Corner has jaggies when fill background

[JohnDWen]

Corner has something like jaggies when fill it with background.
This problem shows recently.

[ericwangjp]

the same question ,how did you solve it ?

[Clors1997]

`
function exportAsPng3() {
var date = new Date();
bootbox.prompt({
title: "Enter output filename (without '.9.png')",
value: "shadow_" + date.getHours() + "" + date.getMinutes() + "" + date.getSeconds(),
callback: function(result) {
if (result !== null && result !== "") {
//Show ninepatches If hidden when exporting
var hideNinepatchesTmp = true;
var showContentAreaTmp = false;
if (hideNinepatches || showContentArea) {
hideNinepatchesTmp = hideNinepatches;
showContentAreaTmp = showContentArea;
showContentArea = false;
hideNinepatches = true; //清除patches
redraw();
}

            //Use BlobHD If supported
            if (canvas.toBlobHD) {
                canvas.toBlobHD(function (blob) {
                    saveAs(blob, result + ".9.png");
                });
            } else {
                canvas.toBlob(function (blob) {
                    saveAs(blob, result + ".9.png");
                });
            }
        }
    }
});

}
`