gpv3 port: create empty frames - add support for group as source

add utility function to check hide-lock state of nested items

utils.py

@@ -155,6 +155,44 @@ def gp_stroke_to_bmesh(strokes):
 ### GP Drawing
 # -----------------
 
+def layer_active_index(gpl):
+    '''Get layer list and return index of active layer
+    Can return None if no active layer found (active item can be a group)
+    '''
+    return next((i for i, l in enumerate(gpl) if l == gpl.active), None)
+
+## Check for nested lock
+def is_locked(stack_item):
+    '''Check if passed stack item (layer or group) is locked
+    either itself or by parent groups'''
+    if stack_item.lock:
+        return True
+    if stack_item.parent_group:
+        return is_locked(stack_item.parent_group)
+    return False
+
+def is_parent_locked(stack_item):
+    '''Check if passed stack item (layer or group) is locked by parent groups'''
+    if stack_item.parent_group:
+        return is_locked(stack_item.parent_group)
+    return False
+
+## Check for nested hide
+def is_hidden(stack_item):
+    '''Check if passed stack item (layer or group) is hidden
+    either itself or by parent groups'''
+    if stack_item.hide:
+        return True
+    if stack_item.parent_group:
+        return is_hidden(stack_item.parent_group)
+    return False
+
+def is_parent_hidden(stack_item):
+    '''Check if passed stack item (layer or group) is hidden by parent groups'''
+    if stack_item.parent_group:
+        return is_hidden(stack_item.parent_group)
+    return False
+
 def simple_draw_gp_stroke(pts, frame, width = 2, mat_id = 0):
     '''
     draw basic stroke by passing list of point 3D coordinate