01: /**
02: * ===========================================
03: * JFreeReport : a free Java reporting library
04: * ===========================================
05: *
06: * Project Info: http://reporting.pentaho.org/
07: *
08: * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
09: *
10: * This library is free software; you can redistribute it and/or modify it under the terms
11: * of the GNU Lesser General Public License as published by the Free Software Foundation;
12: * either version 2.1 of the License, or (at your option) any later version.
13: *
14: * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
15: * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
16: * See the GNU Lesser General Public License for more details.
17: *
18: * You should have received a copy of the GNU Lesser General Public License along with this
19: * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
20: * Boston, MA 02111-1307, USA.
21: *
22: * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
23: * in the United States and other countries.]
24: *
25: * ------------
26: * HideElementIfDataAvailableExpression.java
27: * ------------
28: * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
29: */package org.jfree.report.function;
30:
31: import javax.swing.table.TableModel;
32:
33: import org.jfree.report.Band;
34: import org.jfree.report.Element;
35:
36: /**
37: * This functions checks the tablemodel and shows the named band, if there
38: * is no data available.
39: *
40: * @author Thomas Morgner
41: */
42: public class HideElementIfDataAvailableExpression extends
43: AbstractElementFormatFunction {
44: /**
45: * Default Constructor.
46: */
47: public HideElementIfDataAvailableExpression() {
48: }
49:
50: /**
51: * Applies the computed visiblity to all child elements of the given band.
52: *
53: * @param b the visibility.
54: */
55: protected void processRootBand(final Band b) {
56: final boolean visible = (isDataAvailable() == false);
57: final Element[] elements = FunctionUtilities.findAllElements(b,
58: getElement());
59: for (int i = 0; i < elements.length; i++) {
60: final Element element = elements[i];
61: element.setVisible(visible);
62: }
63:
64: }
65:
66: /**
67: * Computes, if there is data available. This checks the report's data-row and searches for the number of rows
68: * in the underlying tablemodel.
69: * @return true, if the tablemodel contains data, false otherwise.
70: */
71: private boolean isDataAvailable() {
72: final ExpressionRuntime runtime = getRuntime();
73: if (runtime == null) {
74: return false;
75: }
76: final TableModel data = runtime.getData();
77: if (data == null) {
78: return false;
79: }
80: if (data.getRowCount() == 0) {
81: return false;
82: }
83: return true;
84: }
85:
86: /**
87: * Return the current expression value. <P> The value depends (obviously) on
88: * the expression implementation.
89: *
90: * @return the value of the function.
91: */
92: public Object getValue() {
93: if (isDataAvailable()) {
94: return Boolean.TRUE;
95: }
96: return Boolean.FALSE;
97: }
98: }
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