Issue #107: support parallel offset for ways.

map_machine/constructor.py

@@ -292,7 +292,9 @@ class Constructor:
                     line_style.style
                 )
                 new_style["stroke"] = recolor.hex
-                line_style = LineStyle(new_style, line_style.priority)
+                line_style = LineStyle(
+                    new_style, line_style.parallel_offset, line_style.priority
+                )
 
             self.figures.append(
                 StyledFigure(line.tags, inners, outers, line_style)
@@ -341,7 +343,7 @@ class Constructor:
                 "stroke-width": 1.0,
             }
             figure: StyledFigure = StyledFigure(
-                line.tags, inners, outers, LineStyle(style, 1000.0)
+                line.tags, inners, outers, LineStyle(style, 0.0, 1000.0)
             )
             self.figures.append(figure)
 

map_machine/figure.py

@@ -66,6 +66,33 @@ class StyledFigure(Figure):
         super().__init__(tags, inners, outers)
         self.line_style: LineStyle = line_style
 
+    def get_path(
+        self,
+        flinger: Flinger,
+        offset: np.ndarray = np.array((0.0, 0.0)),
+    ) -> str:
+        """
+        Get SVG path commands.
+
+        :param flinger: converter for geo coordinates
+        :param offset: offset vector
+        """
+        path: str = ""
+
+        for outer_nodes in self.outers:
+            commands: str = get_path(
+                outer_nodes, offset, flinger, self.line_style.parallel_offset
+            )
+            path += f"{commands} "
+
+        for inner_nodes in self.inners:
+            commands: str = get_path(
+                inner_nodes, offset, flinger, self.line_style.parallel_offset
+            )
+            path += f"{commands} "
+
+        return path
+
 
 def is_clockwise(polygon: list[OSMNode]) -> bool:
     """
@@ -100,8 +127,13 @@ def make_counter_clockwise(polygon: list[OSMNode]) -> list[OSMNode]:
     return polygon if not is_clockwise(polygon) else list(reversed(polygon))
 
 
-def get_path(nodes: list[OSMNode], shift: np.ndarray, flinger: Flinger) -> str:
+def get_path(
+    nodes: list[OSMNode],
+    shift: np.ndarray,
+    flinger: Flinger,
+    parallel_offset: float = 0.0,
+) -> str:
     """Construct SVG path commands from nodes."""
     return Polyline(
         [flinger.fling(node.coordinates) + shift for node in nodes]
-    ).get_path()
+    ).get_path(parallel_offset)

map_machine/scheme.py

@@ -36,6 +36,7 @@ class LineStyle:
     """SVG line style and its priority."""
 
     style: dict[str, Union[int, float, str]]
+    parallel_offset: float = 0.0
     priority: float = 0.0
 
 
@@ -270,10 +271,15 @@ class WayMatcher(Matcher):
                     self.style[key] = scheme.get_color(style[key]).hex.upper()
                 else:
                     self.style[key] = style[key]
-        self.priority: int = 0
+
+        self.priority: float = 0.0
         if "priority" in structure:
             self.priority = structure["priority"]
 
+        self.parallel_offset: float = 0.0
+        if parallel_offset := structure.get("parallel_offset"):
+            self.parallel_offset = parallel_offset
+
     def get_style(self) -> dict[str, Any]:
         """Return way SVG style."""
         return self.style
@@ -584,7 +590,10 @@ class Scheme:
             if not matching:
                 continue
 
-            line_styles.append(LineStyle(matcher.style, matcher.priority))
+            line_style: LineStyle = LineStyle(
+                matcher.style, matcher.parallel_offset, matcher.priority
+            )
+            line_styles.append(line_style)
 
         return line_styles