threejs: access files through features, for simpler configuration

src/sage/env.py

@@ -214,7 +214,7 @@ def var(key: str, *fallbacks: Optional[str], force: bool = False) -> Optional[st
 JMOL_DIR = var("JMOL_DIR")
 MATHJAX_DIR = var("MATHJAX_DIR", join(SAGE_SHARE, "mathjax"))
 MTXLIB = var("MTXLIB", join(SAGE_SHARE, "meataxe"))
-THREEJS_DIR = var("THREEJS_DIR", join(SAGE_SHARE, "threejs-sage"))
+THREEJS_DIR = var("THREEJS_DIR")
 PPLPY_DOCS = var("PPLPY_DOCS", join(SAGE_SHARE, "doc", "pplpy"))
 MAXIMA = var("MAXIMA", "maxima")
 MAXIMA_FAS = var("MAXIMA_FAS")

src/sage/features/threejs.py

@@ -0,0 +1,47 @@
+import os
+
+from . import StaticFile
+
+
+class Threejs(StaticFile):
+    r"""
+    A :class:`~sage.features.Feature` which describes the presence of
+    threejs-sage in a few standard locations.
+
+    EXAMPLES::
+
+        sage: from sage.features.threejs import Threejs
+        sage: bool(Threejs().is_present())  # needs threejs
+        True
+    """
+
+    def __init__(self):
+        r"""
+        TESTS::
+
+            sage: from sage.features.threejs import Threejs
+            sage: isinstance(Threejs(), Threejs)
+            True
+        """
+        from sage.env import SAGE_SHARE, THREEJS_DIR
+        from sage.repl.rich_output import display_manager
+
+        version = display_manager._required_threejs_version()
+
+        threejs_search_path = THREEJS_DIR or (
+            os.path.join(SAGE_SHARE, "jupyter", "nbextension", "threejs-sage"),
+            os.path.join(SAGE_SHARE, "sagemath", "threejs-sage"),
+            os.path.join(SAGE_SHARE, "threejs-sage")
+            )
+
+        StaticFile.__init__(
+            self, name="threejs",
+            filename=os.path.join(version, "three.min.js"),
+            spkg="threejs",
+            type="standard",
+            search_path=threejs_search_path,
+            description="JavaScript library to display 3D graphics")
+
+
+def all_features():
+    return [Threejs()]

src/sage/repl/ipython_kernel/install.py

@@ -23,7 +23,6 @@
     SAGE_EXTCODE,
     SAGE_VENV,
     SAGE_VERSION,
-    THREEJS_DIR,
 )
 
 
@@ -123,14 +122,18 @@ def use_local_threejs(self):
 
         EXAMPLES::
 
+            sage: # needs threejs
             sage: from sage.repl.ipython_kernel.install import SageKernelSpec
             sage: spec = SageKernelSpec(prefix=tmp_dir())
             sage: spec.use_local_threejs()
             sage: threejs = os.path.join(spec.nbextensions_dir, 'threejs-sage')
             sage: os.path.isdir(threejs)
             True
         """
-        src = THREEJS_DIR
+        from sage.features.threejs import Threejs
+        if not Threejs().is_present():
+            return
+        src = os.path.dirname(os.path.dirname(Threejs().absolute_filename()))
         dst = os.path.join(self.nbextensions_dir, 'threejs-sage')
         self.symlink(src, dst)
 

src/sage/repl/rich_output/backend_ipython.py

@@ -409,15 +409,18 @@ def threejs_offline_scripts(self):
 
         EXAMPLES::
 
+            sage: # needs threejs
             sage: from sage.repl.rich_output.backend_ipython import BackendIPythonCommandline
             sage: backend = BackendIPythonCommandline()
-            sage: backend.threejs_offline_scripts()                                     # needs sage.plot
+            sage: backend.threejs_offline_scripts()
             '...<script ...</script>...'
         """
-        from sage.env import THREEJS_DIR
+        from sage.features.threejs import Threejs
         from sage.repl.rich_output.display_manager import _required_threejs_version
+        if not Threejs().is_present():
+            return ''
 
-        script = os.path.join(THREEJS_DIR, '{}/three.min.js'.format(_required_threejs_version()))
+        script = Threejs().absolute_filename()
 
         return '\n<script src="{0}"></script>'.format(script)