/*******************************************************************************
* Copyright (c) 2002, 2009 Innoopract Informationssysteme GmbH.
* 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:
* Innoopract Informationssysteme GmbH - initial API and implementation
* EclipseSource - ongoing development
******************************************************************************/
package org.eclipse.swt.widgets;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.internal.widgets.IDisplayAdapter;
/**
* 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-->
*
* <p>(current) limitations:</p>
* <ul>
* <li>minimum, maximum, thumb, increment and pageIncrement properties are not
* rendered (no corresponding client-side property)</li>
* </ul>
*
* @since 1.0
*/
// TODO [rh] include ScrollBar in widget hierarchy (child of Scrollable)?
public class ScrollBar extends Widget {
private final Scrollable parent;
private int thumb;
private int selection;
private int minimum;
private int maximum;
/**
* 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>
*
* <p><strong>IMPORTANT:</strong> This method is <em>not</em> part of the RWT
* public API. It is marked public only so that it can be shared
* within the packages provided by RWT. It should never be accessed
* from application code.
* </p>
*
* @see SWT#HORIZONTAL
* @see SWT#VERTICAL
* @see Widget#checkSubclass
* @see Widget#getStyle
*/
// TODO [rh] make package-private as in SWT (not possible since currently
// used by ScrolledComposite, see there)
public ScrollBar( final Scrollable parent, final int style ) {
super( parent, checkStyle( style ) );
this.parent = parent;
}
/**
* 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;
}
/////////////
// Visibility
/**
* 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( final boolean visible ) {
checkWidget();
boolean isVisible = ( state & HIDDEN ) == 0;
if( isVisible != visible ) {
state = visible ? state & ~HIDDEN : state | HIDDEN;
}
}
/**
* 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;
}
/**
* 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();
}
/////////////
// Enablement
/**
* 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();
if( enabled ) {
state &= ~DISABLED;
} else {
state |= DISABLED;
}
}
/**
* 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 <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 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() {
Point result = parent.getSize();
if( ( style & SWT.HORIZONTAL ) != 0 ) {
result.y = getScrollBarSize();
} else {
result.x = getScrollBarSize();
}
return result;
}
/**
* Returns 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();
return thumb;
}
/**
* 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 thumb 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( final int thumb ) {
checkWidget();
this.thumb = thumb;
}
/**
* 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();
return maximum;
}
/**
* 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 maximum 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( final int maximum ) {
checkWidget();
this.maximum = 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();
return minimum;
}
/**
* 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 minimum 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( final int minimum ) {
checkWidget();
this.minimum = minimum;
}
/**
* 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( final int selection ) {
checkWidget();
if( this.selection != selection ) {
this.selection = selection;
}
}
/**
* 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();
return selection;
}
////////////////////
// SelectionListener
/**
* 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( final SelectionListener listener ) {
checkWidget();
SelectionEvent.addListener( this, listener );
}
/**
* 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( final SelectionListener listener ) {
checkWidget();
SelectionEvent.removeListener( this, listener );
}
//////////////////
// Helping methods
private static int checkStyle( final int style ) {
return checkBits( style, SWT.HORIZONTAL, SWT.VERTICAL, 0, 0, 0, 0 );
}
private int getScrollBarSize() {
Object object = getDisplay().getAdapter( IDisplayAdapter.class );
IDisplayAdapter adapter = ( IDisplayAdapter )object;
return adapter.getScrollBarSize();
}
}