drag & drop image upload for concrete5.7.5.x. put this file into application/attributes/image_file/

controller.php

<?php
// LICENSE: MIT
// by Fumito MIZUNO
// forked from controller/attribute/image_file/controller.php

namespace Application\Attribute\ImageFile;


use Core;
use Database;
use File;
use FileImporter;

class Controller extends \Concrete\Attribute\ImageFile\Controller
{

    public function form()
    {
        $bf = false;
        $imgurl = \Core::getApplicationURL() . '/concrete/images/testbg.png';
        $value = 0;
        if ($this->getAttributeValueID() > 0) {
            $bf = $this->getValue();
            if(is_object($bf)) {
                $img = $bf->getApprovedVersion();
                if (in_array($img->getMimeType(),array('image/png','image/jpeg','image/gif'))) {
                    $imgurl = $img->getURL();
                } else {
                    $mime = new \Concrete\Core\File\Service\Mime;
                    $fileext = $mime->mimeToExtension($img->getMimeType());
                    $imgurl = \Core::getApplicationURL() . '/concrete/images/icons/filetypes/' . $fileext . '.png';
                }
                if ($img->getFileID()) {
                    $value = $img->getFileID();
                }
            }
        }

        $form = '<div class="ccm-attribute ccm-attribute-image-file">';
        $form .= Core::make('helper/form')->number($this->field('value'), $value, array('style' => 'display:none'));
        $form .= '<input type="file" accept="image/* style="height:60px;padding:10px;margin-bottom:10px" name="akID' . $this->attributeKey->getAttributeKeyID() . '" id="akID' . $this->attributeKey->getAttributeKeyID() . '" class="" />';
        $form .= '</div>';
        $form .= '<div><img id="thumbnail' . $this->attributeKey->getAttributeKeyID() . '" src="' . $imgurl . '" width="100" height="100"></div>';
        $form .= '<div><input type="checkbox" name="akID' . $this->attributeKey->getAttributeKeyID() . 'delete" id="akID' . $this->attributeKey->getAttributeKeyID() . 'delete" value="delete" />画像を削除する</div>';
        $form .= '<script>
$("#akID' . $this->attributeKey->getAttributeKeyID() . '").change(function(){
  if (this.files.length > 0) {
    var file = this.files[0];    
    // https://developer.mozilla.org/ja/docs/Web/API/FileReader/readAsDataURL
    var reader = new FileReader();
    reader.readAsDataURL(file);
    
    reader.onload = function() {
      $("#thumbnail' . $this->attributeKey->getAttributeKeyID() . '").attr("src", reader.result );
    }
  }
});
</script>';
        print $form;
    }

    public function saveForm($data)
    {


        $id = 'akID' . $this->attributeKey->getAttributeKeyID();
        $delete = $id . 'delete';
        $db = Database::connection();
        $value = $db->GetOne("select fID from atFile where avID = ?", array($this->getAttributeValueID()));

        $f = File::getByID($value);
        if (is_object($f)) {
            $filename = $f->getFileName();
        }
        // concrete5/blocks/form/controller::action_submit_form
        if ($data['value'] > 0 && $_POST[$delete] == 'delete') {
            $db = Database::connection();
            $db->Replace('atFile', array('avID' => $this->getAttributeValueID(), 'fID' => 0), 'avID', true);
        } elseif (isset($_FILES[$id]) && ($filename != $_FILES[$id]['name']) && $_FILES[$id]['tmp_name']) {
            $fi = new FileImporter();
            $resp = $fi->import($_FILES[$id]['tmp_name'], $_FILES[$id]['name']);
            if (!($resp instanceof Version)) {
                switch ($resp) {
                    case FileImporter::E_FILE_INVALID_EXTENSION:
                        $errors['fileupload'] = t('Invalid file extension.');
                        break;
                    case FileImporter::E_FILE_INVALID:
                        $errors['fileupload'] = t('Invalid file.');
                        break;
                }
            }
            $db = Database::connection();
            $db->Replace('atFile', array('avID' => $this->getAttributeValueID(), 'fID' => $resp->getFileID()), 'avID', true);
        } else if ($data['value'] > 0) {
            $db = Database::connection();
            $db->Replace('atFile', array('avID' => $this->getAttributeValueID(), 'fID' => intval($data['value'])), 'avID', true);
        }

    }

}