将图像转换为已加载的画布 [英] Convert an image to canvas that is already loaded

问题描述

我正在开发一个插件，在该插件中我将图像转换为画布并存储为数据 url.此函数触发加载"事件，但如何转换页面上已经存在的图像?(不想刷新页面或再次加载任何图像).我尝试使用 Filereader() 函数，但这也适用于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?

I am working on a plugin in which I'm converting Image into Canvas and storing as data url .This function triggers on 'load' event but how can I convert an image which is already there on the page? (Don't want to refresh the page or load any image again). I tried using the Filereader() function but that also works on 'onload' concept. So how can I save the image as data url when the user clicks on the image?

   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);

推荐答案

现在完美运行.如果您使用 javascript 创建临时图像元素，然后将其存储在 localStorage 中.这对我有用，希望它也能帮助其他人

Now it works perfectly.If you create a temporary image element using javascript then store it in localStorage. This worked for me hope it'll help others too

    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);

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