TodoDetailsPart.java

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

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

import org.eclipse.core.databinding.Binding;
import org.eclipse.core.databinding.DataBindingContext;
import org.eclipse.core.databinding.beans.BeanProperties;
import org.eclipse.core.databinding.observable.ChangeEvent;
import org.eclipse.core.databinding.observable.IChangeListener;
import org.eclipse.core.databinding.observable.list.IObservableList;
import org.eclipse.core.databinding.observable.value.IObservableValue;
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.Persist;
import org.eclipse.e4.ui.model.application.ui.MDirtyable;
import org.eclipse.e4.ui.services.IServiceConstants;
import org.eclipse.jface.databinding.swt.WidgetProperties;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.DateTime;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Text;

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 TodoDetailsPart {

	@Inject
	MDirtyable dirty;

	private Text txtSummary;
	private Text txtDescription;
	private Button btnDone;
	private DateTime dateTime;
	private DataBindingContext ctx = new DataBindingContext();

	// Define listener for the databinding
	IChangeListener listener = new IChangeListener() {
		@Override
		public void handleChange(ChangeEvent event) {
			if (dirty != null) {
				dirty.setDirty(true);
			}
		}
	};
	private Todo todo;

	private Label lblSummary;

	private Label lblDescription;

	@PostConstruct
	public void createControls(Composite parent) {

		GridLayout gl_parent = new GridLayout(2, false);
		gl_parent.marginRight = 10;
		gl_parent.marginLeft = 10;
		gl_parent.horizontalSpacing = 10;
		gl_parent.marginWidth = 0;
		parent.setLayout(gl_parent);

		lblSummary = new Label(parent, SWT.NONE);

		txtSummary = new Text(parent, SWT.BORDER);
		txtSummary
				.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));

		lblDescription = new Label(parent, SWT.NONE);
		lblDescription.setText("Description");

		txtDescription = new Text(parent, SWT.BORDER | SWT.MULTI);
		GridData gd = new GridData(SWT.FILL, SWT.CENTER, true, false);
		gd.heightHint = 122;
		txtDescription.setLayoutData(gd);

		Label lblNewLabel = new Label(parent, SWT.NONE);
		lblNewLabel.setText("Due Date");

		dateTime = new DateTime(parent, SWT.BORDER);
		dateTime.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, false, false,
				1, 1));
		new Label(parent, SWT.NONE);

		btnDone = new Button(parent, SWT.CHECK);
		btnDone.setText("Done");

		updateUserInterface(todo);

	}

	@Inject
	private void translate(@Translation Messages message) {
		if (txtSummary != null && !txtSummary.isDisposed()) {
			lblSummary.setText(message.txtSummary);
			lblDescription.setText(message.txtDescription);
		}
	}

	@Persist
	public void save(MDirtyable dirty, ITodoService model) {
		model.saveTodo(todo);
		dirty.setDirty(false);
	}

	@Inject
	public void setTodo(
			@Optional @Named(IServiceConstants.ACTIVE_SELECTION) Todo todo) {
		if (todo != null) {
			// Remember the todo as field
			this.todo = todo;
			// update the user interface
			updateUserInterface(todo);
		}
	}

	// allows to disable/ enable the user interface fields
	// if no todo is et
	private void enableUserInterface(boolean enabled) {
		if (txtSummary != null && !txtSummary.isDisposed()) {
			txtSummary.setEnabled(enabled);
			txtDescription.setEnabled(enabled);
			dateTime.setEnabled(enabled);
			btnDone.setEnabled(enabled);
		}
	}

	private void updateUserInterface(Todo todo) {

		// check if Todo is null
		if (todo == null) {
			enableUserInterface(false);
			return;
		} else {
			enableUserInterface(true);
		}

		// Check if the user interface is available
		// assume you have a field called "summary"
		// for a widget
		if (txtSummary != null && !txtSummary.isDisposed()) {

			// Deregister change listener to the old binding
			IObservableList providers = ctx.getValidationStatusProviders();
			for (Object o : providers) {
				Binding b = (Binding) o;
				b.getTarget().removeChangeListener(listener);
			}

			// Remove bindings
			ctx.dispose();

			IObservableValue oWidgetSummary = WidgetProperties.text(SWT.Modify)
					.observe(txtSummary);
			IObservableValue oTodoSummary = BeanProperties.value(
					Todo.FIELD_SUMMARY).observe(todo);
			ctx.bindValue(oWidgetSummary, oTodoSummary);

			IObservableValue oWidgetDescription = WidgetProperties.text(
					SWT.Modify).observe(txtDescription);
			IObservableValue oTodoDescription = BeanProperties.value(
					Todo.FIELD_DESCRIPTION).observe(todo);
			ctx.bindValue(oWidgetDescription, oTodoDescription);

			IObservableValue oWidgetButton = WidgetProperties.selection()
					.observe(btnDone);
			IObservableValue oTodoDone = BeanProperties.value(Todo.FIELD_DONE)
					.observe(todo);
			ctx.bindValue(oWidgetButton, oTodoDone);

			IObservableValue oWidgetSelectionDateTime = WidgetProperties
					.selection().observe(dateTime);
			IObservableValue oTodoDueDate = BeanProperties.value(
					Todo.FIELD_DUEDATE).observe(todo);
			ctx.bindValue(oWidgetSelectionDateTime, oTodoDueDate);

			// register listener for any changes
			providers = ctx.getValidationStatusProviders();
			for (Object o : providers) {
				Binding b = (Binding) o;
				b.getTarget().addChangeListener(listener);
			}
		}
	}

	@Focus
	public void onFocus() {
		// The following assumes that you have a Text field
		// called summary
		txtSummary.setFocus();
	}
}