1 files changed, 14 insertions, 8 deletions
diff --git a/dedup/image.py b/dedup/image.py
index 91321f4..a417528 100644
--- a/dedup/image.py
+++ b/dedup/image.py
@@ -3,6 +3,8 @@ import struct
 
 import PIL.Image
 
+from .hashing import HashlibLike
+
 class ImageHash:
     """A hash on the contents of an image data type supported by PIL. This
     disregards mode, depth and meta information. Note that due to limitations
@@ -11,8 +13,9 @@ class ImageHash:
     maxsize = 1024 * 1024 * 32
     # max memory usage is about 5 * maxpixels in bytes
     maxpixels = 1024 * 1024 * 32
+    name_prefix: str
 
-    def __init__(self, hashobj):
+    def __init__(self, hashobj: HashlibLike) -> None:
         """
         @param hashobj: a hashlib-like object
         """
@@ -20,23 +23,26 @@ class ImageHash:
         self.imagedetected = False
         self.content = io.BytesIO()
 
-    def detect(self):
+    def detect(self) -> bool:
         raise NotImplementedError
 
-    def update(self, data):
+    def update(self, data: bytes) -> None:
         self.content.write(data)
         if self.content.tell() > self.maxsize:
             raise ValueError("maximum image size exceeded")
         if not self.imagedetected:
             self.imagedetected = self.detect()
 
-    def copy(self):
+    def copy(self) -> "ImageHash":
         new = self.__class__(self.hashobj.copy())
         new.imagedetected = self.imagedetected
         new.content = io.BytesIO(self.content.getvalue())
         return new
 
-    def hexdigest(self):
+    def digest(self) -> bytes:
+        raise ValueError("an ImageHash cannot produce a raw digest")
+
+    def hexdigest(self) -> str:
         if not self.imagedetected:
             raise ValueError("not a image")
         hashobj = self.hashobj.copy()
@@ -70,7 +76,7 @@ class ImageHash:
         return "%s%8.8x%8.8x" % (hashobj.hexdigest(), width, height)
 
     @property
-    def name(self):
+    def name(self) -> str:
         return self.name_prefix + self.hashobj.name
 
 
@@ -78,7 +84,7 @@ class PNGHash(ImageHash):
     """A hash on the contents of a PNG image."""
     name_prefix = "png_"
 
-    def detect(self):
+    def detect(self) -> bool:
         if self.content.tell() < 33: # header + IHDR
             return False
         curvalue = self.content.getvalue()
@@ -93,7 +99,7 @@ class GIFHash(ImageHash):
     """A hash on the contents of the first frame of a GIF image."""
     name_prefix = "gif_"
 
-    def detect(self):
+    def detect(self) -> bool:
         if self.content.tell() < 10: # magic + logical dimension
             return False
         curvalue = self.content.getvalue()