Canvas2Image.saveAsPNG（帆布）质量

Question

当我使用Canvas2Image.saveAsPNG时，质量很差。

 html2canvas($("#surface"), {
                onrendered: function(canvas) {
                theCanvas = canvas;
                document.body.appendChild(canvas);

                // Convert and download as image 
                Canvas2Image.saveAsPNG(canvas);
                $("#img-out").append(canvas);

前

后