Bits and Pieces: Notifications and Menu Builders
It's been a while since I last wrote something here on Blog-O-Sphere. Probably most of you don't remember me anymore - but I'm still around, still experimenting with things Haiku in my free time.
During the weekends, I'm working on enhancing a very old BeOS application long lost in time. While browsing the Haiku kit and application source tree, sometimes I stumble upon some new (at least for me) but also interesting small elements that Haiku added to the Haiku API during its development. I like to try these elements out. Most of these API additions might change or even disappear in the nearest future, since I understand their development process is not yet finished, but they're interesting to know nevertheless.
I know some of these additions might be obvious to those up-to-date with the Haiku source code. But maybe some readers will find this at least a bit informative.
Just recently I have noticed that already since some time, Haiku has a built-in notifications system present, exported directly through the Application Kit. The class responsible for this functionality is BNotification, included through the Notification.h header file (present in headers/os/app). It's a very easy to use and Be-friendly class.
// (...) BNotification notify(B_INFORMATION_NOTIFICATION); notify.SetApplication("TokuToku"); notify.SetTitle("The title"); notify.SetContent("The contents. Here we can notify about something important!"); notify.SetOnClickApp("application/x-vnd.TokuToku"); be_roster->Notify(notify); // Optional timeout parameter
Screenshot of the resulting notification: here.
Its usage: create a BNotification object with the given notification type as a parameter (similar to the BAlert alert types), set up the application name, title, content and any additional parameters and all that's left is sending the notification to a selected BRooster. Depending on the notification type, the notification icon will be different (along with some colors). The BNotification is sent to the system using the Notify() BRooster call - usually we can use the globally defined be_rooster object for this. The method requires two arguments: the notification to be shown and a timeout value. The timeout value is the time, in microseconds, of how long the notification should be visible to the user. If timeout is a value less-or-equal 0, the default timeout is used.
Another element that caught my eye while browsing the Haiku application tree is the menu builder - an useful subset of the BLayoutBuilder functionality. Using this builder, we can easily create different, even complicated menu structures with ease, similarly to building layouts.
BPopUpMenu *menu = new BPopUpMenu("popup_menu", false, false); // POPUP_* are BMessage-specific int32 command constants BLayoutBuilder::Menu<>(menu) .AddItem("Status", POPUP_STATUS) .AddItem("Send message", POPUP_MSG) .AddItem("Log", POPUP_LOG) .SetEnabled(false) .AddSeparator() .AddMenu("Additional") // A sub-menu .AddItem("Subitem 00", POPUP_00) .AddItem("Subitem 01", POPUP_01) .End() .AddItem("Remove", POPUP_REMOVE) .SetEnabled(false) .AddItem("Ignore", POPUP_IGNORE) .SetEnabled(false) ; // (...)
Screenshot of the resulting pop-up menu: here.
After creating the containing menu object (here, the BPopUpMenu), we can build the menu item hierarchy by using Haiku layout API-like specific calls. For these purposes we have the following methods available: AddItem(), AddMenu() and AddSeparator(). Each adds respectively: a new menu item, a new sub-menu and separator object to the menu structure. The base AddItem() method accepts the same arguments as a BMenuItem constructor, with an additional variant accepting a BMessage command constant instead of a BMessage object. You can read more details here about available methods here: The Haiku Book.
As I said, these things might be obvious to some and unimportant to others. Or even inaccurate. It was just nice seeing new things in the Haiku API.
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