WaveformLayer.updatePlot.swift

private var firstSampleToPlotIdx: Int {
    get {
        let idx = Int(-viewPort.xTrans * viewPort.screenScale)
        return (0..<dataProvider.summarySampleCnt).clamp(idx)
    }
}

private var samplesToPlotInVisibleCnt: Int {
    get {
        return viewPort.visibleXAxisUnits
    }
}

private func updatePlot() {
    guard let samples = dataProvider.summarySamples else {
        return
    }

    let endIdx = (0..<samples.count).clamp(firstSampleToPlotIdx+samplesToPlotInVisibleCnt)
    let samplesToPlot = Array(samples[firstSampleToPlotIdx..<endIdx])

    layers.forEach() {
        $0.isHidden = true
    }

    updateLines(samples: samplesToPlot, yMidline: bounds.height / 2)
}