Add virtual machine based on shapely library (#311)

This pull request introduces new implementation of `VirtualMachine`
interface, `ShapelyVirtualMachine` utilizing `shapely` library for
generation of complex geometry. Alongside the implementation, unit and
e2e tests are included. Currently `ShapelyResult` allows only SVG
export.
Overall performance of implementation is above expectations, seems to be
very close to what `pillow` based implementation offers. On Ryzen 9
7950X rendering of
[A64-OlinuXino_Rev_G-B_Cu.gbr](https://github.com/Argmaster/pygerber/blob/main/test/assets/gerberx3/A64_OLinuXino_rev_G/A64-OlinuXino_Rev_G-B_Cu.gbr)
takes around 20s, including parsing and compilation to RVMC. However I
must admit that this is still like 10x slower than Reference Gerber
Viewer, no idea what kind of black magic they are using to render this
so quickly 😄

Here is sample output:

<p align="center">
<img width="500"
src=https://github.com/user-attachments/assets/a5a99999-59b2-46bc-befe-2eeee82bc6ad
/>
</p>

Also, output is much cleaner than with masking approach used in drawsvg
based rendering in PyGerber 2.4.1. Still, drawsvg backend will be likely
implemented, since it is so easy to do so.

This virtual machine is not enabled by default in PyGerber to avoid
depending on shapely and GEOS. It can be installed with `shapely`
extras:

```bash
pip install pygerber[shapely]
```

Also, it is sick how easy it is to implement new virtual machines, VM
code itself is like 370 lines.

pyproject.toml

@@ -60,6 +60,7 @@ lsprotocol = { version = "^2023.0.0a3", optional = true }
 drawsvg = { version = "^2.3.0", optional = true }
 typing-extensions = "^4.12.2"
 pygments = { version = "^2.18.0", optional = true }
+shapely = {version = "^2.0.6", optional = true}
 
 [tool.poetry.group.dev.dependencies]
 mypy = "^1.6.1"
@@ -102,7 +103,8 @@ black = "^24.4.0"
 language_server = ["pygls", "lsprotocol"]
 svg = ["drawsvg"]
 pygments = ["pygments"]
-all = ["pygls", "lsprotocol", "drawsvg", "pygments"]
+shapely = ["shapely"]
+all = ["pygls", "lsprotocol", "drawsvg", "pygments", "shapely"]
 
 [build-system]
 requires = ["poetry-core"]

src/pygerber/gerber/language_server/status.py

@@ -22,7 +22,7 @@ def is_language_server_available() -> bool:
             _spec_lsprotocol = importlib.util.find_spec("lsprotocol")
 
         except (ImportError, ValueError):
-            return False
+            _IS_LANGUAGE_SERVER_AVAILABLE = False
 
         else:
             _IS_LANGUAGE_SERVER_AVAILABLE = (_spec_pygls is not None) and (

src/pygerber/gerber/pygments.py

@@ -15,16 +15,13 @@ def is_pygments_available() -> bool:
 
     if _IS_PYGMENTS_AVAILABLE is None:
         try:
-            _spec_pygls = importlib.util.find_spec("pygls")
-            _spec_lsprotocol = importlib.util.find_spec("lsprotocol")
+            _spec_pygments = importlib.util.find_spec("pygments")
 
         except (ImportError, ValueError):
-            return False
+            _IS_PYGMENTS_AVAILABLE = False
 
         else:
-            _IS_PYGMENTS_AVAILABLE = (_spec_pygls is not None) and (
-                _spec_lsprotocol is not None
-            )
+            _IS_PYGMENTS_AVAILABLE = _spec_pygments is not None
 
     return _IS_PYGMENTS_AVAILABLE
 

src/pygerber/vm/__init__.py

@@ -22,13 +22,18 @@
 
 
 def render(
-    rvmc: RVMC, *, backend: Literal["pillow"] = "pillow", **options: Any
+    rvmc: RVMC, *, backend: Literal["pillow", "shapely"] = "pillow", **options: Any
 ) -> Result:
     """Render RVMC code using given builder."""
     if backend == "pillow":
         from pygerber.vm.pillow import PillowVirtualMachine
 
         return PillowVirtualMachine(**options).run(rvmc)
 
+    if backend == "shapely":
+        from pygerber.vm.shapely import ShapelyVirtualMachine
+
+        return ShapelyVirtualMachine(**options).run(rvmc)
+
     msg = f"Backend '{backend}' is not supported."  # type: ignore[unreachable]
     raise NotImplementedError(msg)

src/pygerber/vm/pillow/vm.py

@@ -13,11 +13,14 @@
 from pygerber.vm.commands import Arc, Line, PasteLayer, Shape
 from pygerber.vm.pillow.errors import DPMMTooSmallError
 from pygerber.vm.rvmc import RVMC
-from pygerber.vm.types.box import Box
-from pygerber.vm.types.errors import NoMainLayerError, PasteDeferredLayerNotAllowedError
-from pygerber.vm.types.layer_id import LayerID
-from pygerber.vm.types.style import Style
-from pygerber.vm.types.vector import Vector
+from pygerber.vm.types import (
+    Box,
+    LayerID,
+    NoMainLayerError,
+    PasteDeferredLayerNotAllowedError,
+    Style,
+    Vector,
+)
 from pygerber.vm.vm import (
     DeferredLayer,
     DrawCmdT,
@@ -36,7 +39,9 @@
 
 
 class PillowResult(Result):
-    """Result of drawing commands."""
+    """The `PillowResult` class is a wrapper around items returned
+    `PillowVirtualMachine` class as a result of executing rendering instruction.
+    """
 
     def __init__(self, main_box: Box, image: Optional[Image.Image]) -> None:
         super().__init__(main_box)
@@ -138,13 +143,15 @@ def __init__(
 
 
 class PillowVirtualMachine(VirtualMachine):
-    """Execute drawing commands using Pillow library."""
+    """The `PillowVirtualMachine` class is a concrete implementation of
+    `VirtualMachine` which uses Shapely library for rendering commands.
+    """
 
     def __init__(self, dpmm: int) -> None:
         super().__init__()
         self.dpmm = dpmm
         self.angle_length_to_segment_count = lambda angle_length: (
-            segment_count
+            int(segment_count)
             if (segment_count := angle_length * 2) > MIN_SEGMENT_COUNT
             else MIN_SEGMENT_COUNT
         )
@@ -223,7 +230,6 @@ def _calculate_arc_points(
             raise DPMMTooSmallError(self.dpmm)
 
         angle_delta = angle_delta / segment_count
-
         assert angle_delta > 0
 
         angle_generator: Generator[float, None, None]

src/pygerber/vm/shapely/__init__.py

@@ -0,0 +1,25 @@
+"""The `shapely` package contains concrete implementation of `VirtualMachine` using
+Shapely library.
+"""
+
+from __future__ import annotations
+
+from pygerber.vm.shapely.errors import (
+    ShapelyNotInstalledError,
+    ShapelyVirtualMachineError,
+)
+from pygerber.vm.shapely.vm import (
+    ShapelyDeferredLayer,
+    ShapelyEagerLayer,
+    ShapelyResult,
+    ShapelyVirtualMachine,
+)
+
+__all__ = [
+    "ShapelyVirtualMachine",
+    "ShapelyEagerLayer",
+    "ShapelyDeferredLayer",
+    "ShapelyResult",
+    "ShapelyNotInstalledError",
+    "ShapelyVirtualMachineError",
+]

src/pygerber/vm/shapely/errors.py

@@ -0,0 +1,21 @@
+"""`errors` module aggregates all exceptions related to the `ShapelyVirtualMachine`."""
+
+from __future__ import annotations
+
+from pygerber.vm.types.errors import VirtualMachineError
+
+
+class ShapelyVirtualMachineError(VirtualMachineError):
+    """Base class for all exceptions in the `ShapelyVirtualMachine`."""
+
+
+class ShapelyNotInstalledError(ShapelyVirtualMachineError):
+    """Raised when shapely package or other dependencies of `ShapelyVirtualMachine`
+    are not installed.
+
+    To install all dependencies of `ShapelyVirtualMachine`, run:
+
+    ```bash
+    pip install pygerber[shapely]
+    ```
+    """