Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
import android.graphics.Typeface
import android.text.SpannableString
import android.text.TextUtils
import android.text.style.CharacterStyle
import android.text.style.StyleSpan
import android.widget.TextView
import java.text.Normalizer
import java.util.Locale
import java.util.regex.Pattern
/**
* From https://cyrilmottier.com/2017/03/06/highlighting-search-terms/
*/
class QueryHighlighter(
var highlightStyle: CharacterStyle = StyleSpan(Typeface.BOLD),
var queryNormalizer: QueryNormalizer = QueryNormalizer.FOR_SEARCH,
var mode: Mode = Mode.CHARACTERS
) {
enum class Mode { CHARACTERS, WORDS }
class QueryNormalizer(var normalizer: (source: CharSequence) -> CharSequence = { s -> s }) {
operator fun invoke(source: CharSequence) = normalizer(source)
companion object {
val NONE: QueryNormalizer = QueryNormalizer()
val CASE: QueryNormalizer = QueryNormalizer { source ->
if (TextUtils.isEmpty(source)) {
source
} else source.toString().toUpperCase(Locale.ROOT)
}
private val PATTERN_DIACRITICS = Pattern.compile("\\p{InCombiningDiacriticalMarks}+")
private val PATTERN_NON_LETTER_DIGIT_TO_SPACES = Pattern.compile("[^\\p{L}\\p{Nd}]")
val FOR_SEARCH: QueryNormalizer = QueryNormalizer { searchTerm ->
var result = Normalizer.normalize(searchTerm, Normalizer.Form.NFD)
result = PATTERN_DIACRITICS.matcher(result).replaceAll("")
result = PATTERN_NON_LETTER_DIGIT_TO_SPACES.matcher(result).replaceAll(" ")
result.toLowerCase(Locale.ROOT)
}
}
}
fun apply(text: CharSequence, wordPrefix: CharSequence): CharSequence {
val normalizedText = queryNormalizer(text)
val normalizedWordPrefix = queryNormalizer(wordPrefix)
val index = indexOfQuery(normalizedText, normalizedWordPrefix)
return if (index != -1) {
SpannableString(text).apply {
setSpan(highlightStyle, index, index + normalizedWordPrefix.length, 0)
}
} else text
}
fun apply(view: TextView, text: CharSequence, query: CharSequence) {
view.text = apply(text, query)
}
private fun indexOfQuery(text: CharSequence?, query: CharSequence?): Int {
if (query == null || text == null) {
return -1
}
val textLength = text.length
val queryLength = query.length
if (queryLength == 0 || textLength < queryLength) {
return -1
}
for (i in 0..textLength - queryLength) {
// Only match word prefixes
if (mode == Mode.WORDS && i > 0 && text[i - 1] != ' ') {
continue
}
var j = 0
while (j < queryLength) {
if (text[i + j] != query[j]) {
break
}
j++
}
if (j == queryLength) {
return i
}
}
return -1
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment