CustomMarkEditorLinePainter.kt

package de.dieploegers.develop.idea.custommark

import com.intellij.openapi.editor.EditorLinePainter
import com.intellij.openapi.editor.LineExtensionInfo
import com.intellij.openapi.editor.markup.EffectType
import com.intellij.openapi.editor.markup.TextAttributes
import com.intellij.openapi.project.Project
import com.intellij.openapi.vfs.VirtualFile
import java.awt.Color

class CustomMarkEditorLinePainter : EditorLinePainter() {
    override fun getLineExtensions(project: Project, file: VirtualFile, lineNumber: Int): MutableCollection<LineExtensionInfo> {
        val content = file.contentsToByteArray().toString(file.charset).lines()[lineNumber]
        val returnInfos = ArrayList<LineExtensionInfo>()
        val textAttributes = TextAttributes()
        textAttributes.effectType = EffectType.LINE_UNDERSCORE
        textAttributes.backgroundColor = Color(255,0,0)
        textAttributes.foregroundColor = Color(255,255,255)
        if (content.matches(Regex(".*abab.*"))) {
            returnInfos.add(
                LineExtensionInfo("MARK", textAttributes)
            )
        }
        return returnInfos
    }
}