/*
 * #%L
 * digilib measure plugin
 * %%
 * Copyright (C) 2012 - 2014 Bibliotheca Hertziana, MPIWG Berlin
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as 
 * published by the Free Software Foundation, either version 3 of the 
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public 
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/lgpl-3.0.html>.
 * #L%
 * Authors: Martin Raspe, Robert Casties, 2012-2014
 */
/**
 * digilib measure plugin (measure distances on the digilib image in historic units etc.)
**/ 

/* jslint browser: true, debug: true, forin: true
*/

(function($) {

    // the digilib object
    var digilib = null;
    // the normal zoom area
    var FULL_AREA = null;

    // the functions made available by digilib
    var fn = {
        // dummy function to avoid errors, gets overwritten by buttons plugin
        highlightButtons : function () {
            console.debug('measure: dummy function - highlightButtons');
            }
        };
    // affine geometry plugin
    var geom = null;
    // convenience variable, set in init()
    var CSS = '';

    var UNITS = {
        comment : [
          "Angaben nach:",
          "Klimpert, Richard: Lexikon der Münzen, Maße, Gewichte, Zählarten und Zeitgrößen aller Länder der Erde 2) Berlin 1896 (Reprint Graz 1972)",
          "Doursther, Horace: Dictionnaire universel des poids et mesures anciens et modernes. Paris 1840 (Reprint Amsterdam 1965)"
          ],
        sections : [{
            name  : "Längenmaße: metrisch",
            group  : "1",
            units  : [{
				name : "m",
				factor : "1"
				},
				{
				name : "mm",
				factor : "0.001"
				},
				{
				name : "cm",
				factor : "0.01"
				},
				{
				name : "dm",
				factor : "0.1"
				},
				{
				name : "km",
				factor : "1000"
				}]
            },
            {
            name  : "Längenmaße: nautisch",
            group  : "1",
            units  : [{
				name : "geographische Meile",
				factor : "7420"
				},
				{
				name : "Seemeile",
				factor : "1854.965"
				},
				{
				name : "fathom",
				factor : "1.828782"
				},
				{
				name : "cable",
				factor : "182.8782"
				},
				{
				name : "league",
				factor : "5564.895"
				}]
            },
            {
            name  : "Längenmaße: England",
            group  : "1",
            units  : [{
				name : "foot",
				factor : "0.304797",
				subunits : "12"
				},
				{
				name : "inch",
				factor : "0.02539975"
				},
				{
				name : "yard",
				factor : "0.914391",
				subunits : "3"
				},
				{
				name : "pole",
				factor : "5.0291505",
				subunits : "11"
				},
				{
				name : "chain",
				factor : "20.116602",
				subunits : "4"
				},
				{
				name : "furlong",
				factor : "201.16602"
				},
				{
				name : "mile",
				factor : "1609.32816",
				subunits : "8"
				}]
            },
            {
            name  : "Längenmaße: Italien",
            group  : "1",
            units  : [{
				name : "palmo d'architetto (Rom)",
				factor : "0.223425",
				subunits : "12"
				},
				{
				name : "braccio (Florenz)",
				factor : "0.5836"
				},
				{
				name : "braccio (Mailand)",
				factor : "0.5949"
				},
				{
				name : "canna d'architetto (Rom)",
				factor : "2.23425"
				},
				{
				name : "canna di commercio (Rom)",
				factor : "1.9920"
				},
				{
				name : "canna d'architetto (Florenz)",
				factor : "2.9180"
				},
				{
				name : "canna di commercio (Florenz)",
				factor : "2.3344"
				},
				{
				name : "canna (Neapel)",
				factor : "2.0961"
				},
				{
				name : "miglio (Lombardei)",
				factor : "1784.808"
				},
				{
				name : "miglio (Neapel)",
				factor : "1855.110"
				},
				{
				name : "miglio (Rom)",
				factor : "1489.50"
				},
				{
				name : "minuta (Rom)",
				factor : "0.00372375"
				},
				{
				name : "oncia (Rom)",
				factor : "0.01861875"
				},
				{
				name : "oncia (Mailand)",
				factor : "0.49575"
				},
				{
				name : "palmo di commercio (Rom)",
				factor : "0.249"
				},
				{
				name : "palmo (Florenz)",
				factor : "0.2918"
				},
				{
				name : "piede (Brescia)",
				factor : "0.471"
				},
				{
				name : "piede (Carrara)",
				factor : "0.2933"
				},
				{
				name : "piede (Como)",
				factor : "0.4512"
				},
				{
				name : "piede (Modena)",
				factor : "0.523048"
				},
				{
				name : "piede (Reggio Em.)",
				factor : "0.530898"
				},
				{
				name : "piede (Venedig)",
				factor : "0.347735"
				},
				{
				name : "piede (Vicenza)",
				factor : "0.3574"
				},
				{
				name : "piede (Verona)",
				factor : "0.3429"
				},
				{
				name : "piede (Rom)",
				factor : "0.297587"
				},
				{
				name : "piede Lombardo",
				factor : "0.435185"
				},
				{
				name : "piede liprando (Turin)",
				factor : "0.51377"
				},
				{
				name : "piede manuale (Turin)",
				factor : "0.342511"
				},
				{
				name : "piede (Neapel, 'palmo')",
				factor : "0.26455"
				},
				{
				name : "soldo (Florenz)",
				factor : "0.2918"
				},
				{
				name : "trabucco piemontese (Turin)",
				factor : "3.08259"
				}]
            },
            {
            name  : "Längenmaße: Niederlande",
            group  : "1",
            units  : [{
				name : "voet (Amsterdam)",
				factor : "0.283113"
				},
				{
				name : "voet (Antwerpen)",
				factor : "0.2868"
				},
				{
				name : "voet (Aelst)",
				factor : "0.2772"
				},
				{
				name : "voet (Breda)",
				factor : "0.28413"
				},
				{
				name : "voet (Brügge)",
				factor : "0.27439"
				},
				{
				name : "voet (Brüssel)",
				factor : "0.2757503"
				},
				{
				name : "voet (Groningen)",
				factor : "0.2922"
				},
				{
				name : "voet (Haarlem)",
				factor : "0.2858"
				},
				{
				name : "voet (Kortrijk)",
				factor : "0.2977"
				},
				{
				name : "voet (Tournai)",
				factor : "0.2977"
				},
				{
				name : "voet (Utrecht)",
				factor : "0.2683"
				},
				{
				name : "voet (Ypern)",
				factor : "0.2739"
				},
				{
				name : "pied (Hainaut)",
				factor : "0.2934"
				},
				{
				name : "pied St. Hubert (Lüttich)",
				factor : "0.294698"
				},
				{
				name : "pied St. Lambert (Lüttich)",
				factor : "0.291796"
				},
				{
				name : "pied Ste. Gertrude (Nivelles)",
				factor : "0.27709"
				},
				{
				name : "steenvoet (Oudenaerde)",
				factor : "0.2977"
				},
				{
				name : "houtvoet (Oudenaerde)",
				factor : "0.292"
				}]
            },
            {
            name  : "Längenmaße: Frankreich",
            group  : "1",
            units  : [{
				name : "pied du Roi (Paris)",
				factor : "0.32483938497"
				},
				{
				name : "pied (Arras)",
				factor : "0.29777"
				},
				{
				name : "pied (Cambrai)",
				factor : "0.29777"
				},
				{
				name : "Burgundischer Fuß",
				factor : "0.33212"
				}]
            },
            {
            name  : "Längenmaße: Südeuropa",
            group  : "1",
            units  : [{
				name : "pié de Burgos (Spanien)",
				factor : "0.278635"
				},
				{
				name : "pé (Portugal)",
				factor : "0.33"
				}]
            },
            {
            name  : "Längenmaße: deutschspr. Länder",
            group  : "1",
            units  : [{
				name : "Fuß (Basel)",
				factor : "0.29820"
				},
				{
				name : "Fuß (Bayern)",
				factor : "0.2918592"
				},
				{
				name : "Fuß (Braunschweig)",
				factor : "0.2853624"
				},
				{
				name : "Fuß (Gotha)",
				factor : "0.287622"
				},
				{
				name : "Fuß (Hamburg)",
				factor : "0.286575"
				},
				{
				name : "Fuß (Hessen)",
				factor : "0.287669"
				},
				{
				name : "Fuß (Köln)",
				factor : "0.2876"
				},
				{
				name : "Fuß (Mecklenburg)",
				factor : "0.291006"
				},
				{
				name : "Fuß (Münster)",
				factor : "0.2908"
				},
				{
				name : "Fuß (Pommern)",
				factor : "0.2921"
				},
				{
				name : "Fuß (rheinisch)",
				factor : "0.3138535"
				},
				{
				name : "Fuß (Sachsen)",
				factor : "0.2831901"
				},
				{
				name : "Fuß (Preußen)",
				factor : "0.3138535"
				},
				{
				name : "Fuß (Wien)",
				factor : "0.3180807"
				},
				{
				name : "Fuß (Württemberg)",
				factor : "0.2864903"
				},
				{
				name : "Werkschuh (Frankfurt)",
				factor : "0.2846143"
				},
				{
				name : "Meile (Preußen)",
				factor : "7532.485"
				},
				{
				name : "Postmeile (Österreich)",
				factor : "7585.937"
				},
				{
				name : "Dezimalfuß (Preußen)",
				factor : "0.3766242"
				}]
            },
            {
            name  : "Längenmaße: Osteuropa",
            group  : "1",
            units  : [{
				name : "Fuß (Böhmen)",
				factor : "0.2964"
				},
				{
				name : "Fuß (Mähren)",
				factor : "0.29596"
				},
				{
				name : "stopa (Krakauer Fuß)",
				factor : "0.3564"
				},
				{
				name : "stopa (Warschauer Fuß)",
				factor : "0.288"
				},
				{
				name : "Fuß (Rußland)",
				factor : "0.3556"
				},
				{
				name : "arschin",
				factor : "0.7112"
				},
				{
				name : "saschen (Faden)",
				factor : "2.133"
				},
				{
				name : "werst",
				factor : "1066.8"
				},
				{
				name : "milja",
				factor : "7468"
				}]
            },
            {
            name  : "Längenmaße: Antike",
            group  : "1",
            units  : [{
				name : "pes romanus",
				factor : "0.2945"
				},
				{
				name : "pollex (Zoll)",
				factor : "0.0245416667"
				},
				{
				name : "digitus (Fingerbreite)",
				factor : "0.01840625"
				},
				{
				name : "palmus (Handbreite)",
				factor : "0.073625"
				},
				{
				name : "cubitus (Elle)",
				factor : "0.44175"
				},
				{
				name : "passus (Doppelschritt)",
				factor : "1.4725"
				},
				{
				name : "pertica",
				factor : "2.945"
				},
				{
				name : "actus",
				factor : "35.34"
				},
				{
				name : "mille passus (Meile)",
				factor : "1472.5"
				},
				{
				name : "stadium (600 Fuß)",
				factor : "176.7"
				},
				{
				name : "stadium (1/8 Meile)",
				factor : "184.0625"
				},
				{
				name : "stadion (Olympia)",
				factor : "192.25"
				},
				{
				name : "Fuß (attisch)",
				factor : "0.308"
				},
				{
				name : "Fuß (Babylon)",
				factor : "0.35"
				},
				{
				name : "Fuß (Delphi)",
				factor : "0.1848"
				},
				{
				name : "Fuß (Olympia)",
				factor : "0.32041667"
				}]
            },
            {
            name  : "Fläche",
            group  : "4",
            units  : [{
				name : "qm",
				factor : "1"
				},
				{
				name : "qmm",
				factor : "0.000001"
				},
				{
				name : "qcm",
				factor : "0.0001"
				},
				{
				name : "qdm",
				factor : "0.01"
				},
				{
				name : "Ar",
				factor : "100"
				},
				{
				name : "Morgen",
				factor : "2500"
				},
				{
				name : "Hektar",
				factor : "10000"
				},
				{
				name : "qkm",
				factor : "1000000"
				},
				{
				name : "square inch",
				factor : "0.0006452"
				},
				{
				name : "square foot",
				factor : "0.09288"
				},
				{
				name : "square yard",
				factor : "0.836",
				subunits : "9"
				},
				{
				name : "pole (rod, perch)",
				factor : "25.289"
				},
				{
				name : "rood",
				factor : "1012",
				subunits : "40"
				},
				{
				name : "acre",
				factor : "4048",
				subunits : "4"
				},
				{
				name : "square mile",
				factor : "2590000"
				}]
            },
            {
            name  : "Sonstige",
            group  : "0",
            units  : [{
				name : "Maßstab 1:200",
				factor : "200"
				},
				{
				name : "Maßstab",
				factor : "1:100",
				add : "100"
				},
				{
				name : "Maßstab 1:75",
				factor : "75"
				},
				{
				name : "Maßstab 1:60",
				factor : "60"
				},
				{
				name : "Maßstab",
				factor : "1:50",
				add : "50"
				},
				{
				name : "Maßstab 1:25",
				factor : "25"
				},
				{
				name : "Maßstab 1:20",
				factor : "20"
				},
				{
				name : "Maßstab 1:10",
				factor : "10"
				},
				{
				name : "Maßstab 1:5",
				factor : "5"
				},
				{
				name : "Maßstab 1:3",
				factor : "3"
				}]
          }]
        };
    var buttons = {
        measure : {
            onclick : "measurebar",
            tooltip : "show the measuring toolbar",
            icon : "measure.png"
            },
        drawshape : {
            onclick : "drawshape",
            tooltip : "draw a shape",
            }
        };

    var defaults = {
        // buttonset of this plugin
        measureButtonSet : ['measurebar'],
        // unit data
        units : UNITS,
        // choice of colors offered by measure bar
        lineColors : ['white', 'red', 'orange', 'yellow', 'green', 'cyan', 'blue', 'violet', 'black'],
        // default color
        lineColor : 'red',
        // color while the line is drawn
        drawColor : 'green',
        // color of selected objects
        selectColor : 'red',
        // drawing shape types
        shapeTypes : [
            { name : 'line', type : 'Line' },
            { name : 'polyline', type : 'Polygon' },
            { name : 'rectangle', type : 'Rectangle' },
            { name : 'square', type : 'Square' },
            { name : 'circle', type : 'Circle' },
            { name : 'arch', type : 'Arch' },
            { name : 'ratio', type : 'Ratio' },
            { name : 'intercolumnium', type : 'InterCol' },
            { name : 'line grid', type : 'Grid' }
            ],
        // index of default shape
        selectedShape : 0,
        // measuring unit (index into unit list)
        unitFrom : 1,
        // converted unit (index into unit list)
        unitTo : 2,
        // maximal denominator for mixed fractions
        maxDenominator : 20,
        // number of decimal places for convert results
        maxDecimals : 3,
        // show convert result as mixed fraction?
        showMixedFraction : false,
        // show angle relative to last line?
        showRelativeAngle : false,
        // show distance numbers?
        showDistanceNumbers : true,
        // show ratio of rectangle sides?
        showRectangleRatios : false,
        // draw line ends as small crosses
        drawEndPoints : true,
        // draw mid points of lines
        drawMidPoints : false,
        // draw circle centers
        drawCenters : false,
        // draw rectangles from the diagonal and one point
        drawFromDiagonal : false,
        // draw circles from center
        drawFromCenter : false,
        // snap to endpoints
        snapEndPoints : false,
        // snap to mid points of lines
        snapMidPoints : false,
        // snap to circle centers
        snapCenters : false,
        // snap distance (in screen pixels)
        snapDistance : 5,
        // keep original object when moving/scaling/rotating
        keepOriginal : false,
        // number of copies when drawing grids
        gridCopies : 10
        };

    var actions = {
        measurebar : function(data) {
            var $measureBar = data.$measureBar;
            if (!$measureBar) {
                $measureBar = setupMeasureBar(data);
				};
			$measureBar.toggle();
            setScreenPosition(data, $measureBar);
			return;
            },
        drawshape : function(data) {
            var shape = currentShape(data);
            data.measureWidgets.startb.addClass('dl-drawing');
            digilib.actions.addShape(data, shape, shapeCompleted);
            console.debug('action: drawshape', shape);
            }
        };


    // round to 4 decimal places after point
    var mRound = function (num) {
        return Math.round(num * 10000 + 0.00001) / 10000
        };

    // callback for vector.drawshape
    var shapeCompleted = function(data, shape) {
        console.debug('shapeCompleted', shape);
        data.measureWidgets.startb.removeClass('dl-drawing');
        if (shape == null || shape.geometry.coordinates == null) {
            return false; // do nothing if no line was produced
            };
        var $data = $(data);
        $data.on('changeShape', onChangeShape);
        $data.trigger('changeShape', shape); // update
        return false;
        };

    // event handler for changeShape
    var onChangeShape = function(event, shape) {
        var data = this;
        console.debug('onChangeShape', data, shape);
        var dist = rectifiedDist(data, shape);
        updateLength(data, dist);
        };

    // calculate a rectified distance from a shape with digilib coords
    var rectifiedDist = function(data, shape) {
        var coords = shape.geometry.coordinates;
        var p0 = geom.position(coords[0]);
        var p1 = geom.position(coords[1]);
        var dist = fn.getDistance(data, p0, p1);
        return dist.rectified;
        };

    // recalculate units
    var updateUnits = function(data) {
        var val = data.lastMeasuredValue;
        var widgets = data.measureWidgets;
        var u1 = parseFloat(widgets.unit1.val());
        var u2 = parseFloat(widgets.unit2.val());
        var v2 = val * u1 / u2;
        widgets.value2.val(fn.cropFloatStr(mRound(v2)));
        }

    // recalculate after measuring
    var updateLength = function(data, dist) {
        var widgets = data.measureWidgets;
        var fac = data.lastMeasureFactor;
        var val = dist * fac;
        widgets.len.text(fn.cropFloatStr(dist));
        widgets.value1.val(fn.cropFloatStr(mRound(val)));
        data.lastMeasuredValue = val;
        data.lastMeasuredDistance = dist;
        updateUnits(data);
        };

    // recalculate factor after entering a new value in input element "value1"
    var updateFactor = function(data) {
        var widgets = data.measureWidgets;
        var val = parseFloat(widgets.value1.val());
        var dist = data.lastMeasuredDistance;
        var fac = val / dist;
        widgets.fac.text(fn.cropFloatStr(fac));
        data.lastMeasureFactor = fac;

        data.lastMeasuredValue = val;
        updateUnits(data);
        };

    // return a shape of the currently selected shape type
    var currentShape = function(data) {
        var shape = getSelectedShapeType(data);
        var stroke = getSelectedStroke(data);
        var item = {
            geometry : {
                type : shape.type
                },
            properties : {
                stroke : stroke,
                editable : true
                }
            };
        return item;
        };

    // return shape type selected by user (on the toolbar)
    var getSelectedShapeType = function(data) {
        var val = data.measureWidgets.shape.val();
        return data.settings.shapeTypes[val];
    };

    // return line color chosen by user
    var getSelectedStroke = function(data) {
        // TODO: colorpicker
        return data.settings.linecolor;
    };

    // load shapes into select element
    var loadShapeTypes = function(data) {
        var $shape = data.measureWidgets.shape;
        $.each(data.settings.shapeTypes, function(index, item) {
            var $opt = $('<option value="'+ index + '">' + item.name + '</option>');
            $shape.append($opt);
            });
        $shape.children(':not(:disabled)')[data.settings.selectedShape].selected = true;
    };

    // load units into select elements
    var loadSections = function(data) {
        var widgets = data.measureWidgets;
        var $u1 = widgets.unit1;
        var $u2 = widgets.unit2;
        var sections = data.settings.units.sections;
        $.each(sections, function(index, section) {
            var $opt = $('<option class="dl-section" disabled="disabled">'+ section.name +'</option>');
            $u1.append($opt);
            $u2.append($opt.clone());
            $.each(section.units, function(index, unit) {
				var $opt = $('<option class="dl-units" value="'+ unit.factor + '">'+ unit.name + '</option>');
				$opt.data('unit', unit);
				$u1.append($opt);
				$u2.append($opt.clone());
				});
            });
        $u1.children(':not(:disabled)')[data.settings.unitFrom].selected = true;
        $u2.children(':not(:disabled)')[data.settings.unitTo].selected = true;
    };

    // initial position of measure bar (bottom left of browser window)
    var setScreenPosition = function(data, $div) {
        if ($div == null) return;
        var h = geom.rectangle($div).height;
        var s = fn.getFullscreenRect(data);
        geom.position(0, s.height - h).adjustDiv($div);
    };

    // drag measureBar around
    var dragMeasureBar = function(event) {
        var $div = $(this).parent();
        var x = $div.offset().left - event.pageX;
        var y = $div.offset().top - event.pageY;
        $(document.body).on('mousemove.measure', function(event) {
            $div.offset({
                left : event.pageX + x,
                top  : event.pageY + y
            });
        }).on('mouseup.measure', function(event) {
            $(document.body).off('mousemove.measure').off('mouseup.measure');
            });
        return false;
        };

    // setup a div for accessing the measure functionality
    var setupMeasureBar = function(data) {
        console.debug('measure: setupMeasureBar');
        var widgets = {
            names : [
                'move', 'startb', 'shape',
                'lenlabel', 'len',
                'eq1', 'value1', 'unit1',
                'eq2', 'value2', 'unit2'
                ],
            move : $('<img id="dl-measure-move" src="img/move.png" title="move measuring bar around the screen"></img>'),
            startb : $('<button id="dl-measure-startb" title="click to draw a measuring shape on top of the image">M</button>'),
            shape : $('<select id="dl-measure-shape" title="select a shape to use for measuring" />'),
			lenlabel : $('<span class="dl-measure-label" >len</span>'),
			faclabel : $('<span class="dl-measure-label" >factor</span>'),
			eq1 : $('<span class="dl-measure-label">=</span>'),
			eq2 : $('<span class="dl-measure-label">=</span>'),
			len : $('<span id="dl-measure-len" class="dl-measure-number">0.0</span>'),
			fac : $('<span id="dl-measure-factor" class="dl-measure-number" />'),
			value1 : $('<input id="dl-measure-value1" class="dl-measure-input" title="value of the last measured distance - click to change the value" value="0.0" />'),
			value2 : $('<input id="dl-measure-value2" class="dl-measure-input" title="value of the last measured distance, converted to the secondary unit" value="0.0"/>'),
			unit1 : $('<select id="dl-measure-unit1" title="current measuring unit - click to change" />'),
			unit2 : $('<select id="dl-measure-unit2" title="secondary measuring unit - click to change" />'),
			angle : $('<span id="dl-measure-angle" class="dl-measure-number" title="last measured angle" />')
		    };
        var $measureBar = $('<div id="dl-measure-toolbar" />');
        $.each(widgets.names, function(index, item) {
            $measureBar.append(widgets[item]);
            });
        data.$elem.append($measureBar);
        data.$measureBar = $measureBar;
        widgets.fac.text(fn.cropFloatStr(data.lastMeasureFactor));
        data.measureWidgets = widgets;

        loadShapeTypes(data);
        loadSections(data);
        setupMeasureWidgets(data);
        widgets.move.on('mousedown.measure', dragMeasureBar);
        return $measureBar;
        };

    // wire the draw button
    var setupMeasureWidgets = function (data) {
        console.debug('measure: setupMeasureWidgets');
        var widgets = data.measureWidgets;
        var $startb = widgets.startb;
        var buttonConfig = buttons['drawshape']; // not in data.settings.buttons
        // button properties
        var action = buttonConfig.onclick;
        var tooltip = buttonConfig.tooltip;
        $startb.attr('title', tooltip);
        $elem = data.$elem;
        $startb.on('mousedown.measure', function(evt) {
            // prevent mousedown event ot bubble up to measureBar (no dragging!)
            console.debug('mousedown=', action, ' evt=', evt);
            $elem.digilib(action);
            return false;
            });
        widgets.value1.on('change.measure', function(evt) { updateFactor(data) });
        widgets.unit1.on('change.measure', function(evt) { updateUnits(data) });
        widgets.unit2.on('change.measure', function(evt) { updateUnits(data) });
        };

    // event handler
    var handleSetup = function (evt) {
        console.debug("measure: handleSetup");
        var data = this;
        data.lastMeasuredDistance = 0;
        data.lastMeasuredValue = 0;
        data.lastMeasuredAngle = 0;
        data.lastMeasureFactor = 1.0,
        setupMeasureBar(data);
        };

    // event handler
    var handleUpdate = function (evt) {
        var data = this;
        console.debug("measure: handleUpdate");
        };

    // plugin installation called by digilib on plugin object.
    var install = function (plugin) {
        digilib = plugin;
        if (digilib.plugins.vector == null) {
            console.debug('measure plugin: vector plugin is missing, aborting installation.');
            return;
            }
        console.debug('installing measure plugin. digilib:', digilib);
        fn = digilib.fn;
        // import geometry classes
        geom = fn.geometry;
        // add defaults, actions, buttons
        $.extend(true, digilib.defaults, defaults);
        $.extend(digilib.actions, actions);
        $.extend(true, digilib.buttons, buttons);
        // insert in button list -- not elegant
        if (digilib.plugins.buttons != null) {
            // if (digilib.defaults.buttonSettings != null) {
            digilib.defaults.buttonSettings.fullscreen.standardSet.splice(10, 0, 'measure');
            }
        // export functions
        // fn.test = test;
        };

    // plugin initialization
    var init = function (data) {
        console.debug('initialising measure plugin. data:', data);
        var settings = data.settings;
        CSS = settings.cssPrefix;
        FULL_AREA  = geom.rectangle(0, 0, 1, 1);
        // install event handlers
        var $data = $(data);
        $data.on('setup', handleSetup);
        $data.on('update', handleUpdate);
        };

    // plugin object with name and init
    // shared objects filled by digilib on registration
    var pluginProperties = {
            name : 'measure',
            install : install,
            init : init,
            buttons : {},
            actions : {},
            fn : {},
            plugins : {}
        };

    if ($.fn.digilib == null) {
        $.error("jquery.digilib.measure must be loaded after jquery.digilib!");
    } else {
        $.fn.digilib('plugin', pluginProperties);
    }
})(jQuery);