bundles/org.eclipse.ui/Eclipse JFace/org/eclipse/jface/preference/StringButtonFieldEditor.java

package org.eclipse.jface.preference;

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.jface.util.Assert;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.layout.GridData;
import java.io.File;

/**
 * An abstract field editor for a string type preference that presents
 * a string input field with a change button to its right to edit the
 * input field's content. When the user presses the change button, the
 * abstract framework method <code>changePressed()</code> gets called
 * to compute a new string.
 */
public abstract class StringButtonFieldEditor extends StringFieldEditor {

	/**
	 * The change button, or <code>null</code> if none
	 * (before creation and after disposal).
	 */
	private Button changeButton;
	
	/**
	 * The text for the change button, or <code>null</code> if missing.
	 */
	private String changeButtonText;
/**
 * Creates a new string button field editor 
 */
protected StringButtonFieldEditor() {
}
/**
 * Creates a string button field editor.
 * 
 * @param name the name of the preference this field editor works on
 * @param labelText the label text of the field editor
 * @param parent the parent of the field editor's control
 */
protected StringButtonFieldEditor(String name, String labelText, Composite parent) {
	init(name, labelText);
	createControl(parent);
}
/* (non-Javadoc)
 * Method declared on FieldEditor.
 */
protected void adjustForNumColumns(int numColumns) {
	((GridData)getTextControl().getLayoutData()).horizontalSpan = numColumns - 2;
}
/**
 * Notifies that this field editor's change button has been pressed.
 * <p>
 * Subclasses must implement this method to provide a corresponding
 * new string for the text field. If the returned value is <code>null</code>,
 * the currently displayed value remains.
 * </p>
 *
 * @return the new string to display, or <code>null</code> to leave the
 *  old string showing
 */
protected abstract String changePressed();
/* (non-Javadoc)
 * Method declared on StringFieldEditor (and FieldEditor).
 */
protected void doFillIntoGrid(Composite parent, int numColumns) {
	super.doFillIntoGrid(parent, numColumns - 1);
	changeButton = getChangeControl(parent);
	GridData gd = new GridData();
	gd.horizontalAlignment = gd.FILL;
	gd.heightHint = convertVerticalDLUsToPixels(changeButton, IDialogConstants.BUTTON_HEIGHT);
	int widthHint = convertHorizontalDLUsToPixels(changeButton, IDialogConstants.BUTTON_WIDTH);
	gd.widthHint = Math.max(widthHint, changeButton.computeSize(SWT.DEFAULT, SWT.DEFAULT, true).x);
	changeButton.setLayoutData(gd);
}
/* (non-Javadoc)
 * Method declared on FieldEditor.
 */
protected Button getChangeControl(Composite parent) {
	if (changeButton == null) {
		changeButton = new Button(parent, SWT.PUSH);
		if (changeButtonText == null)
			changeButtonText = JFaceResources.getString("openChange");//$NON-NLS-1$
		changeButton.setText(changeButtonText);
		changeButton.addSelectionListener(new SelectionAdapter() {
			public void widgetSelected(SelectionEvent evt) {
				String newValue = changePressed();
				if (newValue != null) {
					setStringValue(newValue);
				}
			}
		});
		changeButton.addDisposeListener(new DisposeListener() {
			public void widgetDisposed(DisposeEvent event) {
				changeButton = null;
			}
		});
	} else {
		checkParent(changeButton, parent);
	}
	return changeButton;
}
/* (non-Javadoc)
 * Method declared on FieldEditor.
 */
public int getNumberOfControls() {
	return 3;
}
/**
 * Returns this field editor's shell.
 *
 * @return the shell
 */
protected Shell getShell() {
	if (changeButton == null)
		return null;
	return changeButton.getShell();
}
/**
 * Sets the text of the change button.
 *
 * @param text the new text
 */
public void setChangeButtonText(String text) {
	Assert.isNotNull(text);
	changeButtonText = text;
	if (changeButton != null)
		changeButton.setText(text);
}
}