Fix highlight offsets of multi-line entries

Fix regression from 4811e52a

src/ansi.go

@@ -278,6 +278,7 @@ func extractColor(str string, state *ansiState, proc func(string, *ansiState) bo
 
 			if code == "\n" {
 				output.WriteRune('\n')
+				runeCount++
 				// Full-background marker
 				if newState.lbg >= 0 {
 					marker := newState

src/core.go

@@ -81,7 +81,7 @@ func Run(opts *Options) (int, error) {
 			lineAnsiState = newState
 
 			// Full line background is found. Add a special marker.
-			if !opts.ReadZero && offsets != nil && newState != nil && len(*offsets) > 0 && newState.lbg >= 0 {
+			if offsets != nil && newState != nil && len(*offsets) > 0 && newState.lbg >= 0 {
 				marker := (*offsets)[len(*offsets)-1]
 				marker.offset[0] = marker.offset[1]
 				marker.color.bg = newState.lbg

src/terminal.go

@@ -3399,13 +3399,8 @@ func (t *Terminal) printHighlighted(result Result, colBase tui.ColorPair, colMat
 		finalLineNum = lineNum
 		offsets := []colorOffset{}
 		lbg := tui.NoColorPair()
-		var lineLen int
 		for idx, offset := range allOffsets {
-			lineLen = len(line)
+			lineEnd := int32(from + len(line))
-			if lineLen > 0 && line[lineLen-1] == '\n' {
-				lineLen--
-			}
-			lineEnd := int32(from + lineLen)
 			if offset.offset[0] >= lineEnd {
 				if offset.IsFullBgMarker(lineEnd) {
 					lbg = offset.color
@@ -3441,7 +3436,7 @@ func (t *Terminal) printHighlighted(result Result, colBase tui.ColorPair, colMat
 				break
 			}
 		}
-		from += lineLen
+		from += len(line)
 		if lineOffset < skipLines {
 			continue
 		}