feat(nuke): adding validate backdrop

checking if there are nodes above backdrop

pype/plugins/nuke/publish/validate_backdrop.py

@@ -0,0 +1,64 @@
+import pyblish
+from avalon.nuke import lib as anlib
+import nuke
+
+
+class SelectCenterInNodeGraph(pyblish.api.Action):
+    """
+    Centering failed instance node in node grap
+    """
+
+    label = "Center node in node graph"
+    icon = "wrench"
+    on = "failed"
+
+    def process(self, context, plugin):
+
+        # Get the errored instances
+        failed = []
+        for result in context.data["results"]:
+            if (result["error"] is not None and result["instance"] is not None
+               and result["instance"] not in failed):
+                failed.append(result["instance"])
+
+        # Apply pyblish.logic to get the instances for the plug-in
+        instances = pyblish.api.instances_by_plugin(failed, plugin)
+
+        all_xC = list()
+        all_yC = list()
+
+        # maintain selection
+        with anlib.maintained_selection():
+            # collect all failed nodes xpos and ypos
+            for instance in instances:
+                bdn = instance[0]
+                xC = bdn.xpos() + bdn.screenWidth()/2
+                yC = bdn.ypos() + bdn.screenHeight()/2
+
+                all_xC.append(xC)
+                all_yC.append(yC)
+
+        self.log.info("all_xC: `{}`".format(all_xC))
+        self.log.info("all_yC: `{}`".format(all_yC))
+
+        # zoom to nodes in node graph
+        nuke.zoom(2, [min(all_xC), min(all_yC)])
+
+
+@pyblish.api.log
+class ValidateBackdrop(pyblish.api.InstancePlugin):
+    """Validate amount of nodes on backdrop node in case user
+    forgoten to add nodes above the publishing backdrop node"""
+
+    order = pyblish.api.ValidatorOrder
+    optional = True
+    families = ["nukenodes"]
+    label = "Validate Backdrop"
+    hosts = ["nuke"]
+    actions = [SelectCenterInNodeGraph]
+
+    def process(self, instance):
+
+        msg = "No content on backdrop node: \"{}\"".format(
+            instance.data["name"])
+        assert len(instance) > 1, msg