27 квітня 2012 р.

A plug-in for fast image loading in MarkItUp

Let's talk about writing a plug-in for the markItUp WYSIWYG editor. The task of the plug-in should be quick and easy loading of images to the server to be inserted into a text afterwards (in the form of img tag).

t all started with the ticket «Upload images in markItUp». Search of ordinary turnkey solutions led almost to nothing. The only solution that worked – was the plug-in https://gist.github.com/783934, but it does have a few drawbacks:

• Many dependencies from «extra» jQuery plugins.
• Too bulky JS and CSS.

Well, we could either alter (or simplify) this plug-in or write our own. After starting to go the first way, I almost insensibly moved to the second one and eventually this JS code appeared:

var InlineUpload = {
    dialog: null,
    options: {
        form_class: 'inline_upload_form', // class form
        action: '/posts/upload', // URL to which the POST with downloaded file will be send
        iframe: 'inline_upload_iframe' // name of the iframe
    },
    display: function(hash) { // method that assumes a click on the button in markItUp
        var self = this;
 
        this.dialog = $(document).find(".inline_upload_container");
 
        if (!this.dialog.size()) { // there is no DOM in our hidden div, let’s create it
            // the form with iframe inside an invisible div and attach it to the body
            this.dialog = $([
                '<div style="opacity:0;position:absolute;" class="inline_upload_container"><form class="',this.options.form_class,'" action="',this.options.action,'" target="',this.options.iframe,'" method="post" enctype="multipart/form-data">',
                '<input name="form[inlineUploadFile]" type="file" /></form>' +
                '<iframe id="',this.options.iframe,'" name="',this.options.iframe,'" class="',this.options.iframe,'" src="about:blank" width="0" height="0"></iframe></div>',
            ].join(''));
            this.dialog.appendTo(document.body);
        }
 
        // Do click on the input [type = file]in the hidden div'e
        // to show the system dialog of the file selection
        $("input[name='form[inlineUploadFile]']").focus(); // Hack for chrome and others
        $("input[name='form[inlineUploadFile]']").trigger('click');
 
        // After the file has been selected, we send our hidden form to the server
        $("input[name='form[inlineUploadFile]']").live('change', function(){
            if ($(this).val() != '') { // if the file was not selected, nothing terrible would happen
                $('.' + self.options.form_class).submit();
            }
        });
 
        // The answer will be given in a hidden iframe
        $('.' + this.options.iframe).bind('load', function() {
            var responseJSONStr = $(this).contents().find('body').html();
            if (responseJSONStr != '') { // server returned us the answer, so we are to parse it
                var response = $.parseJSON(responseJSONStr);
                if (response.status == 'success') { // if all is well
                    var block = ['<img src="' + response.src + '" width="' + response.width + '" height="' + response.height + '" alt="" class=""/>'];
                    $.markItUp({replaceWith: block.join('')} ); // Add the img tag to the text
                } else {
                    alert(response.msg); // got an error message
                }
                self.cleanUp(); // cleanUp() removes a hidden div with the form and iframe out of the DOM
            }
        });
    },
    cleanUp: function() {
        $("input[name='form[inlineUploadFile]']").die('change');
        this.dialog.remove();
    }
};

To connect our plug-in, you need to add a new button to setup of markItUp panels:

{
    name:'PictureUpload', key:'P', beforeInsert: function(markItUp) { InlineUpload.display(markItUp) }
},

And on the side of the backend we need to add a handler for files uploading (an example of action for Symfony2):

/**
 * Upload photo
 *
 * @return string
 * @Route("/posts/upload", name="blog_post_upload_image")
 * @Method({"POST"})
 */
public function uploadImageAction()
{
    // Create a validator
    $collectionConstraint = new Collection(array(
        'inlineUploadFile' => new Image(array('mimeTypes' => array("image/png", "image/jpeg", "image/gif"))),
    ));
 
    // Create "on the fly" the form with our validator
    $form = $this->createFormBuilder(null, array(
        'csrf_protection' => false,
        'validation_constraint' => $collectionConstraint
        ))
            ->add('inlineUploadFile', 'file')
            ->getForm();
 
    $form->bindRequest($this->get('request'));
    if ($form->isValid()) {
        // File processing
        $file = $form->get('inlineUploadFile')->getData();
        $ext = $file->guessExtension();
 
        if ($ext == '') {
            $response = array(
                'msg' => 'A file seems a bit suspicious! I do not want to accept it.',
            );
        } else {
            //Save the file
            $uploadDir = realpath($this->get('kernel')->getRootDir() . '/../web/uploads/images');
            $newName = uniqid() . '.' . $ext;
            $file->move($uploadDir, $newName);
            $info = getImageSize($uploadDir . '/' . $newName);
 
            //Return such an answer, if all is well
            $response = array(
                'status' => 'success',
                'src' => '/uploads/images/' . $newName,
                'width' => $info[0],
                'height' => $info[1],
            );
        }
    } else {
        // Return such an answer if everything is bad
        $response = array(
            'msg' => 'Your file is not valid!',
        );
    }
 
    return new Response(json_encode($response));
}

This way we got the easiest to use plug-in. A user by clicking the icon of the picture immediately receives a file selection dialog, and after selecting has a ready line in the editor.

This example is very simple. If you wish, it can be more difficult, for example, instead of hidden forms - to show it in the dialogue, sending the server a few pictures, etc.