package org.eclipse.swt.widgets;

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved
 */

import org.eclipse.swt.*;
import org.eclipse.swt.widgets.*;

/**
 * This class is the abstract superclass of the classes
 * that represent the built in platform dialogs.
 * A <code>Dialog</code> typically contains other widgets
 * that are not accessible. A <code>Dialog</code> is not
 * a <code>Widget</code>.
 * <p>
 * This class can also be used as the abstract superclass
 * for user-designed dialogs. Such dialogs usually consist
 * of a Shell with child widgets. The basic template for a
 * user-defined dialog typically looks something like this:
 * <code>
 * public class MyDialog extends Dialog {
 *	Object result;
 *		
 *	public MyDialog (Shell parent, int style) {
 *		super (parent, style);
 *	}
 *	public MyDialog (Shell parent) {
 *		this (parent, 0); // your default style bits go here (not the Shell's style bits)
 *	}
 *	public Object open () {
 *		Shell parent = getParent();
 *		Shell shell = new Shell(parent, SWT.DIALOG_TRIM | SWT.APPLICATION_MODAL);
 *		shell.setText(getText());
 *		// Your code goes here (widget creation, set result, etc).
 *		shell.open();
 *		Display display = parent.getDisplay();
 *		while (!shell.isDisposed()) {
 *			if (!display.readAndDispatch()) display.sleep();
 *		}
 *		return result;
 *	}
 * }
 * </code>
 * <p>
 * Note: The <em>modality</em> styles supported by this class
 * must be treated as <em>HINT</em>s, because not all are
 * supported by every subclass on every platform. If a modality style
 * is not supported, it is "upgraded" to a more restrictive modality
 * style that is supported.  For example, if <code>PRIMARY_MODAL</code>
 * is not supported by a particular dialog, it would be upgraded to 
 * <code>APPLICATION_MODAL</code>. In addition, as is the case
 * for shells, the window manager for the desktop on which the
 * instance is visible has ultimate control over the appearance
 * and behavior of the instance, including its modality.
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>APPLICATION_MODAL, MODELESS, PRIMARY_MODAL, SYSTEM_MODAL</dd>
 * <dt><b>Events:</b></dt>
 * <dd>(none)</dd>
 * </dl>
 *
 * @see Shell
 */

public abstract class Dialog {
	int style;
	Shell parent;
	String title;

/**
 * Constructs a new instance of this class given only its
 * parent.
 * <p>
 * Note: Currently, null can be passed in for the parent.
 * This has the effect of creating the dialog on the currently active
 * display if there is one. If there is no current display, the 
 * dialog is created on a "default" display. <b>Passing in null as
 * the parent is not considered to be good coding style,
 * and may not be supported in a future release of SWT.</b>
 * </p>
 *
 * @param parent a shell which will be the parent of the new instance
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 * </ul>
 */
public Dialog (Shell parent) {
	this (parent, 0);
}

/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * <p>
 * The style value is either one of the style constants defined in
 * class <code>SWT</code> which is applicable to instances of this
 * class, or must be built by <em>bitwise OR</em>'ing together 
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>SWT</code> style constants. The class description
 * for all SWT dialog classes should include a comment which
 * describes the style constants which are applicable to the class.
 * </p>
 * Note: Currently, null can be passed in for the parent.
 * This has the effect of creating the dialog on the currently active
 * display if there is one. If there is no current display, the 
 * dialog is created on a "default" display. <b>Passing in null as
 * the parent is not considered to be good coding style,
 * and may not be supported in a future release of SWT.</b>
 * </p>
 *
 * @param parent a shell which will be the parent of the new instance
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 * </ul>
 */
public Dialog (Shell parent, int style) {
	checkParent (parent);
	this.parent = parent;
	this.style = style;
	title = "";
}

/**
 * Checks that this class can be subclassed.
 * <p>
 * IMPORTANT: See the comment in <code>Widget.checkSubclass()</code>.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see Widget#checkSubclass
 */
protected void checkSubclass () {
	if (!Display.isValidClass (getClass ())) {
		error (SWT.ERROR_INVALID_SUBCLASS);
	}
}

/**
 * Throws an exception if the specified widget can not be
 * used as a parent for the receiver.
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the parent is disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 * </ul>
 */
void checkParent (Shell parent) {
	if (parent == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (!parent.isValidThread ()) error (SWT.ERROR_THREAD_INVALID_ACCESS);
	if (parent.isDisposed()) error (SWT.ERROR_INVALID_ARGUMENT);
}

/**
 * Does whatever dialog specific cleanup is required, and then
 * uses the code in <code>SWTError.error</code> to handle the error.
 *
 * @param code the descriptive error code
 *
 * @see SWTError#error
 */
void error (int code) {
	SWT.error(code);
}

/**
 * Returns the receiver's parent, which must be a <code>Shell</code>
 * or null.
 *
 * @return the receiver's parent
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public Shell getParent () {
	return parent;
}

/**
 * Returns the receiver's style information.
 * <p>
 * Note that, the value which is returned by this method <em>may
 * not match</em> the value which was provided to the constructor
 * when the receiver was created. 
 * </p>
 *
 * @return the style bits
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getStyle () {
	return style;
}

/**
 * Returns the receiver's text, which is the string that the
 * window manager will typically display as the receiver's
 * <em>title</em>. If the text has not previously been set, 
 * returns an empty string.
 *
 * @return the text
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public String getText () {
	return title;
}

/**
 * Sets the receiver's text, which is the string that the
 * window manager will typically display as the receiver's
 * <em>title</em>, to the argument, which must not be null. 
 *
 * @param text the new text
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the text is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setText (String string) {
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	title = string;
}

}