Make pycairo an optional dependency. Closes #12.

flopp · flopp · commit ded77cf2f0fb · 2021-03-06T17:57:27.000+01:00
diff --git a/.gitignore b/.gitignore
@@ -2,6 +2,7 @@
 .env
 .mypy_cache
 .pytest_cache
+.vscode
 *.egg-info
 *.pyc
 *.png
diff --git a/README.md b/README.md
@@ -20,15 +20,24 @@ A python module to create static map images (PNG, SVG) with markers, geodesic li
 
 ## Installation
 
+### SVG only version
+
 ```shell
 pip install py-staticmaps
 ```
 
+### SVG + PNG version (via Cairo)
+
+```shell
+pip install py-staticmaps[cairo]
+```
+
 `py-staticmaps` uses `pycairo` for creating antialiased raster-graphics, so make sure `libcairo2` is installed on your system (on Ubuntu just install the `libcairo2-dev` package, i.e. `sudo apt install libcairo2-dev`).
 
 
 ## Examples
 
+Note: PNG support (e.g. `context.render_cairo(...)`) is only available if the `pycairo` module is installed.
 
 ### Markers and Geodesic Lines
 
@@ -195,4 +204,4 @@ Please take a look at the command line program which uses the `staticmaps` packa
 
 ## License
 
-[MIT](LICENSE) &copy; 2020 Florian Pigorsch
+[MIT](LICENSE) &copy; 2020-2012 Florian Pigorsch
diff --git a/examples/custom_objects.py b/examples/custom_objects.py
@@ -3,7 +3,10 @@
 # py-staticmaps
 # Copyright (c) 2021 Florian Pigorsch; see /LICENSE for licensing information
 
-import cairo  # type: ignore
+try:
+    import cairo  # type: ignore
+except ImportError:
+    pass
 import s2sphere  # type: ignore
 import staticmaps
 
@@ -125,8 +128,9 @@ def render_cairo(self, renderer: staticmaps.CairoRenderer) -> None:
 context.set_tile_provider(staticmaps.tile_provider_CartoDarkNoLabels)
 
 # render png
-image = context.render_cairo(800, 500)
-image.write_to_png("custom_objects.png")
+if staticmaps.cairo_is_supported():
+    image = context.render_cairo(800, 500)
+    image.write_to_png("custom_objects.png")
 
 # render svg
 svg_image = context.render_svg(800, 500)
diff --git a/examples/draw_gpx.py b/examples/draw_gpx.py
@@ -27,8 +27,9 @@
     break
 
 # render png
-image = context.render_cairo(800, 500)
-image.write_to_png("running.png")
+if staticmaps.cairo_is_supported():
+    image = context.render_cairo(800, 500)
+    image.write_to_png("running.png")
 
 # render svg
 svg_image = context.render_svg(800, 500)
diff --git a/examples/frankfurt_newyork.py b/examples/frankfurt_newyork.py
@@ -16,8 +16,9 @@
 context.add_object(staticmaps.Marker(newyork, color=staticmaps.RED, size=12))
 
 # render png
-image = context.render_cairo(800, 500)
-image.write_to_png("frankfurt_newyork.png")
+if staticmaps.cairo_is_supported():
+    image = context.render_cairo(800, 500)
+    image.write_to_png("frankfurt_newyork.png")
 
 # render svg
 svg_image = context.render_svg(800, 500)
diff --git a/examples/freiburg_area.py b/examples/freiburg_area.py
@@ -445,8 +445,9 @@
 )
 
 # render png
-image = context.render_cairo(800, 500)
-image.write_to_png("freiburg_area.png")
+if staticmaps.cairo_is_supported():
+    image = context.render_cairo(800, 500)
+    image.write_to_png("freiburg_area.png")
 
 # render svg
 svg_image = context.render_svg(800, 500)
diff --git a/examples/geodesic_circles.py b/examples/geodesic_circles.py
@@ -15,9 +15,11 @@
 context.add_object(staticmaps.Circle(center2, 2000, fill_color=staticmaps.TRANSPARENT, color=staticmaps.GREEN, width=2))
 context.add_object(staticmaps.Marker(center1, color=staticmaps.RED))
 context.add_object(staticmaps.Marker(center2, color=staticmaps.GREEN))
+
 # render png
-image = context.render_cairo(800, 600)
-image.write_to_png("geodesic_circles.png")
+if staticmaps.cairo_is_supported():
+    image = context.render_cairo(800, 600)
+    image.write_to_png("geodesic_circles.png")
 
 # render svg
 svg_image = context.render_svg(800, 600)
diff --git a/examples/tile_providers.py b/examples/tile_providers.py
@@ -20,8 +20,9 @@
     context.set_tile_provider(provider)
 
     # render png
-    image = context.render_cairo(800, 500)
-    image.write_to_png(f"provider_{name}.png")
+    if staticmaps.cairo_is_supported():
+        image = context.render_cairo(800, 500)
+        image.write_to_png(f"provider_{name}.png")
 
     # render svg
     svg_image = context.render_svg(800, 500)
diff --git a/examples/us_capitals.py b/examples/us_capitals.py
@@ -20,8 +20,9 @@
     context.add_object(staticmaps.Marker(capital, size=5))
 
 # render png
-image = context.render_cairo(800, 500)
-image.write_to_png("us_capitals.png")
+if staticmaps.cairo_is_supported():
+    image = context.render_cairo(800, 500)
+    image.write_to_png("us_capitals.png")
 
 # render svg
 svg_image = context.render_svg(800, 500)
diff --git a/requirements-cairo.txt b/requirements-cairo.txt
@@ -0,0 +1 @@
+pycairo
diff --git a/requirements.txt b/requirements.txt
@@ -1,7 +1,6 @@
 appdirs
 geographiclib
 PILLOW
-pycairo
 python-slugify
 requests
 s2sphere
diff --git a/setup.py b/setup.py
@@ -63,6 +63,7 @@ def _read_reqs(rel_path: str) -> typing.List[str]:
     packages=[PACKAGE],
     install_requires=_read_reqs("requirements.txt"),
     extras_require={
+        "cairo": _read_reqs("requirements-cairo.txt"),
         "dev": _read_reqs("requirements-dev.txt"),
         "examples": _read_reqs("requirements-examples.txt"),
     },
diff --git a/staticmaps/__init__.py b/staticmaps/__init__.py
@@ -3,7 +3,7 @@
 
 # flake8: noqa
 from .area import Area
-from .cairo_renderer import CairoRenderer
+from .cairo_renderer import CairoRenderer, cairo_is_supported
 from .circle import Circle
 from .color import (
     parse_color,
diff --git a/staticmaps/cairo_renderer.py b/staticmaps/cairo_renderer.py
@@ -3,9 +3,14 @@
 
 import io
 import math
+import sys
 import typing
 
-import cairo  # type: ignore
+try:
+    import cairo  # type: ignore
+except ImportError:
+    pass
+
 from PIL import Image  # type: ignore
 
 from .color import Color, BLACK, WHITE
@@ -17,21 +22,33 @@
     from .object import Object  # pylint: disable=cyclic-import
 
 
+def cairo_is_supported() -> bool:
+    return "cairo" in sys.modules
+
+
+# Dummy types, so that type annotation works if cairo is missing.
+cairo_Context = typing.Any
+cairo_ImageSurface = typing.Any
+
+
 class CairoRenderer(Renderer):
     def __init__(self, transformer: Transformer) -> None:
         Renderer.__init__(self, transformer)
 
+        if not cairo_is_supported():
+            raise RuntimeError("Cannot render to Cairo since the 'cairo' module could not be imported.")
+
         self._surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, *self._trans.image_size())
         self._context = cairo.Context(self._surface)
 
-    def image_surface(self) -> cairo.ImageSurface:
+    def image_surface(self) -> cairo_ImageSurface:
         return self._surface
 
-    def context(self) -> cairo.Context:
+    def context(self) -> cairo_Context:
         return self._context
 
     @staticmethod
-    def create_image(image_data: bytes) -> cairo.ImageSurface:
+    def create_image(image_data: bytes) -> cairo_ImageSurface:
         image = Image.open(io.BytesIO(image_data))
         if image.format == "PNG":
             return cairo.ImageSurface.create_from_png(io.BytesIO(image_data))
@@ -103,7 +120,7 @@ def render_attribution(self, attribution: typing.Optional[str]) -> None:
 
     def fetch_tile(
         self, download: typing.Callable[[int, int, int], typing.Optional[bytes]], x: int, y: int
-    ) -> typing.Optional[cairo.ImageSurface]:
+    ) -> typing.Optional[cairo_ImageSurface]:
         image_data = download(self._trans.zoom(), x, y)
         if image_data is None:
             return None
diff --git a/staticmaps/context.py b/staticmaps/context.py
@@ -3,15 +3,13 @@
 
 import math
 import os
-import sys
 import typing
 
 import appdirs  # type: ignore
-import cairo  # type: ignore
 import s2sphere  # type: ignore
 import svgwrite  # type: ignore
 
-from .cairo_renderer import CairoRenderer
+from .cairo_renderer import CairoRenderer, cairo_is_supported
 from .color import Color
 from .meta import LIB_NAME
 from .object import Object, PixelBoundsT
@@ -54,8 +52,8 @@ def set_tile_provider(self, provider: TileProvider) -> None:
     def add_object(self, obj: Object) -> None:
         self._objects.append(obj)
 
-    def render_cairo(self, width: int, height: int) -> cairo.ImageSurface:
-        if "cairo" not in sys.modules:
+    def render_cairo(self, width: int, height: int) -> typing.Any:
+        if not cairo_is_supported():
             raise RuntimeError('You need to install the "cairo" module to enable "render_cairo".')
 
         center, zoom = self.determine_center_zoom(width, height)
