UnderlineBar component

src/textual/renderables/tab_underline.py

@@ -0,0 +1,99 @@
+from __future__ import annotations
+
+import random
+
+from rich.color import Color, ANSI_COLOR_NAMES
+from rich.console import ConsoleOptions, Console, RenderResult
+from rich.segment import Segment
+from rich.style import Style
+
+
+class UnderlineBar:
+    def __init__(
+        self,
+        highlight_range: tuple[float, float] = 0,
+        range_color: Color = Color.parse("yellow"),
+        other_color: Color = Color.parse("default"),
+        background_color: Color = Color.parse("default"),
+        width: int | None = None,
+    ) -> None:
+        self.highlight_range = highlight_range
+        self.highlight_style = Style.from_color(
+            color=range_color, bgcolor=background_color
+        )
+        self.other_style = Style.from_color(color=other_color, bgcolor=background_color)
+        self.width = width
+
+    def __rich_console__(
+        self, console: Console, options: ConsoleOptions
+    ) -> RenderResult:
+        half_bar_right = "╸"
+        half_bar_left = "╺"
+        bar = "━"
+        width = self.width or options.max_width
+        start, end = self.highlight_range
+
+        # Round start and end to nearest half
+        start = round(start * 2) / 2
+        end = round(end * 2) / 2
+
+        # start = 3.6; end = 9.6
+        # full bars before = int(start) = 3
+        # half_start = .6 > 0 = True
+
+        # Bars before highlighted range
+        half_start = start - int(start) > 0
+        half_end = end - int(end) > 0
+
+        # Non-highlighted portion of bar
+
+        if half_start:
+            yield Segment(bar * (int(start) + 1), style=self.other_style)
+            yield Segment(half_bar_left, style=self.highlight_style)
+        else:
+            yield Segment(bar * (int(start)), style=self.other_style)
+            yield Segment(half_bar_right, style=self.other_style)
+
+        # If we have a half bar at start and end, we need 1 less full bar
+        full_bar_width = int(end) - int(start)
+        if half_start and half_end:
+            full_bar_width -= 1
+
+        yield Segment(bar * full_bar_width, style=self.highlight_style)
+
+        if half_end:
+            yield Segment(half_bar_right, style=self.highlight_style)
+        else:
+            yield Segment(half_bar_left, style=self.other_style)
+
+        yield Segment(bar * (int(width) - int(end)), style=self.other_style)
+
+
+if __name__ == "__main__":
+    console = Console()
+
+    def frange(start, end, step):
+        current = start
+        while current < end:
+            yield current
+            current += step
+
+        while current >= 0:
+            yield current
+            current -= step
+
+    start_range = frange(0, 12, 0.5)
+    end_range = frange(6, 18, 0.5)
+    ranges = zip(start_range, end_range)
+
+    for range in ranges:
+        color = random.choice(list(ANSI_COLOR_NAMES.keys()))
+        console.print(
+            UnderlineBar(
+                range,
+                range_color=Color.parse(color),
+                other_color=Color.parse("#4f4f4f"),
+                width=18,
+            )
+        )
+        console.print()