/*******************************************************************************
 * Copyright (c) 2000, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.widgets;


import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.internal.*;

/**
 * This class is the abstract superclass of all non-windowed
 * user interface objects that occur within specific controls.
 * For example, a tree will contain tree items.
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>(none)</dd>
 * <dt><b>Events:</b></dt>
 * <dd>(none)</dd>
 * </dl>
 *
 * @see <a href="https://eclipse.dev/eclipse/swt/">Sample code and further information</a>
 */

public abstract class Item extends Widget {
	String text;
	Image image;
	/**
	 * Maximum number of characters Windows can reliably display in one line.
	 * Mac and Linux can display more but we are limited by windows here.
	 */
	static final int TEXT_LIMIT = 8192;

	static final String ELLIPSIS = "...";



/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * The item is added to the end of the items maintained by its parent.
 * <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
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * </p>
 *
 * @param parent a widget which will be the parent of the new instance (cannot be null)
 * @param style the style of item to construct
 *
 * @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>
 *
 * @see SWT
 * @see Widget#getStyle
 */
public Item (Widget parent, int style) {
	super (parent, style);
	text = "";
	this._addListener(SWT.ZoomChanged, this::handleDPIChange);
}

/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance,
 * and the index at which to place it in the items maintained
 * by its parent.
 * <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
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * </p>
 *
 * @param parent a widget which will be the parent of the new instance (cannot be null)
 * @param style the style of item to construct
 * @param index the zero-relative index at which to store the receiver in its parent
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 *    <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the parent (inclusive)</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 * </ul>
 *
 * @see SWT
 * @see Widget#getStyle
 */
public Item (Widget parent, int style, int index) {
	this (parent, style);
}

@Override
protected void checkSubclass () {
	/* Do Nothing - Subclassing is allowed */
}

/**
 * Returns the receiver's image if it has one, or null
 * if it does not.
 *
 * @return the receiver's image
 *
 * @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 Image getImage () {
	checkWidget ();
	return image;
}

@Override
String getNameText () {
	return getText ();
}

/**
 * Returns the receiver's text, which will be an empty
 * string if it has never been set.
 *
 * @return the receiver's 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 () {
	checkWidget();
	return text;
}

@Override
void releaseWidget () {
	super.releaseWidget ();
	text = null;
	image = null;
}

/**
 * Sets the receiver's image to the argument, which may be
 * null indicating that no image should be displayed.
 *
 * @param image the image to display on the receiver (may be null)
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the image has been disposed</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 setImage (Image image) {
	checkWidget ();
	if (this.image == image) return;
	if (image != null && image.isDisposed()) error(SWT.ERROR_INVALID_ARGUMENT);
	this.image = image;
}

/**
 * Sets the receiver's text.
 * <p>
 * Note: If control characters like '\n', '\t' etc. are used
 * in the string, then the behavior is platform dependent.
 * </p>
 * @param string 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) {
	checkWidget ();
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	text = string;
	if ((state & HAS_AUTO_DIRECTION) != 0) {
		updateTextDirection (AUTO_TEXT_DIRECTION);
	}
}

boolean updateTextDirection(int textDirection) {
	/*
	 * textDirection argument passed here is either (1) AUTO_TEXT_DIRECTION, or
	 * (2) 0 (i.e. match orientation) or FLIP_TEXT_DIRECTION (mismatch orientation).
	 */
	if (textDirection == AUTO_TEXT_DIRECTION) {
		state |= HAS_AUTO_DIRECTION;
		textDirection = (style ^ BidiUtil.resolveTextDirection (text)) == 0 ? 0 : SWT.FLIP_TEXT_DIRECTION;
	} else {
		state &= ~HAS_AUTO_DIRECTION;
	}
	if (((style & SWT.FLIP_TEXT_DIRECTION) ^ textDirection) != 0) {
		style ^= SWT.FLIP_TEXT_DIRECTION;
		return true;
	}
	return textDirection == AUTO_TEXT_DIRECTION;
}


private void handleDPIChange(Event event) {
	// Refresh the image
	Image image = getImage();
	if (image != null) {
		setImage(null);
		setImage(image);
	}
}

}
