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/* Flot plugin for showing crosshairs when the mouse hovers over the plot.

Copyright (c) 2007-2014 IOLA and Ole Laursen.

Licensed under the MIT license.

The plugin supports these options:

        crosshair: {

                mode: null or "x" or "y" or "xy"

                color: color

                lineWidth: number

        }

Set the mode to one of "x", "y" or "xy". The "x" mode enables a vertical

crosshair that lets you trace the values on the x axis, "y" enables a

horizontal crosshair and "xy" enables them both. "color" is the color of the

crosshair (default is "rgba(170, 0, 0, 0.80)"), "lineWidth" is the width of

the drawn lines (default is 1).

The plugin also adds four public methods:

  - setCrosshair( pos )

    Set the position of the crosshair. Note that this is cleared if the user

    moves the mouse. "pos" is in coordinates of the plot and should be on the

    form { x: xpos, y: ypos } (you can use x2/x3/... if you're using multiple

    axes), which is coincidentally the same format as what you get from a

    "plothover" event. If "pos" is null, the crosshair is cleared.

  - clearCrosshair()

    Clear the crosshair.

  - lockCrosshair(pos)

    Cause the crosshair to lock to the current location, no longer updating if

    the user moves the mouse. Optionally supply a position (passed on to

    setCrosshair()) to move it to.

    Example usage:

        var myFlot = $.plot( $("#graph"), ..., { crosshair: { mode: "x" } } };

        $("#graph").bind( "plothover", function ( evt, position, item ) {

                if ( item ) {

                        // Lock the crosshair to the data point being hovered

                        myFlot.lockCrosshair({

                                x: item.datapoint[ 0 ],

                                y: item.datapoint[ 1 ]

                        });

                } else {

                        // Return normal crosshair operation

                        myFlot.unlockCrosshair();

                }

        });

  - unlockCrosshair()

    Free the crosshair to move again after locking it.

*/

(function ($) {

    var options = {

        crosshair: {

            mode: null, // one of null, "x", "y" or "xy",

            color: "rgba(170, 0, 0, 0.80)",

            lineWidth: 1

        }

    };

    function init(plot) {

        // position of crosshair in pixels

        var crosshair = { x: -1, y: -1, locked: false };

        plot.setCrosshair = function setCrosshair(pos) {

            if (!pos)

                crosshair.x = -1;

            else {

                var o = plot.p2c(pos);

                crosshair.x = Math.max(0, Math.min(o.left, plot.width()));

                crosshair.y = Math.max(0, Math.min(o.top, plot.height()));

            }

            plot.triggerRedrawOverlay();

        };

        plot.clearCrosshair = plot.setCrosshair; // passes null for pos

        plot.lockCrosshair = function lockCrosshair(pos) {

            if (pos)

                plot.setCrosshair(pos);

            crosshair.locked = true;

        };

        plot.unlockCrosshair = function unlockCrosshair() {

            crosshair.locked = false;

        };

        function onMouseOut(e) {

            if (crosshair.locked)

                return;

            if (crosshair.x != -1) {

                crosshair.x = -1;

                plot.triggerRedrawOverlay();

            }

        }

        function onMouseMove(e) {

            if (crosshair.locked)

                return;

            if (plot.getSelection && plot.getSelection()) {

                crosshair.x = -1; // hide the crosshair while selecting

                return;

            }

            var offset = plot.offset();

            crosshair.x = Math.max(0, Math.min(e.pageX - offset.left, plot.width()));

            crosshair.y = Math.max(0, Math.min(e.pageY - offset.top, plot.height()));

            plot.triggerRedrawOverlay();

        }

        plot.hooks.bindEvents.push(function (plot, eventHolder) {

            if (!plot.getOptions().crosshair.mode)

                return;

            eventHolder.mouseout(onMouseOut);

            eventHolder.mousemove(onMouseMove);

        });

        plot.hooks.drawOverlay.push(function (plot, ctx) {

            var c = plot.getOptions().crosshair;

            if (!c.mode)

                return;

            var plotOffset = plot.getPlotOffset();

            ctx.save();

            ctx.translate(plotOffset.left, plotOffset.top);

            if (crosshair.x != -1) {

                var adj = plot.getOptions().crosshair.lineWidth % 2 ? 0.5 : 0;

                ctx.strokeStyle = c.color;

                ctx.lineWidth = c.lineWidth;

                ctx.lineJoin = "round";

                ctx.beginPath();

                if (c.mode.indexOf("x") != -1) {

                    var drawX = Math.floor(crosshair.x) + adj;

                    ctx.moveTo(drawX, 0);

                    ctx.lineTo(drawX, plot.height());

                }

                if (c.mode.indexOf("y") != -1) {

                    var drawY = Math.floor(crosshair.y) + adj;

                    ctx.moveTo(0, drawY);

                    ctx.lineTo(plot.width(), drawY);

                }

                ctx.stroke();

            }

            ctx.restore();

        });

        plot.hooks.shutdown.push(function (plot, eventHolder) {

            eventHolder.unbind("mouseout", onMouseOut);

            eventHolder.unbind("mousemove", onMouseMove);

        });

    }

    $.plot.plugins.push({

        init: init,

        options: options,

        name: 'crosshair',

        version: '1.0'

    });

})(jQuery);