【作者】 蒋勇；

【导师】 杜中军；

【作者基本信息】 四川大学 ， 计算机软件与理论， 2005， 硕士

【摘要】 伴随着微电子技术和信息技术的迅猛发展,越来越多的电子设备将向微型化方向发展。这些设备不光要具有计算功能,而且还要有良好的用户界面和网络接人功能,它们实际上将会逐步取代我们现在正在广泛使用的PC,使我们的计算真正无处不在,沟通更加方便。 Java语言的“一次编写,任意运行”设计理念及其移植性好、重用性好、简单安全等特点无疑决定了它将成为嵌人式系统中一个新的亮点;使用Java可以极大地降低嵌人式设备应用程序开发的复杂度,缩短开发时间,降低成本。但Java有它自身不适于嵌入式设备的缺陷,它C++需要更多的内存和更快的处理器。为此,Sun推出了面向消费设备的Java平台,这就是J2ME。J2ME不是一个单一的软件实体,而是一系列规范的集合。这些规范只是定义了表现形式及接口,而实现可以根据不同情况有不同的实现方式。 当前最大的工作就是J2ME的移植,而如果采用Sun的参考实现,那么移植的工作量巨大而且细节繁琐。针对这种情形,本文提出了一个内存虚拟屏幕和图形抽象层的概念,它的实现使移植接口简单而且方便,并且提高了图形显示的效率和减少了抖动。 本文的主要工作如下: 1.研究和分析LCDUI移植接口层。这部分的主要工作是研究了KVM的本地实现方法,通过对内部机制的研究,提出了一些更高效率的设计方法;然后在MIDP参考实现的LCDUI接口层的基础上更进一步抽象,提出一个内存虚拟屏幕和图形抽象层的设计。 2.图形抽象层的设计与实现。这部分完成了内存虚拟屏幕结构的设计,它更多还原

【Abstract】 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.更多还原