friendica-github/view/templates/item/compose.tpl

<div class="generic-page-wrapper">
	<h2>{{$l10n.compose_title}}</h2>
    {{if $l10n.always_open_compose}}
	<p>{{$l10n.always_open_compose nofilter}}</p>
	{{/if}}
	<div id="profile-jot-wrapper">
		<form class="comment-edit-form dropzone" data-item-id="{{$id}}" id="comment-edit-form-{{$id}}" action="compose/{{$type}}" method="post">
		    {{*<!--<input type="hidden" name="return" value="{{$return_path}}" />-->*}}
			<input type="hidden" name="post_id_random" value="{{$rand_num}}" />
			<input type="hidden" name="post_type" value="{{$posttype}}" />
			<input type="hidden" name="wall" value="{{$wall}}" />

			<div id="jot-title-wrap">
				<input type="text" name="title" id="jot-title" class="jothidden jotforms form-control" placeholder="{{$l10n.placeholdertitle}}" title="{{$l10n.placeholdertitle}}" value="{{$title}}" tabindex="1" dir="auto" />
			</div>
		    {{if $l10n.placeholdercategory}}
				<div id="jot-category-wrap">
					<input name="category" id="jot-category" class="jothidden jotforms form-control" type="text" placeholder="{{$l10n.placeholdercategory}}" title="{{$l10n.placeholdercategory}}" value="{{$category}}" tabindex="2" dir="auto" />
				</div>
		    {{/if}}

			<p class="comment-edit-bb-{{$id}} comment-icon-list">
				<span>
					<button type="button" class="btn btn-sm template-icon bb-img" aria-label="{{$l10n.edimg}}" title="{{$l10n.edimg}}" data-role="insert-formatting" data-bbcode="img" data-id="{{$id}}" tabindex="7">
						<i class="fa fa-picture-o"></i>
					</button>
					<button type="button" class="btn btn-sm template-icon bb-attach" aria-label="{{$l10n.edattach}}" title="{{$l10n.edattach}}" ondragenter="return commentLinkDrop(event, {{$id}});" ondragover="return commentLinkDrop(event, {{$id}});" ondrop="commentLinkDropper(event);" onclick="commentGetLink({{$id}}, '{{$l10n.prompttext}}');" tabindex="8">
						<i class="fa fa-paperclip"></i>
					</button>
				</span>
				<span>
					<button type="button" class="btn btn-sm template-icon bb-url" aria-label="{{$l10n.edurl}}" title="{{$l10n.edurl}}" onclick="insertFormatting('url',{{$id}});" tabindex="9">
						<i class="fa fa-link"></i>
					</button>
					<button type="button" class="btn btn-sm template-icon underline" aria-label="{{$l10n.eduline}}" title="{{$l10n.eduline}}" onclick="insertFormatting('u',{{$id}});" tabindex="10">
						<i class="fa fa-underline"></i>
					</button>
					<button type="button" class="btn btn-sm template-icon italic" aria-label="{{$l10n.editalic}}" title="{{$l10n.editalic}}" onclick="insertFormatting('i',{{$id}});" tabindex="11">
						<i class="fa fa-italic"></i>
					</button>
					<button type="button" class="btn btn-sm template-icon bold" aria-label="{{$l10n.edbold}}" title="{{$l10n.edbold}}" onclick="insertFormatting('b',{{$id}});" tabindex="12">
						<i class="fa fa-bold"></i>
					</button>
					<button type="button" class="btn btn-sm template-icon quote" aria-label="{{$l10n.edquote}}" title="{{$l10n.edquote}}" onclick="insertFormatting('quote',{{$id}});" tabindex="13">
						<i class="fa fa-quote-left"></i>
					</button>
				</span>
			</p>
			<p>
				<textarea id="comment-edit-text-{{$id}}" class="comment-edit-text form-control text-autosize" name="body" placeholder="{{$l10n.default}}" rows="7" tabindex="3" dir="auto" dir="auto">{{$body}}</textarea>
			</p>

			<p class="comment-edit-submit-wrapper">
{{if $type == 'post'}}
				<span role="presentation" class="form-inline">
					<input type="text" name="location" class="form-control" id="jot-location" value="{{$location}}" placeholder="{{$l10n.location_set}}"/>
					<button type="button" class="btn btn-sm template-icon" id="profile-location"
					        data-title-set="{{$l10n.location_set}}"
					        data-title-disabled="{{$l10n.location_disabled}}"
					        data-title-unavailable="{{$l10n.location_unavailable}}"
					        data-title-clear="{{$l10n.location_clear}}"
					        title="{{$l10n.location_set}}"
					        tabindex="6">
						<i class="fa fa-map-marker" aria-hidden="true"></i>
					</button>
				</span>
{{/if}}
				<span role="presentation" id="profile-rotator-wrapper">
					<img role="presentation" id="profile-rotator" src="images/rotator.gif" alt="{{$l10n.wait}}" title="{{$l10n.wait}}" style="display: none;" />
				</span>
				<span role="presentation" id="character-counter" class="grey text-info"></span>
				<button type="button" class="btn btn-defaul" onclick="preview_comment({{$id}});" id="comment-edit-preview-link-{{$id}}" tabindex="5"><i class="fa fa-eye"></i> {{$l10n.preview}}</button>
				<button type="submit" class="btn btn-primary" id="comment-edit-submit-{{$id}}" name="submit" tabindex="4"><i class="fa fa-envelope"></i> {{$l10n.submit}}</button>
                                <div id="dz-previewsCompose" class="dropzone-previews"></div>
			</p>

			<div id="comment-edit-preview-{{$id}}" class="comment-edit-preview" style="display:none;"></div>

{{if $type == 'post'}}
			<h3>{{$l10n.visibility_title}}</h3>
			{{$acl_selector nofilter}}

			<div class="jotplugins">
				{{$jotplugins nofilter}}
			</div>

			{{if $scheduled_at}}{{$scheduled_at nofilter}}{{/if}}
			{{if $created_at}}{{$created_at nofilter}}{{/if}}
{{else}}
			<input type="hidden" name="group_allow" value="{{$group_allow}}"/>
			<input type="hidden" name="contact_allow" value="{{$contact_allow}}"/>
			<input type="hidden" name="group_deny" value="{{$group_deny}}"/>
			<input type="hidden" name="contact_deny" value="{{$contact_deny}}"/>
{{/if}}
		</form>
	</div>
</div>
<script>
    var dropzoneCompose = new Dropzone(document.body,  { // camelized version of the `id`
    paramName: "userfile", // The name that will be used to transfer the file
    maxFilesize: 2, // MB
    previewsContainer: '#dz-previewsCompose',
    preventDuplicates: true,
    clickable: true,
    thumbnailWidth: 100,
    thumbnailHeight: 100,
    url: "/media/photo/upload?response=url&album=",
    accept: function(file, done) {
      done();
    },
    init: function() {
        this.on("success", function(file, serverResponse) {
                var target = $(':focus').closest('.comment-edit-form').find('.comment-edit-text');
                var resp = $(serverResponse).find('div#content').text()
                if (target.setRangeText) {
                    //if setRangeText function is supported by current browser
                    target.setRangeText(" " + $.trim(resp) + " ")
                } else {
                    target.focus()
                    document.execCommand('insertText', false /*no UI*/, $.trim(resp));
                }
        });
    },
  });
  document.onpaste = function(event){
    const items = (event.clipboardData || event.originalEvent.clipboardData).items;
    items.forEach((item) => {
      if (item.kind === 'file') {
        // adds the file to your dropzone instance
        console.log(item);
        dropzoneCompose.addFile(item.getAsFile())
      }
    })
  }
</script>