Pointless Program: BMOS v0.1 (CURRENT v1.3)

[Frank]

BMOS - BitMap to OnlineSequencer v0.1 - Open Beta

Code:

function bytesToInt(array, start, end) {
   var result = 0;
   for (i = end - 1; i >= start; i--) {
       result = result * 256 + array[i];
   }
   return result;
}

function nearestInstrument(color) {
   //var RGBColor = color.length == 4 ? color.slice(0, 3).map(x => x * color[3] / 255) : color;
   var RGBColor = color.slice(0, 3);
   var result;
   var smallest = Infinity;
   for (i = 0; i < settings.numInstruments; i++) {
       var difference = 0;
       for (j = 0; j < 3; j++) {
           difference += (settings.instrumentColors[i][j] - RGBColor[j]) ** 2;
       }
       if (smallest > difference) {
           smallest = difference;
           result = i;
       }
   }
   return result;
}

function drawBMP() {
   SequencerView.fastGraphics = true;
   //$.get(url, function (r) {
   const fileData = JSON.parse('[' + localStorage.fileData + ']');
   //const fileData = (new TextEncoder()).encode(r);
   const imageDataOffset = bytesToInt(fileData, 10, 14);
   const DIBLength = bytesToInt(fileData, 14, 18);
   if (DIBLength != 40) {
       return 'Not Supported: DIB: ' + DIBLength;
   }
   const width = bytesToInt(fileData, 18, 22);
   const height = bytesToInt(fileData, 22, 26);
   const heightStretch = (height - height % 72) / 72 + 1;
   const bitsPerPixel = bytesToInt(fileData, 28, 30);
   const compression = bytesToInt(fileData, 30, 34);
   if (compression != 0) {
       return 'Not Supported: Compression: ' + compression;
   }
   //var colors = bytesToInt(fileData, 44, 48);
   colorPalette = [];
   for (var i = 54; i < imageDataOffset; i += 4) {
       colorPalette.push(fileData.slice(i, i + 4));
   }
   instrumentPalette = colorPalette.length ? [] : false;
   if (instrumentPalette.length === 0) {
       for (var color in colorPalette) {
           instrumentPalette.push(nearestInstrument(colorPalette[color]));
       }
       const imageData = fileData.slice(imageDataOffset);
       const jDefault = 256 / 2 ** bitsPerPixel,
           jDevide = 2 ** bitsPerPixel;
       var i = 0,
           j = jDefault;
       for (var h = height - 1; h > -1; h--) {
           if (typeof piano[h / heightStretch] !== 'undefined') {
               for (var w = 0; w < width; w++) {
                   song.addNote(new Note(song, piano[h / heightStretch], w, 1, instrumentPalette[((imageData[i] & (256 - j)) / j) % jDevide]));
                   j /= jDevide;
                   if (j < 1 || w == width - 1) {
                       j = jDefault;
                       i++;
                   }
               }
           }
       }
       for (var x in instrumentPalette) {
           audioSystem.setInstrumentVolume(instrumentPalette[x], 0);
       };
   } else {
       const imageData = fileData.slice(imageDataOffset);
       var i = 0;
       for (var h = height - 1; h > -1; h--) {
           if (typeof piano[h / heightStretch] !== 'undefined') {
               for (var w = 0; w < width; w++) {
                   song.addNote(new Note(song, piano[h / heightStretch], w, 1, nearestInstrument(imageData.slice(i, i +
                       bitsPerPixel / 8))));
                   i += bitsPerPixel / 8;
               }
               //i += 8 - (i % 8);
           }
       }
       for (var x = 0; x < settings.numInstruments; x++) {
           audioSystem.setInstrumentVolume(x, 0);
       };
   }
   //})
}

##868861##868963
##869246##869632
This is completely pointless, why am I doing this...
"Fork" this in the comments if you feel like a challenge, I made the code super easy to read compared to my other stuff.
UPDATED CODE (v1.3)

Code:

function nearestInstrument(color) {
   RGBColor = color.slice(0, 3).map(x => x * color[3] / 255);
   var result;
   var smallest = Infinity;
   for (i = 0; i < 40; i++) {
       var difference = 0;
       for (j = 0; j < 3; j++) {
           difference += (settings.instrumentColors[i][j] - RGBColor[j]) ** 2;
       }
       if (smallest > difference) {
           smallest = difference;
           result = i;
       }
   }
   return result;
}

function drawImg(source) {
   var img = new Image();
   img.src = source;
   img.onload = function() {
       canvas.width = 100;
       canvas.height = 50;
       canvas.getContext('2d').drawImage(img, 0, 0, canvas.width, canvas.height);
       var total = ':';
       for (var h = canvas.height - 1; h > -1; h--) {
           for (var w = 0; w < canvas.width; w++) {
                var instrument = nearestInstrument(canvas.getContext('2d').getImageData(w, h, 1, 1).data);
                if (instrument != 37) total += [w, piano50[h], 1, instrument].join(' ') + ';';
           }
       }
       if (window.SequencerView) {
           SequencerView.fastGraphics = true;
           loadData(total);
           $.each(audioSystem.instrumentVolume, x => audioSystem.setInstrumentVolume(x, 0));
       } else {
           console.log(total);
       }
   }
}

var piano50 = ["A6", "G#6", "G6", "F#6", "F6", "E6", "D#6", "D6", "C#6", "C6", "B5", "A#5", "A5", "G#5", "G5", "F#5", "F5", "E5", "D#5", "D5", "C#5", "C5", "B4", "A#4", "A4", "G#4", "G4", "F#4", "F4", "E4", "D#4", "D4", "C#4", "C4", "B3", "A#3", "A3", "G#3", "G3", "F#3", "F3", "E3", "D#3", "D3", "C#3", "C3", "B2", "A#2", "A2", "G#2"];
var settings = {instrumentColors: [[3,169,244],[255,152,0],[183,28,28],[233,30,99],[76,175,80],[33,33,33],[63,81,181],[205,220,57],[21,101,192],[130,119,23],[255,234,0],[141,110,99],[78,52,46],[255,99,99],[117,255,99],[99,224,255],[253,99,255],[255,87,34],[27,94,32],[244,67,54],[255,224,178],[117,117,117],[224,173,0],[233,249,189],[168,200,83],[13,71,161],[29,157,157],[30,197,122],[21,33,79],[5,16,47],[108,243,183],[255,112,112],[161,166,53],[234,121,0],[85,202,202],[0,128,64],[127,32,15],[0,0,0],[0,69,31],[159,15,34]]}
var canvas = document.createElement('canvas');
drawImg(document.URL);