Package org.apache.lucene.search.highlight

Class 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 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.getMaxTermWeight() 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]