javascript - 如何在前端截取包含用户上传图片的 div 的屏幕截图？

Question

请看这段代码。在下面的代码中，用户可以上传图片，他们可以移动、调整大小、旋转上传的图片等。

$(function() {
  var inputLocalFont = $("#user_file");
  inputLocalFont.change(previewImages);

  function previewImages() {
    var fileList = this.files;
    var anyWindow = window.URL || window.webkitURL;

    for (var i = 0; i < fileList.length; i++) {
      var objectUrl = anyWindow.createObjectURL(fileList[i]);
      var $newDiv = $("<div>", {
        class: "img-div"
      });
      var $newImg = $("<img>", {
        src: objectUrl,
        class: "newly-added"
      }).appendTo($newDiv);
      $(".new-multiple").append($newDiv);
      $newDiv.draggable();
      $newDiv.rotatable();
      $newDiv.resizable({
        aspectRatio: true,
        handles: "ne, nw, e, se, sw, w"
      });
      $newDiv.find(".ui-icon").removeClass("ui-icon ui-icon-gripsmall-diagonal-se");
      window.URL.revokeObjectURL(fileList[i]);
    }
    $(".newly-added").on("click", function(e) {
      $(".newly-added").removeClass("img-selected");
      $(this).addClass("img-selected");
      e.stopPropagation()
    });

    $(document).on("click", function(e) {
      if ($(e.target).is(".newly-added") === false) {
        $(".newly-added").removeClass("img-selected");
      }
    });
  }
   $(".user_submit").on("click",function(e){
   e.preventDefault();
   html2canvas($('.new-multiple'), {
     allowTaint: true,
	  onrendered: function(canvas) {
		document.body.appendChild(canvas);
		}
});
  
  
  });

});

.new-multiple {
  width: 400px !important;
  height: 400px !important;
  background: white;
  border: 2px solid red;
  overflow: hidden;
}

.img-div {
  width: 200px;
  height: 200px;
}

.newly-added {
  width: 100%;
  height: 100%;
}

.img-selected {
  box-shadow: 1px 2px 6px 6px rgb(206, 206, 206);
  border: 2px solid rgb(145, 44, 94);
}


/*
.ui-resizable-handle.ui-resizable-se.ui-icon.ui-icon-gripsmall-diagonal-se {
  background-color: white;
  border: 1px solid tomato;
}
*/

.ui-resizable-handle {
  border: 0;
  border-radius: 50%;
  background-color: #00CCff;
  width: 14px;
  height: 14px;
}

.ui-resizable-nw {
  top: -7px;
  left: -7px;
}

.ui-resizable-ne {
  top: -7px;
  right: -7px;
}

.ui-resizable-e {
  top: calc(50% - 7px);
  right: -7px;
}

.ui-resizable-w {
  top: calc(50% - 7px);
  left: -7px;
}

.ui-resizable-sw {
  bottom: -7px;
  left: -7px;
}

.ui-resizable-se {
  right: -7px;
  bottom: -7px;
}

.ui-resizable-se.ui-icon {
  display: none;
}

.ui-rotatable-handle {
  background-size: 14px;
  background-repeat: no-repeat;
  background-position: center;
  border: 0;
  border-radius: 50%;
  background-color: #00CCff;
  margin-left: calc(50% - 9px);
  bottom: -5px;
  width: 18px;
  height: 18px;
}

<link href="https://code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css" rel="stylesheet"/>
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
<link href="https://cdn.jsdelivr.net/gh/godswearhats/jquery-ui-rotatable@1.1/jquery.ui.rotatable.css" rel="stylesheet"/>
<script src="https://cdn.jsdelivr.net/gh/godswearhats/jquery-ui-rotatable@1.1/jquery.ui.rotatable.min.js"></script>
 <script src="https://html2canvas.hertzen.com/build/html2canvas.js"></script>

<form method="post" action="">


<input name="user_file[]" id="user_file" style="position: relative;overflow: hidden" multiple="" type="file">

<div class="new-multiple"></div>
<input type="submit" name="submit" class="user_submit" value="submit" />
</form>

https://jsfiddle.net/s99kxydw/15/

上传图片后，旋转、移动然后用户将按下提交按钮。那个时候我们需要生成窗口的截图，这样用户和我们都可以了解到用户做了什么修改。这是我们的要求。

How we can generate this screenshot ?

我们找到了一个解决方案。即 html2canvas https://html2canvas.hertzen.com/

但问题是 html2canvas 不支持 css transform 属性

因此屏幕截图中没有旋转。我们怎么能克服这个。请检查代码。

有没有不用html2canvas的其他方法？

Answer 1

我明白你的问题是什么，因为我用 html2canvas 做过类似的事情。它的问题。是它不能保存所有内容，所以它可能不完全准确，例如它不能进行 css 文本剪辑。这对我有用(我下载了图像，但您可以轻松保存它，请查看此链接以了解如何执行此操作):

html2canvas($('.classOfElementToSave'), {
      allowTaint: true,
      onrendered: function(canvas) {
        var dataURL = canvas.toDataURL();
        $.ajax({
          type: "POST",
          url: "script.php",
          data: { 
             imgBase64: dataURL
          }
        }).done(function(o) {
          console.log('saved'); 
          // If you want the file to be visible in the browser 
          // simply return the url previously saved
    });
      }
  });

然后在您的 script.php 或文件(或您所称的任何文件)中:

$img = $_POST['data'];
$img = str_replace('data:image/png;base64,', '', $img); //Because saved as a data image
$img = str_replace(' ', '+', $img);
$fileData = base64_decode($img);
//saving the image to server
$fileName = 'image.png';
file_put_contents($fileName, $fileData);