Question

就像标题所说，我有一个表示图像内容的字节数组（可以是jpeg或png）。

我想在常规画布对象上绘制它

<canvas id='thecanvas'></canvas>

我该怎么做？

更新我试过这个（不成功）：（imgData是一个以字节数组形式发送的png，“通过WebSockify”发送给客户端）

function draw(imgData) {
    "use strict";

    var canvas = document.getElementById("myCanvas");
    var ctx = canvas.getContext("2d");
    var rdr = new FileReader();
    var imgBlob = new Blob([imgData], {type: "image/png"});
    rdr.readAsBinaryString(imgBlob);

    rdr.onload = function (data) {
        console.log("Filereader success");
        var img = new Image();
        img.onload = function () {
            console.log("Image Onload");
            ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
        };
        img.onerror = function (stuff) {
            console.log("Img Onerror:", stuff);
        };
        img.src = "data:image/png;base64," + window.btoa(rdr.result);
    };

}

我总是到达img.onerror()

在我的文件系统上使用HEX编辑器读取文件后，我可以看到字节数组与原始文件相同。

Answer 1

本作品：

function draw2(imgData, coords) {
    "use strict";
    var canvas = document.getElementById("myCanvas");
    var ctx = canvas.getContext("2d");

    //var uInt8Array = new Uint8Array(imgData);
    var uInt8Array = imgData;
    var i = uInt8Array.length;
    var binaryString = [i];
    while (i--) {
        binaryString[i] = String.fromCharCode(uInt8Array[i]);
    }
    var data = binaryString.join('');

    var base64 = window.btoa(data);

    var img = new Image();
    img.src = "data:image/png;base64," + base64;
    img.onload = function () {
        console.log("Image Onload");
        ctx.drawImage(img, coords[0], coords[1], canvas.width, canvas.height);
    };
    img.onerror = function (stuff) {
        console.log("Img Onerror:", stuff);
    };

}

如何在jpeg或png格式的字节数组中在画布上绘制图像

1 个答案: