PR: Replace pygraphviz with pydot.

.github/workflows/continuous-integration-quality-unit-tests.yml

@@ -51,7 +51,7 @@ jobs:
         if: matrix.os == 'macOS-latest'
         run: |
           poetry run python -m pip install --upgrade pip
-          poetry install --without graphviz
+          poetry install
       - name: Install Package Dependencies (Ubuntu)
         if: matrix.os == 'ubuntu-latest'
         run: |
@@ -63,7 +63,7 @@ jobs:
         if: matrix.os == 'windows-latest'
         run: |
           poetry run python -m pip install --upgrade pip
-          poetry install --without graphviz
+          poetry install
           poetry run python -c "import imageio;imageio.plugins.freeimage.download()"
         shell: bash
       - name: Install OpenImageIO (macOs)

colour/plotting/graph.py

@@ -9,6 +9,8 @@
 
 from __future__ import annotations
 
+import os
+
 import colour
 from colour.graph import (
     CONVERSION_GRAPH_NODE_LABELS,
@@ -29,13 +31,12 @@
 ]
 
 
-@required("Graphviz")
+@required("Pydot")
 @required("NetworkX")
 def plot_automatic_colour_conversion_graph(
     filename: str,
-    prog: (Literal["circo", "dot", "fdp", "neato", "nop", "twopi"] | str) = "fdp",
-    args: str = "",
-) -> AGraph:  # pyright: ignore  # noqa: F821  # pragma: no cover
+    prog: Literal["circo", "dot", "fdp", "neato", "nop", "twopi"] | str = "fdp",
+) -> Dot:  # pyright: ignore  # noqa: F821  # pragma: no cover
     """
     Plot *Colour* automatic colour conversion graph using
     `Graphviz <https://www.graphviz.org>`__ and
@@ -47,13 +48,11 @@ def plot_automatic_colour_conversion_graph(
         Filename to use to save the image.
     prog
         *Graphviz* layout method.
-    args
-         Additional arguments for *Graphviz*.
 
     Returns
     -------
-    :class:`AGraph`
-        *Pyraphviz* graph.
+    :class:`pydot.Dot`
+        *Pydot* graph.
 
     Notes
     -----
@@ -87,28 +86,31 @@ def plot_automatic_colour_conversion_graph(
     # TODO: Investigate API to trigger the conversion graph build.
     describe_conversion_path("RGB", "RGB", print_callable=lambda x: x)
 
-    agraph = nx.nx_agraph.to_agraph(cast(nx.DiGraph, colour.graph.CONVERSION_GRAPH))
+    dot = nx.drawing.nx_pydot.to_pydot(cast(nx.DiGraph, colour.graph.CONVERSION_GRAPH))
 
-    for node in agraph.nodes():
-        node.attr.update(label=CONVERSION_GRAPH_NODE_LABELS[node.name])
+    for node in dot.get_nodes():
+        label = CONVERSION_GRAPH_NODE_LABELS.get(node.get_name())
 
-    agraph.node_attr.update(
-        style="filled",
-        shape="circle",
-        color="#2196F3FF",
-        fillcolor="#2196F370",
-        fontname="Helvetica",
-        fontcolor="#263238",
-    )
-    agraph.edge_attr.update(color="#26323870")
-    for node in ("CIE XYZ", "RGB", "Spectral Distribution"):
-        agraph.get_node(node.lower()).attr.update(
-            shape="doublecircle",
-            color="#673AB7FF",
-            fillcolor="#673AB770",
-            fontsize=30,
-        )
-    for node in (
+        if label is None:
+            continue
+
+        node.set_label(label)
+        node.set_style("filled")
+        node.set_shape("circle")
+        node.set_color("#2196F3FF")
+        node.set_fillcolor("#2196F370")
+        node.set_fontname("Helvetica")
+        node.set_fontcolor("#263238")
+
+    for name in ("CIE XYZ", "RGB", "Spectral Distribution"):
+        node = next(iter(dot.get_node(name.lower())))
+
+        node.set_shape("doublecircle")
+        node.set_color("#673AB7FF")
+        node.set_fillcolor("#673AB770")
+        node.set_fontsize(30)
+
+    for name in (
         "ATD95",
         "CAM16",
         "CIECAM02",
@@ -120,10 +122,16 @@ def plot_automatic_colour_conversion_graph(
         "RLAB",
         "ZCAM",
     ):
-        agraph.get_node(node.lower()).attr.update(
-            color="#00BCD4FF", fillcolor="#00BCD470"
-        )
+        node = next(iter(dot.get_node(name.lower())))
+
+        node.set_color("#00BCD4FF")
+        node.set_fillcolor("#00BCD470")
+
+    for edge in dot.get_edges():
+        edge.set_color("#26323870")
 
-    agraph.draw(filename, prog=prog, args=args)
+    file_format = os.path.splitext(filename)[-1][1:]
+    write_method = getattr(dot, f"write_{file_format}")
+    write_method(filename, prog=prog, f=file_format)
 
-    return agraph
+    return dot

colour/plotting/tests/test_graph.py

@@ -2,7 +2,7 @@
 import tempfile
 
 from colour.plotting import plot_automatic_colour_conversion_graph
-from colour.utilities import is_graphviz_installed, is_networkx_installed
+from colour.utilities import is_networkx_installed, is_pydot_installed
 
 __author__ = "Colour Developers"
 __copyright__ = "Copyright 2013 Colour Developers"
@@ -28,9 +28,7 @@ def test_plot_automatic_colour_conversion_graph(self):
 plot_automatic_colour_conversion_graph` definition.
         """
 
-        if (
-            not is_graphviz_installed() or not is_networkx_installed()
-        ):  # pragma: no cover
+        if not is_pydot_installed() or not is_networkx_installed():  # pragma: no cover
             return
 
         plot_automatic_colour_conversion_graph(  # pragma: no cover

colour/utilities/__init__.py

@@ -35,12 +35,12 @@
 )
 from .requirements import (
     is_ctlrender_installed,
-    is_graphviz_installed,
     is_matplotlib_installed,
     is_networkx_installed,
     is_opencolorio_installed,
     is_openimageio_installed,
     is_pandas_installed,
+    is_pydot_installed,
     is_tqdm_installed,
     is_trimesh_installed,
     is_xxhash_installed,
@@ -176,12 +176,12 @@
 ]
 __all__ += [
     "is_ctlrender_installed",
-    "is_graphviz_installed",
     "is_matplotlib_installed",
     "is_networkx_installed",
     "is_opencolorio_installed",
     "is_openimageio_installed",
     "is_pandas_installed",
+    "is_pydot_installed",
     "is_tqdm_installed",
     "is_trimesh_installed",
     "is_xxhash_installed",

colour/utilities/network.py

@@ -1919,16 +1919,15 @@ def process(self, **kwargs: Dict) -> None:
 
             node.process()
 
-    @required("Graphviz")
-    def to_graphviz(self) -> AGraph:  # noqa: F821  # pyright: ignore
+    @required("Pydot")
+    def to_graphviz(self) -> Dot:  # noqa: F821  # pyright: ignore
         """
         Return a visualisation node-graph for *Graphviz*.
 
         Returns
         -------
-        :class:`pygraphviz.AGraph`
-            String representation for visualisation of the node-graph with
-            *Graphviz*.
+        :class:`pydot.Dot`
+            *Pydot* graph.
 
         Examples
         --------
@@ -1941,17 +1940,17 @@ def to_graphviz(self) -> AGraph:  # noqa: F821  # pyright: ignore
         >>> graph.add_node(node_2)
         >>> node_1.connect("output", node_2, "a")
         >>> graph.to_graphviz()  # doctest: +SKIP
-        <AGraph <Swig Object of type 'Agraph_t *' at 0x...>>
+        <pydot.core.Dot object at 0x...>
         """
 
         if self._parent is not None:
             return PortNode.to_graphviz(self)
 
-        from pygraphviz import AGraph
+        import pydot
 
-        agraph = AGraph(strict=False)
-        agraph.graph_attr["rankdir"] = "LR"
-        agraph.graph_attr["splines"] = "polyline"
+        dot = pydot.Dot(
+            "digraph", graph_type="digraph", rankdir="LR", splines="polyline"
+        )
 
         graphs = [node for node in self.walk_ports() if isinstance(node, PortGraph)]
 
@@ -1961,8 +1960,12 @@ def is_graph_member(node: PortNode) -> bool:
             return any(node in graph.nodes.values() for graph in graphs)
 
         for node in self.walk_ports():
-            agraph.add_node(
-                f"{node.name} (#{node.id})", label=node.to_graphviz(), shape="record"
+            dot.add_node(
+                pydot.Node(
+                    f"{node.name} (#{node.id})",
+                    label=node.to_graphviz(),
+                    shape="record",
+                )
             )
             input_edges, output_edges = node.edges
 
@@ -1971,16 +1974,18 @@ def is_graph_member(node: PortNode) -> bool:
                 if is_graph_member(edge[0].node) or is_graph_member(edge[1].node):
                     continue
 
-                agraph.add_edge(
-                    f"{edge[1].node.name} (#{edge[1].node.id})",
-                    f"{edge[0].node.name} (#{edge[0].node.id})",
-                    tailport=edge[1].name,
-                    headport=edge[0].name,
-                    key=f"{edge[1]} => {edge[0]}",
-                    dir="forward",
+                dot.add_edge(
+                    pydot.Edge(
+                        f"{edge[1].node.name} (#{edge[1].node.id})",
+                        f"{edge[0].node.name} (#{edge[0].node.id})",
+                        tailport=edge[1].name,
+                        headport=edge[0].name,
+                        key=f"{edge[1]} => {edge[0]}",
+                        dir="forward",
+                    )
                 )
 
-        return agraph
+        return dot
 
 
 class ExecutionPort(Port):