bundles/org.eclipse.swt/Eclipse SWT/gtk1x/org/eclipse/swt/widgets/ScrollBar.java - platform/eclipse.platform.swt - Git at Google

 package org.eclipse.swt.widgets;

 /*
  * (c) Copyright IBM Corp. 2000, 2001.
  * All Rights Reserved
  */

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

 /**
  * 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 <em>selection</em> 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 left and right facing buttons for incrementing and
  * decrementing the value) or <code>VERTICAL</code> (which have
  * up and down facing buttons for incrementing and decrementing
  * the value).
  * </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>
  * IMPORTANT: This class is <em>not</em> intended to be subclassed.
  *
  * @see Slider
  * @see Scrollable
  * @see Scrollable#getHorizontalBar
  * @see Scrollable#getVerticalBar
  */

 public class ScrollBar extends Widget {
 	Scrollable parent;

 ScrollBar () {
 }

 /**
 * Creates a new instance of the widget.
 */
 ScrollBar (Scrollable parent, int style) {
 	super (parent, checkStyle (style));
 	this.parent = parent;
 	createWidget (0);
 }

 /**
  * 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>0</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);
 }

 public Display getDisplay () {
 	Scrollable parent = this.parent;
 	if (parent == null) error (SWT.ERROR_WIDGET_DISPOSED);
 	return parent.getDisplay ();
 }

 /**
  * 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 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 boolean getEnabled () {
 	checkWidget ();
 	return true;
 }

 /**
  * 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 ();
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	return (int) adjustment.step_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 ();
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	return (int) adjustment.upper;
 }

 /**
  * 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 ();
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	return (int) adjustment.lower;
 }

 /**
  * 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 ();
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	return (int) adjustment.page_increment;
 }

 /**
  * Returns the receiver's parent, which must be 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 <em>selection</em> 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 ();
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	return (int) adjustment.value;
 }

 /**
  * For horizontal scroll bars, returns the height of the
  * instance, and for vertical scroll bars, returns the width
  * of the instance.
  *
  * @return the scroll bar 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 ();
 	GtkWidget widget = new GtkWidget ();
 	OS.memmove (widget, handle, GtkWidget.sizeof);
 	return new Point (widget.alloc_width, widget.alloc_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 ();
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	return (int) adjustment.page_size;
 }

 /**
  * 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 true;
 }

 void hookEvents () {
 	signal_connect (handle, "value_changed",  SWT.Selection, 2);
 }

 /**
  * 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.
  * <p>
  * Note: Because of the strong connection between a scroll bar
  * and the widget which contains it (its parent), a scroll bar
  * will not indicate that it is enabled if its parent is not.
  * </p>
  *
  * @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>
  */
 public boolean isEnabled () {
 	checkWidget ();
 	return getEnabled () && getParent ().getEnabled ();
 }

 /**
  * 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 isVisible () {
 	checkWidget ();
 	return getVisible () && getParent ().isVisible ();
 }

 int processSelection (int int0, int int1, int int2) {
 	postEvent (SWT.Selection);
 	return 0;
 }

 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);
 }

 /**
  * 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 ();
 }

 /**
  * 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;
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	adjustment.step_increment = (float) value;
 	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
 	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
 	OS.gtk_adjustment_changed (handle);
 	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
 }

 /**
  * Sets the maximum value which the receiver will allow
  * to be the argument which must be greater than or
  * equal to zero.
  *
  * @param value the new maximum (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 setMaximum (int value) {
 	checkWidget ();
 	if (value < 0) return;
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	adjustment.upper = (float) value;
 	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
 	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
 	OS.gtk_adjustment_changed (handle);
 	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
 }

 /**
  * Sets the minimum value which the receiver will allow
  * to be the argument which must be greater than or
  * equal to zero.
  *
  * @param value the new minimum (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 setMinimum (int value) {
 	checkWidget ();
 	if (value < 0) return;
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	adjustment.lower = (float) value;
 	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
 	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
 	OS.gtk_adjustment_changed (handle);
 	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
 }

 /**
  * 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.
  *
  * @return 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;
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	adjustment.page_increment = (float) value;
 	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
 	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
 	OS.gtk_adjustment_changed (handle);
 	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
 }

 /**
  * 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 value 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 value) {
 	checkWidget ();
 	if (value < 0) return;
 	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
 	OS.gtk_adjustment_set_value (handle, value);
 	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
 }

 /**
  * Sets the size of the receiver's thumb relative to the
  * difference between its maximum and minimum values to the
  * argument which must be at least one.
  *
  * @param value the new thumb value (must be at least one)
  *
  * @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 void setThumb (int value) {
 	checkWidget ();
 	if (value < 1) return;
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	adjustment.page_size = (float) value;
 	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
 	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
 	OS.gtk_adjustment_changed (handle);
 	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
 }

 /**
  * 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 (selection < 0) return;
 	if (minimum < 0) return;
 	if (maximum < 0) return;
 	if (thumb < 1) return;
 	if (maximum - minimum - thumb < 0) return;
 	if (increment < 1) return;
 	if (pageIncrement < 1) return;
 	GtkAdjustment adjustment = new GtkAdjustment ();
 	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
 	adjustment.lower = minimum;
 	adjustment.upper = maximum;
 	adjustment.step_increment = increment;
 	adjustment.page_increment = pageIncrement;
 	adjustment.page_size = thumb;
 	adjustment.value = selection;
 	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
 	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
 	OS.gtk_adjustment_changed (handle);
 	OS.gtk_adjustment_value_changed (handle);
 	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
 }

 /**
  * 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 ();
 }

 }
	package org.eclipse.swt.widgets;

	/*
	* (c) Copyright IBM Corp. 2000, 2001.
	* All Rights Reserved
	*/

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

	/**
	* 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 <em>selection</em> 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 left and right facing buttons for incrementing and
	* decrementing the value) or <code>VERTICAL</code> (which have
	* up and down facing buttons for incrementing and decrementing
	* the value).
	* </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>
	* IMPORTANT: This class is <em>not</em> intended to be subclassed.
	*
	* @see Slider
	* @see Scrollable
	* @see Scrollable#getHorizontalBar
	* @see Scrollable#getVerticalBar
	*/

	public class ScrollBar extends Widget {
	Scrollable parent;

	ScrollBar () {
	}

	/**
	* Creates a new instance of the widget.
	*/
	ScrollBar (Scrollable parent, int style) {
	super (parent, checkStyle (style));
	this.parent = parent;
	createWidget (0);
	}

	/**
	* 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>0</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);
	}

	public Display getDisplay () {
	Scrollable parent = this.parent;
	if (parent == null) error (SWT.ERROR_WIDGET_DISPOSED);
	return parent.getDisplay ();
	}

	/**
	* 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 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 boolean getEnabled () {
	checkWidget ();
	return true;
	}

	/**
	* 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 ();
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	return (int) adjustment.step_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 ();
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	return (int) adjustment.upper;
	}

	/**
	* 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 ();
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	return (int) adjustment.lower;
	}

	/**
	* 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 ();
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	return (int) adjustment.page_increment;
	}

	/**
	* Returns the receiver's parent, which must be 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 <em>selection</em> 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 ();
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	return (int) adjustment.value;
	}

	/**
	* For horizontal scroll bars, returns the height of the
	* instance, and for vertical scroll bars, returns the width
	* of the instance.
	*
	* @return the scroll bar 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 ();
	GtkWidget widget = new GtkWidget ();
	OS.memmove (widget, handle, GtkWidget.sizeof);
	return new Point (widget.alloc_width, widget.alloc_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 ();
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	return (int) adjustment.page_size;
	}

	/**
	* 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 true;
	}

	void hookEvents () {
	signal_connect (handle, "value_changed", SWT.Selection, 2);
	}

	/**
	* 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.
	* <p>
	* Note: Because of the strong connection between a scroll bar
	* and the widget which contains it (its parent), a scroll bar
	* will not indicate that it is enabled if its parent is not.
	* </p>
	*
	* @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>
	*/
	public boolean isEnabled () {
	checkWidget ();
	return getEnabled () && getParent ().getEnabled ();
	}

	/**
	* 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 isVisible () {
	checkWidget ();
	return getVisible () && getParent ().isVisible ();
	}

	int processSelection (int int0, int int1, int int2) {
	postEvent (SWT.Selection);
	return 0;
	}

	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);
	}

	/**
	* 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 ();
	}

	/**
	* 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;
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	adjustment.step_increment = (float) value;
	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
	OS.gtk_adjustment_changed (handle);
	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
	}

	/**
	* Sets the maximum value which the receiver will allow
	* to be the argument which must be greater than or
	* equal to zero.
	*
	* @param value the new maximum (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 setMaximum (int value) {
	checkWidget ();
	if (value < 0) return;
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	adjustment.upper = (float) value;
	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
	OS.gtk_adjustment_changed (handle);
	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
	}

	/**
	* Sets the minimum value which the receiver will allow
	* to be the argument which must be greater than or
	* equal to zero.
	*
	* @param value the new minimum (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 setMinimum (int value) {
	checkWidget ();
	if (value < 0) return;
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	adjustment.lower = (float) value;
	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
	OS.gtk_adjustment_changed (handle);
	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
	}

	/**
	* 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.
	*
	* @return 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;
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	adjustment.page_increment = (float) value;
	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
	OS.gtk_adjustment_changed (handle);
	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
	}

	/**
	* 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 value 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 value) {
	checkWidget ();
	if (value < 0) return;
	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
	OS.gtk_adjustment_set_value (handle, value);
	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
	}

	/**
	* Sets the size of the receiver's thumb relative to the
	* difference between its maximum and minimum values to the
	* argument which must be at least one.
	*
	* @param value the new thumb value (must be at least one)
	*
	* @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 void setThumb (int value) {
	checkWidget ();
	if (value < 1) return;
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	adjustment.page_size = (float) value;
	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
	OS.gtk_adjustment_changed (handle);
	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
	}

	/**
	* 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 (selection < 0) return;
	if (minimum < 0) return;
	if (maximum < 0) return;
	if (thumb < 1) return;
	if (maximum - minimum - thumb < 0) return;
	if (increment < 1) return;
	if (pageIncrement < 1) return;
	GtkAdjustment adjustment = new GtkAdjustment ();
	OS.memmove (adjustment, handle, GtkAdjustment.sizeof);
	adjustment.lower = minimum;
	adjustment.upper = maximum;
	adjustment.step_increment = increment;
	adjustment.page_increment = pageIncrement;
	adjustment.page_size = thumb;
	adjustment.value = selection;
	OS.memmove (handle, adjustment, GtkAdjustment.sizeof);
	OS.gtk_signal_handler_block_by_data (handle, SWT.Selection);
	OS.gtk_adjustment_changed (handle);
	OS.gtk_adjustment_value_changed (handle);
	OS.gtk_signal_handler_unblock_by_data (handle, SWT.Selection);
	}

	/**
	* 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 ();
	}

	}