org.eclipse.swt.widgets.Scrollable Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2002, 2012 Innoopract Informationssysteme GmbH 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:
* Innoopract Informationssysteme GmbH - initial API and implementation
* EclipseSource - ongoing development
******************************************************************************/
package org.eclipse.swt.widgets;
import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.graphics.Rectangle;
/**
* This class is the abstract superclass of all classes which
* represent controls that have standard scroll bars.
*
* - Styles:
* - H_SCROLL, V_SCROLL
* - Events:
*
- (none)
*
*
* IMPORTANT: This class is intended to be subclassed only
* within the SWT implementation.
*
* @since 1.0
*/
public abstract class Scrollable extends Control {
private ScrollBar verticalBar;
private ScrollBar horizontalBar;
Scrollable( Composite parent ) {
// prevent instantiation from outside this package
super( parent );
}
/**
* Constructs a new instance of this class given its parent
* and a style value describing its behavior and appearance.
*
* The style value is either one of the style constants defined in
* class SWT which is applicable to instances of this
* class, or must be built by bitwise OR'ing together
* (that is, using the int "|" operator) two or more
* of those SWT style constants. The class description
* lists the style constants that are applicable to the class.
* Style bits are also inherited from superclasses.
*
*
* @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
* - ERROR_NULL_ARGUMENT - if the parent is null
*
* @exception SWTException
* - ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
* - ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass
*
*
* @see SWT#H_SCROLL
* @see SWT#V_SCROLL
* @see Widget#checkSubclass
* @see Widget#getStyle
*/
public Scrollable( Composite parent, int style ) {
super( parent, style );
createScrollBars();
}
private void createScrollBars() {
if( ( style & SWT.H_SCROLL ) != 0 ) {
horizontalBar = new ScrollBar( this, SWT.H_SCROLL );
horizontalBar.setVisible( false );
}
if( ( style & SWT.V_SCROLL ) != 0 ) {
verticalBar = new ScrollBar( this, SWT.V_SCROLL );
verticalBar.setVisible( false );
}
}
/**
* Returns a rectangle which describes the area of the
* receiver which is capable of displaying data (that is,
* not covered by the "trimmings").
*
* @return the client area
*
* @exception SWTException
* - ERROR_WIDGET_DISPOSED - if the receiver has been disposed
* - ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
*
*
* @see #computeTrim
*/
public Rectangle getClientArea() {
checkWidget();
Rectangle bounds = getBounds();
int borderWidth = getBorderWidth();
Rectangle padding = getPadding();
int width = bounds.width - borderWidth * 2 - padding.width - getVScrollBarWidth();
int height = bounds.height - borderWidth * 2 - padding.height - getHScrollBarHeight();
return new Rectangle( padding.x, padding.y, Math.max( 0, width ), Math.max( 0, height ) );
}
/**
* Given a desired client area for the receiver
* (as described by the arguments), returns the bounding
* rectangle which would be required to produce that client
* area.
*
* In other words, it returns a rectangle such that, if the
* receiver's bounds were set to that rectangle, the area
* of the receiver which is capable of displaying data
* (that is, not covered by the "trimmings") would be the
* rectangle described by the arguments (relative to the
* receiver's parent).
*
*
* @param x the desired x coordinate of the client area
* @param y the desired y coordinate of the client area
* @param width the desired width of the client area
* @param height the desired height of the client area
* @return the required bounds to produce the given client area
*
* @exception SWTException
* - ERROR_WIDGET_DISPOSED - if the receiver has been disposed
* - ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
*
*
* @see #getClientArea
*/
public Rectangle computeTrim( int x, int y, int width, int height ) {
checkWidget();
int borderWidth = getBorderWidth();
Rectangle padding = getPadding();
int newWidth = width + borderWidth * 2 + padding.width + getVScrollBarWidth();
int newHeight = height + borderWidth * 2 + padding.height + getHScrollBarHeight();
int newX = x - borderWidth - padding.x;
int newY = y - borderWidth - padding.y;
return new Rectangle( newX, newY, newWidth, newHeight );
}
/**
* Returns the receiver's horizontal scroll bar if it has
* one, and null if it does not.
*
* @return the horizontal scroll bar (or null)
*
* @exception SWTException
* - ERROR_WIDGET_DISPOSED - if the receiver has been disposed
* - ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
*
*
* @since 1.4
*/
public ScrollBar getHorizontalBar() {
checkWidget();
return horizontalBar;
}
/**
* Returns the receiver's vertical scroll bar if it has
* one, and null if it does not.
*
* @return the vertical scroll bar (or null)
*
* @exception SWTException
* - ERROR_WIDGET_DISPOSED - if the receiver has been disposed
* - ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
*
*
* @since 1.4
*/
public ScrollBar getVerticalBar() {
checkWidget();
return verticalBar;
}
@Override
void releaseChildren() {
super.releaseChildren();
if( verticalBar != null ) {
verticalBar.dispose();
}
if( horizontalBar != null ) {
horizontalBar.dispose();
}
}
int getVScrollBarWidth() {
int result = 0;
if( verticalBar != null && verticalBar.getVisible() ) {
result = verticalBar.getSize().x;
}
return result;
}
int getHScrollBarHeight() {
int result = 0;
if( horizontalBar != null && horizontalBar.getVisible() ) {
result = horizontalBar.getSize().y;
}
return result;
}
}