/*
* Copyright (c) 2009 Lockheed Martin Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.eurekastreams.server.domain;
/**
* This class keeps the page state for a view & controller. The page state is modified accordingly based on the paging
* action taken. Page state represents the result set currently viewed. Each set of results has a start point, an end
* point, total items, and range (or page size).
*
*
*/
public class BasicPager implements Pager
{
/**
* the number of items to view at one time.
*/
private int pageSize = 9 + 1;
/**
* Goes by index.
*/
private int startItem = 0;
/**
* Goes by index.
*/
private int endItem = 9;
/**
* the total number of things that can be paged around. The max usable index should be maxCount-1
*/
private int maxCount = 0;
/**
* Constructor.
*/
public BasicPager()
{
}
/**
* for bean attribute.
*
* @return the pageSize
*/
public int getPageSize()
{
return pageSize;
}
/**
* for bean attribute.
*
* @param inPageSize
* the pageSize to set
*/
public void setPageSize(final int inPageSize)
{
this.pageSize = inPageSize;
}
/**
* for bean attribute.
*
* @return the startItem
*/
public int getStartItem()
{
return startItem;
}
/**
* for bean attribute.
*
* @param inStartItem
* the startItem to set
*/
public void setStartItem(final int inStartItem)
{
this.startItem = inStartItem;
}
/**
* @param inEndItem
* the endItem to set
*/
public void setEndItem(final int inEndItem)
{
this.endItem = inEndItem;
}
/**
* index, inclusive.
*
* @return the endItem
*/
public int getEndItem()
{
return endItem;
}
/**
* for bean attribute.
*
* @return the maxCount
*/
public int getMaxCount()
{
return maxCount;
}
/**
* for bean attribute.
*
* @param inMaxCount
* the maxCount to set
*/
public void setMaxCount(final int inMaxCount)
{
this.maxCount = inMaxCount;
}
/**
* Calculates the start and end bounds for the next page based on page size (number of displayable items).
*/
public void nextPage()
{
// don't do anything if you'd page past the available items
if (startItem + pageSize >= maxCount)
{
return;
}
// make the change
startItem += pageSize;
endItem += pageSize;
// correct for right edge case if necessary
if (endItem >= maxCount)
{
endItem = maxCount - 1;
}
}
/**
* returns current range.
*
* This method is here for symmetry with the other paging methods to be able to express your intent that you want to
* stay on the same page.
*
*/
public void samePage()
{
}
/**
* Calculates the start and end bounds for the previous page based on page size (number of displayable items).
*/
public void previousPage()
{
// don't do anything if you'd page past the available items
if (startItem - pageSize < 0)
{
return;
}
// make the change
endItem = startItem - 1;
startItem -= pageSize;
}
/**
* Change the page.
*
* @param direction
* the direction to change the page.
*/
public void changePage(final PagingDirection direction)
{
if (direction.equals(PagingDirection.FORWARD))
{
nextPage();
}
else if (direction.equals(PagingDirection.BACKWARD))
{
previousPage();
}
else
{
samePage();
}
}
/**
* Determine if the pager is pageable in a given direction.
*
* @param direction
* the direction.
* @return if the pager has another page.
*/
public boolean isPageable(final PagingDirection direction)
{
if (direction.equals(PagingDirection.FORWARD))
{
return isNextPageable();
}
else if (direction.equals(PagingDirection.BACKWARD))
{
return isPreviousPageable();
}
// "Same Page" case.
return true;
}
/**
* Shorthand for setting page location.
*
* @param inStartItem
* start item for a range of data.
* @param inEndItem
* end item for a range of data.
* @param inMaxCount
* total number of items in the result set (not the displayable range).
*/
public void updateRange(final int inStartItem, final int inEndItem, final int inMaxCount)
{
this.startItem = inStartItem;
this.endItem = inEndItem;
this.maxCount = inMaxCount;
}
/**
* if the page can be moved ahead.
*
* @return if a next page exists.
*/
public boolean isNextPageable()
{
return endItem < maxCount - 1; // less than the last index
}
/**
* if the page can be moved back.
*
* @return if a previous. page exists.
*/
public boolean isPreviousPageable()
{
return startItem > 0;
}
}