rich: svg: workaround truncated last captured output line

Workaround upstream rich library issue 3576:
Underscores on the last captured line are clipped
when exporting to SVG.

The main <clipPath> height computed
by the rich library in Console.export_svg() is a bit too small,
and the bottom of the last captured output line may be truncated,
depending on the font and the printed characters (e.g. underscores,
but also the bottom of the letter 'y').

This workaround adds the bottom padding to the height computed
by the rich library.

Ref:
- #8
- Textualize/rich#3576

src/dtsh/rich/svg.py

@@ -216,6 +216,9 @@ def __init__(self, cause: str) -> None:
     # down to the captured output (aka the "Terminal group").
     PADDING_TOP: int = GTITLE_Y - 1
 
+    # Bottom pading.
+    PADDING_BOTTOM: int = 8
+
     # Y coordinate of the SVG group representing the actual capture.
     # as generated by the rich library (aka the "Terminal group").
     GTERM_Y = 41
@@ -415,6 +418,52 @@ class SVGFragmentDefs(SVGFragment):
     RE_BEGIN = SVGFormat.RE_DEFS
     RE_END = SVGFormat.RE_DEFS_CLOSE
 
+    # RE matching the first <rect> that will appear within
+    # the SVG <defs> element.
+    # See _workaround_rich_issue_3576().
+    RE_RECT_3576 = re.compile(
+        r'\s*<rect\s+.*x="0" y="0" width="[\d.]+" height="(?P<h>[\d.]+)"'
+    )
+
+    def __init__(
+        self, endl: int, content: SVGText, matched: re.Match[str]
+    ) -> None:
+        """Initialize rectangle geometry."""
+        super().__init__(endl, content, matched)
+        self._workaround_rich_issue_3576()
+
+    def _workaround_rich_issue_3576(self) -> None:
+        # Workaround upstream rich library issue 3576:
+        # Underscores on the last captured line are clipped
+        # when exporting to SVG.
+        #
+        # The main <clipPath> height computed
+        # by the rich library in Console.export_svg() is a bit too small,
+        # and the bottom of the last captured output line may be truncated,
+        # depending on the font and the printed characters (e.g. underscores,
+        # but also the bottom of the letter 'y').
+        #
+        # This workaround adds the bottom padding to the height computed
+        # by the rich library.
+        #
+        # Ref:
+        # - https://github.com/Textualize/rich/issues/3576
+        matched: Optional[re.Match[str]] = None
+        i_rect: int = 0
+        for i_rect, txt in enumerate(self._content):
+            matched = SVGFragmentDefs.RE_RECT_3576.match(txt)
+            if matched:
+                break
+        if not matched:
+            raise SVGFormat.Error(SVGFragmentDefs.RE_RECT_3576.pattern)
+
+        height = float(matched.group("h"))
+        # Taking account for the missing bottom padding.
+        height += SVGFormat.PADDING_BOTTOM
+        self._content[i_rect] = re.sub(
+            r'height="[\d.]+"', f'height="{height}"', self._content[i_rect]
+        )
+
     def append(self, fragment: "SVGFragmentDefs") -> None:
         """Append SVG clipping paths from another fragment (append nmode).
 

tests/test_dtsh_rich_svg.py

@@ -65,15 +65,22 @@ def test_svg_fragment_defs() -> None:
         [
             "<!-- before -->",
             "<defs>",
+            '<clipPath id="terminal-257872858-clip-terminal">',
+            '<rect x="0" y="0" width="755.4" height="299.4" />',
+            "</clipPath>",
             "...",
             "</defs>",
             "<!-- after -->",
         ]
     )
-    assert 3 == fragment.i_end
-    assert 3 == len(fragment.content)
+    assert 6 == fragment.i_end
+    assert 6 == len(fragment.content)
     assert [
         "<defs>",
+        '<clipPath id="terminal-257872858-clip-terminal">',
+        # 307.4 = 299.4 + 8 (rich library issue 3576)
+        '<rect x="0" y="0" width="755.4" height="307.4" />',
+        "</clipPath>",
         "...",
         "</defs>",
     ] == fragment.content