Visual Programming of User Interfaces for Distributed Graphics Applications

This thesis presents a novel software system called Thekla that facilitates the integration of 2D and 3D user interfaces (UI) employed in interactive, multi-display/multi-user, distributed graphics applications. Combining heterogenous display and interaction devices refers to the idea of providing the most appropriate environment to accomplish diverse interaction tasks to users. Thekla acts as special-purpose communication mediator between complementary Qt 2D GUI and Coin 3D scene graph application components forming consistent (distributed) graphics applications. Each application client is connected to a central Muddleware XML database in a client-server architecture. Thekla transparently synchronizes the shared (graphical) state of the 2D/3D applications. Thekla implements a data-driven publishsubscribe pattern. Applications employ Thekla clients to publish and subscribe observables and to establish synchronized one-to-many connections to observers. The provided pattern allows to flexibly connect Qt UI widgets (buttons, sliders, text boxes) and Coin fields (scene graph nodes and engines) in both directions. The rapid prototyping of 2D UIs is supported by the Qt Designer, a visual UI editor tool that comes with Qt. Thekla provides an extension plugin for the Qt Designer. Using the extension dialogs, UI widgets can be published as observables. On demand the plugin generates source code skeletons and build scripts, allowing to compile and execute GUI applications immediately.