write_html: do not style header row if no <th> is present - fix #740

CHANGELOG.md

@@ -17,9 +17,10 @@ in order to get warned about deprecated features used in your code.
 This can also be enabled programmatically with `warnings.simplefilter('default', DeprecationWarning)`.
 
 ## [2.7.4] - Not released yet
-
 ### Added
 - documentation on how to embed `graphs` and `charts` generated using `Pygal` lib: [documentation section](https://pyfpdf.github.io/fpdf2/Maths.html#using-pygal) - thanks to @ssavi-ict
+### Changed
+- [`FPDF.write_html()`](https://pyfpdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html) does not render the top row as a header, in bold with a line below, when no `<th>` are used, in order to be more backward-compatible with earlier versions of `fpdf2` - _cf._ [#740](https://github.com/PyFPDF/fpdf2/issues/740)
 
 ## [2.7.3] - 2023-04-03
 ### Fixed
@@ -29,7 +30,6 @@ This can also be enabled programmatically with `warnings.simplefilter('default',
 ### Fixed
 - custom fonts can be used with `FPDF.table()` without triggering a `TypeError: cannot pickle 'dict_keys' object` - thanks @aeris07 for the bug report
 - the SVG parser now accepts `<rect>` with `width` / `height` defined as percents
-
 ### Added
 - documentation on how to generate Code128 barcodes using the `python-barcode` lib: [documentation section](https://pyfpdf.github.io/fpdf2/Barcodes.html#Code128)
 

fpdf/html.py

@@ -10,8 +10,9 @@
 from html.parser import HTMLParser
 
 from .enums import TextEmphasis, XPos, YPos
+from .errors import FPDFException
 from .fonts import FontFace
-from .table import Table
+from .table import Table, TableBordersLayout
 
 import re
 
@@ -447,13 +448,23 @@ def handle_starttag(self, tag, attrs):
             )
             self.pdf.ln()
         if tag == "tr":
+            if not self.table:
+                raise FPDFException("Invalid HTML: <tr> used outside any <table>")
             self.tr = {k.lower(): v for k, v in attrs.items()}
             self.table_row = self.table.row()
         if tag in ("td", "th"):
+            if not self.table_row:
+                raise FPDFException(f"Invalid HTML: <{tag}> used outside any <tr>")
             self.td_th = {k.lower(): v for k, v in attrs.items()}
             if tag == "th":
                 self.td_th["align"] = "CENTER"
                 self.td_th["b"] = True
+            elif len(self.table.rows) == 1 and not self.table_row.cells:
+                # => we are in the 1st <tr>, and the 1st cell is a <td>
+                # => we do not treat the first row as a header
+                # pylint: disable=protected-access
+                self.table._borders_layout = TableBordersLayout.NONE
+                self.table._first_row_as_headings = False
             if "height" in attrs:
                 LOGGER.warning(
                     'Ignoring unsupported height="%s" specified on a <%s>',

fpdf/table.py

@@ -186,7 +186,11 @@ def get_cell_border(self, i, j):
     def _render_table_row(self, i, fill=False, **kwargs):
         row = self.rows[i]
         lines_heights_per_cell = self._get_lines_heights_per_cell(i)
-        row_height = max(sum(lines_heights) for lines_heights in lines_heights_per_cell)
+        row_height = (
+            max(sum(lines_heights) for lines_heights in lines_heights_per_cell)
+            if lines_heights_per_cell
+            else 0
+        )
         j = 0
         while j < len(row.cells):
             cell_line_height = row_height / len(lines_heights_per_cell[j])