I'm trying to understand how Facebook implements the chat sidebar. It seems to stay there even as I change pages. For example, if I select some text inside the sidebar, then click to go to another Facebook page, the text remains selected. It's as if it was a separate frame, but when I look at the code, it's not.
All requests are made trough AJAX calls. Only "content" container is replaced when needed.
You don't actually "go" to another page. Just the "content" div gets updated.
There is a container DOM element called "fb_content", its content is replaced through straight-forward AJAX or more technically XMLHttpRequest. (Although when for example you enter an app, the entire page is refreshed.) To update the address bar they use the JavaScript History API.
In addition to what Zeno and lericson said (fb_content gets updated via ajax), the address bar also gets updated while maintaining the history (if you press back/forward).
Related
I'm creating a web-site using GWT for the first time. The aplication has two Composite class, one of them is a menu and the other one is where I show de info about the specific menu that has been clicked. I'm using MVP, the class History and the interface ChangeValueHandler to switch among different pages.
I have one pair presenter-view for each Composite. The app begins well creating the menu and the section info. When you click in the menu it works fine showing the information and the token browser is changed. The thing is that if you load a page(eg: myapp.com#register) without loading the home page, it doesn't show you the menu. It loads the Composite section info, but not the Composite menu (the Composite menu is load with myapp.com#home).
I think it's because of a bad design of the application, but I don't know how to do that in other way. If the app only had one Composite it wouldn't be a problem, but when there are 2 or more Composite per page I don't know how to manage the whole thing to work properly.
It's difficult to tell what exactly is wrong, because of the lack of code. So I'm guessing. You should design to act on the PlaceChangeEvent instead of the ValueChangeEvent. That means a menu click should fire the place change and then the application will handle this event. That way you unbind the menu actions from your content pages. And think more of each page as a separate entity. Also take a look at the GWT Activity mechanism and how it helps having a main page that is always the same and on that main page a content area that changes depending on the page actually shown.
You should include your menu in each page instead of creating it once in the home page and then keeping it on screen. I assume you create the menu and add it to the DOM via
RootPanel.get().add(myMenuWidget);
If you are using UIBinder it should be pretty straightforward to include the menu in each page, just a matter of adding the corresponding tag in each .ui.xml file of your pages.
I am building an application using Zend Framework and i need insert one iframe in footer this application but, when i press F5 or click link or button, all page refresh even iframe.
The layout zend is called everytime when i dispatcher an event to server, ready, the iframe too. (My iframe is in the foorter.phtml, ready, it called together layout).
Someone have an some idea how to resolve this question?
tks
You cannot refresh the whole page except for an iframe on the page. When you ask a browser to refresh a page, it will refresh the whole page, there's no way to do it any differently.
To do what you seem to want to do, without using Javascript/AJAX, you'd have to use two frames. One for the top part of your website, and one for your footer. Here is an introduction to frames and how they work (iframes are similar, they are just "internal frames"): http://www.w3.org/TR/html4/present/frames.html
Please, however, note that using frames/iframes is not a practice I personally encourage. You should ask yourself why you are trying to do this. If it's to reload only a certain part of the page, then you should probably check into Javascript/AJAX alternatives.
If you want to disable the layout for some action you can use $this->_helper->layout ()->disableLayout ();. Put it in the iframe action, which will disable the layout and will show only the view of the action.
When to use HyperLink and when to use Anchor?
When using HyperLink how to handle clicks?
com.google.gwt.user.client.ui.Hyperlink.addClickHandler(ClickHandler) is deprecated
com.google.gwt.user.client.ui.Hyperlink.addClickListener(ClickListener) is deprecated as well.
Doc suggests to use Anchor#addClickHandler, but how to use Anchor#addClickHandler when using HyperLink
Does it mean that if I need to handle click I should always use Anchor and never use HyperLink?
Great question, because it is so simple, and yet opens up what might be a whole new area for a lot of GWT programmers. I've up-voted the question just because it can be a great lead-in for people exploring what GWT can do.
Anchor is a widget for storing and displaying a hyperlink -- essentially the <a> tag. Really not much more exciting than that. If you want your page to link to some external site, use anchor.
Links are also used for internal navigation. Let's say I have a GWT app that requires the user to login, so on my first panel I put a login button. When the user clicks it, I would display a new panel with widgets to collect the user's information, code to validate it, and then if validated successfully, reconstruct that first panel the user was on.
Buttons are nice, but this is a browser, and I want my user's experience to be more like a web page, not a desktop app, so I want to use links instead of buttons. Hyperlink does that. The documentation for hyperlink describes it well:
A widget that serves as an "internal" hyperlink. That is, it is a link
to another state of the running application. When clicked, it will
create a new history frame using History.newItem(java.lang.String),
but without reloading the page.
Being a true hyperlink, it is also possible for the user to
"right-click, open link in new window", which will cause the
application to be loaded in a new window at the state specified by the
hyperlink.
That second sentence should help clear it up. The hyperlink is not changing the page in a URL sense (the way anchor does), though the URL will reflect the state of the program by displaying the "token" associated with the hyperlink appended to the base URL after a slash. You define the token. It would be something descriptive like "login" or "help" or "about". But this isn't a new page. There is no additional HTML file you've had to construct to display a help page, for example. It is the state of the current GWT app that is changing. Even if you "open in a new window" you are just running the same app in a particular state.
It looks like a link, but it is really a widget that manipulates the history frame, which in turn allows you to move the state of your GWT application. You don't write a click handler for the hyperlink widget, but a value change handler for the history stack. When you see that the "help" token has been put on the history stack, your handler will execute GWT code to attach to the RootPanel a FlowPanel with embedded HTML text with your help information. This is perceived by the user as a "new page", which is what he expects when he clicks on a hyperlink. The URL will be something.html/help. Now pretend he returns to this URL via the back button, not your hyperlink. No problem. You don't care about the hyperlink click. You only care that, somehow, the history stack changes. Your value change handler fires again, and does the same thing as before to display the help panel. The user still enjoys the experience of navigating through web pages, even though you and I know that there is only one web page and that you are attaching and detaching panels to the RootPanel (or whatever scheme you are using to display your GWT panels).
And this leads to a bonus topic.
This bonus is a bit more complicated, but ironically, it could help better understand hyperlinks. I say more complicated, but really, it helps solidify this notion that a GWT application is made up of a series of states, and that the web page on the screen is just the user's perception of those state changes. And that is Activities and Places. Activities and Places abstracts away this history frame manipulation, handling it in the background once you've set up a mapper with a GWT-provided class designed for this purpose, allowing you to break down your app into a series of activities, and as the user interacts through these activities he is put into different places, and each place has a view. Moreover, the user can move from place to place using browser controls like the address bar, bookmarks, history, and the backward/forward buttons, giving the user a real web-like experience. If you really want to get a grip on the conceptual difference between hyperlinks and anchors, you should try to learn this GWT topic. It can really make you change the way you see your apps, and for the better.
Hyperlink (or InlineHyperlink) is basically no more than a kind of Anchor with a ClickHandler that calls History.newItem and preventDefault() the event (so that the link is not actually followed).
Actually, Hyperlink won't do that if it thinks (and yes, it's only a guess) you right-clicked or middle-clicked (or ctrl-clicked) on the link (depending on the browser), to open the link in a new window or tab.
If you need any other behavior, then don't use Hyperlink and use Anchor instead. And if you want to add some behavior to an Hyperlink, then use an Anchor and mimic what the Hyperlink does. And you can reuse the HyperlinkImpl to have the right-click/ctrl-click handling (see links below).
But actually, if you need something that looks like a link and do something on click, but does not have a "target URL" (i.e. it shouldn't be right-clicked/ctrl-clicked to open in a new window/tab, or it wouldn't mean anything to do so), then do not use either an ANchor or Hyperlink, use a Label of whatever instead, and make it look like a link (but well, maybe you should use a Button and have it look like a button then; Google used to have link-alike buttons –such as the "refresh" link/button in GMail– and changed them to look like buttons when they really aren't links).
See also https://groups.google.com/d/msg/google-web-toolkit/P7vwRztO6bA/wTshqYs6NM0J and https://groups.google.com/d/msg/google-web-toolkit/CzOvgVsOfTo/IBNaG631-2QJ
I have an activity with a mayStop() method. I am having two issues with it that pertain to a hyperlink on the page.
The first issue is that if I hit refresh or the window's X I get a dialog box that wraps my mayStop() text with "Are you sure you want to navigate away from this page?" and "Press OK to continue, or Cancel to stay on the current page." That is fine.
When I hit the hyperlink, I only see my mayStop() text without the wrapping text. Why is that?
The second issue is that if I hit Cancel in response to the hyperlink click, hitting the link again results in not getting the mayStop() challenge at all. It is as if I am not hitting the hyperlink.
Has anyone run into these issues?
Any thoughts?
Thanks,
Doug
The difference in "behavior" is that the first dialog box is the one from the browser when you try to prevent the user from navigating away, while the other is PlaceController calling Window.confirm(). Each browser uses a different dialog box for the first case, so there's no way to mimic it for everyone, and it's probably not a good thing either (navigating away from the app vs. navigating within the app).
As for your second issue, the events are generated by the browser "history" changing; if you prevent navigating away (from the Place), the URL stays the same (there's noway to know what to do to "rollback" the change: History.back(), History.next(), History.newItem() but then you destroy the existing "next" history ?), so when you click again on the link, you don't make the URL change, and no event is fired.
It's expected that you use PlaceController.goTo to navigate when you use places, not Hyperlink or History.
On Facebook you can browse the site without affecting the floating chat windows. Seems like if the main page was inside an iFrame and the footer and chat windows where floating outside.
(source: k-director.com)
Is the main content inside an iframe or are the footer and chat windows the ones inside an iframe?
The later doesn't seem possible because int this case when you click in a link in the main page everything would have to reload, including the footer iframe.
If you refresh the page the chat windows are reloaded, but if you browse the site by clicking links they are not.
Thank you.
If you install FireBug and enable the net monitor for Facebook, you'll see that when you click most links inside the application, you're not doing a full page refresh, but rather an AJAX call which updates the page with the new content.
It looks like a new page, but in reality you're on the same page with just about everything but the chat-bar replaced.
Probobly just an absolutely positioned div, containing a scrolling div for the content. Ajax would provide the content.
The chat windows do indeed refresh when you load a new page, they maintain their viewstate however (open/close/chat history).
It's an absolutely positioned div, positioned at the bottom of your browser window. It's not hard, I cloned the Facebook chat for ClockingIT from scratch in a weekend.