Histogram.cs

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Histogram {

    List<double> values = new List<double>();
    long[] bins;

    bool textureNeedsToBeRegenerated = true;
    bool needsToBeResorted = true;
    Texture2D texture;

    double binSize;
    double minValue = 0;
    double maxValue = 1;
    int numOfBins;
    long max = 0;

    public Histogram() {
    }

    public void addValue( double val )
    {
        values.Add (val);
        textureNeedsToBeRegenerated = true; // Texture needs to be re-generated.
        needsToBeResorted = true;   // Texture needs to be re-generated.
    }

    public Texture2D asTexture()
    {
        if (textureNeedsToBeRegenerated) {
            generateTexture ();
        }
        return texture;
    }

    public void setMinMaxPixelValues( float min, float max )
    {
        minValue = min;
        maxValue = max;
    }

    public void sortIntoBins( int numOfBins )
    {
        bins = new long[numOfBins];
        binSize = (maxValue - minValue)/(double)numOfBins;
        this.numOfBins = numOfBins;

        for (int i = 1; i < values.Count; i++) {
            if (values[i] < minValue || values[i] > maxValue)
                continue;
            int binIndex = (int)Math.Floor ((values[i] - minValue) / binSize + 0.5);
            if (binIndex >= 0 && binIndex < numOfBins)
                bins [binIndex]++;
        }

        // search the maximum value:
        max = 1;
        for (int i = 0; i < numOfBins; i++) {
            if (bins [i] > max)
                max = bins [i];
        }

        needsToBeResorted = false;
    }

    public void generateTexture()
    {
        if (needsToBeResorted)
            sortIntoBins (200);     // Default values

        int texHeight = 100;

        texture = new Texture2D (numOfBins, texHeight, TextureFormat.ARGB32, false, true);

        for (int i = 0; i < numOfBins; i++) {
            long height = (long)(texHeight-1) * bins [i] / max;
            //Debug.Log (i + " "  + bins [i]);
            if (bins [i] > 0 && height == 0)
                height = 1;
            for (int y = 0; y < height; y++)
                texture.SetPixel (i, y, Color.white);
            for (int y = (int)height; y < texHeight; y++) {
                texture.SetPixel (i, y, Color.black);
            }
        }
        texture.Apply ();
        textureNeedsToBeRegenerated = false;

        // Save to file for debugging purposes:
        /*byte[] bytes = texture.EncodeToPNG ();
        System.IO.File.WriteAllBytes ("histogram.png", bytes);*/
    }

}