pythongh-132267: fix unsynchronized cursor position and buffer mismatch after resize

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], repaint: bool) -> 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 sync_screen(self) -> None: ...
+
     @abstractmethod
     def set_cursor_vis(self, visible: bool) -> None: ...
 

Lib/_pyrepl/reader.py

@@ -631,14 +631,14 @@ def update_screen(self) -> None:
         if self.dirty:
             self.refresh()
 
-    def refresh(self) -> None:
+    def refresh(self, repaint: bool = False) -> None:
         """Recalculate and refresh the screen."""
         if self.in_bracketed_paste and self.buffer and not self.buffer[-1] == "\n":
             return
 
         # this call sets up self.cxy, so call it first.
         self.screen = self.calc_screen()
-        self.console.refresh(self.screen, self.cxy)
+        self.console.refresh(self.screen, self.cxy, repaint)
         self.dirty = False
 
     def do_cmd(self, cmd: tuple[str, list[str]]) -> None:
@@ -716,7 +716,8 @@ def handle1(self, block: bool = True) -> bool:
             elif event.evt == "scroll":
                 self.refresh()
             elif event.evt == "resize":
-                self.refresh()
+                self.console.sync_screen()
+                self.refresh(repaint=True)
             else:
                 translate = False
 

Lib/_pyrepl/unix_console.py

@@ -226,13 +226,14 @@ def change_encoding(self, encoding: str) -> None:
         """
         self.encoding = encoding
 
-    def refresh(self, screen, c_xy):
+    def refresh(self, screen, c_xy, repaint: bool = False):
         """
         Refresh the console screen.
 
         Parameters:
         - screen (list): List of strings representing the screen contents.
         - c_xy (tuple): Cursor position (x, y) on the screen.
+        - repaint (bool): If True, overwrite the old screen and not reuse.
         """
         cx, cy = c_xy
         if not self.__gone_tall:
@@ -292,7 +293,14 @@ def refresh(self, screen, c_xy):
             oldline,
             newline,
         ) in zip(range(offset, offset + height), oldscr, newscr):
-            if oldline != newline:
+            if repaint:
+                # repaint the whole line
+                self.__hide_cursor()
+                self.__move(0, y)
+                self.__write_code(self._el)
+                self.__write(newline)
+                self.posxy = wlen(newline), y
+            elif oldline != newline:
                 self.__write_changed_line(y, oldline, newline, px)
 
         y = len(newscr)
@@ -324,6 +332,44 @@ def move_cursor(self, x, y):
             self.posxy = x, y
             self.flushoutput()
 
+    def sync_screen(self):
+        """
+        Synchronize self.posxy, self.width and self.height.
+        Assuming that the content of the screen doesn't change, only the width changes.
+        """
+        if not self.screen:
+            self.posxy = 0, 0
+            return
+
+        px, py = self.posxy
+
+        groups = []
+        new_line = True
+        for line in self.screen[:py]:
+            l = wlen(line)
+            if new_line:
+                groups.append(l)
+                new_line = False
+            else:
+                groups[-1] += l
+            if l != self.width:
+                new_line = True
+
+        if new_line:
+            groups.append(px)
+        else:
+            groups[-1] += px
+
+        new_height, new_width = self.getheightwidth()
+
+        ny = 0
+        for group in groups:
+            ny += group // new_width
+        nx = groups[-1] % new_width
+
+        self.posxy = nx, ny
+        self.height, self.width = new_height, new_width
+
     def prepare(self):
         """
         Prepare the console for input/output operations.
@@ -757,7 +803,6 @@ def __move_tall(self, x, y):
         self.__write_code(self._cup, y - self.__offset, x)
 
     def __sigwinch(self, signum, frame):
-        self.height, self.width = self.getheightwidth()
         self.event_queue.insert(Event("resize", None))
 
     def __hide_cursor(self):

Lib/_pyrepl/windows_console.py

@@ -158,13 +158,14 @@ 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], repaint: bool = False) -> None:
         """
         Refresh the console screen.
 
         Parameters:
         - screen (list): List of strings representing the screen contents.
         - c_xy (tuple): Cursor position (x, y) on the screen.
+        - repaint (bool): If True, overwrite the old screen and not reuse.
         """
         cx, cy = c_xy
 
@@ -211,7 +212,13 @@ def refresh(self, screen: list[str], c_xy: tuple[int, int]) -> None:
             oldline,
             newline,
         ) in zip(range(offset, offset + height), oldscr, newscr):
-            if oldline != newline:
+            if repaint:
+                self._hide_cursor()
+                self._move_relative(0, y)
+                self._erase_to_end()
+                self.__write(newline)
+                self.posxy = wlen(newline), y
+            elif oldline != newline:
                 self.__write_changed_line(y, oldline, newline, px)
 
         y = len(newscr)
@@ -384,6 +391,45 @@ def move_cursor(self, x: int, y: int) -> None:
             self._move_relative(x, y)
             self.posxy = x, y
 
+    def sync_screen(self):
+        """
+        Synchronize self.posxy, self.width and self.height.
+        Assuming that the content of the screen doesn't change, only the width changes.
+        """
+        if not self.screen:
+            self.posxy = 0, 0
+            return
+
+        px, py = self.posxy
+
+        groups = []
+        new_line = True
+        for line in self.screen[:py]:
+            l = wlen(line)
+            if new_line:
+                groups.append(l)
+                new_line = False
+            else:
+                groups[-1] += l
+            if l != self.width:
+                new_line = True
+
+        if new_line:
+            groups.append(px)
+        else:
+            groups[-1] += px
+
+
+        new_height, new_width = self.getheightwidth()
+
+        ny = 0
+        for group in groups:
+            ny += group // new_width
+        nx = groups[-1] % new_width
+
+        self.posxy = nx, ny
+        self.height, self.width = new_height, new_width
+
     def set_cursor_vis(self, visible: bool) -> None:
         if visible:
             self._show_cursor()