Mechanism Of GUI In Embedded System & Its Application On Set-top-box

The application of GUI(Graphics User Interface) speed up the spread of computer application, and the development of embedded technology speed up the depth of computer application. Late PC Age call on their increasingly close integration.At first, the paper discusses the inner mechanism of GUI system in embedded application. Firstly ,we research the bottom support mechanism of GUI system from two aspects: OSD technology and device independence technology. OSD technology is one important part of hardware layer, device independence technology is another important part of middle layer. Then, sole process(thread) model and Client/Server model are bring forward as two sorts of software architecture of application layer in GUI system on the basis of previous two technology, and the realization of Client/Server model is mainly discussed because of its prevalence from two main aspects: process communication & message transfer and control mechanism. Secondly, GUI system is designed in a whole. It is divided into three sub-systems: graphics, events, objects sub-system according to its function. Graphics and events sub-system is built up on the basis of their inner model partition and relations among inner models or between inner models and outer models. For objects sub-system, rules is put forword to design individual object, but layered logic model and physics display model is put forword to manage collective objects. At the end is application development of GUI system. As an example, digital Set-top-box OSD development is used to make clear the creation and destroy procedure of windows & controls and their response to several typic messages. Finally, an example is explained in detail about the function implement of a window used to setup Set-top-box system, relating to window's procedure to process specific message and common message, two typic controls'(button and selectbox) respective procedure to process specific message and common message, and the similar for dialog created by the two controls.