/**
* 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 com.codeaffine.eclipse.swt.widget.scrollbar.Direction.HORIZONTAL;
import static com.codeaffine.eclipse.swt.widget.scrollbar.ShiftData.calculateSelectionRange;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import com.codeaffine.eclipse.swt.widget.scrollbar.DragControl.DragAction;
final class DragShifter implements DragAction {
private final FlatScrollBar scrollBar;
private final int buttonLength;
public DragShifter( FlatScrollBar scrollBar, int buttonLength ) {
this.scrollBar = scrollBar;
this.buttonLength = buttonLength;
}
@Override
public void start() {
scrollBar.notifyListeners( SWT.DRAG );
}
@Override
public void run( int startX, int startY, int currentX, int currentY ) {
ShiftData shiftData = newShiftData( startX, startY, currentX, currentY );
if( shiftData.canShift() ) {
int selectionRange = calculateSelectionRange( scrollBar );
int selectionDelta = shiftData.calculateSelectionDelta( selectionRange );
int selection = scrollBar.getSelection() + selectionDelta;
scrollBar.setSelectionInternal( selection, SWT.DRAG );
}
}
@Override
public void end() {
scrollBar.notifyListeners( SWT.NONE );
}
private ShiftData newShiftData( int startX, int startY, int currentX, int currentY ) {
ShiftData result;
if( scrollBar.direction == HORIZONTAL ) {
result = new ShiftData( buttonLength, getScrollBarSize().x, getDragSize().x, currentX - startX );
} else {
result = new ShiftData( buttonLength, getScrollBarSize().y, getDragSize().y, currentY - startY );
}
return result;
}
private Point getScrollBarSize() {
return scrollBar.getSize();
}
private Point getDragSize() {
return scrollBar.drag.getControl().getSize();
}
}