org.apache.lucene.search.highlight

## Class GradientFormatter

- java.lang.Object
- - org.apache.lucene.search.highlight.GradientFormatter

All Implemented Interfaces:
  Formatter

Direct Known Subclasses:
  SpanGradientFormatter

    public class GradientFormatter
    extends Object
    implements Formatter

Formats text with different color intensity depending on the score of the term.

### Field Summary

Fields
`protected boolean` `highlightBackground`
`protected boolean` `highlightForeground`

### Constructor Summary

Constructors
Constructor and Description
`GradientFormatter(float maxScore, String minForegroundColor, String maxForegroundColor, String minBackgroundColor, String maxBackgroundColor)` Sets the color range for the IDF scores

### Method Summary

Methods
`protected String` `getBackgroundColorString(float score)`
`protected String` `getForegroundColorString(float score)`
`static int` `hexToInt(String hex)` Converts a hex string into an int.
`String` `highlightTerm(String originalText, TokenGroup tokenGroup)`

### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

### Field Detail

#### highlightForeground

    protected boolean highlightForeground

#### highlightBackground

    protected boolean highlightBackground

### Constructor Detail

#### GradientFormatter

    public GradientFormatter(float maxScore,
                     String minForegroundColor,
                     String maxForegroundColor,
                     String minBackgroundColor,
                     String maxBackgroundColor)

Sets the color range for the IDF scores

Parameters:
  `maxScore` - The score (and above) displayed as maxColor (See QueryScorer.getMaxWeight which can be used to calibrate scoring scale)
  `minForegroundColor` - The hex color used for representing IDF scores of zero eg #FFFFFF (white) or null if no foreground color required
  `maxForegroundColor` - The largest hex color used for representing IDF scores eg #000000 (black) or null if no foreground color required
  `minBackgroundColor` - The hex color used for representing IDF scores of zero eg #FFFFFF (white) or null if no background color required
  `maxBackgroundColor` - The largest hex color used for representing IDF scores eg #000000 (black) or null if no background color required

### Method Detail

#### highlightTerm

    public String highlightTerm(String originalText,
                       TokenGroup tokenGroup)

Specified by:
  `highlightTerm` in interface `Formatter`
Parameters:
  `originalText` - The section of text being considered for markup
  `tokenGroup` - contains one or several overlapping Tokens along with their scores and positions.

#### getForegroundColorString

    protected String getForegroundColorString(float score)

#### getBackgroundColorString

    protected String getBackgroundColorString(float score)

#### hexToInt

    public static final int hexToInt(String hex)

Converts a hex string into an int. Integer.parseInt(hex, 16) assumes the input is nonnegative unless there is a preceding minus sign. This method reads the input as twos complement instead, so if the input is 8 bytes long, it will correctly restore a negative int produced by Integer.toHexString() but not necessarily one produced by Integer.toString(x,16) since that method will produce a string like '-FF' for negative integer values.

Parameters:
  `hex` - A string in capital or lower case hex, of no more then 16 characters.
Throws:
  `NumberFormatException` - if the string is more than 16 characters long, or if any character is not in the set [0-9a-fA-f]