Question

我想在画布上保存图像的像素值。我编写了一个代码来提取点击位置（图像上）的像素值。我想将r，g，b的值保存到文本文件中，以便在python flask中完成的服务器端处理中使用它们。

var imageLoader = document.getElementById('imageLoader');
    imageLoader.addEventListener('change', handleImage, false);
var canvas = document.getElementById('imageCanvas');
var ctx = canvas.getContext('2d');

function handleImage(e){
    var reader = new FileReader();
    reader.onload = function(event){
        var img = new Image();
        img.onload = function(){
            canvas.width = img.width;
            canvas.height = img.height;
            ctx.drawImage(img,0,0);
        }
        img.src = event.target.result;
    }
    reader.readAsDataURL(e.target.files[0]);     
}

canvas.onclick = function(e) {
    var x = e.pageX;
    var y = e.pageY;
    var canvasColor = context.getImageData(x, y, 1,1); // rgba e [0,255]
    var pixels = canvasColor.data;
    var r = pixels[0];
    var g = pixels[1];
    var b = pixels[2];
    // i want to save r,g,b values in a text file for usage in the flask backend
}

<script type = "text/javascript" src="http://fiddle.jshell.net/js/lib/mootools-core-1.4.5-nocompat.js"></script>
<label>Image File:</label><br/>
<input type="file" id="imageLoader" name="imageLoader"/>
<canvas id="imageCanvas"></canvas>

Answer 1

您可以修改您的功能，如：

canvas.onclick = function(e) {
    var x = e.pageX;
    var y = e.pageY;
    var canvasColor = context.getImageData(x, y, 1,1); // rgba e [0,255]
    var pixels = canvasColor.data;
    var r = pixels[0];
    var g = pixels[1];
    var b = pixels[2];
    // i want to save r,g,b values in a text file for usage in the flask backend

    //asign rgb values to the input
    document.getElementById('imageLoader').value = r + ',' + g + ',' + b;
}

然后使用常规表单（提交按钮）使用Ajax o发送并保存在文本文件中。

如何在文本文件中保存javascript变量值？

1 个答案: