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: * ShowElementIfDataAvailableExpression.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 hides the named elements, if there
38: * is no data available.
39: *
40: * @author Thomas Morgner
41: */
42: public class ShowElementIfDataAvailableExpression extends
43: AbstractElementFormatFunction {
44: /**
45: * Default Constructor.
46: */
47: public ShowElementIfDataAvailableExpression() {
48: }
49:
50: /**
51: * Applies the computed visiblity to all elements with the name defined in this expression.
52: * @param b the band.
53: */
54: protected void processRootBand(final Band b) {
55: final boolean visible = isDataAvailable();
56: final Element[] elements = FunctionUtilities.findAllElements(b,
57: getElement());
58: for (int i = 0; i < elements.length; i++) {
59: final Element element = elements[i];
60: element.setVisible(visible);
61: }
62: }
63:
64: /**
65: * Computes the visibility state.
66: *
67: * @return true, if there is data available, false otherwise.
68: */
69: private boolean isDataAvailable() {
70: final ExpressionRuntime runtime = getRuntime();
71: if (runtime == null) {
72: return false;
73: }
74: final TableModel data = runtime.getData();
75: if (data == null) {
76: return false;
77: }
78: if (data.getRowCount() == 0) {
79: return false;
80: }
81: return true;
82: }
83:
84: /**
85: * Return the current expression value. <P> The value depends (obviously) on
86: * the expression implementation.
87: *
88: * @return the value of the function.
89: */
90: public Object getValue() {
91: if (isDataAvailable()) {
92: return Boolean.TRUE;
93: }
94: return Boolean.FALSE;
95: }
96: }
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