/**
* Copyright (c) 2014 - 2017 Frank Appel
* 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:
* Frank Appel - initial API and implementation
*/
package com.codeaffine.eclipse.swt.widget.scrollbar;
import static java.lang.Math.abs;
public class SelectionRaster {
private final FlatScrollBar scrollBar;
private final int rasterSize;
public SelectionRaster( FlatScrollBar scrollBar, int rasterSize ) {
this.scrollBar = scrollBar;
this.rasterSize = rasterSize;
}
public void updateSelection( int selection ) {
int rasterValue = calculateRasterValue( selection );
int scrollBarSelection = scrollBar.getSelection();
if( isDifferentRasterSection( rasterValue, scrollBarSelection ) ) {
scrollBar.setSelection( rasterValue );
}
}
public int calculateRasterValue( int selection ) {
return ( selection / rasterSize ) * rasterSize;
}
private boolean isDifferentRasterSection( int rasterValue, int scrollBarSelection ) {
return abs( rasterValue - scrollBarSelection ) >= rasterSize;
}
}