Reserch And System Implementation Of The Framebuffer-based Graphics Library In Embedded Linux

With the coming of the post-PC era, the embedded ARM-based system has significantly improved and becomes more and more widely-used. There also comes a problem that the older simple human-computer interaction interface becomes unable to meet the requirements of people. At the same time, the graphical interaction interface has already become mature. Thus, gradually some GUI (Graphic User Interface) system has been adopted in the embedded system.GUI can not display without the support of the graphics library. This paper not to discuss how to modify an existing graphics library and tranplant it to our system, but to discuss how to design and implement a small graphics library based on the Framebuffer in Linux ourselves. Framebuffer only provides some primitive graphics operations, such as write some data to the display memory to display a certain point. Eventually the graphics library we implement will be applied in practice.The main work of this paper is as follows:①Design and implement to display vector graphics on the screen using some graphic algorithms: midpoint line drawing algorithm, midpoint circle drawing algorithm and seed filling algorithm.②Design and implement to display the bitmap on the screen by getting its width and height information from its information header and mapping its data array to framebuffer.③Design a small dot-matrix characters library, implement to display common ASCII characters on the screen through dot-matrix characters displaying principle.④Design a new kind of window only containing client area, implement to display this window on the screen using vector graphics displaying method.⑤Implement message-response mechanism by the message queue and circle reading method to achieve human-computer interaction. Main messages include timer messages, touch-screen messages, keyboard messages.⑥Design and implement a series of window controls using single linked list to facilitate the application development.Experiment shows that the graphics library we have implemented have the features mentioned above. This paper shows the operating results of this graphics library and does a comparison between this graphics library and other famous graphics libraries.