Merge pull request #1237 from ZacZhangzhuo/feature/viewer-context-detection

Feature/viewer-context-detection

Author: Licini

CHANGELOG.md

@@ -8,7 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Unreleased
 
 ### Added
-
+* Added `viewerinstance` in `compas.scene.Scene` to support viewers context detection.
 * Added `compas_rhino8` as starting point for Rhino8 support.
 * Added `compas.scene.SceneObjectNode`.
 * Added `compas.scene.SceneTree`.

src/compas/scene/context.py

@@ -1,10 +1,12 @@
-from compas.plugins import pluggable
+import inspect
+from collections import defaultdict
+
+import compas
 from compas.plugins import PluginValidator
+from compas.plugins import pluggable
+
 from .exceptions import NoSceneObjectContextError
 from .exceptions import SceneObjectNotRegisteredError
-import inspect
-import compas
-from collections import defaultdict
 
 ITEM_SCENEOBJECT = defaultdict(dict)
 
@@ -62,15 +64,9 @@ def is_viewer_open():
     bool
 
     """
-    # TODO: implement [without introducing compas_view2 as a dependency..?]
-    # make the viewer app a singleton
-    # check for the exitence of an instance of the singleton
-    # if the instance exists, return True
-    # in this case, the viewer is the current context
-    # to do this without introducing compas_view2 as a dependency,
-    # creating the singleton instance should modify a class attribute of the SceneObject
-    # (or potentially a module level attribute of compas itself)
-    return False
+    from compas.scene import Scene
+
+    return Scene.viewerinstance is not None
 
 
 def _detect_current_context():

src/compas/scene/scene.py

@@ -1,9 +1,10 @@
 from compas.data import Data
 from compas.datastructures import Tree
 from compas.datastructures import TreeNode
-from .sceneobject import SceneObject
-from .context import redraw
+
 from .context import clear
+from .context import redraw
+from .sceneobject import SceneObject
 
 
 class SceneObjectNode(TreeNode):
@@ -201,6 +202,8 @@ class Scene(Data):
 
     """
 
+    viewerinstance = None
+
     def __init__(self, name=None, context=None):
         super(Scene, self).__init__(name)
         self._tree = SceneTree("Scene")