Add site preview task

bookwyrm/models/book.py

@@ -86,7 +86,7 @@ class Book(BookDataModel):
         upload_to="covers/", blank=True, null=True, alt_field="alt_text"
     )
     preview_image = models.ImageField(
-        upload_to="cover_previews/", blank=True, null=True
+        upload_to="previews/covers/", blank=True, null=True
     )
     first_published_date = fields.DateTimeField(blank=True, null=True)
     published_date = fields.DateTimeField(blank=True, null=True)

bookwyrm/models/site.py

@@ -4,9 +4,12 @@ import datetime
 
 from Crypto import Random
 from django.db import models, IntegrityError
+from django.dispatch import receiver
 from django.utils import timezone
 
+from bookwyrm.preview_images import generate_site_preview_image_task
 from bookwyrm.settings import DOMAIN
+from bookwyrm.tasks import app
 from .base_model import BookWyrmModel
 from .user import User
 
@@ -35,6 +38,7 @@ class SiteSettings(models.Model):
     logo = models.ImageField(upload_to="logos/", null=True, blank=True)
     logo_small = models.ImageField(upload_to="logos/", null=True, blank=True)
     favicon = models.ImageField(upload_to="logos/", null=True, blank=True)
+    preview_image = models.ImageField(upload_to="previews/logos/", null=True, blank=True)
 
     # footer
     support_link = models.CharField(max_length=255, null=True, blank=True)
@@ -119,3 +123,12 @@ class PasswordReset(models.Model):
     def link(self):
         """formats the invite link"""
         return "https://{}/password-reset/{}".format(DOMAIN, self.code)
+
+
+@receiver(models.signals.post_save, sender=SiteSettings)
+# pylint: disable=unused-argument
+def preview_image(instance, *args, **kwargs):
+    updated_fields = kwargs["update_fields"]
+
+    if not updated_fields or "preview_image" not in updated_fields:
+        generate_site_preview_image_task.delay()

bookwyrm/preview_images.py

@@ -14,6 +14,7 @@ from django.core.files.uploadedfile import InMemoryUploadedFile
 from django.db.models import Avg
 
 from bookwyrm import models, settings
+from bookwyrm.settings import DOMAIN
 from bookwyrm.tasks import app
 
 # dev
@@ -182,7 +183,7 @@ def generate_default_cover():
     return default_cover
 
 
-def generate_preview_image(book, texts={}, picture=None, rating=None):
+def generate_preview_image(texts={}, picture=None, rating=None, show_instance_layer=True):
     # Cover
     try:
         cover_img_layer = Image.open(picture)
@@ -217,29 +218,33 @@ def generate_preview_image(book, texts={}, picture=None, rating=None):
     content_x = margin + cover_img_layer.width + gutter
     content_width = IMG_WIDTH - content_x - margin
 
-    instance_layer = generate_instance_layer(content_width)
-    texts_layer = generate_texts_layer(texts, content_width)
-
     contents_layer = Image.new(
         "RGBA", (content_width, IMG_HEIGHT), color=TRANSPARENT_COLOR
     )
     contents_composite_y = 0
+
+    if show_instance_layer:
+        instance_layer = generate_instance_layer(content_width)
         contents_layer.alpha_composite(instance_layer, (0, contents_composite_y))
         contents_composite_y = contents_composite_y + instance_layer.height + gutter
+
+    texts_layer = generate_texts_layer(texts, content_width)
     contents_layer.alpha_composite(texts_layer, (0, contents_composite_y))
-    contents_composite_y = contents_composite_y + texts_layer.height + 30
+    contents_composite_y = contents_composite_y + texts_layer.height + gutter
 
     if rating:
         # Add some more margin
-        contents_composite_y = contents_composite_y + 30
+        contents_composite_y = contents_composite_y + gutter
         rating_layer = generate_rating_layer(rating, content_width)
         contents_layer.alpha_composite(rating_layer, (0, contents_composite_y))
-        contents_composite_y = contents_composite_y + rating_layer.height + 30
+        contents_composite_y = contents_composite_y + rating_layer.height + gutter
 
     contents_layer_box = contents_layer.getbbox()
     contents_layer_height = contents_layer_box[3] - contents_layer_box[1]
 
     contents_y = math.floor((IMG_HEIGHT - contents_layer_height) / 2)
+
+    if show_instance_layer:
         # Remove Instance Layer from centering calculations
         contents_y = contents_y - math.floor((instance_layer.height + gutter) / 2)
 
@@ -255,9 +260,56 @@ def generate_preview_image(book, texts={}, picture=None, rating=None):
     return img
 
 
+@app.task
+def generate_site_preview_image_task():
+    """generate preview_image for the website"""
+    site = models.SiteSettings.objects.get()
+
+    if site.logo:
+        logo = site.logo
+    else:
+        logo = path.joinpath("static/images/logo-small.png")
+
+    texts = {
+        'text_zero': DOMAIN,
+        'text_one': site.name,
+        'text_three': site.instance_tagline,
+    }
+
+    img = generate_preview_image(texts=texts,
+                                 picture=logo,
+                                 show_instance_layer=False)
+
+    file_name = "%s.png" % str(uuid4())
+    image_buffer = BytesIO()
+    try:
+        try:
+            old_path = site.preview_image.path
+        except ValueError:
+            old_path = ""
+
+        # Save
+        img.save(image_buffer, format="png")
+        site.preview_image = InMemoryUploadedFile(
+            ContentFile(image_buffer.getvalue()),
+            "preview_image",
+            file_name,
+            "image/png",
+            image_buffer.tell(),
+            None,
+        )
+        site.save(update_fields=["preview_image"])
+
+        # Clean up old file after saving
+        if os.path.exists(old_path):
+            os.remove(old_path)
+    finally:
+        image_buffer.close()
+
+
 @app.task
 def generate_edition_preview_image_task(book_id):
-    """generate preview_image"""
+    """generate preview_image for a book"""
     book = models.Book.objects.select_subclasses().get(id=book_id)
 
     rating = models.Review.objects.filter(
@@ -267,14 +319,12 @@ def generate_edition_preview_image_task(book_id):
     ).aggregate(Avg("rating"))["rating__avg"]
 
     texts = {
-        'text_zero': "ADDED A REVIEW",
         'text_one': book.title,
         'text_two': book.subtitle,
         'text_three': book.author_text
     }
 
-    img = generate_preview_image(book=book,
-                                 texts=texts,
+    img = generate_preview_image(texts=texts,
                                  picture=book.cover,
                                  rating=rating)