gui: can't scroll down after click 'play all' button (feeluown#655)

Makefile

@@ -9,17 +9,22 @@ docs:
 pylint:
 	pylint feeluown/gui/pages/ feeluown/fuoexec/ feeluown/server/
 
-
+# Packages need to check currently.
+# All packages are supposed to be checked in the future.
 MYPY_PKGS=
 MYPY_PKGS+=feeluown/library/
 MYPY_PKGS+=feeluown/player/
 MYPY_PKGS+=feeluown/app/
 MYPY_PKGS+=feeluown/entry_points/
-
+MYPY_STRICT_PKGS=
+MYPY_STRICT_PKGS+=feeluown/utils/reader.py
+MYPY_STRICT_PKGS+=feeluown/server/
+MYPY_STRICT_PKGS+=feeluown/cli/cli.py
+MYPY_STRICT_PKGS+=feeluown/gui/widgets/textlist.py
 mypy:
 # Add flag --check-untyped-defs.
 	mypy  ${MYPY_PKGS}
-	mypy --check-untyped-defs feeluown/server/ feeluown/cli/cli.py feeluown/gui/widgets/textlist.py
+	mypy --check-untyped-defs ${MYPY_STRICT_PKGS}
 
 flake8:
 	flake8 feeluown/ tests/

feeluown/gui/helpers.py

@@ -5,7 +5,6 @@
 和应用逻辑相关的一些工具函数
 """
 import asyncio
-import itertools
 import random
 import sys
 import logging
@@ -20,6 +19,7 @@
     pass
 
 from feeluown.utils import aio
+from feeluown.utils.reader import AsyncReader
 from feeluown.excs import ProviderIOError
 from feeluown.library import NotSupported, ModelType, BaseModel
 from feeluown.models.uri import reverse
@@ -348,7 +348,7 @@ def fetch_more_impl(self):
         reader = self._reader
         step = self._fetch_more_step
 
-        if reader.is_async:
+        if isinstance(reader, AsyncReader):
             async def fetch():
                 items = []
                 count = 0
@@ -362,7 +362,7 @@ async def fetch():
             future.add_done_callback(self._async_fetch_cb)
         else:
             try:
-                items = list(itertools.islice(reader, step))
+                items = reader.read_range(self.rowCount(), step + self.rowCount())
             except ProviderIOError:
                 logger.exception('fetch more items failed')
                 self._fetch_more_cb([])