From 84c2869032fdca29acff4f8089d841f9ded12908 Mon Sep 17 00:00:00 2001
From: CatKasha <CatKasha@users.noreply.github.com>
Date: Wed, 20 Apr 2022 22:40:01 +0300
Subject: [PATCH 1/4] add APNG support (part 1)

references:
https://wiki.mozilla.org/APNG_Specification#Structure
http://www.libpng.org/pub/png/spec/1.2/PNG-Structure.html
---
 filetype/types/image.py | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/filetype/types/image.py b/filetype/types/image.py
index ed1779c..4fabd69 100644
--- a/filetype/types/image.py
+++ b/filetype/types/image.py
@@ -48,6 +48,46 @@ def match(self, buf):
         )
 
 
+class Apng(Type):
+    """
+    Implements the APNG image type matcher.
+    """
+    MIME = 'image/apng'
+    EXTENSION = 'apng'
+
+    def __init__(self):
+        super(Apng, self).__init__(
+            mime=Apng.MIME,
+            extension=Apng.EXTENSION
+        )
+
+    def match(self, buf):
+        if(len(buf) > 8 and
+           buf[:8] == bytearray([0x89, 0x50, 0x4e, 0x47,
+                                 0x0d, 0x0a, 0x1a, 0x0a])):
+            #cursor in buf, skip already readed 8 bytes
+            i = 8
+            while len(buf) > i:
+                data_length = int.from_bytes(buf[i:i+4], byteorder="big")
+                i += 4
+
+                chunk_type = buf[i:i+4].decode("ascii")
+                i += 4
+
+                #acTL chunk in APNG should appears first than IDAT
+                #IEND is end of PNG
+                if (chunk_type == "IDAT" or chunk_type == "IEND"):
+                    return 0
+                elif (chunk_type == "acTL"):
+                    return 1
+
+                #move to the next chank by skipping data and crc (4 bytes)
+                i += data_length + 4
+            return 0
+        else:
+            return 0
+
+
 class Png(Type):
     """
     Implements the PNG image type matcher.

From 96cf5be538ca6df3c1da819e18933d35df8b51e8 Mon Sep 17 00:00:00 2001
From: CatKasha <CatKasha@users.noreply.github.com>
Date: Wed, 20 Apr 2022 22:40:59 +0300
Subject: [PATCH 2/4]  add APNG support (part 2)

---
 filetype/types/__init__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/filetype/types/__init__.py b/filetype/types/__init__.py
index e513edb..70d8789 100644
--- a/filetype/types/__init__.py
+++ b/filetype/types/__init__.py
@@ -16,6 +16,7 @@
     image.Xcf(),
     image.Jpeg(),
     image.Jpx(),
+    image.Apng(),
     image.Png(),
     image.Gif(),
     image.Webp(),

From 27fc3342ac689730598214cc851a751455741075 Mon Sep 17 00:00:00 2001
From: CatKasha <CatKasha@users.noreply.github.com>
Date: Wed, 20 Apr 2022 22:43:32 +0300
Subject: [PATCH 3/4] add APNG support (part 3)

---
 README.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/README.rst b/README.rst
index b4039c3..19098d5 100644
--- a/README.rst
+++ b/README.rst
@@ -67,6 +67,7 @@ Image
 -  **jpg** - ``image/jpeg``
 -  **jpx** - ``image/jpx``
 -  **png** - ``image/png``
+-  **apng** - ``image/apng``
 -  **gif** - ``image/gif``
 -  **webp** - ``image/webp``
 -  **cr2** - ``image/x-canon-cr2``

From 598e179f8c4197804a998989293b579b98ac9f71 Mon Sep 17 00:00:00 2001
From: CatKasha <CatKasha@users.noreply.github.com>
Date: Thu, 21 Apr 2022 01:24:53 +0300
Subject: [PATCH 4/4] fix typo

---
 filetype/types/image.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/filetype/types/image.py b/filetype/types/image.py
index 4fabd69..b64c674 100644
--- a/filetype/types/image.py
+++ b/filetype/types/image.py
@@ -81,7 +81,7 @@ def match(self, buf):
                 elif (chunk_type == "acTL"):
                     return 1
 
-                #move to the next chank by skipping data and crc (4 bytes)
+                #move to the next chunk by skipping data and crc (4 bytes)
                 i += data_length + 4
             return 0
         else: