/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* C E D A R
* S O L U T I O N S "Software done right."
* S O F T W A R E
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* Copyright (c) 2013-2014 Kenneth J. Pronovici.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the Apache License, Version 2.0.
* See LICENSE for more information about the licensing terms.
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* Author : Kenneth J. Pronovici <pronovic@ieee.org>
* Language : Java 6
* Project : Common Java Functionality
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
package com.cedarsolutions.client.gwt.widget.table;
import com.cedarsolutions.client.gwt.custom.pager.SimplePager;
import com.google.gwt.core.client.GWT;
import com.google.gwt.i18n.client.NumberFormat;
import com.google.gwt.view.client.HasRows;
import com.google.gwt.view.client.Range;
/**
* Standard pager for use with DataTable.
*
* <p>
* This pager maintains a set page size and displays page numbers and
* total pages more elegantly than the original Google pager. It also
* fixes rendering problems with the last page button, which should
* only be shown if the last page is known to exist.
* </p>
*
* <p>
* This pager does not support the fast forward button that is provided
* by the original SimplePager widget.
* </p>
*
* <p>
* The initial implementation was taken from a Google Groups posting,
* referenced below. I have modified that implementation over time.
* So much of this class has been overridden that it almost should be
* rewritten from scratch, but I've been trying to avoid that.
* </p>
*
* @see <a href="http://www.mail-archive.com/google-web-toolkit@googlegroups.com/msg62640.html">Google Groups</a>
* @author Kenneth J. Pronovici <pronovic@ieee.org>
*/
public class DataTablePager extends SimplePager {
/** Configured page size. */
private int pageSize;
/** Create a pager with the standard options. */
public DataTablePager(DataTable<?> parent) {
super(TextLocation.CENTER, getResources(), false, 0, true);
this.pageSize = parent.getPageSize();
this.setPageSize(this.pageSize);
this.setDisplay(parent);
}
/** Get the customized style for this widget. */
protected static SimplePager.Resources getResources() {
return GWT.create(SimplePager.Resources.class);
}
/** {@inheritDoc} */
@Override
protected void onRangeOrRowCountChanged() {
super.onRangeOrRowCountChanged();
this.setLastPageButtonDisabled(!this.hasLastPage());
}
/** {@inheritDoc} */
@Override
public int getPageSize() {
// Normally, SimplePager derives this from the visible range
return this.pageSize;
}
/** {@inheritDoc} */
@Override
public void nextPage() {
// Page forward by an exact size rather than the number of visible
// rows as is in the norm in the underlying implementation
if (getDisplay() != null) {
Range range = getDisplay().getVisibleRange();
setPageStart(range.getStart() + getPageSize());
}
}
/** {@inheritDoc} */
@Override
public void previousPage() {
// Page back by an exact size rather than the number of visible rows
// as is in the norm in the underlying implementation
if (getDisplay() != null) {
Range range = getDisplay().getVisibleRange();
setPageStart(range.getStart() - getPageSize());
}
}
/** {@inheritDoc} */
@Override
public void setPageStart(int index) {
// Override so the last page is shown with a number of rows less
// than the pageSize rather than always showing the pageSize number
// of rows and possibly repeating rows on the last and penultimate page
if (getDisplay() != null) {
Range range = getDisplay().getVisibleRange();
int displayPageSize = getPageSize();
if (isRangeLimited() && getDisplay().isRowCountExact()) {
displayPageSize = Math.min(getPageSize(), getDisplay().getRowCount() - index);
}
index = Math.max(0, index);
if (index != range.getStart()) {
getDisplay().setVisibleRange(index, displayPageSize);
}
}
}
/** {@inheritDoc} */
@Override
protected String createText() {
// Override to display "0 of 0" when there are no records (otherwise
// you get "1-1 of 0") and "1 of 1" when there is only one record
// (otherwise you get "1-1 of 1"). Not internationalised (but
// neither is SimplePager). There's also a special case if the
// final page is empty: we get "> 10 of 10" instead of "11 of 10".
NumberFormat formatter = NumberFormat.getFormat("#,###");
HasRows display = getDisplay();
Range range = display.getVisibleRange();
int pageStart = range.getStart() + 1;
int size = range.getLength();
int dataSize = display.getRowCount();
int endIndex = Math.min(dataSize, pageStart + size - 1);
endIndex = Math.max(pageStart, endIndex);
boolean exact = display.isRowCountExact();
if (dataSize == 0) {
return "0 of 0";
} else if (pageStart == endIndex) {
if (pageStart > dataSize) {
// This is better than "11 of 10" if the final page is empty
return "> " + formatter.format(dataSize) + " of " + formatter.format(dataSize);
} else {
return formatter.format(pageStart) + " of " + formatter.format(dataSize);
}
} else {
return formatter.format(pageStart) + "-" + formatter.format(endIndex) + (exact ? " of " : " of over ") + formatter.format(dataSize);
}
}
/**
* Enable or disable the last page button.
* @param disabled true to disable, false to enable
*/
protected void setLastPageButtonDisabled(boolean disabled) {
if (lastPage != null) {
lastPage.setDisabled(disabled);
}
}
/** True if we know for certain there is a last page beyond the one currently displayed. */
protected boolean hasLastPage() {
HasRows display = getDisplay();
Range range = display.getVisibleRange();
int pageStart = range.getStart() + 1;
int size = range.getLength();
int dataSize = display.getRowCount();
int endIndex = Math.min(dataSize, pageStart + size - 1);
endIndex = Math.max(pageStart, endIndex);
boolean exact = display.isRowCountExact();
if (dataSize == 0) {
return false;
} else if (pageStart == endIndex) {
return false;
} else {
return !exact ? false : dataSize > endIndex;
}
}
}