert_called_once_with()
+        mock_image.open.assert_called_once_with(
+            str(TEST_MEDIA_DIR / 'thumbnails' / 'de' / 'deadbeef.png')
+        )
+        mock_image.open.return_value.close.assert_called_once()
+
+        file.refresh_from_db()
+        # Check that the extracted frame is stored instead of the large thumbnail
+        self.assertEqual(file.thumbnail.name, 'thumbnails/de/deadbeef.png')
+        # Check that File metadata and thumbnail fields were updated
+        self.assertEqual(
+            file.metadata,
+            {
+                'thumbnails': {
+                    '1080p': {'path': 'thumbnails/de/deadbeef_1920x1080.png', 'size': [1920, 1080]},
+                    '360p': {'path': 'thumbnails/de/deadbeef_640x360.png', 'size': [640, 360]},
+                },
+            },
+        )

files/tests/test_utils.py

@@ -1,6 +1,20 @@
+from pathlib import Path
+from unittest.mock import patch, ANY
+import tempfile
+
 from django.test import TestCase
 
-from files.utils import find_path_by_name, find_exact_path, filter_paths_by_ext
+from files.utils import (
+    extract_frame,
+    filter_paths_by_ext,
+    find_exact_path,
+    find_path_by_name,
+    get_thumbnail_upload_to,
+    make_thumbnails,
+)
+
+# Reusing test files from the extensions app
+TEST_FILES_DIR = Path(__file__).resolve().parent.parent.parent / 'extensions' / 'tests' / 'files'
 
 
 class UtilsTest(TestCase):
@@ -98,3 +112,49 @@ class UtilsTest(TestCase):
         ]
         paths = filter_paths_by_ext(name_list, '.md')
         self.assertEqual(list(paths), [])
+
+    def test_get_thumbnail_upload_to(self):
+        for file_hash, kwargs, expected in (
+            ('foobar', {}, 'thumbnails/fo/foobar.png'),
+            ('deadbeef', {'width': None, 'height': None}, 'thumbnails/de/deadbeef.png'),
+            ('deadbeef', {'width': 640, 'height': 360}, 'thumbnails/de/deadbeef_640x360.png'),
+        ):
+            with self.subTest(file_hash=file_hash, kwargs=kwargs):
+                self.assertEqual(get_thumbnail_upload_to(file_hash, **kwargs), expected)
+
+    @patch('files.utils.resize_image')
+    def test_make_thumbnails(self, mock_resize_image):
+        self.assertEqual(
+            {
+                '1080p': {'path': 'thumbnails/fo/foobar_1920x1080.png', 'size': [1920, 1080]},
+                '360p': {'path': 'thumbnails/fo/foobar_640x360.png', 'size': [640, 360]},
+            },
+            make_thumbnails(TEST_FILES_DIR / 'test_preview_image_0001.png', 'foobar'),
+        )
+
+        self.assertEqual(len(mock_resize_image.mock_calls), 2)
+        for expected_size in ([1920, 1080], [640, 360]):
+            with self.subTest(expected_size=expected_size):
+                mock_resize_image.assert_any_call(
+                    ANY,
+                    expected_size,
+                    ANY,
+                    output_format='PNG',
+                    quality=83,
+                    optimize=True,
+                    progressive=True,
+                )
+
+    @patch('files.utils.FFmpeg')
+    def test_extract_frame(self, mock_ffmpeg):
+        with tempfile.TemporaryDirectory() as output_dir:
+            extract_frame('path/to/source/video.mp4', output_dir + '/frame.png')
+            mock_ffmpeg.return_value.option.return_value.input.return_value.output.assert_any_call(
+                output_dir + '/frame.png', {'ss': '00:00:00.01', 'frames:v': 1, 'update': 'true'}
+            )
+
+        self.assertEqual(len(mock_ffmpeg.mock_calls), 5)
+        mock_ffmpeg.assert_any_call()
+        mock_ffmpeg.return_value.option.return_value.input.assert_any_call(
+            'path/to/source/video.mp4'
+        )

files/utils.py

@@ -1,19 +1,26 @@
 from pathlib import Path
+import datetime
 import hashlib
 import io
 import logging
 import mimetypes
 import os
 import os.path
+import tempfile
 import toml
 import typing
 import zipfile
 
+from PIL import Image
+from django.conf import settings
 from django.core.files.storage import default_storage
+from ffmpeg import FFmpeg, FFmpegFileNotFound, FFmpegInvalidCommand, FFmpegError
 from lxml import etree
 import clamd
 import magic
 
+from constants.base import THUMBNAIL_FORMAT, THUMBNAIL_SIZES, THUMBNAIL_QUALITY
+
 logger = logging.getLogger(__name__)
 MODULE_DIR = Path(__file__).resolve().parent
 THEME_SCHEMA = []
@@ -185,3 +192,107 @@ def delete_file_in_storage(file_name: str) -> None:
     else:
         logger.info('Deleting %s from storage', file_name)
         default_storage.delete(file_name)
+
+
+def delete_thumbnails(file_metadata: dict) -> None:
+    """Read thumbnail paths from given metadata and delete them from storage."""
+    thumbnails = file_metadata.get('thumbnails', {})
+    for _, thumb in thumbnails.items():
+        path = thumb.get('path', '')
+        if not path:
+            continue
+        delete_file_in_storage(path)
+
+
+def get_thumbnail_upload_to(file_hash: str, width: int = None, height: int = None) -> str:
+    """Return a full media path of a thumbnail.
+
+    Optionally, append thumbnail dimensions to the file name.
+    """
+    prefix = 'thumbnails/'
+    _hash = file_hash.split(':')[-1]
+    thumbnail_ext = THUMBNAIL_FORMAT.lower()
+    if thumbnail_ext == 'jpeg':
+        thumbnail_ext = 'jpg'
+    suffix = f'.{thumbnail_ext}'
+    size_suffix = f'_{width}x{height}' if width and height else ''
+    path = Path(prefix, _hash[:2], f'{_hash}{size_suffix}').with_suffix(suffix)
+    return str(path)
+
+
+def resize_image(image: Image, size: tuple, output, output_format: str = 'PNG', **output_params):
+    """Resize a models.ImageField to a given size and write it into output file."""
+    start_t = datetime.datetime.now()
+
+    source_image = image.convert('RGBA' if output_format == 'PNG' else 'RGB')
+    source_image.thumbnail(size, Image.LANCZOS)
+    source_image.save(output, output_format, **output_params)
+
+    end_t = datetime.datetime.now()
+    args = {'source': image, 'size': size, 'time': (end_t - start_t).microseconds / 1000}
+    logger.info('%(source)s to %(size)s done in %(time)sms', args)
+
+
+def make_thumbnails(
+    source_path: str, file_hash: str, output_format: str = THUMBNAIL_FORMAT
+) -> dict:
+    """Generate thumbnail files for given file and a predefined list of dimensions.
+
+    Resulting thumbnail paths a derived from the given file hash and thumbnail sizes.
+    Return a dict of size keys to output paths of generated thumbnail images.
+    """
+    start_t = datetime.datetime.now()
+    thumbnails = {}
+    abs_path = os.path.join(settings.MEDIA_ROOT, source_path)
+    image = Image.open(abs_path)
+    for size_key, size in THUMBNAIL_SIZES.items():
+        w, h = size
+        output_path = get_thumbnail_upload_to(file_hash, width=w, height=h)
+        with tempfile.TemporaryFile() as f:
+            logger.info('Resizing %s to %s (%s)', abs_path, size, output_format)
+            resize_image(
+                image,
+                size,
+                f,
+                output_format=THUMBNAIL_FORMAT,
+                quality=THUMBNAIL_QUALITY,
+                optimize=True,
+                progressive=True,
+            )
+            logger.info('Saving a thumbnail to %s', output_path)
+            # Overwrite files instead of allowing storage generate a deduplicating suffix
+            if default_storage.exists(output_path):
+                logger.warning('%s exists, overwriting', output_path)
+                default_storage.delete(output_path)
+            default_storage.save(output_path, f)
+            thumbnails[size_key] = {'size': size, 'path': output_path}
+    image.close()
+
+    end_t = datetime.datetime.now()
+    args = {'source': source_path, 'time': (end_t - start_t).microseconds / 1000}
+    logger.info('%(source)s done in %(time)sms', args)
+    return thumbnails
+
+
+def extract_frame(source_path: str, output_path: str, at_time: str = '00:00:00.01'):
+    """Extract a single frame of a video at a given path, write it to the given output path."""
+    try:
+        start_t = datetime.datetime.now()
+        abs_path = os.path.join(settings.MEDIA_ROOT, output_path)
+        ffmpeg = (
+            FFmpeg()
+            .option('y')
+            .input(source_path)
+            .output(abs_path, {'ss': at_time, 'frames:v': 1, 'update': 'true'})
+        )
+        output_dir = os.path.dirname(abs_path)
+        if not os.path.isdir(output_dir):
+            os.mkdir(output_dir)
+        ffmpeg.execute()
+
+        end_t = datetime.datetime.now()
+        args = {'source': source_path, 'time': (end_t - start_t).microseconds / 1000}
+        logger.info('%(source)s done in %(time)sms', args)
+    except (FFmpegError, FFmpegFileNotFound, FFmpegInvalidCommand) as e:
+        logger.exception(f'Failed to extract a frame: {e.message}, {" ".join(ffmpeg.arguments)}')
+        raise

requirements.txt

@@ -40,6 +40,7 @@ mistune==2.0.4
 multidict==6.0.2
 oauthlib==3.2.0
 Pillow==9.2.0
+python-ffmpeg==2.0.12
 python-magic==0.4.27
 requests==2.28.1
 requests-oauthlib==1.3.1

reviewers/templates/reviewers/extensions_review_detail.html

@@ -76,12 +76,14 @@
   <h3>Previews Pending Approval</h3>
   <div class="row">
     {% for preview in pending_previews %}
+      {% with thumbnail_1080p_url=preview.file.thumbnail_1080p_url %}
         <div class="col-md-3">
           <a href="{{ preview.file.source.url }}" class="d-block mb-2" title="{{ preview.caption }}" target="_blank">
-          <img class="img-fluid rounded" src="{{ preview.file.source.url }}" alt="{{ preview.caption }}">
+            <img class="img-fluid rounded" src="{{ thumbnail_1080p_url }}" alt="{{ preview.caption }}">
           </a>
           {% include "common/components/status.html" with object=preview.file class="d-block" %}
         </div>
+      {% endwith %}
     {% endfor %}
   </div>
 </section>