MessageRegion.java

/*******************************************************************************
 * Copyright (c) 2000, 2010 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
 *******************************************************************************/
package org.eclipse.ui.texteditor;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Text;

import org.eclipse.jface.dialogs.Dialog;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.dialogs.IMessageProvider;
import org.eclipse.jface.resource.JFaceColors;
import org.eclipse.jface.resource.JFaceResources;


/**
 * The MessageRegion is the optional area to
 * show messages in the page.
 * <p>
 * XXX: Copied from org.eclipse.jface.preference.PreferencePage.MessageRegion
 * 		see https://bugs.eclipse.org/bugs/show_bug.cgi?id=84061
 * </p>
 *
 * @since 3.1
 */
class MessageRegion {

	private Text messageText;

	private Label messageImageLabel;

	private Composite messageComposite;

	private String lastMessageText = "";//$NON-NLS-1$

	private int lastMessageType;

	/**
	 * Create a new instance of the receiver.
	 */
	public MessageRegion() {
		//No initial behavior
	}

	/**
	 * Create the contents for the receiver.
	 *
	 * @param parent the Composite that the children will be created in
	 */
	public void createContents(Composite parent) {
		messageComposite = new Composite(parent, SWT.NONE);
		GridLayout messageLayout = new GridLayout();
		messageLayout.numColumns = 2;
		messageLayout.marginWidth = 0;
		messageLayout.marginHeight = 0;
		messageLayout.makeColumnsEqualWidth = false;
		messageComposite.setLayout(messageLayout);
		messageImageLabel = new Label(messageComposite, SWT.NONE);

		GridData imageData = new GridData(GridData.VERTICAL_ALIGN_CENTER);
		Image sizingImage = JFaceResources.getImage(Dialog.DLG_IMG_MESSAGE_ERROR);
		Rectangle imageBounds;
		if(sizingImage == null)
			imageBounds = new Rectangle(0,0,IDialogConstants.VERTICAL_MARGIN * 2,IDialogConstants.VERTICAL_MARGIN * 2);
		else
			imageBounds = sizingImage.getBounds();
		imageData.heightHint = imageBounds.height + IDialogConstants.VERTICAL_SPACING;
		imageData.widthHint = imageBounds.width + IDialogConstants.HORIZONTAL_SPACING;
		messageImageLabel.setLayoutData(imageData);

		messageText = new Text(messageComposite, SWT.NONE);
		messageText.setEditable(false);
		messageText.setBackground(parent.getDisplay().getSystemColor(
				SWT.COLOR_WIDGET_BACKGROUND));

		GridData textData = new GridData(GridData.GRAB_HORIZONTAL | GridData.FILL_HORIZONTAL
				| GridData.VERTICAL_ALIGN_CENTER);
		messageText.setLayoutData(textData);
		hideRegion();

	}

	/**
	 * Set the layoutData for the messageArea. In most cases this will be a copy of the layoutData
	 * used in setTitleLayoutData.
	 *
	 * @param layoutData the layoutData for the message area composite.
	 */
	public void setMessageLayoutData(Object layoutData) {
		messageComposite.setLayoutData(layoutData);
	}

	/**
	 * Show the new message in the message text and update the image. Base the background color on
	 * whether or not there are errors.
	 *
	 * @param newMessage The new value for the message
	 * @param newType One of the IMessageProvider constants. If newType is IMessageProvider.NONE
	 *            show the title.
	 * @see IMessageProvider
	 */
	public void updateText(String newMessage, int newType) {
		Image newImage = null;
		boolean showingError = false;
		switch (newType) {
		case IMessageProvider.NONE:
			hideRegion();
			return;
		case IMessageProvider.INFORMATION:
			newImage = JFaceResources.getImage(Dialog.DLG_IMG_MESSAGE_INFO);
			break;
		case IMessageProvider.WARNING:
			newImage = JFaceResources.getImage(Dialog.DLG_IMG_MESSAGE_WARNING);
			break;
		case IMessageProvider.ERROR:
			newImage = JFaceResources.getImage(Dialog.DLG_IMG_MESSAGE_ERROR);
			showingError = true;
			break;
		}

		if(newMessage == null){//No message so clear the area
			hideRegion();
			return;
		}
		showRegion();
		// Any more updates required
		if (newMessage.equals(messageText.getText())
				&& newImage == messageImageLabel.getImage())
			return;
		messageImageLabel.setImage(newImage);
		messageText.setText(newMessage);
		if (showingError)
			setMessageColors(JFaceColors.getErrorBackground(messageComposite.getDisplay()));
		else {
			lastMessageText = newMessage;
			setMessageColors(JFaceColors.getBannerBackground(messageComposite.getDisplay()));
		}

	}

	/**
	 * Show and enable the widgets in the message region
	 */
	private void showRegion() {
		messageComposite.setVisible(true);
	}

	/**
	 * Hide the message region and clear out the caches.
	 */
	private void hideRegion() {
		messageComposite.setVisible(false);
		lastMessageText = null;
		lastMessageType = IMessageProvider.NONE;
	}

	/**
	 * Set the colors of the message area.
	 *
	 * @param color the color to be use in the message area.
	 */
	private void setMessageColors(Color color) {
		messageText.setBackground(color);
		messageComposite.setBackground(color);
		messageImageLabel.setBackground(color);
	}

	/**
	 * Clear the error message. Restore the previously displayed message if
	 * there is one, if not restore the title label.
	 *
	 */
	public void clearErrorMessage() {
		updateText(lastMessageText, lastMessageType);
	}
}