we got the class for the legend

requirements.txt

@@ -9,4 +9,6 @@ osm2geojson
 requests
 shapely
 scikit-learn
-pyarrow
+pyarrow
+svg.py
+matplotlib

webmap/standalone_legend.py

@@ -0,0 +1,94 @@
+import numpy as np
+from matplotlib import pyplot as plt
+from matplotlib.lines import Line2D
+from matplotlib.patches import Patch
+
+# thx ChatGPT, employed to transform a scratch code into the class
+class StandaloneLegend:
+    def __init__(self):
+        # Initialize the figure for the legend
+        self.legend_elements = []
+        self.legend_labels = []
+        self.legendFig = plt.figure("Legend plot")
+
+    def add_line(self, label='Line', **kwargs):
+        """
+        Add a line to the legend with customizable parameters.
+
+        Parameters:
+        label (str): The label for the line element.
+        **kwargs: Additional keyword arguments for Line2D.
+        """
+        line = Line2D([0], [0], label=label, **kwargs)
+        self.legend_elements.append(line)
+        self.legend_labels.append(label)
+
+    def add_marker(self, marker='o', label='Marker', **kwargs):
+        """
+        Add a marker to the legend with customizable parameters.
+
+        Parameters:
+        marker (str): The marker style.
+        label (str): The label for the marker element.
+        **kwargs: Additional keyword arguments for Line2D.
+        """
+        # Add default transparent color to kwargs if not provided
+        kwargs.setdefault('color', (0.0, 0.0, 0.0, 0.0))
+        marker = Line2D([0], [0], marker=marker, label=label, **kwargs)
+        self.legend_elements.append(marker)
+        self.legend_labels.append(label)
+
+    def add_patch(self, facecolor='orange', edgecolor='w', label='Patch', **kwargs):
+        """
+        Add a patch to the legend with customizable parameters.
+
+        Parameters:
+        facecolor (str): The face color of the patch.
+        edgecolor (str): The edge color of the patch.
+        label (str): The label for the patch element.
+        **kwargs: Additional keyword arguments for Patch.
+        """
+        patch = Patch(facecolor=facecolor, edgecolor=edgecolor, label=label, **kwargs)
+        self.legend_elements.append(patch)
+        self.legend_labels.append(label)
+
+    def add_element(self, element_type, label, **kwargs):
+        """
+        Add a custom element to the legend based on the element type.
+
+        Parameters:
+        element_type (str): The type of element ('line', 'marker', 'patch').
+        label (str): The label for the element.
+        **kwargs: Additional keyword arguments for the element.
+        """
+        if element_type == 'line':
+            self.add_line(label=label, **kwargs)
+        elif element_type == 'marker':
+            self.add_marker(label=label, **kwargs)
+        elif element_type == 'patch':
+            self.add_patch(label=label, **kwargs)
+        else:
+            raise ValueError(f"Unknown element type: {element_type}. Supported types are 'line', 'marker', and 'patch'.")
+
+    def export(self, filename='legend.png'):
+        # Export the legend to an image file
+        self.legendFig.legend(handles=self.legend_elements, labels=self.legend_labels, loc='center')
+        self.legendFig.savefig(filename, bbox_inches='tight', transparent=True)
+        plt.close(self.legendFig)  # Close the figure to free memory
+
+# # Example usage:
+# legend = StandaloneLegend()
+# legend.add_line(color='b', linewidth=4, label='Line')
+# legend.add_marker(marker='o', markerfacecolor='g', markersize=15, label='Marker')
+# legend.add_patch(facecolor='orange', edgecolor='r', label='Patch')
+# # Using add_element iteratively
+# elements = [
+#     ('line', {'color': 'red', 'linewidth': 2, 'label': 'Red Line'}),
+#     ('marker', {'marker': 's', 'markerfacecolor': 'blue', 'markersize': 10, 'label': 'Square Marker'}),
+#     ('patch', {'facecolor': 'yellow', 'edgecolor': 'black', 'label': 'Yellow Patch'})
+# ]
+
+# for elem_type, kwargs in elements:
+#     legend.add_element(elem_type, **kwargs)
+
+# legend.export('tests/legend.png')