将图片上传，调整大小并编码为base64会使Chrome在移动设备上崩溃

Question

My users can select an image using the file-upload HTML input element -

1. From there I downscale

2. I convert to base64

For some reason Chrome mobile & Android browser completely crash - and display an 'Out of Memory error'.

If the browser runs on a more 'modern/capable' device all goes perfectly fine.

What could be causing the error here - can it be fixed?

---

Here is the function that downscales(whilst keeping aspect ratios) and returns a Base64 string of the image.

function resizeAndConvertB64(img, maxWidth, maxHeight) {
    var imgWidth = img.width, 
        imgHeight = img.height;

    var ratio = 1, ratio1 = 1, ratio2 = 1;
    ratio1 = maxWidth / imgWidth;
    ratio2 = maxHeight / imgHeight;

    // Use the smallest ratio that the image best fit into the maxWidth x maxHeight box.
    if (ratio1 < ratio2) {
        ratio = ratio1;
    }
    else {
        ratio = ratio2;
    }
    var canvas = document.createElement("canvas");
    var canvasContext = canvas.getContext("2d");
    var canvasCopy = document.createElement("canvas");
    var copyContext = canvasCopy.getContext("2d");
    var canvasCopy2 = document.createElement("canvas");
    var copyContext2 = canvasCopy2.getContext("2d");
    canvasCopy.width = imgWidth;
    canvasCopy.height = imgHeight;  
    copyContext.drawImage(img, 0, 0);

    // init
    canvasCopy2.width = imgWidth;
    canvasCopy2.height = imgHeight;        
    copyContext2.drawImage(canvasCopy, 0, 0, canvasCopy.width, canvasCopy.height, 0, 0, canvasCopy2.width, canvasCopy2.height);


    var rounds = 1;
    var roundRatio = ratio * rounds;
    for (var i = 1; i <= rounds; i++) {


        // tmp
        canvasCopy.width = imgWidth * roundRatio / i;
        canvasCopy.height = imgHeight * roundRatio / i;

        copyContext.drawImage(canvasCopy2, 0, 0, canvasCopy2.width, canvasCopy2.height, 0, 0, canvasCopy.width, canvasCopy.height);

        // copy back
        canvasCopy2.width = imgWidth * roundRatio / i;
        canvasCopy2.height = imgHeight * roundRatio / i;
        copyContext2.drawImage(canvasCopy, 0, 0, canvasCopy.width, canvasCopy.height, 0, 0, canvasCopy2.width, canvasCopy2.height);

    } // end for


    // return Base64 string of the downscaled image
    canvas.width = imgWidth * roundRatio / rounds;
    canvas.height = imgHeight * roundRatio / rounds;
    canvasContext.drawImage(canvasCopy2, 0, 0, canvasCopy2.width, canvasCopy2.height, 0, 0, canvas.width, canvas.height);
    var dataURL = canvas.toDataURL();
    return dataURL;


}

Answer 1

I think it is an error of Chrome mobile.
Chrome mobile is not stable and my handy crashes often when I use it.
The out of memory message says that your device hasn't got enough memory for this script.
Check if it works with Dolphin Browser.
I think it will work but I don't know it.