Preliminary Check

packages/tree_clipper/src/tree_clipper/import_nodes.py

@@ -696,3 +696,7 @@ def import_all(self, parameters: ImportParameters) -> ImportReport:
         while self.step():
             pass
         return self.importer.report
+
+
+def preliminary_check(string: str) -> bool:
+    return string.startswith((MAGIC_STRING, "{"))

packages/tree_clipper_addon/src/tree_clipper_addon/__init__.py

@@ -56,10 +56,15 @@ def draw_export_active(self, _context):
     self.layout.operator(SCENE_OT_Tree_Clipper_Export_Active.bl_idname)
 
 
-def draw_import(self, _context):
+def draw_import(self, context):
+    if not SCENE_OT_Tree_Clipper_Import_Clipboard_Prepare.poll(context):
+        import_text = "Import Tree Clipper (Invalid Clipboard Content)"
+    else:
+        import_text = "Import Tree Clipper"
+
     self.layout.operator(
         SCENE_OT_Tree_Clipper_Import_Clipboard_Prepare.bl_idname,
-        text="Import Tree Clipper",
+        text=import_text,
     )
 
 

packages/tree_clipper_addon/src/tree_clipper_addon/operators_export.py

@@ -21,6 +21,7 @@
 class SCENE_OT_Tree_Clipper_Export_Prepare(bpy.types.Operator):
     bl_idname = "scene.tree_clipper_export_prepare"
     bl_label = "Export"
+    bl_description = "Export the node tree as a Tree Clipper string."
     bl_options: ClassVar[set[str]] = {"REGISTER"}  # ty:ignore[invalid-attribute-override]
 
     is_material: bpy.props.BoolProperty(name="Top level Material")  # type: ignore

packages/tree_clipper_addon/src/tree_clipper_addon/operators_import.py

@@ -11,7 +11,11 @@
 
 from ._vendor.tree_clipper.common import DEFAULT_FILE
 from ._vendor.tree_clipper.dynamic_pointer import add_all_known_pointer_properties
-from ._vendor.tree_clipper.import_nodes import ImportIntermediate, ImportParameters
+from ._vendor.tree_clipper.import_nodes import (
+    ImportIntermediate,
+    ImportParameters,
+    preliminary_check,
+)
 from ._vendor.tree_clipper.specific_handlers import (
     BUILT_IN_IMPORTER,
 )
@@ -25,6 +29,7 @@
 class SCENE_OT_Tree_Clipper_Import_File_Prepare(bpy.types.Operator):
     bl_idname = "scene.tree_clipper_import_file_prepare"
     bl_label = "Import File"
+    bl_description = "Import a Tree Clipper string from a file."
     bl_options: ClassVar[set[str]] = {"REGISTER"}  # ty:ignore[invalid-attribute-override]
 
     input_file: bpy.props.StringProperty(
@@ -52,8 +57,13 @@ def execute(
 class SCENE_OT_Tree_Clipper_Import_Clipboard_Prepare(bpy.types.Operator):
     bl_idname = "scene.tree_clipper_import_clipboard_prepare"
     bl_label = "Import Clipboard"
+    bl_description = "Import a Tree Clipper string from the clipboard."
     bl_options: ClassVar[set[str]] = {"REGISTER"}  # ty:ignore[invalid-attribute-override]
 
+    @classmethod
+    def poll(cls, context: bpy.types.Context) -> bool:
+        return preliminary_check(bpy.context.window_manager.clipboard)  # ty:ignore[unresolved-attribute]
+
     def execute(
         self, context: bpy.types.Context
     ) -> set["rna_enums.OperatorReturnItems"]:

packages/tree_clipper_addon/src/tree_clipper_addon/panel.py

@@ -39,5 +39,11 @@ def draw(self, context: bpy.types.Context) -> None:
         self.layout.separator()  # ty:ignore[possibly-missing-attribute]
 
         import_col = self.layout.column()  # ty:ignore[possibly-missing-attribute]
-        import_col.operator(SCENE_OT_Tree_Clipper_Import_Clipboard_Prepare.bl_idname)
+        if SCENE_OT_Tree_Clipper_Import_Clipboard_Prepare.poll(context):
+            import_text = SCENE_OT_Tree_Clipper_Import_Clipboard_Prepare.bl_label
+        else:
+            import_text = "Invalid Clipboard Content"
+        import_col.operator(
+            SCENE_OT_Tree_Clipper_Import_Clipboard_Prepare.bl_idname, text=import_text
+        )
         import_col.operator(SCENE_OT_Tree_Clipper_Import_File_Prepare.bl_idname)