Design Of Cross-Platform Map Symbol Framework Based On Qt And Application Research

With the increasing importance of personal mobile platforms in modern life, GISstands in a closer relationship with the applications in various fields. The flourishingoperating system platforms, however, make the problem of cross-platform for thedevelopment and design of GIS to be faced. The cross-platform GIS has been a trend inthe development of GIS software. As the data of geospatial is very complicated and thecontents and element categories of which are enormous, it is essential to establish thecomplete map symbols to represent various thematic elements perfectly. Therefore, tocarry out a study in the framework of map symbols with cross-platform compatibility, todesign and implement the library of GIS map symbols with cross-platform compatibilityhave become the primary task of mobile GIS development and applications.Based on Andorid, iOS, Windows, Linux, Mac OS and other major operatingsystem platforms, this study focuses on the design and implementation of theframework of map symbols with cross-platform compatibility. Under the premise thattaking full consideration of the needs of expression for GIS thematic elements content,the research is conducted. Based on the summary of the types of map symbols and thebasic elements of map symbols, the object-oriented design and implementation havebeen adopted. In order to meet the needs of expressions for complicated symbols, andmotivated by the idea of “Layers” management, the paper constructs complicated mapsymbols with multi-layer primitives, which effectively meet the needs of expression forcomplex symbols’ extensions. For the problem that the screen of a personal mobileplatform has difficulty in loading huge text annotation information, automaticconfiguration of rasterized annotation has been proposed to ensure that the map ismarked concisely and clearly. Given the limited memory resources and the processingpower of individual mobile platforms, symbolic structure which is easy to manage has beendesigned to achieve the efficient rendering of map symbol. DIA method based ontemplate brush is proposed for complicated linear symbol. In summary the paperdesigns an extensible and maintainable map symbol framework with cross-platformcompatibility and achieves preliminary implementation by C++, Qt tool and SQLite.The application results have shown that the framework not only reduces codeduplication and human resources, provides a convenient expansion and maintenance forthe later modules, but also achieves satisfying performance in both displaying efficiencyand expression for different thematic elements, proving the feasibility and effectiveness of the proposed technique.