We are used to clicking things in Eclipse and the properties view getting updated to show us additional information about the thing we clicked. However, when clicking on elements in the Eclipse GLSP editor this is not the case. Next, I give some background on how the PropertiesView works and how it is related to the editor selection. Then, I show how we can modify the GLSP editor to make use of the properties view.<\/p>\n\n\n\n
The GLSP tooling, I have found, is really complete out of the box. My issue is that most of the extra tools and things that are already available for you is poorly documented, so you either have to reinvent the wheel, or take some time to go over the code base and find what you need. This was the case with the properties view. In this discussion<\/a>, one of the GLSP maintainers suggests to create a SelectAction handler and then use that to notify the Eclipse Selection Service<\/a>. But taking a look at the code, the GLSP IDE editor plugin provides an IdeSelectActionHandler<\/kbd> and IdeSelectAllActionHandler<\/kbd> that already does that, and that notifies the GLSP Editor about the selection changes. All you need to do, is bind them in your editor module:<\/p>\n\n\n To be precise, the notification is received by the GLSPDiagramComposite<\/kbd> (which is used by the GLSPDiagramEditor<\/kbd> to provide the editor part control – an embedded browser if you need to know). The magic happens in the updateSelection method:<\/p>\n\n\n In the method, the selected element IDs (selectAction.getSelectedElementsIDs()<\/kbd>) are mapped to Graph Model Elements via the index. Then, the selectionListener is notified with the updated list of Graph Model Elements that are currently selected. In this case, the selection listener is just a wrapper to make sure that the notifications are run in the UI thread. Since the GLSPDiagramComposite<\/kbd> was used as the selection provider for the GLSPDiagramEditor<\/kbd>:<\/p>\n\n\n the PropertiesView will be notified that a Graph Model element was selected. Yet… nothing shows in the properties view. To understand why, we need to look at how the PropertiesView work.<\/p>\n\n\n\n There is an Eclipse Corner Article<\/a> that explains how to use the properties view. In a nutshell, there are two ways to provide a property source for a particular selection: The IPropertySource<\/kbd> interface allows the Properties View to dynamically adjust itself to show the properties of any Object within eclipse. It does so, in its simplest way, by providing a set of IPropertyDescriptor<\/kbd>. Each property descriptor will be visually represented by a row in the properties view (but technically provided by the PropertySheetEntry<\/kbd>). Without dwelling into the details of the API, the critical bit is that IPropertyDescriptor<\/kbd> must provide the editor for changing the property value. This can be a simple text editor for changing a text attribute or something like a color picker if the attribute represents a color. But most importantly you must react to the editor changes so you can update the object properties accordingly.<\/p>\n\n\n\n I must confess I panicked a bit when I understood what had to be done. When I was about to tell my boss I needed another month to get this working, I remembered that EMF provides this functionality out of the box. Luckily for me, the domain model (i.e. the mode for which the graph is created) was an EMF model, so all I had to do was hook everything together. If your domain model is not an EMF model…. this is as far as I can help. You need to implement all the property descriptors… (or create an Ecore model of your domain and use the solution that I present next – which I would strongly suggest and offer to help<\/a>).<\/p>\n\n\n\n\n@Override\nprotected void configureActionHandlers(final MultiBinding<ActionHandler> bindings) {\n\tsuper.configureActionHandlers(bindings);\n...\n\tbindings.add(IdeSelectActionHandler.class);\n\tbindings.add(IdeSelectAllActionHandler.class);\n}\n<\/pre><\/div>\n\n\n\npublic void updateSelection(final SelectAction selectAction) {\n getModelStateOnceInitialized().thenAccept(modelState -> {\n Collection<String> selectedIds = selectAction.getSelectedElementsIDs();\n Collection<String> deselectedIds = selectAction.isDeselectAll()\n ? modelState.getIndex().allIds()\n : selectAction.getDeselectedElementsIDs();\n List<GModelElement> selectedGModelElements = toGModelElements(selectedIds, modelState);\n List<GModelElement> deselectedGModelElements = toGModelElements(deselectedIds, modelState);\n List<GModelElement> selection = toGModelElementStream(currentSelection).collect(toList());\n\n selection.removeAll(deselectedGModelElements);\n addUnique(selectedGModelElements, selection);\n\n currentSelection = new StructuredSelection(selection);\n selectionListener.selectionChanged(new SelectionChangedEvent(this, currentSelection));\n });\n }\n<\/pre><\/div>\n\n\n\n@Override\n public void createPartControl(final Composite parent) {\n diagram.createPartControl(parent);\n setPartName(generatePartName());\n getSite().setSelectionProvider(diagram);\n createBrowserMenu();\n }\n<\/pre><\/div>\n\n\nEclipse Properties View<\/h2>\n\n\n\n
– The selected item can implement the\u00a0IAdaptable<\/kbd>\u00a0interface and return an\u00a0IPropertySource<\/kbd>\u00a0object when\u00a0getAdapter<\/kbd>\u00a0is called.
– The selected item can implement the\u00a0IPropertySource<\/kbd>\u00a0interface and provide the properties.
Neither of which GModelElement<\/kbd> satisfies (the super type of selected elements). So in order to solve the issue, we would need to make sure that the updateSelection<\/kbd> method that we discussed previously wraps the Graph Model Elements in a custom IAdaptable<\/kbd>\u00a0or IPropertySource<\/kbd>\u00a0implementation. Before you go and starting doing this, take a moment to understand the extend of the work needed to provide a working IPropertySource<\/kbd>.<\/p>\n\n\n\nIPropertySource<\/h3>\n\n\n\n
The Emf Edit and Editor<\/h2>\n\n\n\n