javascript - 图像只占用盒子内的小空间

Question

我们正在使用 stackoverflow links在站点中上传图片的代码

一旦我们上传，它只占框中的一小部分，如here .

但是图像应该占据整个盒子。

var canvas = new fabric.Canvas('canvas');
document.getElementById('file').addEventListener("change", function (e) {
  var file = e.target.files[0];
  var reader = new FileReader();
  reader.onload = function (f) {
    var data = f.target.result;                    
    fabric.Image.fromURL(data, function (img) {
      var oImg = img.set({left: 0, top: 0, angle: 00,width:100, height:100}).scale(0.9);
      canvas.add(oImg).renderAll();
      var a = canvas.setActiveObject(oImg);
      var dataURL = canvas.toDataURL({format: 'png', quality: 0.8});
    });
  };
  reader.readAsDataURL(file);
});

canvas{
  border: 1px solid black;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://rawgit.com/kangax/fabric.js/master/dist/fabric.min.js"></script>
<input type="file" id="file"><br />
<canvas id="canvas" width="450" height="450"></canvas>

Answer 1

替换行

var oImg = img.set({left: 0, top: 0, angle: 00,width:100, height:100}).scale(0.9);

与

var oImg = img.set({left: 0, top: 0, angle: 00, width: canvas.getWidth(), height: canvas.getHeight()});

这就是限制图像大小的原因。另外，我不知道为什么你在那里有比例 - 但如果你将它保持为 .scale(0.9)，它不会填满整个盒子。相反，它只会填充其宽度和高度的 90%。

片段

var canvas = new fabric.Canvas('canvas');
document.getElementById('file').addEventListener("change", function (e) {
  var file = e.target.files[0];
  var reader = new FileReader();
  reader.onload = function (f) {
    var data = f.target.result;                    
    fabric.Image.fromURL(data, function (img) {
      var oImg = img.set({left: 0, top: 0, angle: 00,width:canvas.getWidth(), height:canvas.getHeight()});
      canvas.add(oImg).renderAll();
      var a = canvas.setActiveObject(oImg);
      var dataURL = canvas.toDataURL({format: 'png', quality: 0.8});
    });
  };
  reader.readAsDataURL(file);
});

canvas{
  border: 1px solid black;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://rawgit.com/kangax/fabric.js/master/dist/fabric.min.js"></script>
<input type="file" id="file"><br />
<canvas id="canvas" width="450" height="450"></canvas>
 Run code snippet