Dropupload
Dropupload
- Demonstration: N/A
- Java API: Dropupload
- JavaScript API: Dropupload
- Style Guide: N/A
- Available in ZK EE only
Employment/Purpose
Dropupload leverages HTML 5 technology to handle file uploading where users can simply drag and drop the file(s) they want to upload into Dropupload and the uploading process will start automatically. The behaviour and operation of this Dropupload component is similar to ZK's file upload button but with better user experience and performance.
Example
Following is a typical example of its implementation, it will always show component and limit the upload file size.
<dropupload maxsize="5120" detection="none" onUpload="doSomething(event)">
<attribute name="content"><![CDATA[
<b>Drop Here</b><br/>
size < 5MB
]]></attribute>
</dropupload>
Another example, it will detect the drag action:
<zk>
<vlayout>
<image id="img" />
Upload your hot shot:
<dropupload maxsize="-1" content="content" detection="browser" onUpload="img.setContent(event.media)" />
</vlayout>
</zk>
Maxsize
The maxsize attribute is used for limiting the file size of a single file in which users are allowed to upload. Users are allowed to drag in two or more files at once but each of them has to be smaller than the size set by Maxsize. If one of the files is larger than the size set by Maxsize, an error message will occur and nothing will be uploaded.
For example, in the case of the previous sample code, you can upload multiple files, say, four files that are smaller than 5120KB at once but if one of them exceeds 5120KB, then an exception will occur and none of the four files will be uploaded to the server.
The unit of MaxsizeM attribute is in KB. If it is not assigned a value, it will use the value of Configuration.getMaxUploadSize() automatically while a negative value would mean that the file size is set as unlimited.
Detection
This attribute will define what users see when they drag and drop files into the application i.e. how the Dropupload component and its content will appear according to their action.
There are four valid values of detection
:
none
: Ignore users' drag action, always show Dropupload and its content.browser
(default setting) : Dropupload is not visible in the application initially but shows up along with the content when users drag files into the browser.self
: Dropupload is visible in the application initially but the content only appears when users drag files into the component.- id of another component : Behaviour of this value is almost identical to
self
, except that the trigger area is inside the component of the appointed id.
The content
value can be any HTML string and remember to surround the content value by CDATA
block .
Note : A Dropupload with detection="browser"
cannot be used with another Dropupload component that has a different detection value; users won't be able to drag a file into the component successfully.
Anchor
since 7.0.2
This attribute allows the dropupload component to anchor to another component and overlay that component when the user drag & drops files to the browser. Much like how Gmail works when dropping attachments to emails.
Example
<zk>
<div height="100px"></div>
<tabbox height="100px">
<tabs>
<tab id="A" label="Tab A" />
<tab id="B" label="Tab B" />
</tabs>
<tabpanels id="tps">
<tabpanel>This is panel A</tabpanel>
<tabpanel>This is panel B</tabpanel>
</tabpanels>
</tabbox>
<dropupload anchor="${tps}"></dropupload>
</zk>
MaxFileCount
Default: -1
Set the maximum number of files a user can upload at once, -1 means no limit. When the number of upload files exceeds the max file count, nothing will be uploaded and onMaxFileCountExceed
event will be fired, developers can listen to that event and get the number of uploaded files by calling event.getData()
.
For example (MVVM pattern):
<dropupload onMaxFileCountExceed="@command('maxFileCountExceed', filesCount=event.data)" />
@Command
public void maxFileCountExceed(@BindingParam("filesCount") Integer filesCount) {
Messagebox.show(filesCount + " files exceed the number of upload files limitation.");
}
Do not Convert File
By default, ZK will convert upload file to image, audio and text file if possible. Developer can use native="true"
to demand ZK don't convert file.
Customized File Viewer
Similar to file upload button, the default file viewer will show the uploading progress via a pop-up bar as illustrated below.
Alternatively, developers can also design customized File Viewer by implementing a JavaScript class to handle the display screen when uploading files. Below is an example of a customized file viewer where the progress bar is shown at the bottom of the browser.
foo.MyFileViewer = zk.$extends(zk.Object, {
updated: null,
$init: function (uplder, file) {
this._uplder = uplder;
var id = uplder.id,
uri = zk.ajaxURI('/web/zk/img/progress2.gif', {au:true}),
html = '<div id="' + id + '" class="viewer"><image class="float-left" src="' + uri + '"/>'
+ '<div class="float-left">FileName: ' + file.name
+ ' <a id="' + id + '-cancel">Cancel</a></div><div class="float-right">'
+ msgzk.FILE_SIZE + ': <span id="' + id + '-sent">0</span> of '
+ '<span id="' + id + '-total">0</span></div><div class="clear"></div></div>';
jq(uplder.getWidget().getPage()).append(html);
this.viewer = jq('#'+ id)[0];
jq('#' + id + '-cancel').click(function() {
uplder.cancel();
});
},
update: function (sent, total) {
jq('#'+ this._uplder.id + '-sent').html(Math.round(sent/1000) + msgzk.KBYTES);
if (!this.updated) {
this.updated = true;
jq('#'+ this._uplder.id + '-total').html(Math.round(total/1024)+msgzk.KBYTES);
}
},
destroy: function () {
jq(this.viewer).remove();
}
});
In the code snippet above, you can see that there are three functions - $init, update, and destroy.
- $init(uplder, file): When the user selects a file from the file chooser, this function will be invoked.
- uplder: An uploader object
- file: The file user uploads. It is a File object.
- update(send, total): After the uploading engine receives the size that has already been uploaded, this function will be invoked.
- sent: An integer of the uploaded size.
- total: An integer of the total uploaded size.
- destroy(): After the file has been uploaded or if the uploading has been canceled or if the uploading has caused an error, this function will be invoked.
After customizing your JavaScript class which in this case is foo.MyFileViewer
, assign it to Dropupload using the viewerClass
attribute as demonstrated below:
<dropupload viewClass="foo.MyFileViewer" content="custom viewer" detection="none" />
Uploader
Below is a summarised description table of the Uploader when passed a selected file from the user.
Method | Usage |
---|---|
getWidget | Indicate which component the widget belongs to |
cancel | Stops the uploading process. |
Transforming the original File Viewer
Customized File Viewers written in the past can also be applied to Dropupload with only some slight changes :
- Originally, the second parameter of
$init()
isfilenm
(type: String). To apply it to the new Dropupload component, change the second parameter tofile
(type: File) object and add another line offilenm = file.name
to solve the issue.
//before
$init: function (uplder, filenm) {
//routine
}
//after
$init: function (uplder, file) {
var filenm = file.name;
//routine
}
- The first parameter of
update()
,send
would originally pass an integer value ranging from 0 to 100, representing the percentage of the uploading process whereas now it will pass the value of the already uploaded size of data in Bytes.
Customize Upload Size Exceeding Message
Please refer to ZK_Component_Reference/Essential_Components/Button#Customize_Upload_Size_Exceeding_Message
Event For Completed Uploads
After the upload is finished, the uploaded files can be retrieved from the companion event, which is an instance of UploadEvent. For example,
<zscript><![CDATA[
public void showFileName(org.zkoss.zk.ui.event.UploadEvent event){
org.zkoss.util.media.Media[] medias = event.getMedias();
StringBuffer sb = new StringBuffer();
for (org.zkoss.util.media.Media m : medias) {
sb.append(m.getName()+"\n");
}
Messagebox.show(sb.toString());
}
]]></zscript>
<dropupload detection="none" onUpload="showFileName(event)" />
Browser Support
As Dropupload leverages HTML5 technology, some browsers don't support it. Currently, it works normally on Firefox (v.13), Chrome (v.19) and Safari (v.5.1.x), but doesn't function in IE 9, Opera v.11.x, and Microsoft Edge.
Moreover, the detection
setting cannot be displayed on some older machines.
Supported Events
Event: UploadEvent
This event will be triggered once a user has uploaded a file. | |
Event: Event
This event will be triggered when number of upload files exceed the maxFileCount. |
- Inherited Supported Events: LabelImageElement
Supported Children
*NONE
Use Cases
Version | Description | Example Location |
---|---|---|
Version History
Version | Date | Content |
---|---|---|
6.5.0 | June, 2012 | Dropupload was introduced. |
7.0.2 | March, 2014 | ZK-2207: Dropupload support anchor |