画布图像绘制失败

canvas image draw failing

本文关键字：绘制 失败 图像 布图像      更新时间：2023-09-26

ctx时，整个函数刚刚停止。调用DrawImage时，这是与调用相关的所有信息。我搞不清楚问题出在哪里。

附加信息：我正在使用DevExtreme，所以这是在安卓操作系统上运行的

var Canvas = document.createElement("canvas");
var ctx = Canvas.getContext("2d");
Canvas.width=640;
Canvas.height=480;
var resultArray = [];
var workerCount = 0;

function onPhotoDataSuccess(imageData) {
   smallPicture = document.getElementById('smallImage');
    alert("1");
    smallPicture.onload = function () {
        alert("3");
        ctx.drawImage(showPicture, 0, 0, Canvas.width, Canvas.height);
        alert("4");
        resultArray = [];
        alert("5");
        workerCount = 2;
        alert("6");
        barcodeNum = "";
        DecodeWorker.postMessage({ ImageData: ctx.getImageData(0, 0, Canvas.width, Canvas.height).data, Width: Canvas.width, Height: Canvas.height, cmd: "normal" });
                };
    alert("2");
    smallPicture.src = "data:image/jpeg;base64," + imageData;
}

您可能想要替换：

ctx.drawImage(showPicture, 0, 0, Canvas.width, Canvas.height);

带有：

ctx.drawImage(smallPicture, 0, 0, Canvas.width, Canvas.height);
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