External drawing/erasing buttons

HTML

<script type="text/javascript" src="http://www.amcharts.com/lib/3/amcharts.js"></script>
<script type="text/javascript" src="http://www.amcharts.com/lib/3/serial.js"></script>
<script type="text/javascript" src="http://www.amcharts.com/lib/3/themes/none.js"></script>
<script type="text/javascript" src="http://www.amcharts.com/lib/3/amstock.js"></script>
<button id="drawing" onclick="toggle(this);">Start Drawing</button>
<button id="erasing" onclick="toggle(this);">Start Erasing</button>
<div id="chartdiv"></div>

CSS

#chartdiv {
	width		: 100%;
	height		: 500px;
	font-size	: 11px;
}

JavaScript

var chartData = generateChartData();

function toggle(b) {
    // Fake button methods
    chart.panels[0].pencilButtonPushed = {
        hide: function () {},
        show: function () {}
    };
    chart.panels[0].eraserButtonPushed = {
        hide: function () {},
        show: function () {}
    };
    
    // Drawing
    if (b.id == 'drawing') {
        b.innerHTML = !chart.panels[0].drawingEnabled ? 'Stop Drawing' : 'Start Drawing';
        document.getElementById('erasing').innerHTML = 'Start Erasing';
        
        // Method to toggle the drawing state
        chart.panels[0].handlePencilClick();
        
    // Erasing
    } else {
        b.innerHTML = !chart.panels[0].erasingEnabled ? 'Stop Erasing' : 'Start Erasing';
        document.getElementById('drawing').innerHTML = 'Start Drawing';
        
        // Method to toggle the erasing state
        chart.panels[0].handleEraserClick();
    }
}

function generateChartData() {
    var chartData = [];
    var firstDate = new Date(2012, 0, 1);
    firstDate.setDate(firstDate.getDate() - 500);
    firstDate.setHours(0, 0, 0, 0);

    for (var i = 0; i < 500; i++) {
        var newDate = new Date(firstDate);
        newDate.setDate(newDate.getDate() + i);

        var value = Math.round(Math.random() * (40 + i)) + 100 + i;

        chartData.push({
            date: newDate,
            value: value
        });
    }
    return chartData;
}


var chart = AmCharts.makeChart("chartdiv", {

    type: "stock",

        "theme": "none",
    pathToImages: "http://www.amcharts.com/lib/3/images/",

    dataSets: [{
        color: "#b0de09",
        fieldMappings: [{
            fromField: "value",
            toField: "value"
        }],
        dataProvider: chartData,
        categoryField: "date"
    }],

    panels: [{
        showCategoryAxis: true,
        title: "Value",
        eraseAll: false, // prevents to erase all in once
        stockGraphs: [{
            id: "g1",
            valueField:...