Question

我需要用来自计算机的文件上传中的新图像替换现有图像，我想用新上传的图像替换图像。 Here is the code (JSFiddle)

var canvas = new fabric.Canvas('c');

function addImage () {
    fabric.Image.fromURL('http://lorempixel.com/400/200', function (img) {
     img.set({ 'left': 50 });
      img.set({ 'top': 50 });
      img.scaleToWidth(100);
      img.scaleToHeight(100);
      canvas.add (img);
    });
}

addImage();

canvas {
    border:1px solid #000;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.6.2/fabric.min.js"></script>
<canvas id="c" width="400" height="200"></canvas>
<span><input type="file" name="" id="span"></span>

Answer 1

你可以通过以下方式实现这一目标......

var canvas = new fabric.Canvas('c');

function addImage(imgLink) {
    fabric.Image.fromURL(imgLink, function(img) {
        img.set({ 'left': 50 });
        img.set({ 'top': 50 });
        img.scaleToWidth(100);
        img.scaleToHeight(100);
				
        var objs = canvas.getObjects();
        if (objs.length) {
            objs.forEach(function(e) {
                if (e && e.type === 'image') {
                    e._element.src = imgLink;
                    canvas.renderAll();
                }
            });
        } else canvas.add(img);
    });
}

addImage('http://lorempixel.com/400/200');

// file upload
var span = document.querySelector('#span');
span.onchange = function(e) {
    var file = e.target.files[0];
    var reader = new FileReader();
    reader.onload = function(file) {
        addImage(file.target.result);
    }
    reader.readAsDataURL(file);
}

canvas {
  border:1px solid lightgrey;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.6.2/fabric.min.js"></script>
<canvas id="c" width="400" height="200"></canvas>
<span><input type="file" name="" id="span"></span>

Answer 2

您可以使用以下代码

document.addEventListener('dblclick', function () {

if (canvas.getActiveObject().id == 'uimg0') {        

    $("input[id='span']").click();
    $("#span").replaceWith($("#span").val('').clone(true)); 
  }
});


var imgname = "http://lorempixel.com/400/200";
var pugImg0 = new Image();
var pug
pugImg0.onload = function (img) {
    pug = new fabric.Image(pugImg0, {
        left: 96,
        top: 65,
        scaleX: 508 / pugImg0.width,
        scaleY: 208 / pugImg0.height,
        id: 'uimg0',
        selectable: true,
        lockMovementX: true,
        lockMovementY: true,
        hasControls: false

    });
    canvas.add(pug);
};
pugImg0.src = imgname;

var imageLoader = document.getElementById('span');
imageLoader.addEventListener('change', handleImage0);


function handleImage0(e) {
    var reader = new FileReader();
    reader.onload = function (event) {
        var img = new Image();
        var pugb;
        img.onload = function () {
            pugb = new fabric.Image(img, {
                left: 78,
                top: 103,
                scaleX: 240 / img.width,
                scaleY: 195 / img.height,

                selectable: true,
                id: "uimg0",
                lockMovementX: true,
                lockMovementY: true,
                hasControls: false

            })

            canvas.add(pugb).renderAll();                
        }
        img.src = event.target.result;
        canvas.remove(canvas.getActiveObject());

    }
    reader.readAsDataURL(e.target.files[0]);
}

如何使用Fabric.js将现有图像替换为画布中的新图像

2 个答案: