11.6. The Laddie Framebuffer UI

As we saw in the previous section, an application that uses STBmenu has two obligations: provide pointers to data to be displayed, and provide callbacks for UI inputs. Figure 11-13 illustrates how the Laddie framebuffer UI meets these two obligations.

On the user side, keyboard or remote control events select a widget and then invoke that widget's Activate method. This action invokes a callback in the application interface, which controls the alarm daemon via the RTA/PostgreSQL protocol. On the application side, logmuxd relays events indicating that the Laddie alarm daemon's status has changed. Responding to these events, the UpdateZoneData code uses the RTA/PostgreSQL protocol to update a local copy of the alarm ...

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