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