[tumblr] add 'offset' option

docs/configuration.rst

@@ -2328,6 +2328,18 @@ Description
     Search posts for inline images and videos.
 
 
+extractor.tumblr.offset
+-----------------------
+Type
+    ``integer``
+Default
+    ``0``
+Description
+    Custom ``offset`` starting value when paginating over blog posts.
+
+    Allows skipping over posts without having to waste API calls.
+
+
 extractor.tumblr.original
 -------------------------
 Type

docs/gallery-dl.conf

@@ -297,6 +297,7 @@
             "external": false,
             "inline": true,
             "posts": "all",
+            "offset": 0,
             "original": true,
             "reblogs": true
         },

gallery_dl/extractor/tumblr.py

@@ -435,11 +435,15 @@ class TumblrAPI(oauth.OAuth1API):
 
     def posts(self, blog, params):
         """Retrieve published posts"""
-        params.update({"offset": 0, "limit": 50, "reblog_info": "true"})
+        params["offset"] = self.extractor.config("offset") or 0
+        params["limit"] = 50
+        params["reblog_info"] = "true"
+
         if self.posts_type:
             params["type"] = self.posts_type
         if self.before:
             params["before"] = self.before
+
         while True:
             data = self._call(blog, "posts", params)
             self.BLOG_CACHE[blog] = data["blog"]