Allow custom cell_fill_mode in tables (py-pdf#1117)

CHANGELOG.md

@@ -19,10 +19,11 @@ This can also be enabled programmatically with `warnings.simplefilter('default',
 ## [2.7.9] - Not released yet
 ### Added
 * support for overriding paragraph direction on bidirectional text
-* new optional `li_prefix_color` parameter for `FPDF.write_html()`
-* support for `start` & `type` attributes of `<ol>` tags, and `type` attribute of `<ul>` tags, when using `FPDF.write_html()`
+* new optional `li_prefix_color` parameter for [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html)
+* support for `start` & `type` attributes of `<ol>` tags, and `type` attribute of `<ul>` tags, when using [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html)
 * [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html) now accepts a `tag_styles` parameter to control the font, color & size of HTML elements: `<a>`, `<blockquote>`, `<li>`...
 * [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html) now accepts a `tag_indents` parameter to control, for example, the indent of `<blockquote>` elements
+* allow to define custom `cell_fill_mode` logic for tables: [_Set cells background_ - documentation section](https://py-pdf.github.io/fpdf2/Tables.html#set-cells-background). Also added 2 new values: `TableCellFillMode.EVEN_ROWS` & `TableCellFillMode.EVEN_COLUMNS`: [documentation](https://py-pdf.github.io/fpdf2/fpdf/enums.html#fpdf.enums.TableCellFillMode)
 ### Changed
 * improved the performance of `FPDF.start_section()` - _cf._ [issue #1092](https://github.com/py-pdf/fpdf2/issues/1092)
 ### Deprecated
@@ -52,7 +53,7 @@ This can also be enabled programmatically with `warnings.simplefilter('default',
 * outer table borders are now drawn continuously for nonzero `gutter_width`/`gutter_height`, with spacing applied inside the border similar to HTML tables - thanks to @mjasperse - cf. [#1071](https://github.com/py-pdf/fpdf2/issues/1071)
 * removed the requirement that all rows in a `Table` have the same number of columns - thanks to @mjasperse
 ### Deprecated
-- font aliases (`Arial` → `Helvetica`, `CourierNew` → `Courer`, `TimesNewRoman` → `Times`). They will be removed in a later release.
+- font aliases (`Arial` → `Helvetica`, `CourierNew` → `Courier`, `TimesNewRoman` → `Times`). They will be removed in a later release.
 
 ## [2.7.7] - 2023-12-10
 ### Added

docs/HTML.md

@@ -81,6 +81,8 @@ 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)_
+
 The style of several HTML tags (`<a>`, `<blockquote>`, `<code>`, `<pre>`, `<h1>`, `<h2>`, `<h3>`...) can be set globally, for the whole HTML document, by passing `tag_styles` to `FPDF.write_html()`:
 
 ```python

docs/Tables.md

@@ -208,6 +208,19 @@ The cell color is set following those settings, ordered by priority:
 4. The table setting `cell_fill_color`, if `cell_fill_mode` indicates to fill a cell
 5. The document `.fill_color` set before rendering the table
 
+Finally, it is possible to define your own cell-filling logic:
+
+```python
+class EvenOddCellFillMode():
+    @staticmethod
+    def should_fill_cell(i, j):
+        return i % 2 and j % 2
+
+...
+with pdf.table(cell_fill_color=lightblue, cell_fill_mode=EvenOddCellFillMode()) as table:
+    ...
+```
+
 
 ## Set borders layout
 

fpdf/enums.py

@@ -54,7 +54,7 @@ def coerce(cls, value):
 
             raise ValueError(f"{value} is not a valid {cls.__name__}")
 
-        raise TypeError(f"{value} cannot convert to a {cls.__name__}")
+        raise TypeError(f"{value} cannot be converted to a {cls.__name__}")
 
 
 class CoerciveIntEnum(IntEnum):
@@ -317,15 +317,32 @@ class TableCellFillMode(CoerciveEnum):
     COLUMNS = intern("COLUMNS")
     "Fill only table cells in odd columns"
 
+    EVEN_ROWS = intern("EVEN_ROWS")
+    "Fill only table cells in even rows"
+
+    EVEN_COLUMNS = intern("EVEN_COLUMNS")
+    "Fill only table cells in even columns"
+
+    @classmethod
+    def coerce(cls, value):
+        "Any class that has a .should_fill_cell() method is considered a valid 'TableCellFillMode' (duck-typing)"
+        if callable(getattr(value, "should_fill_cell", None)):
+            return value
+        return super().coerce(value)
+
     def should_fill_cell(self, i, j):
         if self is self.NONE:
             return False
         if self is self.ALL:
             return True
         if self is self.ROWS:
-            return bool(i % 2)
+            return i % 2 == 1
         if self is self.COLUMNS:
-            return bool(j % 2)
+            return j % 2 == 1
+        if self is self.EVEN_ROWS:
+            return i % 2 == 0
+        if self is self.EVEN_COLUMNS:
+            return j % 2 == 0
         raise NotImplementedError
 
 

test/table/test_table.py

@@ -6,6 +6,8 @@
 from fpdf import FPDF, FPDFException
 from fpdf.drawing import DeviceRGB
 from fpdf.fonts import FontFace
+from fpdf.table import TableCellFillMode
+
 from test.conftest import assert_pdf_equal, LOREM_IPSUM
 
 
@@ -267,6 +269,27 @@ def test_table_with_cell_fill(tmp_path):
     assert_pdf_equal(pdf, HERE / "table_with_cell_fill.pdf", tmp_path)
 
 
+class EvenOddCellFillMode:
+    @staticmethod
+    def should_fill_cell(i, j):
+        return i % 2 and j % 2
+
+
+def test_table_with_cell_fill_custom_class(tmp_path):
+    pdf = FPDF()
+    pdf.add_page()
+    pdf.set_font("Times", size=16)
+    lightblue = (173, 216, 230)
+    with pdf.table(
+        cell_fill_color=lightblue, cell_fill_mode=EvenOddCellFillMode()
+    ) as table:
+        for data_row in TABLE_DATA:
+            row = table.row()
+            for datum in data_row:
+                row.cell(datum)
+    assert_pdf_equal(pdf, HERE / "table_with_cell_fill_custom_class.pdf", tmp_path)
+
+
 def test_table_with_internal_layout(tmp_path):
     pdf = FPDF()
     pdf.add_page()
@@ -732,3 +755,23 @@ def test_table_with_varying_col_count(tmp_path):
             table.row(subset)
 
     assert_pdf_equal(pdf, HERE / "table_with_varying_col_count.pdf", tmp_path)
+
+
+def test_table_cell_fill_mode(tmp_path):
+    pdf = FPDF()
+    pdf.add_page()
+    pdf.set_font("Helvetica")
+    light_sky_blue = (150, 200, 255)
+    headings_style = FontFace(fill_color=128)  # grey
+    for mode in ("ROWS", "COLUMNS", "EVEN_ROWS", "EVEN_COLUMNS"):
+        pdf.cell(text=f"cell_fill_mode=TableCellFillMode.{mode}:")
+        pdf.ln(10)
+        with pdf.table(
+            TABLE_DATA,
+            headings_style=headings_style,
+            cell_fill_mode=getattr(TableCellFillMode, mode),
+            cell_fill_color=light_sky_blue,
+        ):
+            pass
+        pdf.ln()
+    assert_pdf_equal(pdf, HERE / "table_cell_fill_mode.pdf", tmp_path)