fun readRow()

in plot-api/src/commonMain/kotlin/org/jetbrains/letsPlot/util/pngj/PngReader.kt [299:330]
32 lines of code
11 McCabe index (conditional complexity)

    fun readRow(nrow: Int): IImageLine {
        if (chunkseq!!.firstChunksNotYetRead()) readFirstChunks()
        return if (!isInterlaced) {
            if (imlinesSet == null) imlinesSet = createLineSet(true, -1, 0, 1)
            val line: IImageLine = imlinesSet!!.getImageLine(nrow)
            if (nrow == rowNum) return line // already read??
            else if (nrow < rowNum) throw PngjInputException("rows must be read in increasing order: $nrow")
            while (rowNum < nrow) {
                while (!chunkseq.idatSet!!.isRowReady) {
                    if (streamFeeder!!.feed(chunkseq) < 1) throw PngjInputException("premature ending")
                }
                rowNum++
                chunkseq.idatSet!!.updateCrcs(idatCrca, idatCrcb)
                if (rowNum == nrow) {
                    line.readFromPngRaw(
                        chunkseq.idatSet!!.unfilteredRow!!, curImgInfo.bytesPerRow + 1, 0,
                        1
                    )
                    line.endReadFromPngRaw()
                }
                chunkseq.idatSet!!.advanceToNextRow()
            }
            line
        } else { // and now, for something completely different (interlaced!)
            if (imlinesSet == null) {
                imlinesSet = createLineSet(false, curImgInfo.rows, 0, 1)
                loadAllInterlaced(curImgInfo.rows, 0, 1)
            }
            rowNum = nrow
            imlinesSet!!.getImageLine(nrow)
        }
    }