feat(pygal): implement waffle-basic (#1051)

## Implementation: `waffle-basic` - pygal

Implements the **pygal** version of `waffle-basic`.

**File:** `plots/waffle-basic/implementations/pygal.py`

**Parent Issue:** #998

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20260265977)*

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

plots/waffle-basic/implementations/pygal.py

@@ -0,0 +1,174 @@
+"""
+waffle-basic: Basic Waffle Chart
+Library: pygal
+"""
+
+import sys
+
+
+# Temporarily remove current directory from path to avoid name collision
+_cwd = sys.path[0] if sys.path[0] else "."
+if _cwd in sys.path:
+    sys.path.remove(_cwd)
+
+from pygal.graph.graph import Graph  # noqa: E402
+from pygal.style import Style  # noqa: E402
+
+
+# Restore path
+sys.path.insert(0, _cwd)
+
+
+class Waffle(Graph):
+    """Custom Waffle chart for pygal - displays proportions as colored squares in a grid."""
+
+    _serie_margin = 0
+
+    def __init__(self, *args, **kwargs):
+        self.rows = kwargs.pop("rows", 10)
+        self.cols = kwargs.pop("cols", 10)
+        super().__init__(*args, **kwargs)
+
+    def _plot(self):
+        """Draw the waffle grid."""
+        # Calculate total values and percentages
+        total = sum(sum(v for v in serie.values if v is not None) for serie in self.series)
+        if total == 0:
+            return
+
+        total_squares = self.rows * self.cols
+
+        # Get plot area dimensions from the view
+        plot_width = self.view.width
+        plot_height = self.view.height
+
+        # Calculate square size with gap
+        square_size = min(plot_width / self.cols, plot_height / self.rows) * 0.85
+        gap = square_size * 0.12
+
+        # Center the grid
+        grid_width = self.cols * (square_size + gap) - gap
+        grid_height = self.rows * (square_size + gap) - gap
+
+        # Calculate the actual plot area boundaries
+        # view.y(rows) gives the top of the plot area in SVG coordinates
+        x_start = self.view.x(0)
+        y_start = self.view.y(self.rows)  # Top of the plot area in SVG coordinates
+
+        # Center the grid within the plot area
+        x_offset = x_start + (plot_width - grid_width) / 2
+        y_offset = y_start + (plot_height - grid_height) / 2
+
+        # Create a group for waffle squares
+        plot_node = self.nodes["plot"]
+        waffle_group = self.svg.node(plot_node, class_="waffle-chart")
+
+        # Assign squares to each series
+        square_index = 0
+        for serie_index, serie in enumerate(self.series):
+            serie_value = sum(v for v in serie.values if v is not None)
+            num_squares = round(serie_value / total * total_squares)
+
+            color = self.style.colors[serie_index % len(self.style.colors)]
+
+            # Create a group for this series
+            serie_group = self.svg.node(waffle_group, class_="series serie-%d color-%d" % (serie_index, serie_index))
+
+            for _ in range(num_squares):
+                if square_index >= total_squares:
+                    break
+
+                row = square_index // self.cols
+                col = square_index % self.cols
+
+                x = x_offset + col * (square_size + gap)
+                y = y_offset + row * (square_size + gap)
+
+                # Draw square with rounded corners
+                self.svg.node(
+                    serie_group,
+                    "rect",
+                    x=x,
+                    y=y,
+                    width=square_size,
+                    height=square_size,
+                    fill=color,
+                    rx=square_size * 0.1,
+                    ry=square_size * 0.1,
+                    class_="waffle-square reactive",
+                )
+
+                square_index += 1
+
+    def _compute(self):
+        """Compute the box for rendering."""
+        # Set basic box dimensions
+        self._box.xmin = 0
+        self._box.xmax = self.cols
+        self._box.ymin = 0
+        self._box.ymax = self.rows
+
+
+# Custom style for 4800x2700 canvas
+custom_style = Style(
+    background="white",
+    plot_background="white",
+    foreground="#333333",
+    foreground_strong="#333333",
+    foreground_subtle="#666666",
+    colors=("#306998", "#FFD43B", "#4ECDC4", "#FF6B6B"),
+    title_font_size=72,
+    legend_font_size=48,
+    label_font_size=36,
+    value_font_size=32,
+    font_family="sans-serif",
+)
+
+# Data - Budget allocation example (values should sum to 100)
+categories = {"Operations": 42, "Marketing": 28, "R&D": 18, "Admin": 12}
+
+# Create waffle chart
+chart = Waffle(
+    width=4800,
+    height=2700,
+    rows=10,
+    cols=10,
+    style=custom_style,
+    title="Budget Allocation · waffle-basic · pygal · pyplots.ai",
+    show_legend=True,
+    legend_at_bottom=True,
+    legend_at_bottom_columns=4,
+    margin=80,
+    margin_bottom=250,
+    show_x_labels=False,
+    show_y_labels=False,
+)
+
+# Add data series with percentages in labels
+for category, value in categories.items():
+    chart.add(f"{category} ({value}%)", [value])
+
+# Save outputs
+chart.render_to_file("plot.svg")
+chart.render_to_png("plot.png")
+
+# Also save HTML for interactive viewing
+html_content = f"""<!DOCTYPE html>
+<html>
+<head>
+    <title>waffle-basic · pygal · pyplots.ai</title>
+    <style>
+        body {{ margin: 0; padding: 20px; background: #f5f5f5; }}
+        .container {{ max-width: 100%; margin: 0 auto; }}
+        svg {{ max-width: 100%; height: auto; }}
+    </style>
+</head>
+<body>
+    <div class="container">
+        {chart.render(is_unicode=True)}
+    </div>
+</body>
+</html>"""
+
+with open("plot.html", "w") as f:
+    f.write(html_content)

plots/waffle-basic/metadata/pygal.yaml

@@ -0,0 +1,23 @@
+# Per-library metadata for pygal implementation of waffle-basic
+# Auto-generated by impl-generate.yml
+
+library: pygal
+specification_id: waffle-basic
+
+# Preview URLs (filled by workflow)
+preview_url: https://storage.googleapis.com/pyplots-images/plots/waffle-basic/pygal/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/waffle-basic/pygal/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/waffle-basic/pygal/plot.html
+
+current:
+  version: 0
+  generated_at: 2025-12-16T07:48:26Z
+  generated_by: claude-opus-4-5-20251101
+  workflow_run: 20260265977
+  issue: 998
+  quality_score: 92
+  # Version info (filled by workflow)
+  python_version: "3.13.11"
+  library_version: "unknown"
+
+history: []