/*******************************************************************************
 * Copyright (c) 2000, 2007 IBM Corporation and others.
 * Portion Copyright (c) 2008 Nokia Corporation and/or its subsidiary(-ies).
 * 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
 *     Nokia Corporation - Qt implementation
 *******************************************************************************/
package org.eclipse.swt.graphics;

import org.eclipse.swt.SWT;

/**
 * Instances of this class manage the operating system resources that
 * implement SWT's RGB color model. To create a color you can either
 * specify the individual color components as integers in the range 
 * 0 to 255 or provide an instance of an <code>RGB</code>. 
 * <p>
 * Application code must explicitly invoke the <code>Color.dispose()</code> 
 * method to release the operating system resources managed by each instance
 * when those instances are no longer required.
 * </p>
 *
 * @see RGB
 * @see Device#getSystemColor
 */
public final class Color extends Object {

/**
 * the handle to the OS color resource 
 * (Warning: This field is platform dependent)
 * <p>
 * <b>IMPORTANT:</b> This field is <em>not</em> part of the SWT
 * public API. It is marked public only so that it can be shared
 * within the packages provided by SWT. It is not available on all
 * platforms and should never be accessed from application code.
 * </p>
 */
public int handle;

/**
 * the device where this resource was created
 */
Device device;

/**
 * Prevents uninitialized instances from being created outside the package.
 */
Color() {
}

/**	 
 * Constructs a new instance of this class given a device and the
 * desired red, green and blue values expressed as ints in the range
 * 0 to 255 (where 0 is black and 255 is full brightness). On limited
 * color devices, the color instance created by this call may not have
 * the same RGB values as the ones specified by the arguments. The
 * RGB values on the returned instance will be the color values of 
 * the operating system color.
 * <p>
 * You must dispose the color when it is no longer required. 
 * </p>
 *
 * @param device the device on which to allocate the color
 * @param red the amount of red in the color
 * @param green the amount of green in the color
 * @param blue the amount of blue in the color
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the red, green or blue argument is not between 0 and 255</li>
 * </ul>
 *
 * @see #dispose
 */
public Color(Device device, int red, int green, int blue) {
    init(device, red, green, blue);
}

/**	 
 * Constructs a new instance of this class given a device and an
 * <code>RGB</code> describing the desired red, green and blue values.
 * On limited color devices, the color instance created by this call
 * may not have the same RGB values as the ones specified by the
 * argument. The RGB values on the returned instance will be the color
 * values of the operating system color.
 * <p>
 * You must dispose the color when it is no longer required. 
 * </p>
 *
 * @param device the device on which to allocate the color
 * @param rgb the RGB values of the desired color
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li>
 *    <li>ERROR_NULL_ARGUMENT - if the rgb argument is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the red, green or blue components of the argument are not between 0 and 255</li>
 * </ul>
 *
 * @see #dispose
 */
public Color(Device device, RGB rgb) {
    if (rgb == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
    init(device, rgb.red, rgb.green, rgb.blue);
}

/**
 * Disposes of the operating system resources associated with
 * this resource. Applications must dispose of all resources
 * which they allocate.
 */
public void dispose() {
    if (device == null) return;
    if (device.isDisposed()) return;    
    if (Device.tracking) device.dispose_Object(this);
    device = null;
    handle = -1;
}

/**
 * Compares the argument to the receiver, and returns true
 * if they represent the <em>same</em> object using a class
 * specific comparison.
 *
 * @param object the object to compare with this object
 * @return <code>true</code> if the object is the same as this object and <code>false</code> otherwise
 *
 * @see #hashCode
 */
public boolean equals(Object object) {
    if (object == this) return true;
    if (!(object instanceof Color)) return false;
    Color color = (Color)object;
    if (isDisposed() || color.isDisposed()) return false;
    return device == color.device && (handle & 0xFFFFFF) == (color.handle & 0xFFFFFF);
}

/**
 * Returns the amount of blue in the color, from 0 to 255.
 *
 * @return the blue component of the color
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getBlue() {
    if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
    return (handle & 0xFF0000) >> 16;
}

/**
 * Returns the amount of green in the color, from 0 to 255.
 *
 * @return the green component of the color
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getGreen() {
    if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
    return (handle & 0xFF00) >> 8 ;
}

/**
 * Returns the amount of red in the color, from 0 to 255.
 *
 * @return the red component of the color
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getRed() {
    if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
    return handle & 0xFF;
}

/**
 * Returns an <code>RGB</code> representing the receiver.
 *
 * @return the RGB for the color
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public RGB getRGB () {
    if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
    return new RGB(handle & 0xFF, (handle & 0xFF00) >> 8, (handle & 0xFF0000) >> 16);
}

/**
 * Returns an integer hash code for the receiver. Any two 
 * objects that return <code>true</code> when passed to 
 * <code>equals</code> must return the same value for this
 * method.
 *
 * @return the receiver's hash
 *
 * @see #equals
 */
public int hashCode() {
    if (isDisposed()) return 0;
    return handle;
}

/*
 * Invokes platform specific functionality to allocate a new color.
 */
void init(Device device, int red, int green, int blue) {
    if (device == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
    this.device = device;
    
    if ((red > 255)   || (red < 0)   ||
        (green > 255) || (green < 0) ||
        (blue > 255)  || (blue < 0)) {
            SWT.error(SWT.ERROR_INVALID_ARGUMENT);		
    }
    handle = (red & 0xFF) | ((green & 0xFF) << 8) | ((blue & 0xFF) << 16);
    // Keep this after dealing with all exceptions!
    if (Device.tracking) device.new_Object(this);
}

/**
 * Returns <code>true</code> if the color has been disposed,
 * and <code>false</code> otherwise.
 * <p>
 * This method gets the dispose state for the color.
 * When a color has been disposed, it is an error to
 * invoke any other method using the color.
 *
 * @return <code>true</code> when the color is disposed and <code>false</code> otherwise
 */
public boolean isDisposed() {
    return handle == -1;
}

/**
 * Returns a string containing a concise, human-readable
 * description of the receiver.
 *
 * @return a string representation of the receiver
 */
public String toString () {
    if (isDisposed()) return "Color {*DISPOSED*}";
    return "Color {" + getRed() + ", " + getGreen() + ", " + getBlue() + "}";
}

/*
 * Invokes platform specific functionality to allocate a new color.
 */
static Color qt_new(Device device, int handle) {
    Color color = new Color();
    color.device = device;
    color.handle = handle; // Rgb value
    return color;
}
}
