From 97396995d72b1d9c269d5753e48c75c03c7f8e3d Mon Sep 17 00:00:00 2001
From: Stephen Paul Weber <singpolyma@singpolyma.net>
Date: Tue, 28 Feb 2023 00:33:02 -0500
Subject: [PATCH] Convert APNG to WebP

Signal uses APNG for animated stickers, but this is not supported in our apps so
convert to WebP.
---
 guix.scm | 26 ++++++++++++++++++++++++++
 main.py  | 22 ++++++++++++++++++----
 2 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/guix.scm b/guix.scm
index e37487c..8377786 100644
--- a/guix.scm
+++ b/guix.scm
@@ -10,9 +10,34 @@
   (gnu packages python-crypto)
   (gnu packages python-web)
   (gnu packages python-xyz)
+  (gnu packages fontutils)
+  (gnu packages image)
   (ice-9 rdelim)
   (ice-9 popen))
 
+(define-public python-pillow-mine
+  (package
+    (inherit python-pillow)
+    (name "python-pillow-mine")
+    (version "9.0.0.post1")
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/singpolyma/Pillow")
+             (commit "float")))
+       (file-name (git-file-name name version))
+       (sha256
+        (base32 "12zhlhqq8vxykndgsppwvgvyn0vnzbjfkc2kj8nh4r80lqjw916g"))))
+    (inputs
+     (modify-inputs (package-inputs python-pillow)
+       (prepend libraqm libimagequant)))
+    (arguments '(#:tests? #f))
+    (home-page "https://github.com/uploadcare/pillow-simd")
+    (synopsis "Fork of the Python Imaging Library (Pillow)")
+    (description "This package is a fork of Pillow which adds support for SIMD
+parallelism.")))
+
 (define-public python-pymultihash
   (package
     (name "python-pymultihash")
@@ -118,6 +143,7 @@
         python-aiohttp
         python-pymultihash
         python-magic
+        python-pillow-mine
         python-signalstickers-client))
     (home-page "https://git.singpolyma.net/signal-sticker-proxy")
     (synopsis "")
diff --git a/main.py b/main.py
index 7d595f8..963f3c6 100644
--- a/main.py
+++ b/main.py
@@ -3,8 +3,17 @@ import multihash
 import base58
 import magic
 import sys
+import io
 from aiohttp import web
 from signalstickers_client import StickersClient
+from PIL import Image
+
+def to_webp(bytes):
+    out = io.BytesIO()
+    im = Image.open(io.BytesIO(bytes))
+    im.apply_transparency()
+    im.save(out, format='WEBP', save_all=True, lossless=True, minimize_size=True, optimize=True)
+    return out.getvalue()
 
 async def get_pack(request):
     pack_id = request.match_info.get('pack')
@@ -14,15 +23,18 @@ async def get_pack(request):
         pack = await client.get_pack(pack_id, key)
         stickers = []
         for sticker in pack.stickers:
+            image_data = sticker.image_data
+            if magic.from_buffer(image_data, mime=True) != 'image/webp':
+                image_data = to_webp(image_data)
             stickers.append({
                 'url': str(request.url) + "/" + str(sticker.id),
                 'pack': pack.title,
                 'name': sticker.emoji,
                 'copyright': pack.author,
                 'cids': [
-                    'z' + base58.b58encode(b'\x01\x55' + multihash.digest(sticker.image_data, 'sha1').encode()).decode('utf-8'),
-                    'z' + base58.b58encode(b'\x01\x55' + multihash.digest(sticker.image_data, 'sha2-256').encode()).decode('utf-8'),
-                    'z' + base58.b58encode(b'\x01\x55' + multihash.digest(sticker.image_data, 'sha2-512').encode()).decode('utf-8')
+                    'z' + base58.b58encode(b'\x01\x55' + multihash.digest(image_data, 'sha1').encode()).decode('utf-8'),
+                    'z' + base58.b58encode(b'\x01\x55' + multihash.digest(image_data, 'sha2-256').encode()).decode('utf-8'),
+                    'z' + base58.b58encode(b'\x01\x55' + multihash.digest(image_data, 'sha2-512').encode()).decode('utf-8')
                 ]
             })
         return web.json_response(stickers)
@@ -34,8 +46,10 @@ async def get_sticker(request):
 
     async with StickersClient() as client:
         image_data = await client.download_sticker(sticker_id, pack_id, key)
+        if magic.from_buffer(image_data, mime=True) != 'image/webp':
+            image_data = to_webp(image_data)
         result = web.Response(body=image_data)
-        result.headers['Content-Type'] = magic.from_buffer(image_data, mime=True)
+        result.headers['Content-Type'] = 'image/webp'
         return result
 
 app = web.Application()
-- 
2.38.5