Lucene.Net  3.0.3
Lucene.Net is a port of the Lucene search engine library, written in C# and targeted at .NET runtime users.
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SpanGradientFormatter.cs
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1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 
18 using System;
19 using System.Text;
20 
21 namespace Lucene.Net.Search.Highlight
22 {
23  /// <summary>
24  /// Formats text with different color intensity depending on the score of the
25  /// term using the span tag. GradientFormatter uses a bgcolor argument to the font tag which
26  /// doesn't work in Mozilla, thus this class.
27  /// </summary>
28  /// <seealso cref="GradientFormatter"/>
30  {
31  // guess how much extra text we'll add to the text we're highlighting to try to avoid a StringBuilder resize
32  private static readonly String TEMPLATE = "<span style=\"background: #EEEEEE; color: #000000;\">...</span>";
33  private static readonly int EXTRA = TEMPLATE.Length;
34 
35  public SpanGradientFormatter(float maxScore, String minForegroundColor,
36  String maxForegroundColor, String minBackgroundColor,
37  String maxBackgroundColor)
38  : base(maxScore, minForegroundColor, maxForegroundColor, minBackgroundColor, maxBackgroundColor)
39  { }
40 
41  public override String HighlightTerm(String originalText, TokenGroup tokenGroup)
42  {
43  if (tokenGroup.TotalScore == 0)
44  return originalText;
45  float score = tokenGroup.TotalScore;
46  if (score == 0)
47  {
48  return originalText;
49  }
50 
51  // try to size sb correctly
52  var sb = new StringBuilder(originalText.Length + EXTRA);
53 
54  sb.Append("<span style=\"");
55  if (highlightForeground)
56  {
57  sb.Append("color: ");
58  sb.Append(GetForegroundColorString(score));
59  sb.Append("; ");
60  }
61  if (highlightBackground)
62  {
63  sb.Append("background: ");
64  sb.Append(GetBackgroundColorString(score));
65  sb.Append("; ");
66  }
67  sb.Append("\">");
68  sb.Append(originalText);
69  sb.Append("</span>");
70  return sb.ToString();
71  }
72  }
73 }