write_html(): homogenization in handling of tag_styles + new optional…

… arg font_family (#1217)

CHANGELOG.md

@@ -25,6 +25,7 @@ This can also be enabled programmatically with `warnings.simplefilter('default',
 * feature to identify the Unicode script of the input text and break it into fragments when different scripts are used, improving [text shaping](https://py-pdf.github.io/fpdf2/TextShaping.html) results
 * [`FPDF.image()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.image): now handles `keep_aspect_ratio` in combination with an enum value provided to `x`
 * [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html): now supports CSS page breaks properties : [documentation](https://py-pdf.github.io/fpdf2/HTML.html#page-breaks)
+* [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html): new optional `font_family` parameter to set the default font family
 * [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html): spacing before lists can now be adjusted via the `tag_styles` attribute - thanks to @lcgeneralprojects
 * file names are mentioned in errors when `fpdf2` fails to parse a SVG image
 ### Fixed

docs/HTML.md

@@ -78,7 +78,6 @@ pdf.write_html("""
 pdf.output("html.pdf")
 ```
 
-
 ### Styling HTML tags globally
 
 _New in [:octicons-tag-24: 2.7.9](https://github.com/py-pdf/fpdf2/blob/master/CHANGELOG.md)_
@@ -132,10 +131,32 @@ pdf.output("html_dd_indented.pdf")
 and that some [`FontFace`](https://py-pdf.github.io/fpdf2/fpdf/fonts.html#fpdf.fonts.FontFace) or [`TextStyle`](https://py-pdf.github.io/fpdf2/fpdf/fonts.html#fpdf.fonts.TextStyle) properties may not be honored.
 However, **Pull Request are welcome** to implement missing features!
 
+### Default font
+
+_New in [:octicons-tag-24: 2.7.10](https://github.com/py-pdf/fpdf2/blob/master/CHANGELOG.md)_
+
+The default font used by [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html) is **Times**.
+
+You can change this default font by passing `font_family` to this method:
+```python
+from fpdf import FPDF
+
+pdf = FPDF()
+pdf.add_page()
+pdf.write_html("""
+  <h1>Big title</h1>
+  <section>
+    <h2>Section title</h2>
+    <p>Hello world!</p>
+  </section>
+""", font_family="Helvetica")
+pdf.output("html_helvetica.pdf")
+```
+
 
 ## Supported HTML features
 
-* `<h1>` to `<h8>`: headings (and `align` attribute)
+* `<h1>` to `<h6>`: headings (and `align` attribute)
 * `<p>`: paragraphs (and `align`, `line-height` attributes)
 * `<br>` & `<hr>` tags
 * `<b>`, `<i>`, `<u>`: bold, italic, underline

fpdf/fpdf.py

@@ -293,11 +293,12 @@ def __init__(
         # Graphics state variables defined as properties by GraphicsStateMixin.
         # We set their default values here.
         self.font_family = ""  # current font family
-        self.font_style = ""  # current font style
+        # current font style (BOLD/ITALICS - does not handle UNDERLINE):
+        self.font_style = ""
+        self.underline = False  # underlining flag
         self.font_size_pt = 12  # current font size in points
         self.font_stretching = 100  # current font stretching
         self.char_spacing = 0  # current character spacing
-        self.underline = False  # underlining flag
         self.current_font = None  # None or an instance of CoreFont or TTFFont
         self.draw_color = self.DEFAULT_DRAW_COLOR
         self.fill_color = self.DEFAULT_FILL_COLOR
@@ -410,11 +411,18 @@ def _set_min_pdf_version(self, version):
         self.pdf_version = max(self.pdf_version, version)
 
     @property
-    def is_ttf_font(self):
+    def emphasis(self) -> TextEmphasis:
+        "The current text emphasis: bold, italics and/or underlined."
+        return TextEmphasis.coerce(
+            f"{self.font_style}U" if self.underline else self.font_style
+        )
+
+    @property
+    def is_ttf_font(self) -> bool:
         return self.current_font and self.current_font.type == "TTF"
 
     @property
-    def page_mode(self):
+    def page_mode(self) -> PageMode:
         return self._page_mode
 
     @page_mode.setter