Don’t assume we’re wrapping a content line

Though it should be the most common case, maybe we may have to wrap some
is_input=False content.

examples/full-screen/simple-demos/word-wrapping.py

@@ -81,8 +81,7 @@ def get_line_prefix(lineno, wrap_count):
                 BufferControl(buffer=buff),
                 wrap_lines=True,
                 wrap_finder=Window._whitespace_wrap_finder(
-                    lambda n: [] if n else to_formatted_text(LIPSUM),
-                    continuation=to_formatted_text(" ⮠"),
+                    continuation=to_formatted_text(" ⮠")
                 ),
                 get_line_prefix=lambda lineno, wrap_count: to_formatted_text("    ⭢ ")
                 if wrap_count
@@ -92,15 +91,14 @@ def get_line_prefix(lineno, wrap_count):
             Window(
                 BufferControl(buffer=buff),
                 wrap_lines=True,
-                wrap_finder=lambda lineno,
+                wrap_finder=lambda line,
+                lineno,
                 wrap_count,
                 start,
                 end,
-                fallback=Window._whitespace_wrap_finder(
-                    lambda n: [] if n else to_formatted_text(LIPSUM),
-                ): (end - 3, -1, "...")
+                fallback=Window._whitespace_wrap_finder(): (end - 3, -1, "...")
                 if wrap_count > 0
-                else fallback(lineno, wrap_count, start, end),
+                else fallback(line, lineno, wrap_count, start, end),
             ),
         ]
     ),

src/prompt_toolkit/layout/containers.py

@@ -1784,9 +1784,7 @@ def _write_to_screen_at_index(
             ui_content, write_position.width - total_margin_width, write_position.height
         )
         wrap_finder = self.wrap_finder or (
-            self._whitespace_wrap_finder(ui_content.get_line)
-            if self.word_wrap()
-            else None
+            self._whitespace_wrap_finder() if self.word_wrap() else None
         )
 
         # Erase background and fill with `char`.
@@ -1946,7 +1944,6 @@ def render_margin(m: Margin, width: int) -> UIContent:
     @classmethod
     def _whitespace_wrap_finder(
         cls,
-        get_line: Callable[[int], StyleAndTextTuples],
         sep: str | re.Pattern[str] = r"[ \t]",  # Don’t include \xA0 by default (in \s)
         split: str = "remove",
         continuation: StyleAndTextTuples = [],
@@ -1969,9 +1966,9 @@ def _whitespace_wrap_finder(
         cont_width = fragment_list_width(continuation)
 
         def wrap_finder(
-            lineno: int, wrap_count: int, start: int, end: int
+            line: AnyFormattedText, lineno: int, wrap_count: int, start: int, end: int
         ) -> tuple[int, int, AnyFormattedText]:
-            line = explode_text_fragments(get_line(lineno))
+            line = explode_text_fragments(to_formatted_text(line))
             cont_reserved = 0
             while cont_reserved < cont_width:
                 style, char, *_ = line[end - 1]
@@ -2027,6 +2024,7 @@ def _copy_body(
         rowcol_to_yx: dict[tuple[int, int], tuple[int, int]] = {}
 
         def find_next_wrap(
+            line: StyleAndTextTuples,
             remaining_width: int,
             is_input: bool,
             lineno: int,
@@ -2037,7 +2035,6 @@ def find_next_wrap(
             if not wrap_lines:
                 return sys.maxsize, 0, []
 
-            line = ui_content.get_line(lineno)
             try:
                 style0, text0, *more = line[fragment]
             except IndexError:
@@ -2069,7 +2066,7 @@ def find_next_wrap(
                 max_wrap_pos += 1
 
             return (
-                wrap_finder(lineno, wrap_count, min_wrap_pos, max_wrap_pos)
+                wrap_finder(line, lineno, wrap_count, min_wrap_pos, max_wrap_pos)
                 if is_input and wrap_finder
                 else None
             ) or (
@@ -2126,7 +2123,11 @@ def copy_line(
 
             new_buffer_row = new_buffer[y + ypos]
             wrap_start, wrap_replaced, continuation = find_next_wrap(
-                width - x, is_input, lineno, 0
+                line,
+                width - x,
+                is_input,
+                lineno,
+                0,
             )
             continuation = to_formatted_text(continuation)
 
@@ -2183,6 +2184,7 @@ def copy_line(
 
                         new_buffer_row = new_buffer[y + ypos]
                         wrap_start, wrap_replaced, continuation = find_next_wrap(
+                            line,
                             width - x,
                             is_input,
                             lineno,

src/prompt_toolkit/layout/controls.py

@@ -58,7 +58,9 @@
 ]
 
 GetLinePrefixCallable = Callable[[int, int], AnyFormattedText]
-WrapFinderCallable = Callable[[int, int, int, int], Tuple[int, int, AnyFormattedText]]
+WrapFinderCallable = Callable[
+    [AnyFormattedText, int, int, int, int], Tuple[int, int, AnyFormattedText]
+]
 
 
 class UIControl(metaclass=ABCMeta):
@@ -206,9 +208,10 @@ def get_height_for_line(
                 height = 10**8
             else:
                 # Calculate line width first.
-                line = fragment_list_to_text(self.get_line(lineno))[:slice_stop]
+                line = self.get_line(lineno)
+                line_text = fragment_list_to_text(line)[:slice_stop]
                 start = 0
-                text_width = get_cwidth(line[start:])
+                text_width = get_cwidth(line_text[start:])
 
                 if get_line_prefix or wrap_finder:
                     # Add prefix width.
@@ -229,17 +232,17 @@ def get_height_for_line(
                         if wrap_finder:
                             # Decent guess for max breakpoint place?
                             end = start + width - prefix_width
-                            start_end_width = get_cwidth(line[start:end])
+                            start_end_width = get_cwidth(line_text[start:end])
                             while start_end_width >= width - prefix_width:
-                                start_end_width -= get_cwidth(line[end - 1])
+                                start_end_width -= get_cwidth(line_text[end - 1])
                                 end -= 1
                             wrap, skip, cont = wrap_finder(
-                                lineno, height - 1, start, end
+                                line, lineno, height - 1, start, end
                             )
                             if skip < 0:
                                 break  # Truncate line
                             start = wrap + skip
-                            text_width = get_cwidth(line[start:])
+                            text_width = get_cwidth(line_text[start:])
                         else:
                             text_width -= width