Fixes displaying single newlines in output markdown and add renderer_options

examples/reference/panes/Markdown.ipynb

@@ -29,6 +29,8 @@
     "* **``object``** (str or object): A string containing Markdown, or an object with a ``_repr_markdown_`` method.\n",
     "* **``plugins``** (function): A list of additional markdown-it-py plugins to apply.\n",
     "* **``renderer``** (literal: `'markdown-it'`, `'markdown'`, `'myst'`): Markdown renderer implementation.\n",
+    "* \n",
+    "* **`renderer_options`** (dict): Options to pass to the markdown renderer.\n",
     "\n",
     "___"
    ]

panel/pane/markup.py

@@ -330,12 +330,15 @@ class Markdown(HTMLBasePane):
         'markdown-it', 'myst', 'markdown'], doc="""
         Markdown renderer implementation.""")
 
+    renderer_options = param.Dict(default={}, doc="""
+        Options to pass to the markdown renderer.""")
+
     # Priority depends on the data type
     priority: ClassVar[float | bool | None] = None
 
     _rename: ClassVar[Mapping[str, str | None]] = {
         'dedent': None, 'disable_math': None, 'extensions': None,
-        'plugins': None, 'renderer': None
+        'plugins': None, 'renderer': None, 'renderer_options': None
     }
 
     _rerender_params: ClassVar[List[str]] = [
@@ -361,9 +364,11 @@ def applies(cls, obj: Any) -> float | bool | None:
 
     @classmethod
     @functools.lru_cache(maxsize=None)
-    def _get_parser(cls, renderer, plugins):
+    def _get_parser(cls, renderer, plugins, **renderer_options):
         if renderer == 'markdown':
             return None
+        if "breaks" not in renderer_options:
+            renderer_options["breaks"] = True
         from markdown_it import MarkdownIt
         from markdown_it.renderer import RendererHTML
         from mdit_py_plugins.anchors import anchors_plugin
@@ -379,15 +384,19 @@ def hilite(token, langname, attrs):
                 return token
 
         if renderer == 'markdown-it':
-            parser = MarkdownIt('gfm-like', renderer_cls=RendererHTML)
+            parser = MarkdownIt(
+                'gfm-like',
+                renderer_cls=RendererHTML,
+                options_update=renderer_options
+            )
         elif renderer == 'myst':
             from myst_parser.parsers.mdit import (
                 MdParserConfig, create_md_parser,
             )
             config = MdParserConfig(heading_anchors=1, enable_extensions=[
                 'colon_fence', 'linkify', 'smartquotes', 'tasklist',
                 'attrs_block'
-            ], enable_checkboxes=True)
+            ], enable_checkboxes=True, **renderer_options)
             parser = create_md_parser(config, RendererHTML)
         parser = (
             parser
@@ -412,12 +421,18 @@ def _transform_object(self, obj: Any) -> Dict[str, Any]:
             obj = obj._repr_markdown_()
         if self.dedent:
             obj = textwrap.dedent(obj)
+
         if self.renderer == 'markdown':
             html = markdown.markdown(
-                obj, extensions=self.extensions, output_format='html5'
+                obj,
+                extensions=self.extensions,
+                output_format='html5',
+                **self.renderer_options
             )
         else:
-            html = self._get_parser(self.renderer, tuple(self.plugins)).render(obj)
+            html = self._get_parser(
+                self.renderer, tuple(self.plugins), **self.renderer_options
+            ).render(obj)
         return dict(object=escape(html))
 
     def _process_param_change(self, params):

panel/tests/pane/test_markup.py

@@ -73,6 +73,35 @@ def test_markdown_pane_dedent(document, comm):
     pane.dedent = False
     assert model.text.startswith('<pre><code>ABC')
 
+def test_markdown_pane_newline(document, comm):
+    # Newlines should be separated by a br
+    pane = Markdown(
+        "Hello\nWorld\nI'm here!",
+        renderer="markdown-it",
+    )
+    model = pane.get_root(document, comm=comm)
+    assert pane._models[model.ref['id']][0] is model
+    # <p>Hello<br>World<br>I'm here!</p>
+    assert model.text == "&lt;p&gt;Hello&lt;br /&gt;\nWorld&lt;br /&gt;\nI&#x27;m here!&lt;/p&gt;\n"
+
+    # Two newlines should be separated by a div
+    pane = Markdown("Hello\n\nWorld")
+    model = pane.get_root(document, comm=comm)
+    assert pane._models[model.ref['id']][0] is model
+    # <p>Hello</p><p>World</p>
+    assert model.text == "&lt;p&gt;Hello&lt;/p&gt;\n&lt;p&gt;World&lt;/p&gt;\n"
+
+    # Disable newlines
+    pane = Markdown(
+        "Hello\nWorld\nI'm here!",
+        renderer="markdown-it",
+        renderer_options={"breaks": False},
+    )
+    model = pane.get_root(document, comm=comm)
+    assert pane._models[model.ref['id']][0] is model
+    assert model.text == "&lt;p&gt;Hello\nWorld\nI&#x27;m here!&lt;/p&gt;\n"
+
+
 def test_markdown_pane_markdown_it_renderer(document, comm):
     pane = Markdown("""
     - [x] Task1

panel/widgets/base.py

@@ -113,9 +113,10 @@ def _process_param_change(self, params: Dict[str, Any]) -> Dict[str, Any]:
             ] + params['stylesheets']
         if "description" in params:
             description = params["description"]
+            renderer_options = params.pop("renderer_options", {})
             if isinstance(description, str):
                 from ..pane.markup import Markdown
-                parser = Markdown._get_parser('markdown-it', ())
+                parser = Markdown._get_parser('markdown-it', (), **renderer_options)
                 html = parser.render(description)
                 params['description'] = Tooltip(
                     content=HTML(html), position='right',