Node editor README

examples/README.md

@@ -70,8 +70,13 @@
 
 <hr>
 
+### [Nodeeditor: how to implement the node editor.](nodeeditor/README.md)
+
+![saveloadproject](../doc/assets/nodeeditor.png)
+
+<hr>
+
 ### Under development
 
 + modelinqml
-+ nodeeditor
 

examples/nodeeditor/README.md

@@ -1,9 +1,59 @@
 # Example "nodeeditor".
 
-The example shows a node editor (similar to the one we can find in LabView, Blender, 
-and others).
+The example shows a node editor similar to those we can find in LabView,
+Blender, Maya, and other applications. It allows organizing complex settings in
+the form of a dependency graph, displaying nodes and the connections between
+their attributes.
 
 > Node editor: original code is taken from
 > http://algoholic.eu/qnodeseditor-qt-nodesports-based-data-processing-flow-editor/
-> Copyright (c) 2012, STANISLAW ADASZEWSKI
+> Copyright (c) 2012, STANISLAW ADASZEWSKI.
+
+The example from the link was adapted for `qt-mvvm` library. The resulting
+application provides a data model, various view models (e.g. node editor,
+property editor, hierarchy view), serialization, and undo/redo.
+
+![plotgraphs](../../doc/assets/nodeeditor.png)
+
+## The context.
+
+In this particular example, the node editor is used to set up `ParticleLayout`
+for further simulation of neutron scattering from some nano-particle arrangement.
+The layout carries information about particles populating a crystal lattice.
+The `ParticleLayout` can have an arbitrary amount of particles attached, but
+only one single lattice. Particles can be rotated with the help of the
+`Transformation` object. There can be many layouts on the scene.
+
+## Widgets.
+
+- The list view on the left. Items from the list can be drag-and-dropped on the scene.
+- Node editor. Ports of the same color can be connected together.
+- Tree view present same data model as node editor in the form of object hierarchy.
+- Property editor shows all properties of currently selected node.
+
+## Details.
+
+### `ConnectableItem, ConnectableView and ConnectableItemController`
+
+The `ConnectableItem` is a base class for all items representing nodes. Doesn't
+have own visual representation. Serves as a building block for `SampleModel`. The
+`ConnectableView` is a counterpart of `ConnectableItem` on the graphics scene.
+The `ConnectableItemController` provides updates of view's position/appearance on
+graphics scene, when underlying item changes. Similarly, it provides update of
+item's properties while view is moved on the scene by the user.
+
+### `NodePort, NodeConnection and NodeController`
+
+This is the part which came originally from [Node Editor by STANISLAW ADASZEWSKI](http://algoholic.eu/qnodeseditor-qt-nodesports-based-data-processing-flow-editor).
+Contains machinery to establish elastic connections between ports.
+
+### `GraphicsScene and GraphicsSceneController`
+
+The `GraphicsSceneController` listens to the original `SampleModel` 
+and updates scene on model change. When item is removed from the model, the corresponding view will be removed too. When item is added to the model, 
+new view will be added to the scene.
+When elastic connection is established between two nodes, this triggers parent change request to the `SampleModel`. This in turn, leads to the
+connections in the node editor created as necessary to represent new parent/child relationships in the underlying model.
+
+![plotgraphs](../../doc/assets/nodeeditor.gif)