在Dropzone.js之前使用cropper.js将图像发送到服务器

Question

我想在这里做的是在Dropzone.js将丢弃的图像发送到服务器之前,使用cropper.js(fengyuanchen脚本)出现一个模态,这样用户就可以裁剪图像,当裁剪图像时,使用Dropzone.js发送它到服务器.

因此,当我使用函数fileToBase64更改#cropbox的图像src并使用函数cropper('replace')替换cropper的图像时,它会一直显示default.jpg图像,而不是从用户上传的新图像

HTML

<div class="wrapper-crop-box">
    <div class="crop-box">
        <img src="default.jpg" alt="Cropbox" id="cropbox">
    </div>
</div>

JS:

function fileToBase64(file) {
  var preview = document.querySelector('.crop-box img');
  var reader  = new FileReader();

  reader.onloadend = function () {
    preview.src = reader.result;
  }

  if (file) {
    reader.readAsDataURL(file);
  } else {
    preview.src = "";
  }
}

$(function() {
    Dropzone.options.avtDropzone = {
        acceptedFiles: 'image/*',
        autoProcessQueue: true,
        paramName: 'file',
        maxFilesize: 2,
        maxFiles: 1,
        thumbnailWidth: 200,
        thumbnailHeight: 200,
        accept: function(file, done) {
            fileToBase64(file); 
            $('#cropbox').cropper('replace', $('#cropbox').attr('src'));
            $('.wrapper-crop-box').fadeIn();
            done();
        },
        init: function() {
            this.on("addedfile", function(file) {
                if (this.files[1]!=null){
                    this.removeFile(this.files[0]);
                }
            });
        }
    };

    $('#cropbox').cropper({
      aspectRatio: 1 / 1,
      resizable: false,
      guides: false,
      dragCrop: false,
      autoCropArea: 0.4,
      checkImageOrigin: false,
      preview: '.avatar'
    });
});

Answer 1

你可能不再需要了,但我会把它留在这里:)

这有点棘手,我的解决方案可能在某种程度上"hackish",但它的工作原理,您不必上传服务器上的文件来调整大小.

我也在模态窗口中使用裁剪器.我想在上传到服务器之前强制用户将图像裁剪到一定的尺寸.

确认模态图像中的裁剪后立即上传.

// transform cropper dataURI output to a Blob which Dropzone accepts
function dataURItoBlob(dataURI) {
    var byteString = atob(dataURI.split(',')[1]);
    var ab = new ArrayBuffer(byteString.length);
    var ia = new Uint8Array(ab);
    for (var i = 0; i < byteString.length; i++) {
        ia[i] = byteString.charCodeAt(i);
    }
    return new Blob([ab], { type: 'image/jpeg' });
}

// modal window template
var modalTemplate = '<div class="modal"><!-- bootstrap modal here --></div>';

// initialize dropzone
Dropzone.autoDiscover = false;
var myDropzone = new Dropzone(
    "#my-dropzone-container",
    {
        autoProcessQueue: false,
        // ..your other parameters..
    }
);

// listen to thumbnail event
myDropzone.on('thumbnail', function (file) {
    // ignore files which were already cropped and re-rendered
    // to prevent infinite loop
    if (file.cropped) {
        return;
    }
    if (file.width < 800) {
        // validate width to prevent too small files to be uploaded
        // .. add some error message here
        return;
    }
    // cache filename to re-assign it to cropped file
    var cachedFilename = file.name;
    // remove not cropped file from dropzone (we will replace it later)
    myDropzone.removeFile(file);

    // dynamically create modals to allow multiple files processing
    var $cropperModal = $(modalTemplate);
    // 'Crop and Upload' button in a modal
    var $uploadCrop = $cropperModal.find('.crop-upload');

    var $img = $('<img />');
    // initialize FileReader which reads uploaded file
    var reader = new FileReader();
    reader.onloadend = function () {
        // add uploaded and read image to modal
        $cropperModal.find('.image-container').html($img);
        $img.attr('src', reader.result);

        // initialize cropper for uploaded image
        $img.cropper({
            aspectRatio: 16 / 9,
            autoCropArea: 1,
            movable: false,
            cropBoxResizable: true,
            minContainerWidth: 850
        });
    };
    // read uploaded file (triggers code above)
    reader.readAsDataURL(file);

    $cropperModal.modal('show');

    // listener for 'Crop and Upload' button in modal
    $uploadCrop.on('click', function() {
        // get cropped image data
        var blob = $img.cropper('getCroppedCanvas').toDataURL();
        // transform it to Blob object
        var newFile = dataURItoBlob(blob);
        // set 'cropped to true' (so that we don't get to that listener again)
        newFile.cropped = true;
        // assign original filename
        newFile.name = cachedFilename;

        // add cropped file to dropzone
        myDropzone.addFile(newFile);
        // upload cropped file with dropzone
        myDropzone.processQueue();
        $cropperModal.modal('hide');
    });
});