apply style to widget

tests/test_border.py

@@ -0,0 +1,25 @@
+from rich.segment import Segment
+from rich.style import Style
+
+from textual._border import get_box, render_row
+
+
+def test_border_render_row():
+
+    style = Style.parse("red")
+    row = (Segment("┏", style), Segment("━", style), Segment("┓", style))
+
+    assert render_row(row, 5, False, False) == [Segment(row[1].text * 5, row[1].style)]
+    assert render_row(row, 5, True, False) == [
+        row[0],
+        Segment(row[1].text * 4, row[1].style),
+    ]
+    assert render_row(row, 5, False, True) == [
+        Segment(row[1].text * 4, row[1].style),
+        row[2],
+    ]
+    assert render_row(row, 5, True, True) == [
+        row[0],
+        Segment(row[1].text * 3, row[1].style),
+        row[2],
+    ]

tests/test_segment_tools.py

@@ -2,7 +2,7 @@ from rich.segment import Segment
 from rich.style import Style
 
 
-from textual._segment_tools import line_crop, line_trim
+from textual._segment_tools import line_crop, line_trim, line_pad
 
 
 def test_line_crop():
@@ -89,3 +89,25 @@ def test_line_trim():
     ]
 
     assert line_trim([], True, True) == []
+
+
+def test_line_pad():
+    segments = [Segment("foo"), Segment("bar")]
+    style = Style.parse("red")
+    assert line_pad(segments, 2, 3, style) == [
+        Segment("  ", style),
+        *segments,
+        Segment("   ", style),
+    ]
+
+    assert line_pad(segments, 0, 3, style) == [
+        *segments,
+        Segment("   ", style),
+    ]
+
+    assert line_pad(segments, 2, 0, style) == [
+        Segment("  ", style),
+        *segments,
+    ]
+
+    assert line_pad(segments, 0, 0, style) == segments

tests/test_styles_cache.py

@@ -0,0 +1,260 @@
+from rich.segment import Segment
+
+from textual.color import Color
+from textual.geometry import Region, Size
+from textual.css.styles import Styles
+from textual._styles_cache import StylesCache
+from textual._types import Lines
+
+
+def _extract_content(lines: Lines):
+    """Extract the text content from lines."""
+    content = ["".join(segment.text for segment in line) for line in lines]
+    return content
+
+
+def test_set_dirty():
+    cache = StylesCache()
+    cache.set_dirty(Region(3, 4, 10, 2))
+    assert not cache.is_dirty(3)
+    assert cache.is_dirty(4)
+    assert cache.is_dirty(5)
+    assert not cache.is_dirty(6)
+
+
+def test_no_styles():
+    """Test that empty style returns the content un-altered"""
+    content = [
+        [Segment("foo")],
+        [Segment("bar")],
+        [Segment("baz")],
+    ]
+    styles = Styles()
+    cache = StylesCache()
+    lines = cache.render(
+        styles,
+        Size(3, 3),
+        Color.parse("blue"),
+        Color.parse("green"),
+        content.__getitem__,
+    )
+    expected = [
+        [Segment("foo", styles.rich_style)],
+        [Segment("bar", styles.rich_style)],
+        [Segment("baz", styles.rich_style)],
+    ]
+    assert lines == expected
+
+
+def test_border():
+    content = [
+        [Segment("foo")],
+        [Segment("bar")],
+        [Segment("baz")],
+    ]
+    styles = Styles()
+    styles.border = ("heavy", "white")
+    cache = StylesCache()
+    lines = cache.render(
+        styles,
+        Size(5, 5),
+        Color.parse("blue"),
+        Color.parse("green"),
+        content.__getitem__,
+    )
+
+    text_content = _extract_content(lines)
+
+    expected_text = [
+        "┏━━━┓",
+        "┃foo┃",
+        "┃bar┃",
+        "┃baz┃",
+        "┗━━━┛",
+    ]
+
+    assert text_content == expected_text
+
+
+def test_padding():
+    content = [
+        [Segment("foo")],
+        [Segment("bar")],
+        [Segment("baz")],
+    ]
+    styles = Styles()
+    styles.padding = 1
+    cache = StylesCache()
+    lines = cache.render(
+        styles,
+        Size(5, 5),
+        Color.parse("blue"),
+        Color.parse("green"),
+        content.__getitem__,
+    )
+
+    text_content = _extract_content(lines)
+
+    expected_text = [
+        "     ",
+        " foo ",
+        " bar ",
+        " baz ",
+        "     ",
+    ]
+
+    assert text_content == expected_text
+
+
+def test_padding_border():
+    content = [
+        [Segment("foo")],
+        [Segment("bar")],
+        [Segment("baz")],
+    ]
+    styles = Styles()
+    styles.padding = 1
+    styles.border = ("heavy", "white")
+    cache = StylesCache()
+    lines = cache.render(
+        styles,
+        Size(7, 7),
+        Color.parse("blue"),
+        Color.parse("green"),
+        content.__getitem__,
+    )
+
+    text_content = _extract_content(lines)
+
+    expected_text = [
+        "┏━━━━━┓",
+        "┃     ┃",
+        "┃ foo ┃",
+        "┃ bar ┃",
+        "┃ baz ┃",
+        "┃     ┃",
+        "┗━━━━━┛",
+    ]
+
+    assert text_content == expected_text
+
+
+def test_outline():
+    content = [
+        [Segment("foo")],
+        [Segment("bar")],
+        [Segment("baz")],
+    ]
+    styles = Styles()
+    styles.outline = ("heavy", "white")
+    cache = StylesCache()
+    lines = cache.render(
+        styles,
+        Size(3, 3),
+        Color.parse("blue"),
+        Color.parse("green"),
+        content.__getitem__,
+    )
+
+    text_content = _extract_content(lines)
+    expected_text = [
+        "┏━┓",
+        "┃a┃",
+        "┗━┛",
+    ]
+    assert text_content == expected_text
+
+
+def test_crop():
+    content = [
+        [Segment("foo")],
+        [Segment("bar")],
+        [Segment("baz")],
+    ]
+    styles = Styles()
+    styles.padding = 1
+    styles.border = ("heavy", "white")
+    cache = StylesCache()
+    lines = cache.render(
+        styles,
+        Size(7, 7),
+        Color.parse("blue"),
+        Color.parse("green"),
+        content.__getitem__,
+        crop=Region(2, 2, 3, 3),
+    )
+    text_content = _extract_content(lines)
+    expected_text = [
+        "foo",
+        "bar",
+        "baz",
+    ]
+    assert text_content == expected_text
+
+
+def test_dirty_cache():
+    """Check that we only render content once or if it has been marked as dirty."""
+
+    content = [
+        [Segment("foo")],
+        [Segment("bar")],
+        [Segment("baz")],
+    ]
+    rendered_lines: list[int] = []
+
+    def get_content_line(y: int) -> list[Segment]:
+        rendered_lines.append(y)
+        return content[y]
+
+    styles = Styles()
+    styles.padding = 1
+    styles.border = ("heavy", "white")
+    cache = StylesCache()
+    lines = cache.render(
+        styles,
+        Size(7, 7),
+        Color.parse("blue"),
+        Color.parse("green"),
+        get_content_line,
+    )
+    assert rendered_lines == [0, 1, 2]
+    del rendered_lines[:]
+
+    text_content = _extract_content(lines)
+    expected_text = [
+        "┏━━━━━┓",
+        "┃     ┃",
+        "┃ foo ┃",
+        "┃ bar ┃",
+        "┃ baz ┃",
+        "┃     ┃",
+        "┗━━━━━┛",
+    ]
+    assert text_content == expected_text
+
+    # Re-render styles, check that content was not requested
+    lines = cache.render(
+        styles,
+        Size(7, 7),
+        Color.parse("blue"),
+        Color.parse("green"),
+        get_content_line,
+    )
+    assert rendered_lines == []
+    del rendered_lines[:]
+    text_content = _extract_content(lines)
+    assert text_content == expected_text
+
+    # Mark 2 lines as dirty
+    cache.set_dirty(Region(0, 2, 7, 2))
+
+    lines = cache.render(
+        styles,
+        Size(7, 7),
+        Color.parse("blue"),
+        Color.parse("green"),
+        get_content_line,
+    )
+    assert rendered_lines == [0, 1]
+    text_content = _extract_content(lines)
+    assert text_content == expected_text