/*******************************************************************************
 * Copyright (c) 2000, 2005 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.swt.widgets;

import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.internal.RunnableCompatibility;
import org.eclipse.swt.internal.browser.OS;
import org.eclipse.swt.internal.xhtml.CSSStyle;
import org.eclipse.swt.internal.xhtml.Element;
import org.eclipse.swt.internal.xhtml.document;

/**
 * Instances of this class are selectable user interface
 * objects that represent a range of positive, numeric values. 
 * <p>
 * At any given moment, a given scroll bar will have a 
 * single 'selection' that is considered to be its
 * value, which is constrained to be within the range of
 * values the scroll bar represents (that is, between its
 * <em>minimum</em> and <em>maximum</em> values).
 * </p><p>
 * Typically, scroll bars will be made up of five areas:
 * <ol>
 * <li>an arrow button for decrementing the value</li>
 * <li>a page decrement area for decrementing the value by a larger amount</li>
 * <li>a <em>thumb</em> for modifying the value by mouse dragging</li>
 * <li>a page increment area for incrementing the value by a larger amount</li>
 * <li>an arrow button for incrementing the value</li>
 * </ol>
 * Based on their style, scroll bars are either <code>HORIZONTAL</code>
 * (which have a left facing button for decrementing the value and a
 * right facing button for incrementing it) or <code>VERTICAL</code>
 * (which have an upward facing button for decrementing the value
 * and a downward facing buttons for incrementing it).
 * </p><p>
 * On some platforms, the size of the scroll bar's thumb can be
 * varied relative to the magnitude of the range of values it
 * represents (that is, relative to the difference between its
 * maximum and minimum values). Typically, this is used to
 * indicate some proportional value such as the ratio of the
 * visible area of a document to the total amount of space that
 * it would take to display it. SWT supports setting the thumb
 * size even if the underlying platform does not, but in this
 * case the appearance of the scroll bar will not change.
 * </p><p>
 * Scroll bars are created by specifying either <code>H_SCROLL</code>,
 * <code>V_SCROLL</code> or both when creating a <code>Scrollable</code>.
 * They are accessed from the <code>Scrollable</code> using
 * <code>getHorizontalBar</code> and <code>getVerticalBar</code>.
 * </p><p>
 * Note: Scroll bars are not Controls.  On some platforms, scroll bars
 * that appear as part of some standard controls such as a text or list
 * have no operating system resources and are not children of the control.
 * For this reason, scroll bars are treated specially.  To create a control
 * that looks like a scroll bar but has operating system resources, use
 * <code>Slider</code>. 
 * </p>
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>HORIZONTAL, VERTICAL</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Selection</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles HORIZONTAL and VERTICAL may be specified.
 * </p><p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 *
 * @see Slider
 * @see Scrollable
 * @see Scrollable#getHorizontalBar
 * @see Scrollable#getVerticalBar
 * 
 * @j2sPrefix
 * $WTC$$.registerCSS ("$wt.widgets.ScrollBar");
 */

public class ScrollBar extends Widget {
	Scrollable parent;
	
	int increment, pageIncrement;
	
	int minimum;
	int maximum;
	int thumb;
	int selection;

	int size;
	
	Element outerHandle;
	Element sbHandle;
	Element innerHandle;

/**
 * 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
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * </p>
 *
 * @param parent a composite control which will be the parent of the new instance (cannot be null)
 * @param style the style of control 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>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see SWT#HORIZONTAL
 * @see SWT#VERTICAL
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
ScrollBar (Scrollable parent, int style) {
	super (parent, checkStyle (style));
	this.parent = parent;
	createWidget ();
	//setVisible(false);
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when the receiver's value changes, by sending
 * it one of the messages defined in the <code>SelectionListener</code>
 * interface.
 * <p>
 * When <code>widgetSelected</code> is called, the event object detail field contains one of the following values:
 * <code>SWT.NONE</code> - for the end of a drag.
 * <code>SWT.DRAG</code>.
 * <code>SWT.HOME</code>.
 * <code>SWT.END</code>.
 * <code>SWT.ARROW_DOWN</code>.
 * <code>SWT.ARROW_UP</code>.
 * <code>SWT.PAGE_DOWN</code>.
 * <code>SWT.PAGE_UP</code>.
 * <code>widgetDefaultSelected</code> is not called.
 * </p>
 *
 * @param listener the listener which should be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener 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>
 *
 * @see SelectionListener
 * @see #removeSelectionListener
 * @see SelectionEvent
 */
public void addSelectionListener (SelectionListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener(listener);
	addListener (SWT.Selection,typedListener);
	addListener (SWT.DefaultSelection,typedListener);
}

static int checkStyle (int style) {
	return checkBits (style, SWT.HORIZONTAL, SWT.VERTICAL, 0, 0, 0, 0);
}

void createWidget () {
	increment = 1;
	pageIncrement = 10;
	state = state | HIDDEN;
	/*
	* Do not set the intial values of the maximum
	* or the thumb.  These values normally default
	* to 100 and 10 but may have been set already
	* by the widget that owns the scroll bar.  For
	* example, a scroll bar that is created for a
	* list widget, setting these defaults would
	* override the initial values provided by the
	* list widget.
	*/
	minimum = 0;
	maximum = 100;
	thumb = 10;
	selection = 0;
	increment = 1;
	pageIncrement = 10;
	size = 100;
	
	if ((style & SWT.H_SCROLL) != 0) {
		createHorizontalScrollBar(parent.scrolledHandle(), size, size * (maximum - minimum) / thumb);
	} else {
		createVerticalScrollBar(parent.scrolledHandle(), size, size * (maximum - minimum) / thumb);
	}
	sbHandle.onscroll = new RunnableCompatibility() {
		
		public void run() {
			/*
			 * Send the event because WM_HSCROLL and
			 * WM_VSCROLL are sent from a modal message
			 * loop in Windows that is active when the
			 * user is scrolling.
			 */
			Event event = new Event ();
			event.detail = SWT.NONE;
			/*
				switch (code) {
					case OS.SB_THUMBPOSITION:	event.detail = SWT.NONE;  break;
					case OS.SB_THUMBTRACK:		event.detail = SWT.DRAG;  break;
					case OS.SB_TOP: 			event.detail = SWT.HOME;  break;
					case OS.SB_BOTTOM:			event.detail = SWT.END;  break;
					case OS.SB_LINEDOWN:		event.detail = SWT.ARROW_DOWN;  break;
					case OS.SB_LINEUP: 			event.detail = SWT.ARROW_UP;  break;
					case OS.SB_PAGEDOWN:		event.detail = SWT.PAGE_DOWN;  break;
					case OS.SB_PAGEUP:			event.detail = SWT.PAGE_UP;  break;
				}
			 */
			sendEvent (SWT.Selection, event);
		}
		
	};
}


protected void createVerticalScrollBar(Element parent, int sbOuterHeight, int sbInnerHeight) {
	outerHandle = document.createElement("DIV");
	parent.appendChild(outerHandle);
	CSSStyle style = outerHandle.style;
	style.position = "absolute";
	style.margin = "0";
	style.padding = "0";
	style.borderStyle = "none";
	style.overflow = "hidden";
	style.zIndex = "1";
	int sbWidth = OS.getScrollBarWidth();
	style.width = sbWidth + "px";
	style.height = sbOuterHeight + "px";
	
	sbHandle = document.createElement("DIV");
	sbHandle.style.backgroundColor = "blue";
	sbHandle.style.overflow = "auto";
	sbHandle.style.cssText = sbHandle.style.cssText + ";overflow-y:scroll;";
	
	if (OS.isIE) {
		sbHandle.style.width = (sbWidth + 1) + "px";
		sbHandle.style.marginLeft = "-1px";
	} else {
		sbHandle.style.width = sbWidth + "px";
	}
	sbHandle.style.height = sbOuterHeight + "px";
	outerHandle.appendChild(sbHandle);
	
	innerHandle = document.createElement("DIV");
	innerHandle.style.height = sbInnerHeight + "px";
	sbHandle.appendChild(innerHandle);
}


protected void createHorizontalScrollBar(Element parent, int sbOuterWidth, int sbInnerWidth) {
	outerHandle = document.createElement("DIV");
	parent.appendChild(outerHandle);
	CSSStyle style = outerHandle.style;
	style.position = "absolute";
	style.margin = "0";
	style.padding = "0";
	style.borderStyle = "none";
	style.overflow = "hidden";
	style.zIndex = "1";
	style.width = sbOuterWidth + "px";
	int sbHeight = OS.getScrollBarHeight();
	style.height = sbHeight + "px";
	
	sbHandle = document.createElement("DIV");
	sbHandle.style.backgroundColor = "blue";
	sbHandle.style.overflow = "auto";
	sbHandle.style.cssText = sbHandle.style.cssText + ";overflow-x:scroll;overflow-y:hidden;";
	
	if (OS.isIE || OS.isOpera) {
		sbHandle.style.height = (sbHeight + 1) + "px";
		sbHandle.style.marginTop = "-1px";
	} else {
		sbHandle.style.height = sbHeight + "px";
	}
	sbHandle.style.width = sbOuterWidth + "px";
	outerHandle.appendChild(sbHandle);
	
	innerHandle = document.createElement("DIV");
	innerHandle.style.width = sbInnerWidth + "px";
	if (OS.isOpera) {
		innerHandle.style.lineHeight = "1px";
		innerHandle.style.fontSize = "1px";
		innerHandle.style.height = "1px";
	}
	sbHandle.appendChild(innerHandle);
}

protected void updateSizeBinding(int size) {
	this.size = size;
	if ((style & SWT.H_SCROLL) != 0) {
		outerHandle.style.width = (size > 0 ? size : 0) + "px";
		sbHandle.style.width = (size > 0 ? size : 0) + "px";
	} else {
		outerHandle.style.height = (size > 0 ? size : 0) + "px";
		sbHandle.style.height = (size > 0 ? size : 0) + "px";
	}
	// update scrollbar size binding.
	updateScrollBar();
}

void updateScrollBar() {
	int innerSize = Math.round(size * (maximum - minimum) / thumb);
	if ((style & SWT.V_SCROLL) != 0) {
		innerHandle.style.height = innerSize + "px";
	} else {
		innerHandle.style.width = innerSize + "px";
	}
	if (maximum != minimum) { 
		if ((style & SWT.H_SCROLL) != 0) {
			sbHandle.scrollLeft = (this.selection - this.minimum) * sbHandle.scrollWidth / (maximum - minimum);
		} else {
			sbHandle.scrollTop = (this.selection - this.minimum) * sbHandle.scrollHeight / (maximum - minimum);
		}
	}
}

public void dispose () {
	if (isDisposed()) return;
	if (!isValidThread ()) error (SWT.ERROR_THREAD_INVALID_ACCESS);
	//int hwnd = hwndScrollBar (), type = scrollBarType ();
	super.dispose ();
	/*
	if (OS.IsWinCE) {
		SCROLLINFO info = new SCROLLINFO ();
		info.cbSize = SCROLLINFO.sizeof;
		info.fMask = OS.SIF_RANGE | OS.SIF_PAGE;
		info.nPage = 101;
		info.nMax = 100;
		info.nMin = 0;
		OS.SetScrollInfo (hwnd, type, info, true);
	} else {
		OS.ShowScrollBar (hwnd, type, false);
	}
	*/
	if (innerHandle != null) {
		OS.destroyHandle(innerHandle);
		innerHandle = null;
	}
	if (sbHandle != null) {
		OS.destroyHandle(sbHandle);
		sbHandle = null;
	}
	if (outerHandle != null) {
		OS.destroyHandle(outerHandle);
		outerHandle = null;
	}
}

/*
* Not currently used.
*/
Rectangle getBounds () {
//	checkWidget ();
	parent.forceResize ();
	/*
	RECT rect = new RECT ();
	OS.GetClientRect (parent.scrolledHandle (), rect);
	int x = 0, y = 0, width, height;
	if ((style & SWT.HORIZONTAL) != 0) {
		y = rect.bottom - rect.top;
		width = rect.right - rect.left;
		height = OS.GetSystemMetrics (OS.SM_CYHSCROLL);
	} else {
		x = rect.right - rect.left;
		width = OS.GetSystemMetrics (OS.SM_CXVSCROLL);
		height = rect.bottom - rect.top;
	}
	return new Rectangle (x, y, width, height);
	*/
	//return new Rectangle (0, 0, 0, 0);
	return new Rectangle (0, 0, OS.getContainerWidth(outerHandle), OS.getContainerHeight(outerHandle));
}

/**
 * Returns <code>true</code> if the receiver is enabled, and
 * <code>false</code> otherwise. A disabled control is typically
 * not selectable from the user interface and draws with an
 * inactive or "grayed" look.
 *
 * @return the receiver's enabled state
 *
 * @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>
 * 
 * @see #isEnabled
 */
public boolean getEnabled () {
	checkWidget();
	return (state & DISABLED) == 0;
}

/**
 * Returns the amount that the receiver's value will be
 * modified by when the up/down (or right/left) arrows
 * are pressed.
 *
 * @return the increment
 *
 * @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 getIncrement () {
	checkWidget();
	return increment;
}

/**
 * Returns the maximum value which the receiver will allow.
 *
 * @return the maximum
 *
 * @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 getMaximum () {
	checkWidget();
	/*
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_RANGE;
	int hwnd = hwndScrollBar ();
	int type = scrollBarType ();
	OS.GetScrollInfo (hwnd, type, info);
	return info.nMax;
	*/
	return maximum;
}

/**
 * Returns the minimum value which the receiver will allow.
 *
 * @return the minimum
 *
 * @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 getMinimum () {
	checkWidget();
	/*
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_RANGE;
	int hwnd = hwndScrollBar ();
	int type = scrollBarType ();
	OS.GetScrollInfo (hwnd, type, info);
	return info.nMin;
	*/
	return minimum;
}

/**
 * Returns the amount that the receiver's value will be
 * modified by when the page increment/decrement areas
 * are selected.
 *
 * @return the page increment
 *
 * @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 getPageIncrement () {
	checkWidget();
	return pageIncrement;
}

/**
 * Returns the receiver's parent, which must be a Scrollable.
 *
 * @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 Scrollable getParent () {
	checkWidget();
	return parent;
}

/**
 * Returns the single 'selection' that is the receiver's value.
 *
 * @return the selection
 *
 * @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 getSelection () {
	checkWidget();
	/*
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_POS;
	int hwnd = hwndScrollBar ();
	int type = scrollBarType ();
	OS.GetScrollInfo (hwnd, type, info);
	return info.nPos;
	*/
	if (maximum != minimum) { 
		if ((style & SWT.H_SCROLL) != 0) {
			this.selection = minimum + sbHandle.scrollLeft * (maximum - minimum) / sbHandle.scrollWidth;
		} else {
			this.selection = minimum + sbHandle.scrollTop * (maximum - minimum) / sbHandle.scrollHeight;
		}
	}
	return selection;
}

/**
 * Returns a point describing the receiver's size. The
 * x coordinate of the result is the width of the receiver.
 * The y coordinate of the result is the height of the
 * receiver.
 *
 * @return the receiver's size
 *
 * @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 Point getSize () {
	checkWidget();
	parent.forceResize ();
	/*
	RECT rect = new RECT ();
	OS.GetClientRect (parent.scrolledHandle (), rect);
	*/
	int width, height;
	if ((style & SWT.HORIZONTAL) != 0) {
//		width = rect.right - rect.left;
//		height = OS.GetSystemMetrics (OS.SM_CYHSCROLL);
		width = size;
		height = OS.getScrollBarHeight();
	} else {
//		width = OS.GetSystemMetrics (OS.SM_CXVSCROLL);
//		height = rect.bottom - rect.top;
		width = OS.getScrollBarWidth();
		height = size;
	}
	return new Point (width, height);
}

/**
 * Answers the size of the receiver's thumb relative to the
 * difference between its maximum and minimum values.
 *
 * @return the thumb value
 *
 * @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>
 *
 * @see ScrollBar
 */
public int getThumb () {
	checkWidget();
	/*
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_PAGE;
	int hwnd = hwndScrollBar ();
	int type = scrollBarType ();
	OS.GetScrollInfo (hwnd, type, info);
	if (info.nPage != 0) --info.nPage;
	return info.nPage;
	*/
	return thumb;
}

/**
 * Returns <code>true</code> if the receiver is visible, and
 * <code>false</code> otherwise.
 * <p>
 * If one of the receiver's ancestors is not visible or some
 * other condition makes the receiver not visible, this method
 * may still indicate that it is considered visible even though
 * it may not actually be showing.
 * </p>
 *
 * @return the receiver's visibility state
 *
 * @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 boolean getVisible () {
	checkWidget();
	return (state & HIDDEN) == 0;
}

Element hwndScrollBar () {
	return parent.scrolledHandle ();
}

/**
 * Returns <code>true</code> if the receiver is enabled and all
 * of the receiver's ancestors are enabled, and <code>false</code>
 * otherwise. A disabled control is typically not selectable from the
 * user interface and draws with an inactive or "grayed" look.
 *
 * @return the receiver's enabled state
 *
 * @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>
 * 
 * @see #getEnabled
 */
public boolean isEnabled () {
	checkWidget();
	return getEnabled () && parent.isEnabled ();
}

/**
 * Returns <code>true</code> if the receiver is visible and all
 * of the receiver's ancestors are visible and <code>false</code>
 * otherwise.
 *
 * @return the receiver's visibility state
 *
 * @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>
 *
 * @see #getVisible
 */
public boolean isVisible () {
	checkWidget();
	return getVisible () && parent.isVisible ();
}

protected void releaseChild () {
	super.releaseChild ();
	if (parent.horizontalBar == this) parent.horizontalBar = null;
	if (parent.verticalBar == this) parent.verticalBar = null;
}

void releaseWidget () {
	super.releaseWidget ();
	parent = null;
}

/**
 * Removes the listener from the collection of listeners who will
 * be notified when the receiver's value changes.
 *
 * @param listener the listener which should no longer be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener 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>
 *
 * @see SelectionListener
 * @see #addSelectionListener
 */
public void removeSelectionListener (SelectionListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (SWT.Selection, listener);
	eventTable.unhook (SWT.DefaultSelection,listener);	
}

/*
int scrollBarType () {
	if ((style & SWT.VERTICAL) != 0) return OS.SB_VERT;
	/*
	* This line is intentionally commented.  There should
	* only ever be HORIZONTAL and VERTICAL scroll bars.
	* The commented code reminds us that this is the case
	* and that the default style is HORIZONTAL.
	*-/	
//	if ((style & SWT.HORIZONTAL) != 0) return OS.SB_HORZ;
	return OS.SB_HORZ;
}
*/

/**
 * Enables the receiver if the argument is <code>true</code>,
 * and disables it otherwise. A disabled control is typically
 * not selectable from the user interface and draws with an
 * inactive or "grayed" look.
 *
 * @param enabled the new enabled state
 *
 * @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 setEnabled (boolean enabled) {
	checkWidget();
	/*
	* This line is intentionally commented.  Currently
	* always show scrollbar as being enabled and visible.
	*/
//	if (OS.IsWinCE) error (SWT.ERROR_NOT_IMPLEMENTED);
	/*
	if (!OS.IsWinCE) {
		int hwnd = hwndScrollBar (), type = scrollBarType ();
		int flags = enabled ? OS.ESB_ENABLE_BOTH : OS.ESB_DISABLE_BOTH;
		OS.EnableScrollBar (hwnd, type, flags);
		if (enabled) {
			state &= ~DISABLED;
		} else {
			state |= DISABLED;
		}
	}
	*/
}

/**
 * Sets the amount that the receiver's value will be
 * modified by when the up/down (or right/left) arrows
 * are pressed to the argument, which must be at least 
 * one.
 *
 * @param value the new increment (must be greater than zero)
 *
 * @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 setIncrement (int value) {
	checkWidget();
	if (value < 1) return;
	if (increment == value) return;
	increment = value;
}

/**
 * Sets the maximum. If this value is negative or less than or
 * equal to the minimum, the value is ignored. If necessary, first
 * the thumb and then the selection are adjusted to fit within the
 * new range.
 *
 * @param value the new maximum
 *
 * @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 setMaximum (int value) {
	checkWidget();
	if (value < 0) return;
	/*
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	int hwnd = hwndScrollBar (), type = scrollBarType ();
	info.fMask = OS.SIF_RANGE | OS.SIF_DISABLENOSCROLL;
	OS.GetScrollInfo (hwnd, type, info);
	if (value - info.nMin - info.nPage < 1) return;
	info.nMax = value;
	SetScrollInfo (hwnd, type, info, true);
	*/
	if (value < minimum) return;
	if (maximum == value) return;
	maximum = value;
	if (selection > maximum) {
		selection = maximum;
	}
	updateScrollBar();
}

/**
 * Sets the minimum value. If this value is negative or greater
 * than or equal to the maximum, the value is ignored. If necessary,
 * first the thumb and then the selection are adjusted to fit within
 * the new range.
 *
 * @param value the new minimum
 *
 * @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 setMinimum (int value) {
	checkWidget();
	if (value < 0) return;
	/*
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	int hwnd = hwndScrollBar (), type = scrollBarType ();
	info.fMask = OS.SIF_RANGE | OS.SIF_DISABLENOSCROLL;
	OS.GetScrollInfo (hwnd, type, info);
	if (info.nMax - value - info.nPage < 1) return;
	info.nMin = value;
	SetScrollInfo (hwnd, type, info, true);
	*/
	if (value > maximum) return;
	if (minimum == value) return;
	minimum = value;
	if (selection < minimum) {
		selection = minimum;
	}
	updateScrollBar();
}

/**
 * Sets the amount that the receiver's value will be
 * modified by when the page increment/decrement areas
 * are selected to the argument, which must be at least
 * one.
 *
 * @param value the page increment (must be greater than zero)
 *
 * @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 setPageIncrement (int value) {
	checkWidget();
	if (value < 1) return;
	pageIncrement = value;
}

/*
boolean SetScrollInfo (int hwnd, int flags, SCROLLINFO info, boolean fRedraw) {
	/*
	* Bug in Windows.  For some reason, when SetScrollInfo()
	* is used with SIF_POS and the scroll bar is hidden,
	* the opposite scroll bar is incorrectly made visible
	* so that the next time the parent is resized (or another
	* scroll bar operation is performed), the opposite scroll
	* bar draws.  The fix is to hide both scroll bars.
	*-/
	if ((state & (DISABLED | HIDDEN)) != 0) fRedraw = false;
	boolean result = OS.SetScrollInfo (hwnd, flags, info, fRedraw);
	
	/*
	* Bug in Windows.  For some reason, when the widget
	* is a standard scroll bar, and SetScrollInfo() is
	* called with SIF_RANGE or SIF_PAGE, the widget is
	* incorrectly made visible so that the next time the
	* parent is resized (or another scroll bar operation
	* is performed), the scroll bar draws.  The fix is
	* to hide the scroll bar (again) when already hidden.
	*-/
	if ((state & HIDDEN) != 0) {
		/*
		* This line is intentionally commented.  Currently
		* always show scrollbar as being enabled and visible.
		*-/
//		if (OS.IsWinCE) error (SWT.ERROR_NOT_IMPLEMENTED);
		if (!OS.IsWinCE) {
			ScrollBar bar = null;
			switch (flags) {
				case OS.SB_HORZ:
					bar = parent.getVerticalBar ();
					break;
				case OS.SB_VERT:
					bar = parent.getHorizontalBar ();
					break;
			}
			boolean both = bar != null && !bar.getVisible ();
			OS.ShowScrollBar (hwnd, both ? OS.SB_BOTH : flags, false);
		}
	}
		
	/*
	* Feature in Windows.  Using SIF_DISABLENOSCROLL,
	* SetScrollInfo () can change enabled and disabled
	* state of the scroll bar causing a scroll bar that
	* was disabled by the application to become enabled.
	* The fix is to disable the scroll bar (again) when
	* the application has disabled the scroll bar.
	*-/
	if ((state & DISABLED) != 0) {
		/*
		* This line is intentionally commented.  Currently
		* always show scrollbar as being enabled and visible.
		*-/
//		if (OS.IsWinCE) error (SWT.ERROR_NOT_IMPLEMENTED);
		if (!OS.IsWinCE) {
			OS.EnableScrollBar (hwnd, flags, OS.ESB_DISABLE_BOTH);
		}
	}
	return result;
}
*/

/**
 * Sets the single <em>selection</em> that is the receiver's
 * value to the argument which must be greater than or equal
 * to zero.
 *
 * @param selection the new selection (must be zero or greater)
 *
 * @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 setSelection (int selection) {
	checkWidget();
	/*
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	int hwnd = hwndScrollBar (), type = scrollBarType ();
	info.fMask = OS.SIF_POS;
	info.nPos = selection;
	SetScrollInfo (hwnd, type, info, true);
	*/
	if (selection < 0) return;
	if (this.selection == selection) return;
	if (selection < minimum) {
		this.selection = minimum; 
	} else if (selection > maximum - thumb) {
		this.selection = maximum - thumb;
	} else {
		this.selection = selection;
	}
	updateScrollBar();
}

/**
 * Sets the size of the receiver's thumb relative to the
 * difference between its maximum and minimum values.  This new
 * value will be ignored if it is less than one, and will be
 * clamped if it exceeds the receiver's current range.
 *
 * @param value the new thumb value, which must be at least one and not
 * larger than the size of the current range
 *
 * @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 setThumb (int value) {
	checkWidget();
	if (value < 1) return;
	/*
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	int hwnd = hwndScrollBar (), type = scrollBarType ();
	info.fMask = OS.SIF_PAGE | OS.SIF_RANGE | OS.SIF_DISABLENOSCROLL;
	OS.GetScrollInfo (hwnd, type, info);
	info.nPage = value;
	if (info.nPage != 0) info.nPage++;
	SetScrollInfo (hwnd, type, info, true);
	*/
	if (thumb == value) return;
	thumb = value;
	updateScrollBar();
}

/**
 * Sets the receiver's selection, minimum value, maximum
 * value, thumb, increment and page increment all at once.
 * <p>
 * Note: This is equivalent to setting the values individually
 * using the appropriate methods, but may be implemented in a 
 * more efficient fashion on some platforms.
 * </p>
 *
 * @param selection the new selection value
 * @param minimum the new minimum value
 * @param maximum the new maximum value
 * @param thumb the new thumb value
 * @param increment the new increment value
 * @param pageIncrement the new pageIncrement value
 *
 * @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 setValues (int selection, int minimum, int maximum, int thumb, int increment, int pageIncrement) {
	checkWidget();
	if (minimum < 0) return;
	if (maximum < 0) return;
	if (thumb < 1) return;
	if (increment < 1) return;
	if (pageIncrement < 1) return;
	this.increment = increment;	
	this.pageIncrement = pageIncrement;
	/*
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_POS | OS.SIF_PAGE | OS.SIF_RANGE | OS.SIF_DISABLENOSCROLL;
	info.nPos = selection;
	info.nMin = minimum;
	info.nMax = maximum;
	info.nPage = thumb;
	if (info.nPage != 0) info.nPage++;
	int hwnd = hwndScrollBar (), type = scrollBarType ();
	SetScrollInfo (hwnd, type, info, true);
	*/
	
	this.minimum = minimum;
	this.maximum = maximum;
	this.thumb = thumb;
	
	if (this.selection < this.minimum) {
		this.selection = this.minimum;
	} else if (this.selection > this.maximum) {
		this.selection = this.maximum;
	}
	updateScrollBar();
}

/**
 * Marks the receiver as visible if the argument is <code>true</code>,
 * and marks it invisible otherwise. 
 * <p>
 * If one of the receiver's ancestors is not visible or some
 * other condition makes the receiver not visible, marking
 * it visible may not actually cause it to be displayed.
 * </p>
 *
 * @param visible the new visibility state
 *
 * @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 setVisible (boolean visible) {
	checkWidget();
//	System.out.println("setvisible of scrollbar called : " + visible + " parent : " + parent);
	boolean isVisible = (state & HIDDEN) == 0;
	if (isVisible == visible) return;
	if(visible) {
		state = state & ~HIDDEN;
	}else{
		state = state | HIDDEN;
	}
	if(parent == null || parent.handle == null){
		return;
	}
	
	String scrollClass = "hscroll-default";
	if((style & SWT.VERTICAL)!=0){
		scrollClass = "vscroll-default";
	}
	String className = this.parent.handle.className;
	int idx = this.parent.handle.className.indexOf(scrollClass);
//	System.out.println("parent scroll class name is " + className + " " + idx + " " + visible);
	if(!visible && idx != -1){
		className = className.substring(0, idx) + className.substring(idx + scrollClass.length());
	}
	else if(visible && idx == -1){ 
		className += " " + scrollClass;
	}
//	System.out.println("setting parent scrollable to " + className);
	this.parent.handle.className = className;
	/*
	/*
	* On Windows CE, use SIF_DISABLENOSCROLL to show and
	* hide the scroll bar when the page size is equal to
	* the range.
	*-/
	if (OS.IsWinCE) {
		SCROLLINFO info = new SCROLLINFO ();
		info.cbSize = SCROLLINFO.sizeof;
		int hwnd = hwndScrollBar (), type = scrollBarType ();
		info.fMask = OS.SIF_RANGE | OS.SIF_PAGE;
		if (visible) info.fMask |= OS.SIF_DISABLENOSCROLL;
		OS.GetScrollInfo (hwnd, type, info);
		if (info.nPage == info.nMax - info.nMin + 1) {
			/*
			* Bug in Windows.  When the only changed flag to
			* SetScrollInfo () is OS.SIF_DISABLENOSCROLL, 
			* Windows does not update the scroll bar state.
			* The fix is to increase and then decrease the
			* maximum, causing Windows to honour the flag.
			*-/  
			int max = info.nMax;
			info.nMax++;
			OS.SetScrollInfo (hwnd, type, info, false);
			info.nMax = max;
			OS.SetScrollInfo (hwnd, type, info, true);
		} else {
        	/*
        	* This line is intentionally commented.  Currently
        	* always show scrollbar as being enabled and visible.
        	*-/
//			if (OS.IsWinCE) error (SWT.ERROR_NOT_IMPLEMENTED);
		}
		return;
	}
	
	/*
	* Set the state bits before calling ShowScrollBar ()
	* because hiding and showing the scroll bar can cause
	* WM_SIZE messages when the client area is resized.
	* Setting the state before the call means that code
	* that runs during WM_SIZE that queries the visibility
	* of the scroll bar will get the correct value.
	*-/
	state = visible ? state & ~HIDDEN : state | HIDDEN;
	int hwnd = hwndScrollBar (), type = scrollBarType ();
	if (OS.ShowScrollBar (hwnd, type, visible)) {
		/*
		* Bug in Windows.  For some reason, when the widget
		* is a standard scroll bar, and SetScrollInfo () is
		* called with SIF_RANGE or SIF_PAGE while the widget
		* is not visible, the widget is incorrectly disabled
		* even though the values for SIF_RANGE and SIF_PAGE,
		* when set for a visible scroll bar would not disable
		* the scroll bar.  The fix is to enable the scroll bar
		* when not disabled by the application and the current
		* scroll bar ranges would cause the scroll bar to be
		* enabled had they been set when the scroll bar was
		* visible.
		*-/
		if ((state & DISABLED) == 0) {
			SCROLLINFO info = new SCROLLINFO ();
			info.cbSize = SCROLLINFO.sizeof;
			info.fMask = OS.SIF_RANGE | OS.SIF_PAGE;
			OS.GetScrollInfo (hwnd, type, info);
			if (info.nMax - info.nMin - info.nPage >= 0) {
				OS.EnableScrollBar (hwnd, type, OS.ESB_ENABLE_BOTH);
			}
		}
		sendEvent (visible ? SWT.Show : SWT.Hide);
		// widget could be disposed at this point
	}
	*/
}

/*
LRESULT wmScrollChild (int wParam, int lParam) {

	/* Do nothing when scrolling is ending *-/
	int code = wParam & 0xFFFF;
	if (code == OS.SB_ENDSCROLL) return null;

	/*
	* Send the event because WM_HSCROLL and
	* WM_VSCROLL are sent from a modal message
	* loop in Windows that is active when the
	* user is scrolling.
	*-/
	Event event = new Event ();
	switch (code) {
		case OS.SB_THUMBPOSITION:	event.detail = SWT.NONE;  break;
		case OS.SB_THUMBTRACK:		event.detail = SWT.DRAG;  break;
		case OS.SB_TOP: 			event.detail = SWT.HOME;  break;
		case OS.SB_BOTTOM:			event.detail = SWT.END;  break;
		case OS.SB_LINEDOWN:		event.detail = SWT.ARROW_DOWN;  break;
		case OS.SB_LINEUP: 			event.detail = SWT.ARROW_UP;  break;
		case OS.SB_PAGEDOWN:		event.detail = SWT.PAGE_DOWN;  break;
		case OS.SB_PAGEUP:			event.detail = SWT.PAGE_UP;  break;
	}
	sendEvent (SWT.Selection, event);
	// the widget could be destroyed at this point
	return null;
}
*/

}
