add AVIF support

src/lib.rs

@@ -93,6 +93,8 @@ pub enum Type {
     Flif,
     /// ICO files
     Ico,
+    /// AVIF files
+    Avif,
 }
 
 /// Try to determine image format from a bytes slice.

src/patterns.rs

@@ -22,6 +22,7 @@ const BGP: &'static [u8] = b"BPG\xfb";
 const RGB: &'static [u8] = b"\x01\xda";
 const FLIF: &'static [u8] = b"FLIF";
 const ICO: &'static [u8] = b"\x00\x00\x01\x00";
+const AVIF: &'static [u8] = b"avif";
 
 #[inline]
 fn is_pbm(bytes: &[u8]) -> bool {
@@ -86,6 +87,7 @@ pub fn guess(bytes: &[u8]) -> Option<Type> {
         _ if &bytes[..2] == RGB => Some(Type::Rgb),
         _ if &bytes[..4] == FLIF => Some(Type::Flif),
         _ if &bytes[..4] == ICO => Some(Type::Ico),
+        _ if (&bytes[8..12] == AVIF) => Some(Type::Avif),
         _ if is_pbm(bytes) => Some(Type::Pbm),
         _ if is_pgm(bytes) => Some(Type::Pgm),
         _ if is_ppm(bytes) => Some(Type::Ppm),

tests/mod.rs

@@ -107,6 +107,11 @@ fn test_ico() {
     assert_result!(Some(imghdr::Type::Ico), "./tests/images/example.ico");
 }
 
+#[test]
+fn test_avif() {
+    assert_result!(Some(imghdr::Type::Avif), "./tests/images/example.avif");
+}
+
 #[test]
 fn test_not_a_image() {
     assert_result!(None::<imghdr::Type>, "./tests/images/not-a-image.txt");