javascript - 将图像转换为已加载的 Canvas

Question

我正在开发一个插件，我在其中将图像转换为 Canvas 并存储为数据 url。此函数触发“加载”事件，但我如何转换页面上已有的图像？ (不想刷新页面或再次加载任何图像)。我尝试使用 Filereader() 函数，但它也适用于“onload”概念。那么如何在用户点击图片时将图片保存为数据url呢？

   image.addEventListener("load", function () {

         var imgCanvas = document.createElement("canvas"),
            imgContext = imgCanvas.getContext("2d");
            imgCanvas.width = image.width;
            imgCanvas.height = image.height;

            imgContext.drawImage(image, 0, 0, image.width, image.height);       
            imgInfo = imgCanvas.toDataURL("image/png");

            localStorage.setItem("imgInfo", imgInfo);
        }, false);

Answer 1

现在它完美地工作了。如果您使用 javascript 创建一个临时图像元素，然后将其存储在 localStorage 中。这对我有用，希望它也能帮助其他人

    image = document.createElement('img');
    document.body.appendChild(image);
    image.setAttribute('style','display:none');
    image.setAttribute('alt','script div');
    image.setAttribute("src", path);

    var imgCanvas = document.createElement("canvas"),
    imgContext = imgCanvas.getContext("2d");

    // Make sure canvas is as big as the picture
    imgCanvas.width = image.width;
    imgCanvas.height = image.height;

    // Draw image into canvas element
    imgContext.drawImage(image, 0, 0, image.width, image.height);
    // Save image as a data URL
    imgInfom = imgCanvas.toDataURL("image/png");
    localStorage.setItem("imgInfo",imgInfom);
    document.body.removeChild(image);