using System;

using System.Linq;

using SkiaSharp;

namespace Spectrogram;

public class Colormap(ScottPlot.IColormap colormap)

{

private ScottPlot.IColormap _Colormap { get; } = colormap;

public string Name => _Colormap.Name;

public override string ToString() => _Colormap.ToString();

public static Colormap[] GetColormaps() => ScottPlot.Colormap.GetColormaps()

.Select(x => new Colormap(x))

.ToArray();

public static string[] GetColormapNames() => ScottPlot.Colormap.GetColormaps()

.Select(x => new Colormap(x).Name)

.ToArray();

public static Colormap GetColormap(string colormapName)

{

foreach (Colormap cmap in GetColormaps())

if (string.Equals(cmap.Name, colormapName, StringComparison.InvariantCultureIgnoreCase))

return cmap;

throw new ArgumentException($"Colormap does not exist: {colormapName}");

}

public (byte r, byte g, byte b) GetRGB(byte value) => GetRGB(value / 255.0);

public (byte r, byte g, byte b) GetRGB(double fraction)

{

ScottPlot.Color color = _Colormap.GetColor(fraction);

return (color.R, color.G, color.B);

}

public int GetInt32(byte value)

{

var (r, g, b) = GetRGB(value);

return 255 << 24 | r << 16 | g << 8 | b;

}

public int GetInt32(double fraction)

{

var (r, g, b) = GetRGB(fraction);

return 255 << 24 | r << 16 | g << 8 | b;

}

public SKColor GetColor(byte value)

{

var color = GetInt32(value);

return new SKColor((uint)color);

}

public SKColor GetColor(double fraction)

{

var color = GetInt32(fraction);

return new SKColor((uint)color);

}

public SKBitmap ApplyFilter(SKBitmap bmp)

{

SKImageInfo info = new(bmp.Width, bmp.Height, SKColorType.Rgba8888);

SKBitmap newBitmap = new(info);

using SKCanvas canvas = new(newBitmap);

canvas.Clear();

using SKPaint paint = new SKPaint();

byte[] A = new byte[256];

byte[] R = new byte[256];

byte[] G = new byte[256];

byte[] B = new byte[256];

for (int i = 0; i < 256; i++)

{

var color = GetColor((byte)i);

A[i] = color.Alpha;

R[i] = color.Red;

G[i] = color.Green;

B[i] = color.Blue;

}

paint.ColorFilter = SKColorFilter.CreateTable(A, R, G, B);

canvas.DrawBitmap(bmp, 0, 0, paint);

return newBitmap;

}

}