createAsciiVisualization static method

String createAsciiVisualization(List<int> measurements)

Implementation

static String createAsciiVisualization(List<int> measurements) {
  final buf = StringBuffer();

  final histogram = Histogram(measurements, forceRange: _histogramRange);

  // We want a bucket for the exact middle of the range.
  assert(Histogram.bucketCount.isOdd);
  // Number of characters on each side of the center line.
  const sideSize = (Histogram.bucketCount - 1) ~/ 2;

  // How many characters should the largest bucket be high?
  const height = 20;

  for (var row = 1; row <= height; row++) {
    for (var column = 0; column < Histogram.bucketCount; column++) {
      final value = histogram.bucketsNormalized[column];
      if (value > (height - row + 0.5) / height) {
        // Definitely above the line.
        buf.write('█');
      } else if (value > (height - row + 0.05) / height) {
        // Meaningfully above the line.
        buf.write('▄');
      } else if (value > (height - row) / height && row == height) {
        // A tiny bit above the line, and also at the very bottom
        // of the graph (just above the axis). We show a dot here so that
        // this information isn't completely lost, even if it was just
        // one measurement.
        buf.write('.');
      } else {
        buf.write(' ');
      }
    }
    buf.writeln();
  }

  buf.writeln('─' * Histogram.bucketCount);

  final boundValueString =
      '${(histogram.lowestBound / 1000).abs().toStringAsFixed(1)}ms';

  buf.writeln('-${boundValueString.padRight(sideSize - 1)}'
      '^'
      '${boundValueString.padLeft(sideSize)}');

  return buf.toString();
}