Rename Röntgen to Map Machine.

map_machine/direction.py

@@ -0,0 +1,160 @@
+"""
+Direction tag support.
+"""
+from typing import Iterator, Optional
+
+import numpy as np
+from portolan import middle
+
+from map_machine.drawing import PathCommands
+
+__author__ = "Sergey Vartanov"
+__email__ = "me@enzet.ru"
+
+SHIFT: float = -np.pi / 2
+SMALLEST_ANGLE: float = np.pi / 15
+DEFAULT_ANGLE: float = np.pi / 30
+
+
+def parse_vector(text: str) -> Optional[np.ndarray]:
+    """
+    Parse vector from text representation: compass points or 360-degree
+    notation.  E.g. "NW", "270".
+
+    :param text: vector text representation
+    :return: parsed normalized vector
+    """
+    try:
+        radians: float = np.radians(float(text)) + SHIFT
+        return np.array((np.cos(radians), np.sin(radians)))
+    except ValueError:
+        pass
+
+    try:
+        radians: float = np.radians(middle(text)) + SHIFT
+        return np.array((np.cos(radians), np.sin(radians)))
+    except KeyError:
+        pass
+
+    return None
+
+
+def rotation_matrix(angle: float) -> np.ndarray:
+    """
+    Get a matrix to rotate 2D vector by the angle.
+
+    :param angle: angle in radians
+    """
+    return np.array(
+        [[np.cos(angle), np.sin(angle)], [-np.sin(angle), np.cos(angle)]]
+    )
+
+
+class Sector:
+    """
+    Sector described by two vectors.
+    """
+
+    def __init__(self, text: str, angle: Optional[float] = None) -> None:
+        """
+        :param text: sector text representation (e.g. "70-210", "N-NW")
+        :param angle: angle in degrees
+        """
+        self.start: Optional[np.ndarray] = None
+        self.end: Optional[np.ndarray] = None
+        self.main_direction: Optional[np.ndarray] = None
+
+        if "-" in text:
+            parts: list[str] = text.split("-")
+            self.start = parse_vector(parts[0])
+            self.end = parse_vector(parts[1])
+            self.main_direction = (self.start + self.end) / 2
+        else:
+            result_angle: float
+            if angle is None:
+                result_angle = DEFAULT_ANGLE
+            else:
+                result_angle = max(SMALLEST_ANGLE, np.radians(angle) / 2)
+
+            vector: Optional[np.ndarray] = parse_vector(text)
+            self.main_direction = vector
+
+            if vector is not None:
+                self.start = np.dot(rotation_matrix(result_angle), vector)
+                self.end = np.dot(rotation_matrix(-result_angle), vector)
+
+    def draw(self, center: np.ndarray, radius: float) -> Optional[PathCommands]:
+        """
+        Construct SVG path commands for arc element.
+
+        :param center: arc center point
+        :param radius: arc radius
+        :return: SVG path commands
+        """
+        if self.start is None or self.end is None:
+            return None
+
+        start: np.ndarray = center + radius * self.end
+        end: np.ndarray = center + radius * self.start
+
+        return ["L", start, "A", radius, radius, 0, "0", 0, end]
+
+    def is_right(self) -> Optional[bool]:
+        """
+        Check if main direction of the sector is right.
+
+        :return: true if direction is right, false if direction is left, and
+            None otherwise.
+        """
+        if self.main_direction is not None:
+            if np.allclose(self.main_direction[0], 0):
+                return None
+            elif self.main_direction[0] > 0:
+                return True
+            else:
+                return False
+
+    def __str__(self) -> str:
+        return f"{self.start}-{self.end}"
+
+
+class DirectionSet:
+    """
+    Describes direction, set of directions.
+    """
+
+    def __init__(self, text: str) -> None:
+        """
+        :param text: direction tag value
+        """
+        self.sectors: Iterator[Optional[Sector]] = map(Sector, text.split(";"))
+
+    def __str__(self) -> str:
+        return ", ".join(map(str, self.sectors))
+
+    def draw(self, center: np.ndarray, radius: float) -> Iterator[PathCommands]:
+        """
+        Construct SVG "d" for arc elements.
+
+        :param center: center point of all arcs
+        :param radius: radius of all arcs
+        :return: list of "d" values
+        """
+        return filter(
+            lambda x: x is not None,
+            map(lambda x: x.draw(center, radius), self.sectors),
+        )
+
+    def is_right(self) -> Optional[bool]:
+        """
+        Check if main direction of the sector is right.
+
+        :return: true if direction is right, false if direction is left, and
+            None otherwise.
+        """
+        result: list[bool] = [x.is_right() for x in self.sectors]
+        if result == [True] * len(result):
+            return True
+        if result == [False] * len(result):
+            return False
+        return None