Implement fully undo/redo with checks

While these actions are short in the backend--taking about 0.01 seconds to run--the Blender UI lags a lot leading to 2-3 second pauses because of the "refresh_brick_viewer" function being slow. This should be investigated.

src/blenderbim/blenderbim/bim/module/brick/__init__.py

@@ -33,6 +33,8 @@ classes = (
     operator.RewindBrickClass,
     operator.ViewBrickClass,
     operator.ViewBrickItem,
+    operator.UndoBrick,
+    operator.RedoBrick,
     operator.SerializeBrick,
     prop.Brick,
     prop.BIMBrickProperties,

src/blenderbim/blenderbim/bim/module/brick/operator.py

@@ -190,6 +190,20 @@ class RemoveBrick(bpy.types.Operator, Operator):
             brick_uri=props.bricks[props.active_brick_index].uri,
         )
 
+class UndoBrick(bpy.types.Operator, Operator):
+    bl_idname = "bim.undo_brick"
+    bl_label = "Undo Brick"
+
+    def _execute(self, context):
+        core.undo_brick(tool.Brick)
+
+class RedoBrick(bpy.types.Operator, Operator):
+    bl_idname = "bim.redo_brick"
+    bl_label = "Redo Brick"
+
+    def _execute(self, context):
+        core.redo_brick(tool.Brick)
+
 class SerializeBrick(bpy.types.Operator, Operator):
     bl_idname = "bim.serialize_brick"
     bl_label = "Serialize Brick"

src/blenderbim/blenderbim/bim/module/brick/ui.py

@@ -58,6 +58,10 @@ class BIM_PT_brickschema(Panel):
         row.operator("bim.add_brick_feed", text="", icon="PLUGIN")
         row.operator("bim.remove_brick", text="", icon="X")
 
+        row = self.layout.row(align=True)
+        row.operator("bim.undo_brick", icon="LOOP_BACK")
+        row.operator("bim.redo_brick", icon="LOOP_FORWARDS")
+
         row = self.layout.row(align=True)
         row.operator("bim.serialize_brick")
 

src/blenderbim/blenderbim/core/brick.py

@@ -110,5 +110,13 @@ def remove_brick(ifc, brick, library=None, brick_uri=None):
     brick.remove_brick(brick_uri)
     brick.run_refresh_brick_viewer()
 
+def undo_brick(brick):
+    brick.undo_brick()
+    brick.run_refresh_brick_viewer()
+
+def redo_brick(brick):
+    brick.redo_brick()
+    brick.run_refresh_brick_viewer()
+
 def serialize_brick(brick, file_name="BlenderBIMSerializeTest.ttl"):
     brick.serialize_brick(file_name)

src/blenderbim/blenderbim/tool/brick.py

@@ -282,9 +282,10 @@ class Brick(blenderbim.core.tool.Brick):
 
     @classmethod
     def remove_brick(cls, brick_uri):
-        with BrickStore.graph.new_changeset("PROJECT") as cs:
+        if(BrickStore.graph.triples((URIRef(brick_uri), None, None))):
-            for triple in BrickStore.graph.triples((URIRef(brick_uri), None, None)):
+            with BrickStore.graph.new_changeset("PROJECT") as cs:
-                cs.remove(triple)
+                for triple in BrickStore.graph.triples((URIRef(brick_uri), None, None)):
+                    cs.remove(triple)
 
     @classmethod
     def run_assign_brick_reference(cls, element=None, library=None, brick_uri=None):
@@ -312,11 +313,17 @@ class Brick(blenderbim.core.tool.Brick):
 
     @classmethod
     def undo_brick(cls):
-        BrickStore.graph.undo()
+        if(len(BrickStore.graph.versions()) > 1):
+            BrickStore.graph.undo()
 
     @classmethod
     def redo_brick(cls):
-        BrickStore.graph.redo()        
+        with BrickStore.graph.conn() as conn:
+            redo_record = conn.execute(
+            "SELECT * from redos " "ORDER BY timestamp ASC LIMIT 1"
+            ).fetchone()
+        if redo_record is not None:
+            BrickStore.graph.redo()  
 
     @classmethod
     def serialize_brick(cls, file_name):