bundles/org.eclipse.emf.ecp.edit.swt/src/org/eclipse/emf/ecp/edit/internal/swt/util/SWTControl.java - emfclient/org.eclipse.emf.ecp.core - Git at Google

 /*******************************************************************************
  * Copyright (c) 2011-2013 EclipseSource Muenchen GmbH and others.
  *
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * Eugen Neufeld - initial API and implementation
  *
  *******************************************************************************/
 package org.eclipse.emf.ecp.edit.internal.swt.util;

 import org.eclipse.emf.databinding.edit.EMFEditObservables;
 import org.eclipse.emf.ecore.EStructuralFeature;
 import org.eclipse.emf.ecp.edit.ECPAbstractControl;
 import org.eclipse.emf.ecp.edit.ECPControlContext;
 import org.eclipse.emf.ecp.edit.internal.swt.Activator;
 import org.eclipse.emf.edit.command.SetCommand;
 import org.eclipse.emf.edit.provider.IItemPropertyDescriptor;

 import org.eclipse.core.databinding.Binding;
 import org.eclipse.core.databinding.DataBindingContext;
 import org.eclipse.core.databinding.observable.value.IObservableValue;
 import org.eclipse.jface.action.Action;
 import org.eclipse.jface.dialogs.IDialogLabelKeys;
 import org.eclipse.jface.dialogs.MessageDialog;
 import org.eclipse.jface.layout.GridDataFactory;
 import org.eclipse.jface.layout.GridLayoutFactory;
 import org.eclipse.jface.resource.JFaceResources;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.custom.StackLayout;
 import org.eclipse.swt.events.MouseEvent;
 import org.eclipse.swt.events.MouseListener;
 import org.eclipse.swt.events.SelectionAdapter;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.widgets.Button;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Label;

 /**
  * This class defines a SWTCOntrol which is an abstract class defining an {@link ECPAbstractControl} for SWT.
  *
  * @author Eugen Neufeld
  *
  */
 public abstract class SWTControl extends ECPAbstractControl {

 	/**
 	 * RAP theming variable to set.
 	 */
 	protected static final String CUSTOM_VARIANT = "org.eclipse.rap.rwt.customVariant";

 	protected static final String VALIDATION_ERROR_ICON = "icons/validation_error.png";//$NON-NLS-1$

 	protected Label validationLabel;

 	private IObservableValue modelValue;
 	private Binding binding;

 	private Composite controlComposite;
 	private Composite parentComposite;
 	private StackLayout sl;
 	private Label unsetLabel;

 	/**
 	 * Constructor for a swt control.
 	 *
 	 * @param showLabel whether to show a label
 	 * @param itemPropertyDescriptor the {@link IItemPropertyDescriptor} to use
 	 * @param feature the {@link EStructuralFeature} to use
 	 * @param modelElementContext the {@link ECPControlContext} to use
 	 * @param embedded whether this control is embedded in another control
 	 */
 	public SWTControl(boolean showLabel, IItemPropertyDescriptor itemPropertyDescriptor, EStructuralFeature feature,
 		ECPControlContext modelElementContext, boolean embedded) {
 		super(showLabel, itemPropertyDescriptor, feature, modelElementContext, embedded);
 	}

 	/*
 	 * (non-Javadoc)
 	 * @see org.eclipse.emf.ecp.internal.edit.controls.AbstractControl#createControl(org.eclipse.swt.widgets.Composite)
 	 */
 	public Composite createControl(final Composite parent) {
 		final Composite composite = new Composite(parent, SWT.NONE);
 		int numColumns = 2;
 		if (isEmbedded()) {
 			numColumns--;
 		}
 		if (getModelElementContext().isRunningAsWebApplication()) {
 			numColumns++;
 		}
 		GridLayoutFactory.fillDefaults().numColumns(numColumns).spacing(10, 0).applyTo(composite);
 		GridDataFactory.fillDefaults().grab(true, false).align(SWT.FILL, SWT.BEGINNING).applyTo(composite);
 		if (!isEmbedded()) {
 			validationLabel = new Label(composite, SWT.NONE);
 			// set the size of the label to the size of the image
 			GridDataFactory.fillDefaults().hint(16, 17).applyTo(validationLabel);
 		}

 		Composite innerComposite = new Composite(composite, SWT.NONE);
 		GridDataFactory.fillDefaults().grab(true, false).align(SWT.FILL, SWT.BEGINNING).applyTo(innerComposite);
 		GridLayoutFactory.fillDefaults().numColumns(1).applyTo(innerComposite);
 		createContentControl(innerComposite);
 		setEditable(isEditable());

 		binding = bindValue();

 		// write initial values to model (if they differ from the default value of the model-element)
 		if (!getStructuralFeature().isUnsettable()
 			&& !getModelElementContext().getModelElement().eIsSet(getStructuralFeature())) {
 			if (binding != null) {
 				binding.updateTargetToModel();
 			}
 		}

 		if (getModelElementContext().isRunningAsWebApplication() && getHelpText() != null
 			&& getHelpText().length() != 0) {
 			Label l = new Label(composite, SWT.PUSH);
 			l.setImage(Activator.getImage("icons/help.png"));
 			l.setData(CUSTOM_VARIANT, "org_eclipse_emf_ecp_control_help");
 			l.addMouseListener(new MouseListener() {

 				public void mouseUp(MouseEvent e) {
 					MessageDialog dialog = new MessageDialog(parent.getShell(), "Help", null, getHelpText(),
 						MessageDialog.INFORMATION, new String[] { JFaceResources
 							.getString(IDialogLabelKeys.OK_LABEL_KEY) }, 0);
 					new ECPDialogExecutor(dialog) {

 						@Override
 						public void handleResult(int codeResult) {

 						}
 					}.execute();
 				}

 				public void mouseDown(MouseEvent e) {
 					// TODO Auto-generated method stub

 				}

 				public void mouseDoubleClick(MouseEvent e) {
 					// TODO Auto-generated method stub

 				}
 			});
 			// Button b = new Button(composite, SWT.PUSH);
 			// b.addSelectionListener(new SelectionAdapter() {
 			//
 			// @Override
 			// public void widgetSelected(SelectionEvent e) {
 			// super.widgetSelected(e);
 			// MessageDialog dialog = new MessageDialog(parent.getShell(), "Help", null, getHelpText(),
 			// MessageDialog.INFORMATION, new String[] { JFaceResources
 			// .getString(IDialogLabelKeys.OK_LABEL_KEY) }, 0);
 			// new ECPDialogExecutor(dialog) {
 			//
 			// @Override
 			// public void handleResult(int codeResult) {
 			//
 			// }
 			// }.execute();
 			// }
 			//
 			// });
 			// Control[] tabList = new Control[composite.getTabList().length - 1];
 			// System.arraycopy(composite.getTabList(), 0, tabList, 0, tabList.length);
 			// composite.setTabList(tabList);
 		} else {
 			Control[] controls = getControlsForTooltip();
 			if (controls != null) {
 				for (Control control : controls) {
 					control.setToolTipText(getHelpText());
 				}
 			}

 		}
 		return composite;
 	}

 	/**
 	 * @return
 	 */
 	protected abstract Control[] getControlsForTooltip();

 	/**
 	 * Helper for creating the unset stacklayout and creating the control's composite.
 	 *
 	 * @param composite the parent {@link Composite} to create the control onto
 	 */
 	protected void createContentControl(Composite composite) {
 		parentComposite = new Composite(composite, SWT.NONE);
 		GridDataFactory.fillDefaults().grab(true, true).align(SWT.FILL, SWT.FILL).applyTo(parentComposite);
 		sl = new StackLayout();
 		parentComposite.setLayout(sl);
 		controlComposite = new Composite(parentComposite, SWT.NONE);
 		// 1 column for control, 1 for default unset button
 		GridLayoutFactory.fillDefaults().numColumns(2).spacing(2, 0).applyTo(controlComposite);

 		unsetLabel = new Label(parentComposite, SWT.NONE);
 		unsetLabel.setBackground(composite.getBackground());
 		unsetLabel.setForeground(composite.getShell().getDisplay().getSystemColor(SWT.COLOR_DARK_GRAY));
 		unsetLabel.setAlignment(SWT.CENTER);
 		unsetLabel.setText(getUnsetLabelText());
 		unsetLabel.addMouseListener(new MouseListener() {

 			public void mouseUp(MouseEvent e) {
 				sl.topControl = controlComposite;
 				parentComposite.layout(true);
 				if (binding != null) {
 					binding.updateTargetToModel();
 				} else {
 					Object currentUnsetValue = getModelElementContext().getModelElement().eGet(getStructuralFeature());
 					getModelElementContext().getModelElement().eSet(getStructuralFeature(), currentUnsetValue);
 				}
 			}

 			public void mouseDown(MouseEvent e) {
 				// nothing to do
 			}

 			public void mouseDoubleClick(MouseEvent e) {
 				// nothing to do
 			}
 		});

 		fillControlComposite(controlComposite);

 		if (!isEmbedded() && getStructuralFeature().isUnsettable()) {
 			Button unsetButton = getCustomUnsetButton();
 			if (unsetButton == null) {
 				unsetButton = new Button(controlComposite, SWT.PUSH);
 				unsetButton.setToolTipText(getUnsetButtonTooltip());
 				unsetButton.setImage(Activator.getImage("icons/delete.png")); //$NON-NLS-1$
 			}
 			unsetButton.addSelectionListener(new SelectionAdapter() {
 				@Override
 				public void widgetSelected(SelectionEvent e) {
 					getModelElementContext()
 						.getEditingDomain()
 						.getCommandStack()
 						.execute(
 							new SetCommand(getModelElementContext().getEditingDomain(), getModelElementContext()
 								.getModelElement(), getStructuralFeature(), SetCommand.UNSET_VALUE));

 					showUnsetLabel();
 				}
 			});
 			unsetButton.setData(CUSTOM_VARIANT, "org_eclipse_emf_ecp_control_unset");
 		}

 		if (!getStructuralFeature().isUnsettable()
 			|| getModelElementContext().getModelElement().eIsSet(getStructuralFeature())) {
 			sl.topControl = controlComposite;
 		} else {
 			sl.topControl = unsetLabel;
 		}

 		parentComposite.layout();
 	}

 	/**
 	 *
 	 */
 	protected void showUnsetLabel() {
 		sl.topControl = unsetLabel;
 		parentComposite.layout();
 	}

 	/**
 	 * This method must be overridden by concrete classes. Here the widget displaying the data is added to the
 	 * composite.
 	 *
 	 * @param controlComposite the {@link Composite} to add the widget to
 	 */
 	protected abstract void fillControlComposite(Composite controlComposite);

 	/**
 	 * The default unset button will be displayed to the right of the control's composite. Concrete classes may override
 	 * this method to include an own unset button in their composite rather than using the default positioning.
 	 *
 	 * @return The custom unset button of the concrete class
 	 */
 	protected Button getCustomUnsetButton() {
 		return null;
 	}

 	/**
 	 * Returns the {@link DataBindingContext} set in the constructor.
 	 *
 	 * @return the {@link DataBindingContext}
 	 */
 	protected DataBindingContext getDataBindingContext() {
 		return getModelElementContext().getDataBindingContext();
 	}

 	/**
 	 * The model value used for databinding. It is either the set one or the calculated.
 	 *
 	 * @return the {@link IObservableValue}
 	 */
 	protected IObservableValue getModelValue() {
 		if (modelValue != null) {
 			return modelValue;
 		}
 		modelValue = EMFEditObservables.observeValue(getModelElementContext().getEditingDomain(),
 			getModelElementContext().getModelElement(), getStructuralFeature());
 		return modelValue;
 	}

 	/**
 	 * Allows the user to set the {@link IObservableValue} to use in the control during databinding.
 	 *
 	 * @param modelValue the set {@link IObservableValue}
 	 */
 	public void setObservableValue(IObservableValue modelValue) {
 		this.modelValue = modelValue;
 	}

 	/**
 	 * A helper method which creates a button for an action on a composite.
 	 *
 	 * @param action the action to create a button for
 	 * @param composite the composite to create the button onto
 	 * @return the created button
 	 */
 	protected Button createButtonForAction(final Action action, final Composite composite) {
 		Button selectButton = new Button(composite, SWT.PUSH);
 		selectButton.setImage(action.getImageDescriptor().createImage());
 		selectButton.setToolTipText(action.getToolTipText());
 		selectButton.addSelectionListener(new SelectionAdapter() {
 			@Override
 			public void widgetSelected(SelectionEvent e) {
 				action.run();
 				composite.layout();
 			}

 		});
 		return selectButton;
 	}

 	/**
 	 * Triggers the control to perform the databinding.
 	 *
 	 * @return The {@link Binding}
 	 */
 	protected abstract Binding bindValue();

 	/**
 	 * Returns the help information.
 	 *
 	 * @return The help text
 	 */
 	protected String getHelpText() {
 		return getItemPropertyDescriptor().getDescription(null);
 	}

 	/**
 	 * Returns the string for the unset label.
 	 *
 	 * @return The unset label text
 	 */
 	protected abstract String getUnsetLabelText();

 	/**
 	 * Returns the string for the unset button tooltip.
 	 *
 	 * @return The unset button tooltip
 	 */
 	protected abstract String getUnsetButtonTooltip();
 }
	/*******************************************************************************
	* Copyright (c) 2011-2013 EclipseSource Muenchen GmbH and others.
	*
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* Eugen Neufeld - initial API and implementation
	*
	*******************************************************************************/
	package org.eclipse.emf.ecp.edit.internal.swt.util;

	import org.eclipse.emf.databinding.edit.EMFEditObservables;
	import org.eclipse.emf.ecore.EStructuralFeature;
	import org.eclipse.emf.ecp.edit.ECPAbstractControl;
	import org.eclipse.emf.ecp.edit.ECPControlContext;
	import org.eclipse.emf.ecp.edit.internal.swt.Activator;
	import org.eclipse.emf.edit.command.SetCommand;
	import org.eclipse.emf.edit.provider.IItemPropertyDescriptor;

	import org.eclipse.core.databinding.Binding;
	import org.eclipse.core.databinding.DataBindingContext;
	import org.eclipse.core.databinding.observable.value.IObservableValue;
	import org.eclipse.jface.action.Action;
	import org.eclipse.jface.dialogs.IDialogLabelKeys;
	import org.eclipse.jface.dialogs.MessageDialog;
	import org.eclipse.jface.layout.GridDataFactory;
	import org.eclipse.jface.layout.GridLayoutFactory;
	import org.eclipse.jface.resource.JFaceResources;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.custom.StackLayout;
	import org.eclipse.swt.events.MouseEvent;
	import org.eclipse.swt.events.MouseListener;
	import org.eclipse.swt.events.SelectionAdapter;
	import org.eclipse.swt.events.SelectionEvent;
	import org.eclipse.swt.widgets.Button;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Control;
	import org.eclipse.swt.widgets.Label;

	/**
	* This class defines a SWTCOntrol which is an abstract class defining an {@link ECPAbstractControl} for SWT.
	*
	* @author Eugen Neufeld
	*
	*/
	public abstract class SWTControl extends ECPAbstractControl {

	/**
	* RAP theming variable to set.
	*/
	protected static final String CUSTOM_VARIANT = "org.eclipse.rap.rwt.customVariant";

	protected static final String VALIDATION_ERROR_ICON = "icons/validation_error.png";//$NON-NLS-1$

	protected Label validationLabel;

	private IObservableValue modelValue;
	private Binding binding;

	private Composite controlComposite;
	private Composite parentComposite;
	private StackLayout sl;
	private Label unsetLabel;

	/**
	* Constructor for a swt control.
	*
	* @param showLabel whether to show a label
	* @param itemPropertyDescriptor the {@link IItemPropertyDescriptor} to use
	* @param feature the {@link EStructuralFeature} to use
	* @param modelElementContext the {@link ECPControlContext} to use
	* @param embedded whether this control is embedded in another control
	*/
	public SWTControl(boolean showLabel, IItemPropertyDescriptor itemPropertyDescriptor, EStructuralFeature feature,
	ECPControlContext modelElementContext, boolean embedded) {
	super(showLabel, itemPropertyDescriptor, feature, modelElementContext, embedded);
	}

	/*
	* (non-Javadoc)
	* @see org.eclipse.emf.ecp.internal.edit.controls.AbstractControl#createControl(org.eclipse.swt.widgets.Composite)
	*/
	public Composite createControl(final Composite parent) {
	final Composite composite = new Composite(parent, SWT.NONE);
	int numColumns = 2;
	if (isEmbedded()) {
	numColumns--;
	}
	if (getModelElementContext().isRunningAsWebApplication()) {
	numColumns++;
	}
	GridLayoutFactory.fillDefaults().numColumns(numColumns).spacing(10, 0).applyTo(composite);
	GridDataFactory.fillDefaults().grab(true, false).align(SWT.FILL, SWT.BEGINNING).applyTo(composite);
	if (!isEmbedded()) {
	validationLabel = new Label(composite, SWT.NONE);
	// set the size of the label to the size of the image
	GridDataFactory.fillDefaults().hint(16, 17).applyTo(validationLabel);
	}

	Composite innerComposite = new Composite(composite, SWT.NONE);
	GridDataFactory.fillDefaults().grab(true, false).align(SWT.FILL, SWT.BEGINNING).applyTo(innerComposite);
	GridLayoutFactory.fillDefaults().numColumns(1).applyTo(innerComposite);
	createContentControl(innerComposite);
	setEditable(isEditable());

	binding = bindValue();

	// write initial values to model (if they differ from the default value of the model-element)
	if (!getStructuralFeature().isUnsettable()
	&& !getModelElementContext().getModelElement().eIsSet(getStructuralFeature())) {
	if (binding != null) {
	binding.updateTargetToModel();
	}
	}

	if (getModelElementContext().isRunningAsWebApplication() && getHelpText() != null
	&& getHelpText().length() != 0) {
	Label l = new Label(composite, SWT.PUSH);
	l.setImage(Activator.getImage("icons/help.png"));
	l.setData(CUSTOM_VARIANT, "org_eclipse_emf_ecp_control_help");
	l.addMouseListener(new MouseListener() {

	public void mouseUp(MouseEvent e) {
	MessageDialog dialog = new MessageDialog(parent.getShell(), "Help", null, getHelpText(),
	MessageDialog.INFORMATION, new String[] { JFaceResources
	.getString(IDialogLabelKeys.OK_LABEL_KEY) }, 0);
	new ECPDialogExecutor(dialog) {

	@Override
	public void handleResult(int codeResult) {

	}
	}.execute();
	}

	public void mouseDown(MouseEvent e) {
	// TODO Auto-generated method stub

	}

	public void mouseDoubleClick(MouseEvent e) {
	// TODO Auto-generated method stub

	}
	});
	// Button b = new Button(composite, SWT.PUSH);
	// b.addSelectionListener(new SelectionAdapter() {
	//
	// @Override
	// public void widgetSelected(SelectionEvent e) {
	// super.widgetSelected(e);
	// MessageDialog dialog = new MessageDialog(parent.getShell(), "Help", null, getHelpText(),
	// MessageDialog.INFORMATION, new String[] { JFaceResources
	// .getString(IDialogLabelKeys.OK_LABEL_KEY) }, 0);
	// new ECPDialogExecutor(dialog) {
	//
	// @Override
	// public void handleResult(int codeResult) {
	//
	// }
	// }.execute();
	// }
	//
	// });
	// Control[] tabList = new Control[composite.getTabList().length - 1];
	// System.arraycopy(composite.getTabList(), 0, tabList, 0, tabList.length);
	// composite.setTabList(tabList);
	} else {
	Control[] controls = getControlsForTooltip();
	if (controls != null) {
	for (Control control : controls) {
	control.setToolTipText(getHelpText());
	}
	}

	}
	return composite;
	}

	/**
	* @return
	*/
	protected abstract Control[] getControlsForTooltip();

	/**
	* Helper for creating the unset stacklayout and creating the control's composite.
	*
	* @param composite the parent {@link Composite} to create the control onto
	*/
	protected void createContentControl(Composite composite) {
	parentComposite = new Composite(composite, SWT.NONE);
	GridDataFactory.fillDefaults().grab(true, true).align(SWT.FILL, SWT.FILL).applyTo(parentComposite);
	sl = new StackLayout();
	parentComposite.setLayout(sl);
	controlComposite = new Composite(parentComposite, SWT.NONE);
	// 1 column for control, 1 for default unset button
	GridLayoutFactory.fillDefaults().numColumns(2).spacing(2, 0).applyTo(controlComposite);

	unsetLabel = new Label(parentComposite, SWT.NONE);
	unsetLabel.setBackground(composite.getBackground());
	unsetLabel.setForeground(composite.getShell().getDisplay().getSystemColor(SWT.COLOR_DARK_GRAY));
	unsetLabel.setAlignment(SWT.CENTER);
	unsetLabel.setText(getUnsetLabelText());
	unsetLabel.addMouseListener(new MouseListener() {

	public void mouseUp(MouseEvent e) {
	sl.topControl = controlComposite;
	parentComposite.layout(true);
	if (binding != null) {
	binding.updateTargetToModel();
	} else {
	Object currentUnsetValue = getModelElementContext().getModelElement().eGet(getStructuralFeature());
	getModelElementContext().getModelElement().eSet(getStructuralFeature(), currentUnsetValue);
	}
	}

	public void mouseDown(MouseEvent e) {
	// nothing to do
	}

	public void mouseDoubleClick(MouseEvent e) {
	// nothing to do
	}
	});

	fillControlComposite(controlComposite);

	if (!isEmbedded() && getStructuralFeature().isUnsettable()) {
	Button unsetButton = getCustomUnsetButton();
	if (unsetButton == null) {
	unsetButton = new Button(controlComposite, SWT.PUSH);
	unsetButton.setToolTipText(getUnsetButtonTooltip());
	unsetButton.setImage(Activator.getImage("icons/delete.png")); //$NON-NLS-1$
	}
	unsetButton.addSelectionListener(new SelectionAdapter() {
	@Override
	public void widgetSelected(SelectionEvent e) {
	getModelElementContext()
	.getEditingDomain()
	.getCommandStack()
	.execute(
	new SetCommand(getModelElementContext().getEditingDomain(), getModelElementContext()
	.getModelElement(), getStructuralFeature(), SetCommand.UNSET_VALUE));

	showUnsetLabel();
	}
	});
	unsetButton.setData(CUSTOM_VARIANT, "org_eclipse_emf_ecp_control_unset");
	}

	if (!getStructuralFeature().isUnsettable()
	\|\| getModelElementContext().getModelElement().eIsSet(getStructuralFeature())) {
	sl.topControl = controlComposite;
	} else {
	sl.topControl = unsetLabel;
	}

	parentComposite.layout();
	}

	/**
	*
	*/
	protected void showUnsetLabel() {
	sl.topControl = unsetLabel;
	parentComposite.layout();
	}

	/**
	* This method must be overridden by concrete classes. Here the widget displaying the data is added to the
	* composite.
	*
	* @param controlComposite the {@link Composite} to add the widget to
	*/
	protected abstract void fillControlComposite(Composite controlComposite);

	/**
	* The default unset button will be displayed to the right of the control's composite. Concrete classes may override
	* this method to include an own unset button in their composite rather than using the default positioning.
	*
	* @return The custom unset button of the concrete class
	*/
	protected Button getCustomUnsetButton() {
	return null;
	}

	/**
	* Returns the {@link DataBindingContext} set in the constructor.
	*
	* @return the {@link DataBindingContext}
	*/
	protected DataBindingContext getDataBindingContext() {
	return getModelElementContext().getDataBindingContext();
	}

	/**
	* The model value used for databinding. It is either the set one or the calculated.
	*
	* @return the {@link IObservableValue}
	*/
	protected IObservableValue getModelValue() {
	if (modelValue != null) {
	return modelValue;
	}
	modelValue = EMFEditObservables.observeValue(getModelElementContext().getEditingDomain(),
	getModelElementContext().getModelElement(), getStructuralFeature());
	return modelValue;
	}

	/**
	* Allows the user to set the {@link IObservableValue} to use in the control during databinding.
	*
	* @param modelValue the set {@link IObservableValue}
	*/
	public void setObservableValue(IObservableValue modelValue) {
	this.modelValue = modelValue;
	}

	/**
	* A helper method which creates a button for an action on a composite.
	*
	* @param action the action to create a button for
	* @param composite the composite to create the button onto
	* @return the created button
	*/
	protected Button createButtonForAction(final Action action, final Composite composite) {
	Button selectButton = new Button(composite, SWT.PUSH);
	selectButton.setImage(action.getImageDescriptor().createImage());
	selectButton.setToolTipText(action.getToolTipText());
	selectButton.addSelectionListener(new SelectionAdapter() {
	@Override
	public void widgetSelected(SelectionEvent e) {
	action.run();
	composite.layout();
	}

	});
	return selectButton;
	}

	/**
	* Triggers the control to perform the databinding.
	*
	* @return The {@link Binding}
	*/
	protected abstract Binding bindValue();

	/**
	* Returns the help information.
	*
	* @return The help text
	*/
	protected String getHelpText() {
	return getItemPropertyDescriptor().getDescription(null);
	}

	/**
	* Returns the string for the unset label.
	*
	* @return The unset label text
	*/
	protected abstract String getUnsetLabelText();

	/**
	* Returns the string for the unset button tooltip.
	*
	* @return The unset button tooltip
	*/
	protected abstract String getUnsetButtonTooltip();
	}