Adjust limits used for at_current() loop

src/pyj/read_book/cfi.pyj

@@ -821,20 +821,16 @@ def at_point(x, y):  # {{{
 # }}}
 
 def at_current():  # {{{
-    wini, winb = scroll_viewport.inline_size(), scroll_viewport.block_size()
-
-    # We subtract one because the the actual position query for CFI elements is relative to the
+    # We subtract one because the actual position query for CFI elements is relative to the
     # viewport, and the viewport coordinates actually go from 0 to the size - 1.
     # If we don't do this, the first line of queries will always fail in those cases where we
     # start at the right of the viewport because they'll be outside the viewport
-    wini -= 1
-    winb -= 1
+    wini, winb = scroll_viewport.inline_size() - 1, scroll_viewport.block_size() - 1
 
-    # Don't let the deltas go below 10 or above 30, to prevent perverse cases where
+    # Don't let the deltas go too small or too large, to prevent perverse cases where
     # we don't loop at all, loop too many times, or skip elements because we're
     # looping too fast.
-    deltai = min(max(Math.ceil(rem_size() / 2), 5), 30)
-    deltab = min(max(Math.ceil(rem_size() / 2), 5), 30)
+    deltai = deltab = max(8, min(Math.ceil(rem_size() / 2), 32))
 
     # i.e. English, Hebrew:
     if scroll_viewport.horizontal_writing_mode: