ASCII-ize scrollbar in --ascii-only mode

src/textual_paint/paint.py

@@ -28,6 +28,7 @@ from textual.containers import Container, Vertical, Horizontal
 from textual.geometry import Offset, Region, Size
 from textual.css._style_properties import BorderDefinition
 from textual.reactive import var, reactive
+from textual.scrollbar import ScrollBar, ScrollBarRender
 from textual.strip import Strip
 from textual.dom import DOMNode
 from textual.widget import Widget
@@ -51,6 +52,7 @@ from .graphics_primitives import (
 )
 from .menus import MenuBar, Menu, MenuItem, Separator
 from .windows import Window, DialogWindow, CharacterSelectorDialogWindow, MessageBox, get_warning_icon, get_question_icon, get_paint_icon
+from .scrollbars import ASCIIScrollBarRender
 from .file_dialogs import SaveAsDialogWindow, OpenDialogWindow
 from .edit_colors import EditColorsDialogWindow
 from .localization.i18n import get as _, load_language, remove_hotkey
@@ -5253,6 +5255,9 @@ if args.ascii_only:
     RadioButton.BUTTON_LEFT = "["
     RadioButton.BUTTON_RIGHT = "]"
 
+    ScrollBar.renderer = ASCIIScrollBarRender
+
+
 # header_icon_markup = "[on white][blue]\\\\[/][red]|[/][yellow]/[/][/]"
 # header_icon_markup = "[black]..,[/]\n[blue]\\\\[/][on white][red]|[/][yellow]/[/][/]\n[black on rgb(192,192,192)]\\[_][/]"
 # trying different geometries for the page going behind the cup of brushes:

src/textual_paint/scrollbars.py

@@ -0,0 +1,95 @@
+
+from math import ceil
+from rich.color import Color
+from rich.segment import Segment, Segments
+from rich.style import Style
+from textual.scrollbar import ScrollBarRender
+
+
+class ASCIIScrollBarRender(ScrollBarRender):
+    """A scrollbar renderer that uses ASCII characters."""
+    @classmethod
+    def render_bar(
+        cls,
+        size: int = 25,
+        virtual_size: float = 50,
+        window_size: float = 20,
+        position: float = 0,
+        thickness: int = 1,
+        vertical: bool = True,
+        back_color: Color = Color.parse("#555555"),
+        bar_color: Color = Color.parse("bright_magenta"),
+    ) -> Segments:
+        if vertical:
+            # bars = ["▁", "▂", "▃", "▄", "▅", "▆", "▇", " "]
+            # bars = ["_", "=", "#", " "]
+            bars = [" "]
+        else:
+            # bars = ["▉", "▊", "▋", "▌", "▍", "▎", "▏", " "]
+            # bars = ["#", " "]
+            bars = [" "]
+
+        back = back_color
+        bar = bar_color
+
+        len_bars = len(bars)
+
+        width_thickness = thickness if vertical else 1
+
+        _Segment = Segment
+        _Style = Style
+        blank = " " * width_thickness
+
+        foreground_meta = {"@mouse.up": "release", "@mouse.down": "grab"}
+        if window_size and size and virtual_size and size != virtual_size:
+            bar_ratio = virtual_size / size
+            thumb_size = max(1, window_size / bar_ratio)
+
+            position_ratio = position / (virtual_size - window_size)
+            position = (size - thumb_size) * position_ratio
+
+            start = int(position * len_bars)
+            end = start + ceil(thumb_size * len_bars)
+
+            start_index, start_bar = divmod(max(0, start), len_bars)
+            end_index, end_bar = divmod(max(0, end), len_bars)
+
+            upper = {"@mouse.up": "scroll_up"}
+            lower = {"@mouse.up": "scroll_down"}
+
+            upper_back_segment = Segment(blank, _Style(bgcolor=back, meta=upper))
+            lower_back_segment = Segment(blank, _Style(bgcolor=back, meta=lower))
+
+            segments = [upper_back_segment] * int(size)
+            segments[end_index:] = [lower_back_segment] * (size - end_index)
+
+            segments[start_index:end_index] = [
+                _Segment(blank, _Style(bgcolor=bar, meta=foreground_meta))
+            ] * (end_index - start_index)
+
+            # Apply the smaller bar characters to head and tail of scrollbar for more "granularity"
+            if start_index < len(segments):
+                bar_character = bars[len_bars - 1 - start_bar]
+                if bar_character != " ":
+                    segments[start_index] = _Segment(
+                        bar_character * width_thickness,
+                        _Style(bgcolor=back, color=bar, meta=foreground_meta)
+                        if vertical
+                        else _Style(bgcolor=bar, color=back, meta=foreground_meta),
+                    )
+            if end_index < len(segments):
+                bar_character = bars[len_bars - 1 - end_bar]
+                if bar_character != " ":
+                    segments[end_index] = _Segment(
+                        bar_character * width_thickness,
+                        _Style(bgcolor=bar, color=back, meta=foreground_meta)
+                        if vertical
+                        else _Style(bgcolor=back, color=bar, meta=foreground_meta),
+                    )
+        else:
+            style = _Style(bgcolor=back)
+            segments = [_Segment(blank, style=style)] * int(size)
+        if vertical:
+            return Segments(segments, new_lines=True)
+        else:
+            return Segments((segments + [_Segment.line()]) * thickness, new_lines=False)