content: package ts.eclipse.ide.internal.ui.dialogs.fields;
  
  /*******************************************************************************
   * Copyright (c) 2000, 2007 IBM Corporation 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:
   *     IBM Corporation - initial API and implementation
   *     Angelo ZERR : copied from  org.eclipse.wst.jsdt.internal.ui.wizards.dialogfield.DialogField
   *******************************************************************************/
  
  import org.eclipse.core.runtime.Assert;
  import org.eclipse.swt.SWT;
  import org.eclipse.swt.layout.GridData;
  import org.eclipse.swt.widgets.Composite;
  import org.eclipse.swt.widgets.Control;
  import org.eclipse.swt.widgets.Display;
  import org.eclipse.swt.widgets.Label;
  
  
  /**
   * Base class of all dialog fields.
   * Dialog fields manage controls together with the model, independed
   * from the creation time of the widgets.
   * - support for automated layouting.
   * - enable / disable, set focus a concept of the base class.
   * 
   * DialogField have a label.
   */ 
  public class DialogField {
  
  	private Label fLabel;
  	protected String fLabelText;
  	
  	private IDialogFieldListener fDialogFieldListener;
  	
  	private boolean fEnabled;
  
  	public DialogField() {
  		fEnabled= true;
  		fLabel= null;
  		fLabelText= ""; //$NON-NLS-1$
  	}
  	
  	/**
  	 * Sets the label of the dialog field.
  	 */
  	public void setLabelText(String labeltext) {
  		fLabelText= labeltext;
  		if (isOkToUse(fLabel)) {
  			fLabel.setText(labeltext);
  		}
  	}
  		
  	// ------ change listener
  	
  	/**
  	 * Defines the listener for this dialog field.
  	 */	
  	public final void setDialogFieldListener(IDialogFieldListener listener) {
  		fDialogFieldListener= listener;
  	}
  
  	/**
  	 * Programatical invocation of a dialog field change.
  	 */		
  	public void dialogFieldChanged() {
  		if (fDialogFieldListener != null) {
  			fDialogFieldListener.dialogFieldChanged(this);
  		}
  	}	
  	
  	// ------- focus management
  	
  	/**
  	 * Tries to set the focus to the dialog field.
  	 * Returns <code>true</code> if the dialog field can take focus.
  	 * 	To be reimplemented by dialog field implementors.
  	 */
  	public boolean setFocus() {
  		return false;
  	}
  
  	/**
  	 * Posts <code>setFocus</code> to the display event queue.
  	 */	
  	public void postSetFocusOnDialogField(Display display) {
  		if (display != null) {
  			display.asyncExec(
  				new Runnable() {
  					public void run() {
  						setFocus();
  					}
  				}
  			);
  		}
  	}		
  	
  	// ------- layout helpers
  	
  	/**
  	 * Creates all controls of the dialog field and fills it to a composite.
  	 * The composite is assumed to have <code>MGridLayout</code> as
  	 * layout.
  	 * The dialog field will adjust its controls' spans to the number of columns given.
  	 * 	To be reimplemented by dialog field implementors.
  	 */
  	public Control[] doFillIntoGrid(Composite parent, int nColumns) {
  		assertEnoughColumns(nColumns);
  		
  		Label label= getLabelControl(parent);
  		label.setLayoutData(gridDataForLabel(nColumns));
  		
  		return new Control[] { label };
  	}
  	
  	/**
  	 * Returns the number of columns of the dialog field.
  	 * 	To be reimplemented by dialog field implementors.
  	 */
  	public int getNumberOfControls() {
  		return 1;	
  	}	
  	
  	protected static GridData gridDataForLabel(int span) {
  		GridData gd= new GridData(GridData.HORIZONTAL_ALIGN_FILL);
  		gd.horizontalSpan= span;
  		return gd;
  	}
  	
  	// ------- ui creation
  
  	/**
  	 * Creates or returns the created label widget.
  	 * @param parent The parent composite or <code>null</code> if the widget has
  	 * already been created.
  	 */			
  	public Label getLabelControl(Composite parent) {
  		if (fLabel == null) {
  			assertCompositeNotNull(parent);
  			
  			fLabel= new Label(parent, SWT.LEFT | SWT.WRAP);
  			fLabel.setFont(parent.getFont());
  			fLabel.setEnabled(fEnabled);		
  			if (fLabelText != null && !"".equals(fLabelText)) { //$NON-NLS-1$
  				fLabel.setText(fLabelText);
  			} else {
  				// XXX: to avoid a 16 pixel wide empty label - revisit
  				fLabel.setText("."); //$NON-NLS-1$
  				fLabel.setVisible(false);
  			}			
  		}
  		return fLabel;
  	}
  
  	/**
  	 * Creates a spacer control.
  	 * @param parent The parent composite
  	 */		
  	public static Control createEmptySpace(Composite parent) {
  		return createEmptySpace(parent, 1);
  	}
  
  	/**
  	 * Creates a spacer control with the given span.
  	 * The composite is assumed to have <code>MGridLayout</code> as
  	 * layout.
  	 * @param parent The parent composite
  	 */			
  	public static Control createEmptySpace(Composite parent, int span) {
  		Label label= new Label(parent, SWT.LEFT);
  		GridData gd= new GridData();
  		gd.horizontalAlignment= GridData.BEGINNING;
  		gd.grabExcessHorizontalSpace= false;
  		gd.horizontalSpan= span;
  		gd.horizontalIndent= 0;
  		gd.widthHint= 0;
  		gd.heightHint= 0;
  		label.setLayoutData(gd);
  		return label;
  	}
  	
  	/**
  	 * Tests is the control is not <code>null</code> and not disposed.
  	*/
  	protected final boolean isOkToUse(Control control) {
  		return (control != null) && (Display.getCurrent() != null) && !control.isDisposed();
  	}
  	
  	// --------- enable / disable management
  	
  	/**
  	 * Sets the enable state of the dialog field.
  	 */
  	public final void setEnabled(boolean enabled) {
  		if (enabled != fEnabled) {
  			fEnabled= enabled;
  			updateEnableState();
  		}
  	}
  	
  	/**
  	 * Called when the enable state changed.
  	 * To be extended by dialog field implementors.
  	 */
  	protected void updateEnableState() {
  		if (fLabel != null) {
  			fLabel.setEnabled(fEnabled);
  		}
  	}
  	
  	/**
  	 * Brings the UI in sync with the model. Only needed when model was changed
  	 * in different thread whil UI was lready created.
  	 */
  	public void refresh() {
  		updateEnableState();
  	}
  
  	/**
  	 * Gets the enable state of the dialog field.
  	 */	
  	public final boolean isEnabled() {
  		return fEnabled;
  	}
  
  	protected final void assertCompositeNotNull(Composite comp) {
  		Assert.isNotNull(comp, "uncreated control requested with composite null"); //$NON-NLS-1$
  	}
  	
  	protected final void assertEnoughColumns(int nColumns) {
  		Assert.isTrue(nColumns >= getNumberOfControls(), "given number of columns is too small"); //$NON-NLS-1$
  	}
  	
  	
  
  	
  }