How to prevent GWT onload flicker in the Web Application Starter Project? - gwt

I'm new to GWT, and I'm sure this is answered in SO somewhere but I've yet to find
I downloaded the GWT 2.0 eclipse plugin, and was pleased to see it comes with a starter project.
However, I was surprised that when running it, there is an unpleasent flickering...
The text loads without the CSS first
It takes a while untill the select box apears
(If you don't see the flicker, try and press F5 to refresh)
All mature GWT apps seem to have a loader before that but I didn't find an easy, standard way to add it.
It seems this app loads in this order: (correct me please if I mixed it up, its only my guess)
Basic layout HTML,
All JavaScript, and CSS
Runs the logic on the "onload" event (soonest time your compiled javaScript can start - ?)
So I can't programmatically add a loading spinner before GWT was loaded, a bit of a catch 22 for me
Am I missing something basic? is there a best practice way to add that initial spinner?
I was thinking simply adding a div with an animated gif, and in the onload event - hide it.
But I'm sure there is something better.
Let me know if this is a duplicate question
Update: found this related question, not answering mine though...

I've handled this problem before by not using the GWT module to load CSS, but loading it directly in the tag itself. If you do this, the browser will always load the CSS first, even before the GWT JS is loaded.
This means you'll lose a bit of flexibility and speed, but its the only workaround I've used so far.
EDIT: Extra info cause I want the bounty :D
If you do not remove the
<inherits name='com.google.gwt.user.theme.standard.Standard'/> from your module.gwt.xml file, then the GWT standard theme is loaded in the JS file that GWT creates. This JS file loads after the HTML page renders, and injects the CSS after load. Hence the flicker.
To avoid the flicker, you can comment out that line and insert your own stylesheet into the <head> of your HTML file. This ensures your CSS loads before the HTML renders, avoiding any flicker. If you really want the GWT theme, you get it out of the source code.
To use a spinner with GWT is quite easy. One simple way would be to keep it in a div with an id in the HTML file itself. Then, in the onModuleLoad(), simply hide that div by calling RootPanel.get("spinner").setVisible(false);
That should show the spinner till GWT loads itself.

Here's what we do to implement a spinner.
You put something like the following HTML just below the script line that loads your application (ie. the one with nocache.js). e.g.:
<div id="loading">
<div id="loading-msg">
<img src="icons/loading-page.gif" lt="loading">
<span>Loading the application, please wait...</span>
</div>
</div>
Then in your application EntryPoint you reach into the page using the DOM and remove that div. e.g.
final RootPanel loading = RootPanel.get("loading");
if (loading != null) {
DOM.removeChild(RootPanel.getBodyElement(),
loading.getElement());
}

Ehrann: I'm afraid the practice mentioned in the above answers is the only way for now. GWT doesn't provide similar features to show/hide a "loading" frame "on the fly". I guess one of the reason is that this requirement is not so "common" for all GWT users, one person might want a very different style of the "loading" than others. So you have to do that by yourself.
You can have a look at the GXT showcase page (based on GWT too): http://www.extjs.com/explorer/ for how they do that. For the source of it, download Ext GWT 2.1.0 SDK here: http://www.extjs.com/products/gxt/download.php and check the samples/explorer folder after extracting it. For details see the edit below:
EDIT
Check the source code for http://www.extjs.com/examples/explorer.html and you can see a div with id "loading". For each samples (extending Viewport), GXT.hideLoadingPanel(loadingPanelId) is called in onAttach() (the initialization), which hides the loading frame.
Check source code of Viewport here
Check source code of GXT.hideLoadingPanel here
You can do it in a similar way.

You could put an HTML loading message in the host page (use style attributes or embed the style tag in the header to make sure that it's styled), and remove the message once your modules has loaded, e. g. Document.get().getBody() with .setInnerHTML("") or .removeChild(), and then present your application programmatically however you want.

Related

Joomla 'PageNavigation' Plugin

If this isn't possible please let me know!
I'm hoping there's a solution to what I'm asking.
I need to move the Next/Prev buttons, located in the pagenavigation plugin to after the <jdoc:include type="component" />; Basically render it anywhere in my templates' index.php?
Is there any way to do this?
This is the code that renders the pagination:
<?php
if (!empty($this->item->pagination) && $this->item->pagination && $this->item->paginationposition && !$this->item->paginationrelative):
echo $this->item->pagination;
?>
<?php endif; ?>
As you can see the pagination is part of the item. As you can see if you look at the pagenavigation content plugin the pagination values are created in response to the onContentBeforeDisplay event. The plugin is hard coded to only work for articles in the single article view.
So to use it in a different component you would really need to create a second plugin for that component (or you could do any component or anything besides the single article view, that all would be easy to code using context).
To locate it in a different place in the single article view you would have to move the block of code to the desired location in the layout. Potentially you could also use css to locate the rendering of the block somewhere else on the page. (But more on this at the bottom.)
Unfortunately (but nor surprisingly given its name) onContentBeforeDisplay comes really late, in the view (unlike with pagination in the backend).
I always find it confusing because this frontend "pagination" property controlled by this plugin has nothing to do with backend pagination which is controlled by a JPagination object. I believe if is because of backward compatibility all the way to 1.0. ALso because the template chrome for pagination chrome are called pagination.php.
That leads me to the next thing I'll mention. You can make a file pagination.php and put it in the html folder of your template. You can see an example of this in the core template protostar. THat's where you would do the CSS or whatever other tricks you want to do to make the pagination do what you want. I think if you work hard enough at it (possibly using javascript or possibly calling that file from a module) you can pretty much achieve whatever you want.

How to show message during initial loading of gwt application?

I want to display a message (please wait...) or animated gif before the initial entire loading of my gwt application.
Can you give me a full example please.
Thanks
Because the GWT app is not yet loaded, you have to do it in pure HTML/CSS and/or JS in your HTML host page. The easiest is to just put it in your <body> and when the GWT app loads it starts by cleaning that "loading" message (e.g. Document.get().getElementByid("loading").removeFromParent())
Another possibility is to use code-splitting: make a first fragment that's as small as possible and will display your "loading" message, and load the rest of the app in the background. In the RunAsyncCallback, hide your "loading" message.
That said, if you feel the need to display such a "loading" message, then IMO you have a bigger problem than finding how to display it (and if you struggle to find how to display one, you're in bad shape to build an app that people will enjoy using; fortunately, this is fixable: keep learning!).

How to keep NPAPI plugins alive in ExtJS tabbed views

I'm trying to use a custom video player NPAPI plugin (view FireBreath) inside an tabbed ExtJS application. The plugin lives in one tab, and the others contain presentations of other non-video data.
When switching from tab to tab, the element that contains the plugin is destroyed, and all plugin state is lost. Is there any way to configure an ExtJS tabbed panel so that the html contained in it is not altered when switching to another tab (just hidden)? The alternative is to re-populate the plugin state when returning to the tab, but this would be associated with an unacceptable delay (mostly while waiting for video key frames).
Thanks,
O
I don't know about your ExtJS approach, if you can solve it on that side that would of course be preferrable.
However, if you can't, you can avoid the reinitialization by moving the stream handling to a helper application that is running in the background. The plugin would launch it as needed and receive the stream data from it after registering for it.
The helper would be told when to kill a stream and possibly kill it by itself after some timeout (to avoid session leaks in case of crashing plugins etc.).
I was about to consider a helper application as recommended above, or look into rewriting the plugin to be windowless. Both might be more robust solutions for other JS frameworks.
Fortunately, the solution ended up being simpler than this, at least for ExtJS. By default, ExtJS sets "display: none" on the tabbed view's div whenever it is undisplayed, which calls the plugin destructor. After doing a little more looking through their enormous API, ExtJS has a parameter hideMode as part of the Ext.panel.Panel base class:
'display' : The Component will be hidden using the display: none style.
'visibility' : The Component will be hidden using the visibility: hidden style.
'offsets' : The Component will be hidden by absolutely positioning it out of the visible area of the document. This is useful when a hidden Component must maintain measurable dimensions. Hiding using display results in a Component having zero dimensions.
Defaults to: "display"
Setting the parent Panel that contains the plugin to hideMode: 'offsets' fixed the problem perfectly.

jQuery Show/Hide divs using same class not working because of html.push?

The object is to Show-Hide text located under their respective Titles, so a User reads the title and shows or hides text belonging to that title if the User wants to read more.
I tried whatever I could find so far on here, we're talking dynamically setting text coming from a spreadsheet, can't use IDs, must work with .class, must be missing something, I have this piece of code:
... html.push('<div class="comments">' + comment + '</div></div></div>');
but when I try this Show-Hide code nothing happens, even if the error console shows nothing. Basically I want to Show-Hide the .comments class divs with a show-hide toggle link located under each of them. I say them because the .comments divs are reproduced dynamically while extracting text coming from Google spreadsheet cells/row (one .comments div per spreadsheet row). I tried .next, child and parent but they all divorced me so I dunno looks like a dynamic issue. So far I only managed to globally toggle all divs to a visible or hidden state but I need to toggle independantly individual divs.
I prefer a jQuery solution but whatever worked so far was achieved with native javascript.
Note: If a cross-browser truncate function which would append a more-less link after a number of words (var) in each .comments divs would be easier to implement then I would gladly take that option. Thx for any help, remember I am still learning lol!
I have been working on an entirely JS UI project and have brought myself to using $('', { properties }).appendTo(BaseElement) to work best for adding HTML elements because it appropriately manipulates the DOM every time.
If you are having good luck with push elsewhere, however, breakpointing on the line where you do your $('.class').hide() and see what $('.class').length is. Alternately, you can just add alert($('.class').length) to your code if you are unable to breakpoint the code. If it is 0, then your elements have not been properly added to the DOM. Changing to append will ensure they are part of the DOM and therefore targetable via JQuery.

SmartGWT Widgets not displaying properly

I have a basic GWT Maven project going. I added SmartGWT and started playing around with some widgets and nothing displays correctly. The ListGrid seems to somewhat render but things are off and even data isnt showing up (though the rows respond to indicate there is data within the row). Sorting arrows dont appear but are clickable, and filters are wildy off. Whats causing this. I deleted everything in the .css file.
GWT newbie here.
Did you add the following to your host html file?
var isomorphicDir = "MODULE_NAME/sc/";
where MODULE_NAME is the name of your GWT module. ie the name you have in your GWT module xml file.
See http://forums.smartclient.com/showthread.php?t=8159#aImages
fyi the next release of Smart GWT will no longer require users to add the isomorphicDir variable to the host html file.