using System;

using System.Collections.Generic;

using System.Drawing;

using System.Drawing.Imaging;

using System.Linq;

using System.Text;

namespace Spectrogram

{

static class Scale

{

public static Bitmap Vertical(int width, Settings settings, int offsetHz = 0, int tickSize = 3, int reduction = 1)

{

double tickHz = 1;

int minSpacingPx = 50;

double[] multipliers = { 2, 2.5, 2 };

int multiplier = 0;

while (true)

{

tickHz *= multipliers[multiplier++ % multipliers.Length];

double tickCount = settings.FreqSpan / tickHz;

double pxBetweenTicks = settings.Height / tickCount;

if (pxBetweenTicks >= minSpacingPx * reduction)

break;

}

Bitmap bmp = new Bitmap(width, settings.Height / reduction, PixelFormat.Format32bppPArgb);

using (var gfx = Graphics.FromImage(bmp))

using (var pen = new Pen(Color.Black))

using (var brush = new SolidBrush(Color.Black))

using (var font = new Font(FontFamily.GenericMonospace, 10))

using (var sf = new StringFormat() { LineAlignment = StringAlignment.Center })

{

gfx.Clear(Color.White);

List<double> freqs = new List<double>();

for (double f = settings.FreqMin; f <= settings.FreqMax; f += tickHz)

freqs.Add(f);

// don't show first or last tick

if (freqs.Count >= 2)

{

freqs.RemoveAt(0);

freqs.RemoveAt(freqs.Count - 1);

}

foreach (var freq in freqs)

{

int y = settings.PixelY(freq) / reduction;

gfx.DrawLine(pen, 0, y, tickSize, y);

gfx.DrawString($"{freq + offsetHz:N0} Hz", font, brush, tickSize, y, sf);

}

}

return bmp;

}

}

}