gistfile1.js

var tempArrays = {};

function getArray(size) {
    var tmp = tempArrays[size];
    if (tmp) {
        return tmp;
    }
     tmp=tempArrays[size] = new Uint8ClampedArray(size * 4);

    for (var s = 0; s < size*4; s++) {
        tmp[s]=255;
    }

    return tmp;
}

var tempBArrays = {};

function getInt32Array(size) {
    var tmp = tempBArrays[size];
    if (tmp) {
        return tmp;
    }
    return tempBArrays[size] = new Uint32Array(size);
}

var tempCnvs = {};

function getCnv(width, height) {

    var s = (width + " " + height);
    var tempCnv = tempCnvs[s];
    if (tempCnv) {
        return tempCnv;
    }


    var newCanvas = document.createElement('canvas');
    newCanvas.width = width;
    newCanvas.height = height;
    var newContext = newCanvas.getContext('2d');

    newContext.mozImageSmoothingEnabled = false;
    newContext.webkitImageSmoothingEnabled = false;
    newContext.imageSmoothingEnabled = false; /// future

    return tempCnvs[s] = {
        canvas: newCanvas,
        context: newContext
    };
}


var posLookups={};
function getPosLookup(width, height) {
    var posLookup = posLookups[width * height];
    if(posLookup)return posLookup;

    var posLookup = posLookups[width * height]={
        left:new Uint32Array (width * height),
        right:new Uint32Array (width * height),
        top:new Uint32Array (width * height),
        bottom:new Uint32Array (width * height),
        middle:new Uint32Array (width * height)
    };
    var cc=0;

    for (var y = 0; y < height; y++) {
        for (var x = 0; x < width; x++) {


            posLookup.top[cc]= _top(x, y, width, height);
            posLookup.left[cc] = _left(x, y, width, height);
            posLookup.middle[cc] = ((y) * width + (x)) * 4;
            posLookup.right[cc] = _right(x, y, width, height);
            posLookup.bottom[cc] = _bottom(x, y, width, height);


            cc++;

        }
    }
    return posLookup
}



var colsLookups={};
function getColsLookup(imageData,width,height) {
    var cols = getInt32Array(width * height*4);
var pixels_=imageData;
    var cc=0;
    for (var y = 0; y < height; y++) {
        for (var x = 0; x < width; x++) {



            cols[cc]=(((pixels_[(y*width+x)*4] << 8) + pixels_[(y*width+x)*4 + 1]) << 8) + pixels_[(y*width+x)*4 + 2];


            cc+=4;

        }
    }
    return cols
}




window.scaleIt = function scaleMe(imageData,width,height) {
    var width2 = width * 2;
    var height2 = height * 2;
    var pixels2_ = getArray(width2 * height2);
    var cnv = getCnv(width2, height2);

    doPixelCompare(imageData, width, height, width2, height2, pixels2_,getPosLookup(width,height),getColsLookup(imageData,width,height));
    return pixels2_;
};
var imageDataCaches={};
function imageDataCache(canvas,width,height){
    var s = ((width ) + " " + (height ));
    if(imageDataCaches[ s]){
        return imageDataCaches[ s];
    }
    return imageDataCaches[ s]=canvas.createImageData(width,height);
};
window.scaleTwice = function scaleMe(canvas,x,y,width,height) {
var imageData=canvas.getImageData(x,y,width,height).data;
    imageData=window.scaleIt(imageData,width,height);
    imageData=window.scaleIt(imageData,width*2,height*2);
    var id=imageDataCache(canvas,width*2*2,height*2*2);
    id.data.set(imageData);


    var canvas=getCnv(id.width,id.height);
    canvas.context.putImageData(id,0,0);
    return canvas.canvas;
};


function _top(x, y, width, height) {
    if (y <= 0)
        return ((y ) * width + (x)) * 4;
    else
        return ((y - 1) * width + (x)) * 4;
}

function _left(x, y, width, height) {
    if (x <= 0)
        return ((y) * width + (x )) * 4;
    else
        return ((y) * width + (x - 1)) * 4;
}

function _right(x, y, width, height) {
    if (x + 1 >= width)
        return ((y) * width + (x)) * 4;
    else
        return ((y) * width + (x + 1)) * 4;
}

function _bottom(x, y, width, height) {
    if (y + 1 >= height)
        return ((y) * width + (x)) * 4;
    else
        return ((y + 1) * width + (x)) * 4;
}

function doPixelCompare(pixels_, width, height, width2, height2, pixels2_,posLookup,colsLookup) {

var cc=0;

    for (var y = 0; y < height; y++) {
    for (var x = 0; x < width; x++) {



            var Bid = posLookup.top[cc];
            var Did = posLookup.left[cc];
            var Eid = posLookup.middle[cc];
            var Fid = posLookup.right[cc];
            var Hid = posLookup.bottom[cc];


        cc++;


/*
        var B = (((pixels_[Bid] << 8) + pixels_[Bid + 1]) << 8) + pixels_[Bid + 2];
        var D = (((pixels_[Did] << 8) + pixels_[Did + 1]) << 8) + pixels_[Did + 2];
        var F = (((pixels_[Fid] << 8) + pixels_[Fid + 1]) << 8) + pixels_[Fid + 2];
        var H = (((pixels_[Hid] << 8) + pixels_[Hid + 1]) << 8) + pixels_[Hid + 2];
*/

        var B = colsLookup[Bid];
        var D = colsLookup[Did];
        var F = colsLookup[Fid];
        var H = colsLookup[Hid];

        var E0, E1, E2, E3;
            if (B !== (H) && D !== (F)) {
                E0 = D == (B) ? Did : Eid;
                E1 = B == (F) ? Fid : Eid;
                E2 = D == (H) ? Did : Eid;
                E3 = H == (F) ? Fid : Eid;
            } else {
                E0 = Eid;
                E1 = Eid;
                E2 = Eid;
                E3 = Eid;
            }


        var tl = (((y * 2) * width2 + (x * 2)) * 4);
        var tr = (((y * 2) * width2 + (x * 2 + 1)) * 4);
        var bl = (((y * 2 + 1) * width2 + (x * 2)) * 4);
        var br = (((y * 2 + 1) * width2 + (x * 2 + 1)) * 4);


        pixels2_[ tl ] = pixels_[E0 ];
        pixels2_[ tr ] = pixels_[E1 ];
        pixels2_[ bl ] = pixels_[E2];
        pixels2_[ br ] = pixels_[E3 ];


        pixels2_[tl + 1] = pixels_[E0 + 1];
        pixels2_[tr + 1] = pixels_[E1 + 1];
        pixels2_[bl + 1] = pixels_[E2 + 1];
        pixels2_[br +1] = pixels_[E3 + 1];


        pixels2_[tl + 2] = pixels_[E0 + 2];
        pixels2_[tr +2] = pixels_[E1 + 2];
        pixels2_[bl + 2] = pixels_[E2 + 2];
        pixels2_[br + 2] = pixels_[E3 + 2];



        }
    }

}