使用Chart JS的空白PNG图像.toBase64Image()函数

Question

我正在尝试保存使用Chart.JS图形库创建的图表副本.当我使用.toBase64Image()函数显示或保存.png图像时,我得到一个空白图像.我尝试在img标签中显示并使用PHP保存图像.save64Img是我显示/保存图像的功能.有没有人有运气使用此功能？

lineOptions = {
        scaleShowGridLines : true,
        scaleGridLineColor : "rgba(0,0,0,.05)",
        scaleGridLineWidth : 1,
        bezierCurve : false,
        pointDot : true,
        pointDotRadius : 4,
        pointDotStrokeWidth : 1,
        pointHitDetectionRadius : 20,
        datasetStroke : true,
        datasetStrokeWidth : 1,
        datasetFill : true,
        responsive: true,      
        scaleOverride : true,
        scaleSteps : 5,
        scaleStepWidth : 20,
        scaleStartValue : 0

    }

    lineChart = {
            labels : label,
            datasets : [
                {
                    label: "stat1",
                    fillColor : "rgba(128,0,0,0.2)",
                    strokeColor : "rgba(128,0,0,1)",
                    pointColor : "rgba(128,0,0,1)",
                    pointStrokeColor : "#fff",
                    pointHighlightFill : "#fff",
                    pointHighlightStroke : "rgba(128,0,0,1)",
                    data : stat1
                },
                {
                    label: "stat2",
                    fillColor : "rgba(151,187,205,0.2)",
                    strokeColor : "rgba(151,187,205,1)",
                    pointColor : "rgba(151,187,205,1)",
                    pointStrokeColor : "#fff",
                    pointHighlightFill : "#fff",
                    pointHighlightStroke : "rgba(151,187,205,1)",
                    data : stat2
                }
            ]

    };

var myChart = new Chart(ctx).Line(lineChart, lineOptions);

save64Img(myChart.toBase64Image());

----------

<?php 
$data = base64_decode(preg_replace('#^data:image/\w+;base64,#i', '', $img));

file_put_contents('/tmp/image.png', $data);

?>

Answer 1

您必须调用save64Img(myChart.toBase64Image())额外的回调。您可以将此回调添加到选项中

lineOptions = {
    onAnimationComplete: function () {
       save64Img(myChart.toBase64Image());
    }
}