c3nav.mapdata.render.image → c3nav.mapdata.render

src/c3nav/mapdata/render/engines/base.py

@@ -0,0 +1,74 @@
+import math
+from abc import ABC, abstractmethod
+from typing import Optional
+
+
+class FillAttribs:
+    __slots__ = ('color', 'opacity')
+
+    def __init__(self, color, opacity=None):
+        self.color = color
+        self.opacity = opacity
+
+
+class StrokeAttribs:
+    __slots__ = ('color', 'width', 'min_px', 'opacity')
+
+    def __init__(self, color, width, min_px=None, opacity=None):
+        self.color = color
+        self.width = width
+        self.min_px = min_px
+        self.opacity = opacity
+
+
+class RenderEngine(ABC):
+    # draw an svg image. supports pseudo-3D shadow-rendering
+    def __init__(self, width: int, height: int, xoff=0, yoff=0, scale=1, buffer=0, background='#FFFFFF'):
+        self.width = width
+        self.height = height
+        self.minx = xoff
+        self.miny = yoff
+        self.scale = scale
+        self.buffer = int(math.ceil(buffer*self.scale))
+        self.background = background
+
+        self.maxx = self.minx + width / scale
+        self.maxy = self.miny + height / scale
+
+        # how many pixels around the image should be added and later cropped (otherwise rsvg does not blur correctly)
+        self.buffer = int(math.ceil(buffer*self.scale))
+        self.buffered_width = self.width + 2 * self.buffer
+        self.buffered_height = self.height + 2 * self.buffer
+
+        self.background_rgb = tuple(int(background[i:i + 2], 16) for i in range(1, 6, 2))
+
+    @abstractmethod
+    def get_png(self) -> bytes:
+        # render the image to png.
+        pass
+
+    def add_geometry(self, geometry, fill: Optional[FillAttribs] = None, stroke: Optional[StrokeAttribs] = None,
+                     filter=None, clip_path=None, altitude=None, elevation=None, shape_cache_key=None):
+        # draw a shapely geometry with a given style
+        # if altitude is set, the geometry will get a calculated shadow relative to the other geometries
+        # if elevation is set, the geometry will get a shadow with exactly this elevation
+
+        # if fill_color is set, filter out geometries that cannot be filled
+        if fill is not None:
+            try:
+                geometry.geoms
+            except AttributeError:
+                if not hasattr(geometry, 'exterior'):
+                    return
+            else:
+                geometry = type(geometry)(tuple(geom for geom in geometry.geoms if hasattr(geom, 'exterior')))
+        if geometry.is_empty:
+            return
+
+        self._add_geometry(geometry=geometry, fill=fill, stroke=stroke, filter=filter, clip_path=clip_path,
+                           altitude=altitude, elevation=elevation, shape_cache_key=shape_cache_key)
+
+    @abstractmethod
+    def _add_geometry(self, geometry, fill: Optional[FillAttribs] = None, stroke: Optional[StrokeAttribs] = None,
+                      filter=None, clip_path=None, altitude=None, elevation=None, shape_cache_key=None):
+        pass