TodoDeletionPart.java

package com.example.e4.rcp.todo.parts;

import java.util.List;

import javax.annotation.PostConstruct;
import javax.inject.Inject;

import org.eclipse.core.commands.ParameterizedCommand;
import org.eclipse.e4.core.commands.ECommandService;
import org.eclipse.e4.core.commands.EHandlerService;
import org.eclipse.e4.core.contexts.IEclipseContext;
import org.eclipse.e4.core.di.annotations.Optional;
import org.eclipse.e4.core.services.nls.Translation;
import org.eclipse.e4.ui.di.Focus;
import org.eclipse.e4.ui.di.UIEventTopic;
import org.eclipse.e4.ui.workbench.modeling.ESelectionService;
import org.eclipse.jface.viewers.ArrayContentProvider;
import org.eclipse.jface.viewers.ComboViewer;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;

import com.example.e4.rcp.todo.events.MyEventConstants;
import com.example.e4.rcp.todo.i18n.Messages;
import com.example.e4.rcp.todo.model.ITodoService;
import com.example.e4.rcp.todo.model.Todo;

public class TodoDeletionPart {
	@Inject
	private ITodoService model;
	
	@Inject
	@Translation
	Messages message;
	
	@Inject 
	ESelectionService selectionService;
	
	@Inject EHandlerService handlerService;
	@Inject ECommandService commandService;
	@Inject IEclipseContext ctx;
	
	private ComboViewer viewer;

	@PostConstruct
	public void createControls(Composite parent ) {
		parent.setLayout(new GridLayout(2, false));
		viewer = new ComboViewer(parent, SWT.READ_ONLY);
		viewer.setLabelProvider(new LabelProvider() {
			@Override
			public String getText(Object element) {
				Todo todo = (Todo) element;
				return todo.getSummary();
			}
		});
		viewer.setContentProvider(ArrayContentProvider.getInstance());

		List<Todo> todos = model.getTodos();
		updateViewer(todos);

		Button button = new Button(parent, SWT.PUSH);
		button.addSelectionListener(new SelectionAdapter() {
			@Override
			public void widgetSelected(SelectionEvent e) {
				ISelection selection = viewer.getSelection();
				IStructuredSelection sel = (IStructuredSelection) selection;
				if (sel.size() > 0) {
					selectionService.setSelection(sel.getFirstElement());
					// assure that "com.example.e4.rcp.todo.remove" is the ID
					// of the command which deletes todos in your application model
					ParameterizedCommand cmd =
							commandService.createCommand("com.example.e4.rcp.todo.remove", null);
					handlerService.executeHandler(cmd, ctx);
				}

			}
		});
		button.setText(message.part_deletion_button_deletetodo);
	}

	private void updateViewer(List<Todo> todos) {
		viewer.setInput(todos);
		if (todos.size() > 0) {
			viewer.setSelection(new StructuredSelection(todos.get(0)));
		}
	}
	
	@Inject
	@Optional
	private void getNotified(
			@UIEventTopic(
					MyEventConstants.TOPIC_TODO_ALLTOPICS) 
			 	    Todo todo) {
		updateViewer(model.getTodos());
	}

	@Focus
	public void focus() {
		viewer.getControl().setFocus();
	}
}