renderers: add a get_compatible_output_formats() method

The single page renderers can output PNG, SVGZ, PDF and CSV, but by
design, the multi page renderer can only output PDF and CSV. So we
introduce a get_compatible_output_formats() in the renderer class so
that users of OcitySMap2 can find out which formats are possible
depending on the choosen layout.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@enix.org>

ocitysmap2/layoutlib/abstract_renderer.py

@@ -295,6 +295,10 @@ class Renderer:
         """
         raise NotImplementedError
 
+    @staticmethod
+    def get_compatible_output_formats():
+        return [ "png", "svgz", "pdf", "csv" ]
+
     @staticmethod
     def get_compatible_paper_sizes(bounding_box, zoom_level,
                                    resolution_km_in_mm):

ocitysmap2/layoutlib/multi_page_renderer.py

@@ -664,6 +664,11 @@ class MultiPageRenderer(Renderer):
     def _paper_pt_to_geo_m(self, paper_pt):
         return self._paper_mm_to_geo_m(commons.convert_pt_to_mm(paper_pt))
 
+    # In multi-page mode, we only render pdf and csv formats
+    @staticmethod
+    def get_compatible_output_formats():
+        return [ "pdf", "csv" ]
+
     # In multi-page mode, we only accept A4, A5 and US letter as paper
     # sizes. The goal is to render booklets, not posters.
     @staticmethod