The Native Implementation Of MIDP Graphics System

With the rapid development of microelectronics and information technology, more and more electronic device will grow towards micromation. These devices should be provided with function of calculation, good user interface and network access. Actually, they will gradually take the place of PC which is being widely used. It will make calculation be everywhere, communication will get more convenient.Java's design theory of "Written once, Run anywhere" and traits of good reusability, well independence, simpleness and safety, undoubtedly, decide it being the new shining point of embedded system. Java will greatly reduce the complexity of embedded system programming, it will also shorten the time of development and reduce the cost of project. However, Java technology has some shortcomings unfit for embedded system, it needs more memory and faster processor than C++. Facing increasingly huge market demand, Sun pushes out it's Java platform aimed squarely at consumer devices with limited horsepower, it is J2ME. J2ME isn't one single software entity, but a series of specification gathering. These specification just define behaving format and interface, but different instance has different implementation.The current main work is porting of J2ME, but it is huge and superfluous if based on Sun's reference implementation. So, a virtual screen and graphics abstract layer is proposed, the porting based on it is simple and convenient, and it improves graphics refreshment efficiency and reduces flicker.Basically, the main work of this paper are as follows:1. Research and analyze on LCDU1 porting interface. The main work is research of inner mechanism of KVM native implementation, and introduction of a better design technique; then, a virtual screen and graphics abstract layer is proposed based on LCDU1 porting interface.2. The design and implementation of GAL. The virtual screen structure is designed, it simulate a true screen; and a graphics abstract layer is proposed, it similar to Linux virtual file system, upper graphics operation and bottom implementation are separated.3. The implementation of Image object. The image object is mostly rooted in network picture file, the implementation is decode it and create a memory reflection.4. The implementation of 16bits graphics engine. The engine support 16bits color depth and 8bits alpha value. It provide basics graphics operation and many image copyings.