// namespaces
var dwvOemr = dwvOemr || {};
dwvOemr.gui = dwvOemr.gui || {};
dwvOemr.gui.info = dwvOemr.gui.info || {};

/**
 * MiniColourMap info layer.
 * @constructor
 * @param {Object} div The HTML element to add colourMap info to.
 * @param {Object} app The associated application.
 */
dwvOemr.gui.info.MiniColourMap = function ( div, app )
{
    /**
     * Create the mini colour map info div.
     */
    this.create = function ()
    {
        // clean div
        var elems = div.getElementsByClassName("colour-map-info");
        if ( elems.length !== 0 ) {
            dwvOemr.html.removeNodes(elems);
        }
        // colour map
        var canvas = document.createElement("canvas");
        canvas.className = "colour-map-info";
        canvas.width = 98;
        canvas.height = 10;
        // add canvas to div
        div.appendChild(canvas);
    };

    /**
     * Update the mini colour map info div.
     * @param {Object} event The windowing change event containing the new values.
     * Warning: expects the mini colour map div to exist (use after createMiniColourMap).
     */
    this.update = function (event)
    {
        var windowCenter = event.wc;
        var windowWidth = event.ww;
        // retrieve canvas and context
        var canvas = div.getElementsByClassName("colour-map-info")[0];
        var context = canvas.getContext('2d');
        // fill in the image data
        var colourMap = app.getViewController().getColourMap();
        var imageData = context.getImageData(0,0,canvas.width, canvas.height);
        // histogram sampling
        var c = 0;
        var minInt = app.getImage().getRescaledDataRange().min;
        var range = app.getImage().getRescaledDataRange().max - minInt;
        var incrC = range / canvas.width;
        // Y scale
        var y = 0;
        var yMax = 255;
        var yMin = 0;
        // X scale
        var xMin = windowCenter - 0.5 - (windowWidth-1) / 2;
        var xMax = windowCenter - 0.5 + (windowWidth-1) / 2;
        // loop through values
        var index;
        for ( var j = 0; j < canvas.height; ++j ) {
            c = minInt;
            for ( var i = 0; i < canvas.width; ++i ) {
                if ( c <= xMin ) {
                    y = yMin;
                }
                else if ( c > xMax ) {
                    y = yMax;
                }
                else {
                    y = ( (c - (windowCenter-0.5) ) / (windowWidth-1) + 0.5 ) *
                        (yMax-yMin) + yMin;
                    y = parseInt(y,10);
                }
                index = (i + j * canvas.width) * 4;
                imageData.data[index] = colourMap.red[y];
                imageData.data[index+1] = colourMap.green[y];
                imageData.data[index+2] = colourMap.blue[y];
                imageData.data[index+3] = 0xff;
                c += incrC;
            }
        }
        // put the image data in the context
        context.putImageData(imageData, 0, 0);
    };
}; // class dwvOemr.gui.info.MiniColourMap