Add "minimal" mode for template files

Add a specific option to save a graph as a template ("Save As
Template") in "minimal" mode.

This mode only saves, for each node in the graph, the input and
output attributes whose values differ from the default ones. Any
attribute that is not serialized in the saved template file is
assumed to have its default value.
If a conflict is detected on a node when opening the template
file, it is logged but solved automatically.

The goal of this minimal mode is to prevent template files from
needing an update every single time a modification (may it be
minor or major) is done on a node description. Templates can
thus follow node changes and still be usable.

meshroom/core/graph.py

@@ -261,6 +261,9 @@ class Graph(BaseObject):
         self.header = fileData.get(Graph.IO.Keys.Header, {})
         nodesVersions = self.header.get(Graph.IO.Keys.NodesVersions, {})
 
+        # check whether the file was saved as a template in minimal mode
+        isTemplate = self.header.get("template", False)
+
         with GraphModification(self):
             # iterate over nodes sorted by suffix index in their names
             for nodeName, nodeData in sorted(graphData.items(), key=lambda x: self.getNodeIndexFromName(x[0])):
@@ -273,7 +276,8 @@ class Graph(BaseObject):
                 #   3. fallback to no version "0.0": retro-compatibility
                 if "version" not in nodeData:
                     nodeData["version"] = nodesVersions.get(nodeData["nodeType"], "0.0")
-                n = nodeFactory(nodeData, nodeName)
+
+                n = nodeFactory(nodeData, nodeName, template=isTemplate)
 
                 # Add node to the graph with raw attributes values
                 self._addNode(n, nodeName)
@@ -999,7 +1003,7 @@ class Graph(BaseObject):
     def asString(self):
         return str(self.toDict())
 
-    def save(self, filepath=None, setupProjectFile=True):
+    def save(self, filepath=None, setupProjectFile=True, template=False):
         path = filepath or self._filepath
         if not path:
             raise ValueError("filepath must be specified for unsaved files.")
@@ -1015,10 +1019,18 @@ class Graph(BaseObject):
             for p in usedNodeTypes
         }
 
-        data = {
-            Graph.IO.Keys.Header: self.header,
-            Graph.IO.Keys.Graph: self.toDict()
-        }
+        data = {}
+        if template:
+            self.header["template"] = True
+            data = {
+                Graph.IO.Keys.Header: self.header,
+                Graph.IO.Keys.Graph: self.getNonDefaultAttributes()
+            }
+        else:
+            data = {
+                Graph.IO.Keys.Header: self.header,
+                Graph.IO.Keys.Graph: self.toDict()
+            }
 
         with open(path, 'w') as jsonFile:
             json.dump(data, jsonFile, indent=4)
@@ -1026,6 +1038,35 @@ class Graph(BaseObject):
         if path != self._filepath and setupProjectFile:
             self._setFilepath(path)
 
+    def getNonDefaultAttributes(self):
+        """
+        Instead of getting all the inputs/outputs attribute keys, only get the keys of
+        the attributes whose value is not the default one.
+
+        Returns:
+            dict: self.toDict() with all the inputs/outputs attributes with default values removed
+        """
+        graph = self.toDict()
+        for nodeName in graph.keys():
+            node = self.node(nodeName)
+
+            inputKeys = list(graph[nodeName]["inputs"].keys())
+            outputKeys = list(graph[nodeName]["outputs"].keys())
+
+            for attrName in inputKeys:
+                attribute = node.attribute(attrName)
+                # check that attribute is not a link for choice attributes
+                if attribute.isDefault and not attribute.isLink:
+                    del graph[nodeName]["inputs"][attrName]
+
+            for attrName in outputKeys:
+                attribute = node.attribute(attrName)
+                # check that attribute is not a link for choice attributes
+                if attribute.isDefault and not attribute.isLink:
+                    del graph[nodeName]["outputs"][attrName]
+
+        return graph
+
     def _setFilepath(self, filepath):
         """
         Set the internal filepath of this Graph.

meshroom/core/node.py

@@ -1393,7 +1393,7 @@ class CompatibilityNode(BaseNode):
     issueDetails = Property(str, issueDetails.fget, constant=True)
 
 
-def nodeFactory(nodeDict, name=None):
+def nodeFactory(nodeDict, name=None, template=False):
     """
     Create a node instance by deserializing the given node data.
     If the serialized data matches the corresponding node type description, a Node instance is created.
@@ -1437,9 +1437,10 @@ def nodeFactory(nodeDict, name=None):
             compatibilityIssue = CompatibilityIssue.VersionConflict
         # in other cases, check attributes compatibility between serialized node and its description
         else:
-            # check that the node has the exact same set of inputs/outputs as its description
-            if sorted([attr.name for attr in nodeDesc.inputs]) != sorted(inputs.keys()) or \
-                    sorted([attr.name for attr in nodeDesc.outputs]) != sorted(outputs.keys()):
+            # check that the node has the exact same set of inputs/outputs as its description, except if the node
+            # is described in a template file, in which only non-default parameters are saved
+            if not template and (sorted([attr.name for attr in nodeDesc.inputs]) != sorted(inputs.keys()) or \
+                    sorted([attr.name for attr in nodeDesc.outputs]) != sorted(outputs.keys())):
                 compatibilityIssue = CompatibilityIssue.DescriptionConflict
             # verify that all inputs match their descriptions
             for attrName, value in inputs.items():
@@ -1463,5 +1464,7 @@ def nodeFactory(nodeDict, name=None):
         if not internalFolder and nodeDesc:
             logging.warning("No serialized output data: performing automatic upgrade on '{}'".format(name))
             node = node.upgrade()
+        elif template:  # if the node comes from a template file and there is a conflict, it should be upgraded anyway
+            node = node.upgrade()
 
     return node

meshroom/ui/graph.py

@@ -354,6 +354,14 @@ class UIGraph(QObject):
 
     @Slot(QUrl)
     def saveAs(self, url):
+        self._saveAs(url)
+
+    @Slot(QUrl)
+    def saveAsTemplate(self, url):
+        self._saveAs(url, setupProjectFile=False, template=True)
+
+    def _saveAs(self, url, setupProjectFile=True, template=False):
+        """ Helper function for 'save as' features. """
         if isinstance(url, (str)):
             localFile = url
         else:
@@ -361,7 +369,7 @@ class UIGraph(QObject):
         # ensure file is saved with ".mg" extension
         if os.path.splitext(localFile)[-1] != ".mg":
             localFile += ".mg"
-        self._graph.save(localFile)
+        self._graph.save(localFile, setupProjectFile=setupProjectFile, template=template)
         self._undoStack.setClean()
         # saving file on disk impacts cache folder location
         # => force re-evaluation of monitored status files paths

meshroom/ui/qml/main.qml

@@ -142,6 +142,22 @@ ApplicationWindow {
         onRejected: closed(Platform.Dialog.Rejected)
     }
 
+    Platform.FileDialog {
+        id: saveTemplateDialog
+
+        signal closed(var result)
+
+        title: "Save Template"
+        nameFilters: ["Meshroom Graphs (*.mg)"]
+        defaultSuffix: ".mg"
+        fileMode: Platform.FileDialog.SaveFile
+        onAccepted: {
+            _reconstruction.saveAsTemplate(file)
+            closed(Platform.Dialog.Accepted)
+        }
+        onRejected: closed(Platform.Dialog.Rejected)
+    }
+
     Item {
         id: computeManager
 
@@ -550,6 +566,17 @@ ApplicationWindow {
                     saveFileDialog.open()
                 }
             }
+            Action {
+                id: saveAsTemplateAction
+                text: "Save As Template..."
+                shortcut: "Ctrl+Shift+T"
+                onTriggered: {
+                    if(_reconstruction.graph && _reconstruction.graph.filepath) {
+                        saveTemplateDialog.folder = Filepath.stringToUrl(Filepath.dirname(_reconstruction.graph.filepath))
+                    }
+                    saveTemplateDialog.open()
+                }
+            }
             MenuSeparator { }
             Action {
                 text: "Quit"