Add Inskcape requirement.

roentgen/raster.py

@@ -10,16 +10,22 @@ from typing import List
 __author__ = "Sergey Vartanov"
 __email__ = "me@enzet.ru"
 
+INKSCAPE_BIN: str = "INKSCAPE_BIN"
+
 
 def rasterize(from_: Path, to_: Path, area: str = "", dpi: float = 90) -> None:
     """
     Make PNG image out of SVG using Inkscape.
-    """
-    inkscape: str = "inkscape"
-    if "INKSCAPE_BIN" in os.environ:
-        inkscape: str = os.environ["INKSCAPE_BIN"]
 
-    commands: List[str] = [inkscape]
+    See https://inkscape.org/
+    """
+    if "INKSCAPE_BIN" not in os.environ:
+        logging.fatal(
+            f"Environment variable {INKSCAPE_BIN} not set. Please, install "
+            f"Inkscape and set the variable to be able to rasterize SVG files."
+        )
+
+    commands: List[str] = [os.environ[INKSCAPE_BIN]]
     commands += ["--export-png", to_.absolute()]
     commands += ["--export-dpi", str(dpi)]
     if area:

roentgen/road.py

@@ -83,12 +83,7 @@ class RoadPart:
 
     @classmethod
     def from_nodes(
-        cls,
-        node_1: OSMNode,
-        node_2: OSMNode,
-        flinger: Flinger,
-        road,
-        scale,
+        cls, node_1: OSMNode, node_2: OSMNode, flinger: Flinger, road, scale
     ) -> "RoadPart":
         """
         Construct road part from OSM nodes.