Notes

The solution presented in this article is for CODESYS V3.4 and later. It will not work with older versions of CODESYS.

Idea

In the Automation Platform, there is a central implementation of a so-called NavigatorControl, accessible through the interface _3S.CODESYS.NavigatorControl.INavigatorControl. This control is able to display the contents of an arbitrary project in the Object Manager by specifying its project handle and the GUID of the structured view (The explanation of structured views goes beyond this article). The out-of-the-box functionality of NavigatorControl comprises amongst other things:

• For each object in the project, it displays a node. The node hierarchy reflects the underlying structured view.
• For each single node, the object's icon and name are displayed.
• If the navigator control is not set to read-only, clipboard and DnD functionality is available.
• The control contains a toolbar with four buttons: Perform action, Sort order, Sort by, and Find. The latter three ones are completely implemented, while the first one triggers an event that can be consumed by the using code.

And there is an additional interface which makes customization easy: _3S.CODESYS.NavigatorControl.INavigatorControlExtension.

Solution

Simply create a new class within your plug-in that implements the _3S.CODESYS.NavigatorControl.INavigatorControlExtension interface. This interface has got two methods:

• GetAdditionalFilterCallback: This method returns a delegate which is called for each node in the tree. The resulting value determines whether this particular node will be visible or not.
• GetAdditionalRenderingCallback: This method returns another delegate which is also called for each node in the tree. Here, the appearance attributes of each visible node can be adjusted: text, fore color, back color, font style, and decorating icons.

Compared to the old approach, such an implementation is very easy (approx. 60 lines of code compared to some 340 lines of code). Furthermore, it has got the advantage that it influences all instances of navigator control: while the old approach only hooks into the main navigator windows of CODESYS, the new approach also functions on print preview, export, and all the other locations where a navigator control is displayed.

Running the sample

• Download the attached sources.
• If not already done, set the environment variable %APCOMMON% to the Common directory of your CODESYS installation. (This is the directory where CODESYS.exe, IPMCLI.exe, and IPM.exe are installed.)
• Start Visual Studio and open the solution NavigatorOverrideNewApproach.sln.
• Depending on your installation, you must correct some references to interface components, so that they point into the Interface Binaries folder in your Automation Platform SDK installation.
• Build the sample. The plug-in will be automatically installed.
• Use IPM.exe in order to add the plug-in Sample: Navigator Override (new approach) to one of your version profiles.
• Start CODESYS and ignore the message about the missing plug-in key.

The sample implementation appends the object GUID of all objects to the node text, highlights all POU objects with a yellow background, and hides all objects which name starts with "hide". Please make sure that you uninstall that plug-in again at a later time, our you'll never see objects that start with "hide" any more!

Best practices

• When using the sample code in any serious development, please make sure that you exchange all type GUIDs and the plug-in GUID by GUIDs generated on your machine.
• Rendering and filter callbacks are called very often, so they must perform very fast!
• If you need to get a readable copy of an object in order to render or filter it correctly, it is highly recommended that you check whether this object is already loaded, and do nothing if this is not the case. Otherwise, the lazy load mechanism during loading a project will be broken because the painting routines will then indirectly force an immediate load of the objects. You can observe the good implementation in practice: if you open a large project, then on the first appearance POUs are only displayed with their name, but once the lazy load mechanism starts (take a look at the status bar), one after the other POU node is decorated with the POU kind. Mostly however, it is enough to check the ObjectType property of the meta object stub that is passed into the callback methods.