se/SE/stuff/RGraph/libraries/RGraph.thermometer.js

    /**
    * o------------------------------------------------------------------------------o
    * | This file is part of the RGraph package - you can learn more at:             |
    * |                                                                              |
    * |                          http://www.rgraph.net                               |
    * |                                                                              |
    * | This package is licensed under the RGraph license. For all kinds of business |
    * | purposes there is a small one-time licensing fee to pay and for non          |
    * | commercial  purposes it is free to use. You can read the full license here:  |
    * |                                                                              |
    * |                      http://www.rgraph.net/LICENSE.txt                       |
    * o------------------------------------------------------------------------------o
    */

    if (typeof(RGraph) == 'undefined') RGraph = {};

    /**
    * The chart constructor. This function sets up the object. It takes the ID (the HTML attribute) of the canvas as the
    * first argument and the data as the second. If you need to change this, you can.
    * 
    * NB: If tooltips are ever implemented they must go below the use event listeners!!
    * 
    * @param string id    The canvas tag ID
    * @param number min   The minimum value
    * @param number max   The maximum value
    * @param number value The value reported by the thermometer
    */
    RGraph.Thermometer = function (id, min, max, value)
    {
        this.id                = id;
        this.canvas            = document.getElementById(typeof id === 'object' ? id.id : id);
        this.context           = this.canvas.getContext ? this.canvas.getContext("2d") : null;
        this.canvas.__object__ = this;
        this.uid               = RGraph.CreateUID();
        this.canvas.uid        = this.canvas.uid ? this.canvas.uid : RGraph.CreateUID();
        this.colorsParsed      = false;
        this.type              = 'thermometer';
        this.isRGraph          = true;
        this.min               = min;
        this.max               = max;
        this.value             = value;
        this.coords            = [];
        this.graphArea         = [];
        this.currentValue      = null;
        this.bulbRadius        = 0;
        this.bulbTopRadius     = 0;
        this.bulbTopCenterX    = 0
        this.bulbTopCenterY    = 0;
        this.coordsText        = [];

        RGraph.OldBrowserCompat(this.context);


        this.properties = {
            'chart.colors':                 ['Gradient(#c00:red:#f66:#fcc)'],
            'chart.gutter.left':            15,
            'chart.gutter.right':           15,
            'chart.gutter.top':             15,
            'chart.gutter.bottom':          15,
            'chart.ticksize':               5,
            'chart.text.color':             'black',
            'chart.text.font':              'Arial',
            'chart.text.size':              10,
            'chart.units.pre':              '',
            'chart.units.post':             '',
            'chart.zoom.factor':            1.5,
            'chart.zoom.fade.in':           true,
            'chart.zoom.fade.out':          true,
            'chart.zoom.hdir':              'right',
            'chart.zoom.vdir':              'down',
            'chart.zoom.frames':            25,
            'chart.zoom.delay':             16.666,
            'chart.zoom.shadow':            true,
            'chart.zoom.background':        true,
            'chart.title':                  '',
            'chart.title.side':             '',
            'chart.title.side.bold':        true,
            'chart.title.side.font':        null,
            'chart.shadow':                 true,
            'chart.shadow.offsetx':         0,
            'chart.shadow.offsety':         0,
            'chart.shadow.blur':            15,
            'chart.shadow.color':           'gray',
            'chart.resizable':              false,
            'chart.contextmenu':            null,
            'chart.adjustable':             false,
            'chart.value.label':            true,
            'chart.value.label.decimals':   null,
            'chart.value.label.thousand':   ',',
            'chart.value.label.point':      '.',
            'chart.labels.count':           5,
            'chart.scale.visible':          false,
            'chart.scale.decimals':         0,
            'chart.annotatable':            false,
            'chart.annotate.color':         'black',
            'chart.scale.decimals':         0,
            'chart.scale.point':            '.',
            'chart.scale.thousand':         ',',
            'chart.tooltips':               null,
            'chart.tooltips.highlight':     true,
            'chart.tooltips.effect':        'fade',
            'chart.tooltips.event':         'onclick',
            'chart.highlight.stroke':       'rgba(0,0,0,0)',
            'chart.highlight.fill':         'rgba(255,255,255,0.7)'
        }



        /**
        * A simple check that the browser has canvas support
        */
        if (!this.canvas) {
            alert('[THERMOMETER] No canvas support');
            return;
        }
        
        /**
        * The thermometer can only have one data point so only this.$0 needs to be created
        */
        this.$0 = {}


        /**
        * Translate half a pixel for antialiasing purposes - but only if it hasn't beeen
        * done already
        */
        if (!this.canvas.__rgraph_aa_translated__) {
            this.context.translate(0.5,0.5);
            
            this.canvas.__rgraph_aa_translated__ = true;
        }




        ///////////////////////////////// SHORT PROPERTIES /////////////////////////////////




        var RG   = RGraph;
        var ca   = this.canvas;
        var co   = ca.getContext('2d');
        var prop = this.properties;




        //////////////////////////////////// METHODS ///////////////////////////////////////




        /**
        * A setter.
        * 
        * @param name  string The name of the property to set
        * @param value mixed  The value of the property
        */
        this.Set = function (name, value)
        {
            /**
            * This should be done first - prepend the property name with "chart." if necessary
            */
            if (name.substr(0,6) != 'chart.') {
                name = 'chart.' + name;
            }
            
            /**
            * Change of name
            */
            if (name == 'chart.ylabels.count') {
                name = 'chart.labels.count';
            }
            
            prop[name.toLowerCase()] = value;
    
            return this;
        }




        /**
        * A getter.
        * 
        * @param name  string The name of the property to get
        */
        this.Get = function (name)
        {
            /**
            * This should be done first - prepend the property name with "chart." if necessary
            */
            if (name.substr(0,6) != 'chart.') {
                name = 'chart.' + name;
            }
    
            return prop[name];
        }
    
    
    
    
        /**
        * Draws the thermometer
        */
        this.Draw = function ()
        {
            /**
            * Fire the custom RGraph onbeforedraw event (which should be fired before the chart is drawn)
            */
            RG.FireCustomEvent(this, 'onbeforedraw');
    
            /**
            * Parse the colors. This allows for simple gradient syntax
            */
            if (!this.colorsParsed) {
                this.parseColors();
                
                // Don't want to do this again
                this.colorsParsed = true;
            }
    
            /**
            * Set the current value
            */
            this.currentValue = this.value;
            
            /**
            * This is new in May 2011 and facilitates indiviual gutter settings,
            * eg chart.gutter.left
            */
            this.gutterLeft   = prop['chart.gutter.left'];
            this.gutterRight  = prop['chart.gutter.right'];
            this.gutterTop    = prop['chart.gutter.top'];
            this.gutterBottom = prop['chart.gutter.bottom'];
            
            /**
            * Get the scale
            */
            this.scale2 = RG.getScale2(this, {
                                       'max':this.max,
                                       'min':this.min,
                                       'strict':true,
                                       'scale.thousand':prop['chart.scale.thousand'],
                                       'scale.point':prop['chart.scale.point'],
                                       'scale.decimals':prop['chart.scale.decimals'],
                                       'ylabels.count':prop['chart.labels.count'],
                                       'scale.round':prop['chart.scale.round'],
                                       'units.pre': prop['chart.units.pre'],
                                       'units.post': prop['chart.units.post']
                                      });
    
    
            /**
            * Draw the background
            */
            this.DrawBackground();
    
            /**
            * Draw the bar that represents the value
            */
            this.DrawBar();



    
            /**
            * Draw the tickmarks/hatchmarks
            */
            this.DrawTickMarks();



            /**
            * Draw the label
            */
            this.DrawLabels();



            /**
            * Draw the title
            */
            if (prop['chart.title']) {
                this.DrawTitle();
            }
            
            /**
            * Draw the side title
            */
            if (prop['chart.title.side']) {
                this.DrawSideTitle();
            }
            
            /**
            * This function enables resizing
            */
            if (prop['chart.resizable']) {
                RG.AllowResizing(this);
            }
    
    
    
            
            /**
            * Setup the context menu if required
            */
            if (prop['chart.contextmenu']) {
                RG.ShowContext(this);
            }



    
            /**
            * This installs the event listeners
            */
            RG.InstallEventListeners(this);
    
            
            /**
            * Fire the custom RGraph ondraw event (which should be fired when you have drawn the chart)
            */
            RG.FireCustomEvent(this, 'ondraw');

            return this;
        }
    
    
    
    
    
        /**
        * Draws the thermometer itself
        */
        this.DrawBackground = function ()
        {
            var bulbRadius = (ca.width - this.gutterLeft - this.gutterRight) / 2;
            
            // This is the radius/x/y of the top "semi-circle"
            this.bulbTopRadius  = (ca.width - this.gutterLeft - this.gutterRight - 24)/ 2
            this.bulbTopCenterX = this.gutterLeft + bulbRadius;
            this.bulbTopCenterY = this.gutterTop + bulbRadius;
    
            //This is the radius/x/y of the bottom bulb
            this.bulbBottomRadius  = bulbRadius;
            this.bulbBottomCenterX = this.gutterLeft + bulbRadius;
            this.bulbBottomCenterY = ca.height - this.gutterBottom - bulbRadius;
            
            // Save the bulbRadius as an object variable
            this.bulbRadius = bulbRadius;
    
            // Draw the black background that becomes the border
            co.beginPath();
                co.fillStyle = 'black';
    
                if (prop['chart.shadow']) {
                    RG.SetShadow(this, prop['chart.shadow.color'], prop['chart.shadow.offsetx'], prop['chart.shadow.offsety'], prop['chart.shadow.blur']);
                }
    
                co.fillRect(this.gutterLeft + 12,this.gutterTop + bulbRadius,ca.width - this.gutterLeft - this.gutterRight - 24, ca.height - this.gutterTop - this.gutterBottom - bulbRadius - bulbRadius);
                
                // Bottom bulb
                co.arc(this.bulbBottomCenterX, this.bulbBottomCenterY, bulbRadius, 0, TWOPI, 0);
                
                // Top bulb (which is actually a semi-circle)
                co.arc(this.bulbTopCenterX,this.bulbTopCenterY,this.bulbTopRadius,0,TWOPI,0);
            co.fill();
            
            // Save the radius of the top semi circle
            
    
            RG.NoShadow(this);
    
            // Draw the white inner content background that creates the border
            co.beginPath();
                co.fillStyle = 'white';
                co.fillRect(this.gutterLeft + 12 + 1,this.gutterTop + bulbRadius,ca.width - this.gutterLeft - this.gutterRight - 24 - 2,ca.height - this.gutterTop - this.gutterBottom - bulbRadius - bulbRadius);
                co.arc(this.gutterLeft + bulbRadius, ca.height - this.gutterBottom - bulbRadius, bulbRadius - 1, 0, TWOPI, 0);
                co.arc(this.gutterLeft + bulbRadius,this.gutterTop + bulbRadius,((ca.width - this.gutterLeft - this.gutterRight - 24)/ 2) - 1,0,TWOPI,0);
            co.fill();
    
            // Draw the bottom content of the thermometer
            co.beginPath();
                co.fillStyle = prop['chart.colors'][0];
                co.arc(this.gutterLeft + bulbRadius, ca.height - this.gutterBottom - bulbRadius, bulbRadius - 1, 0, TWOPI, 0);
                co.rect(this.gutterLeft + 12 + 1, ca.height - this.gutterBottom - bulbRadius - bulbRadius,ca.width - this.gutterLeft - this.gutterRight - 24 - 2, bulbRadius);
            co.fill();


            // Save the X/Y/width/height
            this.graphArea[0] = this.gutterLeft + 12 + 1;
            this.graphArea[1] = this.gutterTop + bulbRadius;
            this.graphArea[2] = ca.width - this.gutterLeft - this.gutterRight - 24 - 2;
            this.graphArea[3] = (ca.height - this.gutterBottom - bulbRadius - bulbRadius) - (this.graphArea[1]);
        }


    
    
        /**
        * This draws the bar that indicates the value of the thermometer
        */
        this.DrawBar = function ()
        {
            var barHeight = ((this.value - this.min) / (this.max - this.min)) * this.graphArea[3];
    
            // Draw the actual bar that indicates the value
            co.beginPath();
                co.fillStyle = prop['chart.colors'][0];
                
                // This solves an issue with ExCanvas showing a whiite cutout in the chart
                if (ISOLD) {
                    co.arc(this.bulbBottomCenterX, this.bulbBottomCenterY, this.bulbBottomRadius - 1, 0, TWOPI, false)
                }


                co.rect(this.graphArea[0],
                        this.graphArea[1] + this.graphArea[3] - barHeight,
                        this.graphArea[2],
                        barHeight + 2);
            co.fill();
            
            this.coords[0] = [this.graphArea[0],this.graphArea[1] + this.graphArea[3] - barHeight,this.graphArea[2],barHeight];
        }




        /**
        * Draws the tickmarks of the thermometer
        */
        this.DrawTickMarks = function ()
        {
            co.strokeStyle = 'black'
            var ticksize = prop['chart.ticksize'];
    
            // Left hand side tickmarks
                co.beginPath();
                    for (var i=this.graphArea[1]; i<=(this.graphArea[1] + this.graphArea[3]); i += (this.graphArea[3] / 10)) {
                        co.moveTo(this.gutterLeft + 12, Math.round(i));
                        co.lineTo(this.gutterLeft + 12 + ticksize, Math.round(i));
                    }
                co.stroke();
    
            // Right hand side tickmarks
                co.beginPath();
                    for (var i=this.graphArea[1]; i<=(this.graphArea[1] + this.graphArea[3]); i += (this.graphArea[3] / 10)) {
                        co.moveTo(ca.width - (this.gutterRight + 12), Math.round(i));
                        co.lineTo(ca.width - (this.gutterRight + 12 + ticksize), Math.round(i));
                    }
                co.stroke();
        }




        /**
        * Draws the labels of the thermometer. Now (4th August 2011) draws
        * the scale too
        */
        this.DrawLabels = function ()
        {
            /**
            * This draws draws the label that sits at the top of the chart
            */
            if (prop['chart.value.label']) {
                co.fillStyle = prop['chart.text.color'];
                
                // Weird...
                var text = prop['chart.scale.visible'] ? RG.number_format(this,
                                                                          this.value.toFixed(typeof prop['chart.value.label.decimals'] == 'number' ? prop['chart.value.label.decimals'] : prop['chart.scale.decimals'])
                                                                         )
                                                         :
                                                         RG.number_format(this,
                                                                          this.value.toFixed(typeof prop['chart.value.label.decimals'] == 'number' ? prop['chart.value.label.decimals'] : prop['chart.scale.decimals']),
                                                                          prop['chart.units.pre'],
                                                                          prop['chart.units.post']
                                                                         );

                RG.Text2(this, {'font': prop['chart.text.font'],
                                'size': prop['chart.text.size'],
                                'x':this.gutterLeft + this.bulbRadius,
                                'y': this.coords[0][1] + 7,
                                'text': text,
                                'valign':'top',
                                'halign':'center',
                                'bounding':true,
                                'boundingFill':'white',
                                'tag': 'value.label'
                               });
            }
    
    
            /**
            * Draw the scale if requested
            */
            if (prop['chart.scale.visible']) {
                this.DrawScale();
            }
        }




        /**
        * Draws the title
        */
        this.DrawTitle = function ()
        {
            co.fillStyle = prop['chart.text.color'];
                RG.Text2(this, {'font': prop['chart.text.font'],
                                'size': prop['chart.text.size'] + 2,
                                'x':this.gutterLeft + ((ca.width - this.gutterLeft - this.gutterRight) / 2),
                                'y': this.gutterTop,
                                'text': String(prop['chart.title']),
                                'valign':'center',
                                'halign':'center',
                                'bold':true,
                                'tag': 'title'
                               });
        }




        /**
        * Draws the title
        */
        this.DrawSideTitle = function ()
        {
            var font = prop['chart.title.side.font'] ? prop['chart.title.side.font'] : prop['chart.text.font'];
            var size = prop['chart.title.side.size'] ? prop['chart.title.side.size'] : prop['chart.text.size'] + 2;

            co.fillStyle = prop['chart.text.color'];
            RG.Text2(this, {'font': font,
                            'size': size + 2,
                            'x':this.gutterLeft - 3,
                            'y': ((ca.height - this.gutterTop - this.gutterBottom) / 2) + this.gutterTop,
                            'text': String(prop['chart.title.side']),
                            'valign':'center',
                            'halign':'center',
                            'angle':270,
                            'bold':prop['chart.title.side.bold'],
                            'tag': 'title.side'
                           });
        }




        /**
        * Draw the scale if requested
        */
        this.DrawScale = function ()
        {
            var numLabels = prop['chart.labels.count']; // The -1 is so that  the number of labels tallies with what is displayed
            var step      = (this.max - this.min) / numLabels;
            
            co.fillStyle = prop['chart.text.color'];
            
            var font       = prop['chart.text.font'];
            var size       = prop['chart.text.size'];
            var units_pre  = prop['chart.units.pre'];
            var units_post = prop['chart.units.post'];
            var decimals   = prop['chart.scale.decimals'];
    
            for (var i=1; i<=numLabels; ++i) {
    
                var x          = ca.width - this.gutterRight;
                var y          = ca.height - this.gutterBottom - (2 * this.bulbRadius) - ((this.graphArea[3] / numLabels) * i);
                var text       = RG.number_format(this, String((this.min + (i * step)).toFixed(decimals)), units_pre, units_post);
    
                RG.Text2(this, {'font':font,
                                'size':size,
                                'x':x-6,
                                'y':y,
                                'text':text,
                                'valign':'center',
                                'tag': 'scale'
                               });
            }
            
            // Draw zero
            RG.Text2(this, {'font':font,
                            'size':size,
                            'x':x-6,
                            'y':ca.height - this.gutterBottom - (2 * this.bulbRadius),
                            'text':RG.number_format(this, (this.min).toFixed(decimals),units_pre,units_post),
                            'valign':'center',
                            'tag': 'scale'
                           });
        }




        /**
        * Returns the focused/clicked bar
        * 
        * @param event  e The event object
        */
        this.getShape =
        this.getBar = function (e)
        {
            for (var i=0; i<this.coords.length; i++) {
    
                var mouseCoords = RGraph.getMouseXY(e);
                var mouseX = mouseCoords[0];
                var mouseY = mouseCoords[1];
    
                var left   = this.coords[i][0];
                var top    = this.coords[i][1];
                var width  = this.coords[i][2];
                var height = this.coords[i][3];
    
                if (    (mouseX >= left && mouseX <= (left + width) && mouseY >= top && mouseY <= (top + height + this.bulbBottomRadius)) // The bulbBottomRadius is added as the rect and the bulb don't fully cover the red bit
                     || RG.getHypLength(this.bulbBottomCenterX, this.bulbBottomCenterY, mouseX, mouseY) <= this.bulbBottomRadius) {
    
                
                    var tooltip = RG.parseTooltipText ? RG.parseTooltipText(prop['chart.tooltips'], i) : '';
                    
    
                    return {0: this,   'object': this,
                            1: left,   'x': left,
                            2: top,    'y': top,
                            3: width,  'width': width,
                            4: height, 'height': height,
                            5: i,      'index': i,
                                       'tooltip': tooltip
                           };
                }
            }
            
            return null;
        }




        /**
        * This function returns the value that the mouse is positioned t, regardless of
        * the actual indicated value.
        * 
        * @param object e The event object (or it can also be an two element array containing the X/Y coords)
        */
        this.getValue = function (arg)
        {
            if (arg.length == 2) {
                var mouseX = arg[0];
                var mouseY = arg[1];
            } else {
                var mouseCoords = RGraph.getMouseXY(arg);
                var mouseX      = mouseCoords[0];
                var mouseY      = mouseCoords[1];
            }

    
            
            var value = this.graphArea[3] - (mouseY - this.graphArea[1]);
                value = (value / this.graphArea[3]) * (this.max - this.min);
                value = value + this.min;
            
            value = Math.max(value, this.min);
            value = Math.min(value, this.max);
    
            return value;
        }




        /**
        * Each object type has its own Highlight() function which highlights the appropriate shape
        * 
        * @param object shape The shape to highlight
        */
        this.Highlight = function (shape)
        {
            if (prop['chart.tooltips.highlight']) {
    
                // Add the new highlight
                //RGraph.Highlight.Rect(this, shape);
    
                co.beginPath();
                    co.strokeStyle = prop['chart.highlight.stroke'];
                    co.fillStyle   = prop['chart.highlight.fill'];
                    co.rect(shape['x'],shape['y'],shape['width'],shape['height'] + this.bulbBottomRadius);
                    co.arc(this.bulbBottomCenterX, this.bulbBottomCenterY, this.bulbBottomRadius - 1, 0, TWOPI, false);
                co.stroke;
                co.fill();
            }
        }




        /**
        * The getObjectByXY() worker method. Don't call this - call:
        * 
        * RGraph.ObjectRegistry.getObjectByXY(e)
        * 
        * @param object e The event object
        */
        this.getObjectByXY = function (e)
        {
            var mouseXY = RGraph.getMouseXY(e);
    
            if (
                   mouseXY[0] > this.gutterLeft
                && mouseXY[0] < (ca.width - this.gutterRight)
                && mouseXY[1] >= this.gutterTop
                && mouseXY[1] <= (ca.height - this.gutterBottom)
                ) {
    
                return this;
            }
        }




        /**
        * This method handles the adjusting calculation for when the mouse is moved
        * 
        * @param object e The event object
        */
        this.Adjusting_mousemove = function (e)
        {
            /**
            * Handle adjusting for the Thermometer
            */
            if (prop['chart.adjustable'] && RG.Registry.Get('chart.adjusting') && RG.Registry.Get('chart.adjusting').uid == this.uid) {
    
                var mouseXY = RGraph.getMouseXY(e);
                var value   = this.getValue(e);
                
                if (typeof(value) == 'number') {
    
                    // Fire the onadjust event
                    RG.FireCustomEvent(this, 'onadjust');
    
                    this.value = Number(value.toFixed(prop['chart.scale.decimals']));
    
                    RG.RedrawCanvas(ca);
                }
            }
        }




        /**
        * This function positions a tooltip when it is displayed
        * 
        * @param obj object    The chart object
        * @param int x         The X coordinate specified for the tooltip
        * @param int y         The Y coordinate specified for the tooltip
        * @param objec tooltip The tooltips DIV element
        */
        this.positionTooltip = function (obj, x, y, tooltip, idx)
        {
            var coordX     = obj.coords[tooltip.__index__][0];
            var coordY     = obj.coords[tooltip.__index__][1];
            var coordW     = obj.coords[tooltip.__index__][2];
            var coordH     = obj.coords[tooltip.__index__][3];
            var canvasXY   = RGraph.getCanvasXY(ca);
            var gutterLeft = obj.gutterLeft;
            var gutterTop  = obj.gutterTop;
            var width      = tooltip.offsetWidth;
            var height     = tooltip.offsetHeight;
    
            // Set the top position
            tooltip.style.left = 0;
            tooltip.style.top  = canvasXY[1] + coordY - height - 7 + 'px';
            
            // By default any overflow is hidden
            tooltip.style.overflow = '';
    
            // The arrow
            var img = new Image();
                img.src = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABEAAAAFCAYAAACjKgd3AAAARUlEQVQYV2NkQAN79+797+RkhC4M5+/bd47B2dmZEVkBCgcmgcsgbAaA9GA1BCSBbhAuA/AagmwQPgMIGgIzCD0M0AMMAEFVIAa6UQgcAAAAAElFTkSuQmCC';
                img.style.position = 'absolute';
                img.id = '__rgraph_tooltip_pointer__';
                img.style.top = (tooltip.offsetHeight - 2) + 'px';
            tooltip.appendChild(img);
            
            // Reposition the tooltip if at the edges:
    
            // LEFT edge
            if ((canvasXY[0] + coordX - (width / 2)) < 10) {
                tooltip.style.left = (canvasXY[0] + coordX - (width * 0.1)) + (coordW / 2) + 'px';
                img.style.left = ((width * 0.1) - 8.5) + 'px';
    
            // RIGHT edge
            } else if ((canvasXY[0] + coordX + (width / 2)) > document.body.offsetWidth) {
                tooltip.style.left = canvasXY[0] + coordX - (width * 0.9) + (coordW / 2) + 'px';
                img.style.left = ((width * 0.9) - 8.5) + 'px';
    
            // Default positioning - CENTERED
            } else {
                tooltip.style.left = (canvasXY[0] + coordX + (coordW / 2) - (width * 0.5)) + 'px';
                img.style.left = ((width * 0.5) - 8.5) + 'px';
            }
        }




        /**
        * Returns the appropriate Y coord for a value
        * 
        * @param number value The value to return the coord for
        */
        this.getYCoord = function (value)
        {
            if (value > this.max || value < this.min) {
                return null;
            }
    
            var y = (this.graphArea[1] + this.graphArea[3]) - (((value - this.min) / (this.max - this.min)) * this.graphArea[3]);
    
            return y;
        }




        /**
        * This returns true/false as to whether the cursor is over the chart area.
        * The cursor does not necessarily have to be over the bar itself.
        */
        this.overChartArea = function  (e)
        {
            var mouseXY = RG.getMouseXY(e);
            var mouseX  = mouseXY[0];
            var mouseY  = mouseXY[1];

            // Is the mouse in the "graphArea"?
            // ( with a little extra height added)
            if (   mouseX >= this.graphArea[0]
                && mouseX <= (this.graphArea[0] + this.graphArea[2])
                && mouseY >= this.graphArea[1]
                && mouseY <= (this.graphArea[1] + this.graphArea[3] + this.bulbRadius)
                ) {
                
                return true;
            }
            
            // Is the mouse over the bottom bulb?
            if (RG.getHypLength(this.bulbBottomCenterX, this.bulbBottomCenterY, mouseX, mouseY) <= this.bulbRadius) {
                return true;
            }
            
            // Is the mouse over the semi-circle at the top?
            if (RG.getHypLength(this.bulbTopCenterX, this.bulbTopCenterY, mouseX, mouseY) <= this.bulbTopRadius) {
                return true;
            }
    
            return false;
        }




        /**
        * This allows for easy specification of gradients
        */
        this.parseColors = function ()
        {
            var colors = prop['chart.colors'];
    
            for (var i=0; i<colors.length; ++i) {
                colors[i] = this.parseSingleColorForGradient(colors[i]);
            }
        }




        /**
        * This parses a single color value
        */
        this.parseSingleColorForGradient = function (color)
        {
            if (!color || typeof(color) != 'string') {
                return color;
            }
    
            if (color.match(/^gradient\((.*)\)$/i)) {
                
                var parts = RegExp.$1.split(':');
    
                // Create the gradient
                var grad = co.createLinearGradient(prop['chart.gutter.left'], 0, ca.width - prop['chart.gutter.right'],0);
    
                var diff = 1 / (parts.length - 1);
    
                grad.addColorStop(0, RG.trim(parts[0]));
    
                for (var j=1; j<parts.length; ++j) {
                    grad.addColorStop(j * diff, RG.trim(parts[j]));
                }
            }
                
            return grad ? grad : color;
        }




        /**
        * Now, because canvases can support multiple charts, canvases must always be registered
        */
        RG.Register(this);
    }