Echarts服务端生成图片

Echarts是百度发布的一套优秀的浏览器端图表控件，Echarts是基于html5的cavens绘图实现。而使用server端生成图片无法借用浏览器端渲染。通用的做法有两种：

1. 是用headless浏览器渲染，例如Phantomjs
2. node-cavens渲染，类似node-echarts等方案，虽然Phantomjs也是基于Nodejs。

环境准备：

下载Phantomjs

从　http://phantomjs.org/download.html　下载指定版本，配置好环境变量，当

$ phantomjs -v
2.1.1

就算完成了。

相关依赖下载

jquery，echarts从相关CDN或者官网下载。

主流程

使用命令：

$ phantomjs echarts-convert.js -infile option.js -outfile t.png
Echarts.options has been parsed
The images have been loaded
render complete:t.png

• echarts-convert.js　类似一个浏览器页面，执行js的入口。
• infile 注入参数
• outfile 输出的文件

echarts-convert.js

(function () {
    var system = require('system');
    var fs = require('fs');
    var config = {
        // define the location of js files
        JQUERY: 'jquery.1.9.1.min.js',
        ESL: 'esl.js',
        ECHARTS: 'echarts-all.js',
        // default container width and height
        DEFAULT_WIDTH: '600',
        DEFAULT_HEIGHT: '700'
    }, parseParams, render, pick, usage;

    usage = function () {
        console.log("\nUsage: phantomjs echarts-convert.js -options options -outfile filename -width width -height height"
            + "OR"
            + "Usage: phantomjs echarts-convert.js -infile URL -outfile filename -width width -height height\n");
    };

    pick = function () {
        var args = arguments, i, arg, length = args.length;
        for (i = 0; i < length; i += 1) {
            arg = args[i];
            if (arg !== undefined && arg !== null && arg !== 'null' && arg != '0') {
                return arg;
            }
        }
    };

    parseParams = function () {
        var map = {}, i, key;
        if (system.args.length < 2) {
            usage();
            phantom.exit();
        }
        for (i = 0; i < system.args.length; i += 1) {
            if (system.args[i].charAt(0) === '-') {
                key = system.args[i].substr(1, i.length);
                if (key === 'infile') {
                    // get string from file
                    // force translate the key from infile to options.
                    key = 'options';
                    try {
                        map[key] = fs.read(system.args[i + 1]).replace(/^\s+/, '');
                    } catch (e) {
                        console.log('Error: cannot find file, ' + system.args[i + 1]);
                        phantom.exit();
                    }
                } else {
                    map[key] = system.args[i + 1];
                }
            }
        }
        return map;
    };

    render = function (params) {
        var page = require('webpage').create(), createChart;

        var bodyMale = config.SVG_MALE;
        page.onConsoleMessage = function (msg) {
            console.log(msg);
        };

        page.onAlert = function (msg) {
            console.log(msg);
        };

        createChart = function (inputOption, width, height,config) {
            var counter = 0;
            function decrementImgCounter() {
                counter -= 1;
                if (counter < 1) {
                    console.log(messages.imagesLoaded);
                }
            }

            function loadScript(varStr, codeStr) {
                var script = $('<script>').attr('type', 'text/javascript');
                script.html('var ' + varStr + ' = ' + codeStr);
                document.getElementsByTagName("head")[0].appendChild(script[0]);
                if (window[varStr] !== undefined) {
                    console.log('Echarts.' + varStr + ' has been parsed');
                }
            }

            function loadImages() {
                var images = $('image'), i, img;
                if (images.length > 0) {
                    counter = images.length;
                    for (i = 0; i < images.length; i += 1) {
                        img = new Image();
                        img.onload = img.onerror = decrementImgCounter;
                        img.src = images[i].getAttribute('href');
                    }
                } else {
                    console.log('The images have been loaded');
                }
            }
            // load opitons
            if (inputOption != 'undefined') {
                // parse the options
                loadScript('options', inputOption);
                // disable the animation
                options.animation = false;
            }

            // we render the image, so we need set background to white.
            $(document.body).css('backgroundColor', 'white');
            var container = $("<div>").appendTo(document.body);
            container.attr('id', 'container');
            container.css({
                width: width,
                height: height
            });
            // render the chart
            var myChart = echarts.init(container[0]);
            myChart.setOption(options);
            // load images
            loadImages();
            return myChart.getDataURL();
        };

        // parse the params
        page.open("about:blank", function (status) {
            // inject the dependency js
            page.injectJs(config.ESL);
            page.injectJs(config.JQUERY);
            page.injectJs(config.ECHARTS);

            var width = pick(params.width, config.DEFAULT_WIDTH);
            var height = pick(params.height, config.DEFAULT_HEIGHT);

            // create the chart
            var base64 = page.evaluate(createChart, params.options, width, height,config);
            fs.write("base64.txt",base64);
            // define the clip-rectangle
            page.clipRect = {
                top: 0,
                left: 0,
                width: width,

                height: height
            };
            // render the image
            page.render(params.outfile);
            console.log('render complete:' + params.outfile);
            // exit
            phantom.exit();
        });
    };
    // get the args
    var params = parseParams();

    // validate the params
    if (params.options === undefined || params.options.length === 0) {
        console.log("ERROR: No options or infile found.");
        usage();
        phantom.exit();
    }
    // set the default out file
    if (params.outfile === undefined) {
        var tmpDir = fs.workingDirectory + '/tmp';
        // exists tmpDir and is it writable?
        if (!fs.exists(tmpDir)) {
            try {
                fs.makeDirectory(tmpDir);
            } catch (e) {
                console.log('ERROR: Cannot make tmp directory');
            }
        }
        params.outfile = tmpDir + "/" + new Date().getTime() + ".png";
    }

    // render the image
    render(params);
}());

option.js

{
    title : {
        text: '某地区蒸发量和降水量',
        subtext: '纯属虚构'
    },
    tooltip : {
        trigger: 'axis'
    },
    legend: {
        data:['蒸发量','降水量']
    },
    toolbox: {
        show : true,
        feature : {
            mark : {show: true},
            dataView : {show: true, readOnly: false},
            magicType : {show: true, type: ['line', 'bar']},
            restore : {show: true},
            saveAsImage : {show: true}
        }
    },
    calculable : true,
    xAxis : [
        {
            type : 'category',
            data : ['1月','2月','3月','4月','5月','6月','7月','8月','9月','10月','11月','12月']
        }
    ],
    yAxis : [
        {
            type : 'value'
        }
    ],
    series : [
        {
            name:'蒸发量',
            type:'bar',
            data:[2.0, 4.9, 7.0, 23.2, 25.6, 76.7, 135.6, 162.2, 32.6, 20.0, 6.4, 3.3],
            markPoint : {
                data : [
                    {type : 'max', name: '最大值'},
                    {type : 'min', name: '最小值'}
                ]
            },
            markLine : {
                data : [
                    {type : 'average', name: '平均值'}
                ]
            }
        },
        {
            name:'降水量',
            type:'bar',
            data:[2.6, 5.9, 9.0, 26.4, 28.7, 70.7, 175.6, 182.2, 48.7, 18.8, 6.0, 2.3],
            markPoint : {
                data : [
                    {name : '年最高', value : 182.2, xAxis: 7, yAxis: 183, symbolSize:18},
                    {name : '年最低', value : 2.3, xAxis: 11, yAxis: 3}
                ]
            },
            markLine : {
                data : [
                    {type : 'average', name : '平均值'}
                ]
            }
        }
    ]
};

运行结果：

外部资源无法加载

{
    title : {
        text: '某地区蒸发量和降水量',
        subtext: '纯属虚构'
    },
    tooltip : {
        trigger: 'axis'
    },
    legend: {
        data:['蒸发量','降水量']
    },
    toolbox: {
        show : true,
        feature : {
            mark : {show: true},
            dataView : {show: true, readOnly: false},
            magicType : {show: true, type: ['line', 'bar']},
            restore : {show: true},
            saveAsImage : {show: true}
        }
    },
    calculable : true,
    xAxis : [
        {
            type : 'category',
            data : ['1月','2月','3月','4月','5月','6月','7月','8月','9月','10月','11月','12月']
        }
    ],
    yAxis : [
        {
            type : 'value'
        }
    ],
    series : [
        {
            name:'蒸发量',
            type:'bar',
            data:[2.0, 4.9, 7.0, 23.2, 25.6, 76.7, 135.6, 162.2, 32.6, 20.0, 6.4, 3.3],
            markPoint : {
                data : [
                    {type : 'max', name: '最大值'},
                    {type : 'min', name: '最小值'}
                ]
            },
            markLine : {
                data : [
                    {type : 'average', name: '平均值'}
                ]
            }
        },
        {
            name:'降水量',
            type:'bar',
            data:[2.6, 5.9, 9.0, 26.4, 28.7, 70.7, 175.6, 182.2, 48.7, 18.8, 6.0, 2.3],
            markPoint : {
                data : [
                    {name : '年最高', value : 192.2, xAxis: 7, yAxis: 183, symbolSize:18,symbol:"image://./organ/gall.png"},
                    {name : '年最低', value : 2.3, xAxis: 11, yAxis: 3}
                ]
            },
            markLine : {
                data : [
                    {type : 'average', name : '平均值'}
                ]
            }
        }
    ]
};

执行后，

没有symbol丢失。怀疑是symbol的图片无法外部加载。