Image converter version IDK

/*=============*\
|░ image thing ░|
\*=============*/setTimeout(function(){
function log(a){
    console.log("[] "+a); //just a thing so I can read the messages more easily
}
//variables
//var canvas=document.querySelector("#chatdraw canvas");
//canvas.width=300;
var z=new Image(); //best variable name (c) Trinitro 2016
var noise=0;
var isImage=false;
var elemX=0;
var elemY=0;
var offsetX,offsetY;
var moving=false;
var scale=1;
var colorButtons=document.querySelectorAll("#chatdraw button-area button.colorChange");
var paletteSize=colorButtons.length;
document.getElementById("colorPicker").addEventListener("change",()=>{updateImage()});
document.querySelector("#chatdraw button-area button").addEventListener("click",()=>{
    isImage=false;
    moveBoxParent.style.backgroundImage="";
    pc2d.clearRect(0,0,cW,cH);
});//✖ button
var canvas=document.querySelector("#chatdraw canvas");
var c2d=canvas.getContext("2d");
var cW=canvas.width,cH=canvas.height;
var cR=cW/cH;
var cM=Math.min(cW,cH);
//html stuff
var sidePane=document.querySelector("#sidepane");
//paste box
var pasteImageHere=document.createElement("div");
pasteImageHere.style.width="3.25rem";
pasteImageHere.contentEditable=true;
pasteImageHere.oninput=function(){
    var thing=this.getElementsByTagName("img")[0];
    if (thing) {
        loadImage(thing.src);
    }
    while (this.firstChild) this.removeChild(this.lastChild); //delete everything
};
document.querySelector("#sendpane").appendChild(pasteImageHere);
//file upload button
var fileBrowse=document.createElement("input");
fileBrowse.type="file";
fileBrowse.onchange=function(){
    log("User uploaded an image...");
    var reader=new FileReader();
    reader.readAsDataURL(this.files[0]);
    reader.onload=function(){loadImage(this.result)};
};
sidePane.appendChild(fileBrowse);
//dither slider
var ditherSlider=document.createElement("input");
ditherSlider.type="range";
ditherSlider.min="0";
ditherSlider.max="1";
ditherSlider.step="0.001";
ditherSlider.onchange=function(){
    updateImage();
};
sidePane.appendChild(ditherSlider);
//blurring checkbox
var blurring=document.createElement("input");
blurring.type="checkbox";
blurring.checked=true;
blurring.onchange=function(){
    c2d.webkitImageSmoothingEnabled=c2d.mozImageSmoothingEnabled=c2d.imageSmoothingEnabled=this.checked;
    pc2d.webkitImageSmoothingEnabled=pc2d.mozImageSmoothingEnabled=pc2d.imageSmoothingEnabled=this.checked;
    updateImage();
};
sidePane.appendChild(blurring);
//
var moveBoxParent=document.createElement("div");
moveBoxParent.style.width=cW+"px";
moveBoxParent.style.height=cH+"px";
moveBoxParent.style.backgroundSize="contain";
moveBoxParent.style.backgroundRepeat="no-repeat";
moveBoxParent.style.backgroundColor="white";
moveBoxParent.style.border="1px solid black";
moveBoxParent.onmousemove=function(e){
    if (moving){
        updateMoveBoxPos(e.pageX-offsetX,e.pageY-offsetY);
        updatePreview();
    }
};
moveBoxParent.onmouseup=moveBoxParent.onmouseleave=function(){
    moving=false;
    moveBox.style.cursor="grab";
    updateImage();
};
var updateImageTimeout;
var mouseSens=200;
moveBoxParent.onwheel=function(e){
    updateScale(scale+e.deltaY/mouseSens);
    updatePreview();
    window.clearTimeout(updateImageTimeout);
    updateImageTimeout=window.setTimeout(function(){updateImage();},mouseSens);
};
sidepane.appendChild(moveBoxParent);
var scaleSlider=document.createElement("input");
scaleSlider.type="range";
scaleSlider.min=0.0001;
scaleSlider.max=1;
scaleSlider.step=0.0001;
scaleSlider.value=1;
scaleSlider.oninput=function() {
    updateScale(this.value);
};
scaleSlider.onchange=function(){updateImage()};
sidepane.appendChild(scaleSlider);
var pCanvas=document.createElement("canvas");
pCanvas.width=cW;
pCanvas.height=cH;
//pCanvas.style.cursor="crosshair";//this cursor sucks...
pCanvas.style.backgroundColor="white";
pCanvas.style.border="1px solid black";
var pc2d=pCanvas.getContext("2d");
pCanvas.onclick=function(e){
    if (isImage){
        var rect=pCanvas.getBoundingClientRect();
        var x=Math.round(e.clientX-rect.left-1);
        var y=Math.round(e.clientY-rect.top-1);
        var pixel=pc2d.getImageData(x,y,1,1).data;
        if (pixel[3]==-0) pixel=[255,255,255,255];
        var button=document.querySelector('#chatdraw button-area button[data-selectedcolor="true"]');
        button.style.color=rgbToFillStyle(pixel);
        log(x+","+y+" "+pixel.join());
        updateImage();
    }
    return false;
};
sidePane.appendChild(pCanvas);
//
var moveBox=document.createElement("div");
//moveBox.style.backgroundColor="rgba(128,128,128,0.5)";
moveBox.style.position="relative";
moveBox.style.border="1px solid red";
moveBox.style.width=cW-2+"px";
moveBox.style.height=cH-2+"px";
moveBox.style.cursor="grab";
moveBox.onmousedown=function(e){
   moving=true;
   moveBox.style.cursor="grabbing";
   offsetX=e.pageX-elemX;
   offsetY=e.pageY-elemY;
};
moveBoxParent.appendChild(moveBox);
//more functions
function updateScale(newScale){
    var oldScale=scale;
    scale=Math.min(Math.max(newScale,0.001),1);
    midX=elemX+oldScale*cW/2;
    midY=elemY+oldScale*cH/2;
    updateMoveBoxPos(midX-scale*cW/2,midY-scale*cH/2);
    moveBox.style.width=scale*cW-2+"px";
    moveBox.style.height=scale*cH-2+"px";
    scaleSlider.value=scale;
    if (oldScale!=scale) updatePreview();
}
function updateMoveBoxPos(x,y){
    elemX=Math.min(Math.max(x,0),(1-scale)*cW);
    elemY=Math.min(Math.max(y,0),(1-scale)*cH);
    moveBox.style.left=elemX+"px";
    moveBox.style.top=elemY+"px";
}
function loadImage(source){
    log("Found an image. (assume load failed)");
    z=new Image();
    z.crossOrigin="Anonymous";
    z.onload=function(){
        log("Image loaded successfully!");
        moveBoxParent.style.backgroundImage="url('"+source+"')";
        isImage=true;
        updateImage();
    };
    z.src=source;
}
function updateImage(){
    if (isImage){
        updatePreview();
        putImage(z);
    }
}
function updatePreview(){
    if (isImage){
        pc2d.clearRect(0,0,cW,cH);
        var maxHeight=Math.max(z.width/cW,z.height/cH)*cM;
        pc2d.drawImage(z,elemX/cW*maxHeight*cR,elemY/cH*maxHeight,scale*maxHeight*cR,scale*maxHeight,0,0,cW,cH);
    }
}
//put image on canvas, and convert to 4 colors.
function putImage(img){
    var dither=ditherSlider.value;
    var i,palette=[];
    for(i=0;i<paletteSize;i++) palette.push(fillStyleToRgb(colorButtons[i].style.color));
    c2d.rect(0,0,cW,cH);c2d.fillStyle="white";c2d.fill(); //clear canvas
    var maxHeight=Math.max(img.width/cW,img.height/cH)*cM;
    c2d.drawImage(img,elemX/cW*maxHeight*cR,elemY/cH*maxHeight,scale*maxHeight*cR,scale*maxHeight,0,0,cW,cH);
    var data=c2d.getImageData(0,0,cW,cH);
    for(var x=0,bestIndex,nextErr;x<cW*cH*4;x+=4){
        if (noise) for (i=0;i<3;i++) data.data[x+i]+=Math.random()*noise-noise/2;
        //find the best color
        var bestDist=Infinity;
        for (i=0;i<paletteSize&&bestDist!==0;i++) {
            for (var j=0,dist=0,color=palette[i];j<3;j++) dist+=Math.abs(data.data[x+j]-color[j])*(1+(j==1));
            if (dist<bestDist){bestDist=dist;bestIndex=i}
        }
        //dithering
        if (dither){
            for (i=0;i<3;i++) {
                var err=(data.data[x+i]-palette[bestIndex][i])*dither/3;
                //if (err<0) nextErr=-err; else nextErr=0;
                data.data[x+i]=palette[bestIndex][i];
                data.data[x     +4+i]+=err;   // right
                data.data[x+cW*4-4+i]+=err/2; // bottom left
                data.data[x+cW*4  +i]+=err;   // bottom
                data.data[x+cW*4+4+i]+=err/2; // bottom right
            }
        } else for (i=0;i<3;i++) data.data[x+i]=palette[bestIndex][i];
    }
    c2d.putImageData(data,0,0);
    log("Image conversion sucessful.");
}
},2000);