fix: refresh line-by-line instead of clearing entire screen

Author: ImFeH2

Lib/_pyrepl/console.py

@@ -71,7 +71,7 @@ def __init__(
             self.output_fd = f_out.fileno()
 
     @abstractmethod
-    def refresh(self, screen: list[str], xy: tuple[int, int]) -> None: ...
+    def refresh(self, screen: list[str], xy: tuple[int, int], clear_to_end: bool = False) -> None: ...
 
     @abstractmethod
     def prepare(self) -> None: ...
@@ -82,6 +82,9 @@ def restore(self) -> None: ...
     @abstractmethod
     def move_cursor(self, x: int, y: int) -> None: ...
 
+    @abstractmethod
+    def reset_cursor(self) -> None: ...
+
     @abstractmethod
     def set_cursor_vis(self, visible: bool) -> None: ...
 

Lib/_pyrepl/reader.py

@@ -641,6 +641,17 @@ def refresh(self) -> None:
         self.console.refresh(self.screen, self.cxy)
         self.dirty = False
 
+    def handle_resize(self) -> None:
+        """Handle a resize event."""
+        self.console.height, self.console.width = self.console.getheightwidth()
+        self.console.reset_cursor()
+        ns = len(self.console.screen) * ["\000" * self.console.width]
+        self.console.screen = ns
+
+        self.screen = self.calc_screen()
+        self.console.refresh(self.screen, self.cxy, clear_to_end=True)
+        self.dirty = True
+
     def do_cmd(self, cmd: tuple[str, list[str]]) -> None:
         """`cmd` is a tuple of "event_name" and "event", which in the current
         implementation is always just the "buffer" which happens to be a list
@@ -716,9 +727,7 @@ def handle1(self, block: bool = True) -> bool:
             elif event.evt == "scroll":
                 self.refresh()
             elif event.evt == "resize":
-                self.console.height, self.console.width = self.console.getheightwidth()
-                self.console.clear()
-                self.refresh()
+                self.handle_resize()
             else:
                 translate = False
 

Lib/_pyrepl/unix_console.py

@@ -223,7 +223,7 @@ def change_encoding(self, encoding: str) -> None:
         """
         self.encoding = encoding
 
-    def refresh(self, screen, c_xy):
+    def refresh(self, screen, c_xy, clear_to_end = False):
         """
         Refresh the console screen.
 
@@ -301,6 +301,12 @@ def refresh(self, screen, c_xy):
             self.__write_code(self._el)
             y += 1
 
+        if clear_to_end:
+            self.__move(wlen(newscr[-1]), len(newscr) - 1 + self.__offset)
+            self.posxy = wlen(newscr[-1]), len(newscr) - 1 + self.__offset
+            self.__write_code(b"\x1b[J") # clear to end of line
+            self.flushoutput()
+
         self.__show_cursor()
 
         self.screen = screen.copy()
@@ -322,6 +328,10 @@ def move_cursor(self, x, y):
             self.posxy = x, y
             self.flushoutput()
 
+    def reset_cursor(self) -> None:
+        self.posxy = 0, self.__offset
+        self.__write_code(self._cup, 0, 0)
+
     def prepare(self):
         """
         Prepare the console for input/output operations.

Lib/_pyrepl/windows_console.py

@@ -111,6 +111,7 @@ def __init__(self, err: int | None, descr: str | None = None) -> None:
 MOVE_UP = "\x1b[{}A"
 MOVE_DOWN = "\x1b[{}B"
 CLEAR = "\x1b[H\x1b[J"
+HOME = "\x1b[H"
 
 # State of control keys: https://learn.microsoft.com/en-us/windows/console/key-event-record-str
 ALT_ACTIVE = 0x01 | 0x02
@@ -171,7 +172,7 @@ def __init__(
             # Console I/O is redirected, fallback...
             self.out = None
 
-    def refresh(self, screen: list[str], c_xy: tuple[int, int]) -> None:
+    def refresh(self, screen: list[str], c_xy: tuple[int, int], clear_to_end: bool = False) -> None:
         """
         Refresh the console screen.
 
@@ -237,6 +238,12 @@ def refresh(self, screen: list[str], c_xy: tuple[int, int]) -> None:
             self._erase_to_end()
             y += 1
 
+        if clear_to_end:
+            self._move_relative(wlen(newscr[-1]), self.__offset + len(newscr) - 1)
+            self.posxy = wlen(newscr[-1]), self.__offset + len(newscr) - 1
+            self.__write("\x1b[J")
+            self.flushoutput()
+
         self._show_cursor()
 
         self.screen = screen
@@ -398,6 +405,10 @@ def move_cursor(self, x: int, y: int) -> None:
             self._move_relative(x, y)
             self.posxy = x, y
 
+    def reset_cursor(self) -> None:
+        self.posxy = 0, self.__offset
+        self.__write(HOME)
+
     def set_cursor_vis(self, visible: bool) -> None:
         if visible:
             self._show_cursor()