Cosmo, G

CERN Document Server

Graphical User Interface ToolsG. Cosmo CERN-CN/ASD, Geneva, SwitzerlandAbstractThe use of GUI builder tools in developing modern software applications has nowadaysbecome a requirement. In this paper, a summary of some evaluations tests performed oncommercial GUI tools and C++ graphics class libraries is presented. The evaluations havebeen performed in order to choose a suitable GUI tool to be used for designing the GEANT4[1] graphical user interface.Keywords: GUI; Object-oriented design; Widget; Gadget; Notifiers1 Motivations & evaluation criteriaThe user interface (UI) software is often large, complex and difficult to implement, debug and modify.A study found that about 50% of the implementation time is devoted to implementing the UI portionand that 48% of the code of applications is devoted to the user interface[2]. In the last few years,there has been significant progress in software tools to help with creating user interfaces, and todayalmost all user interface software is created using tools that make the implementation easier, make itpossible to do fast prototyping, to organise the development process into working-groups, to assurecode-rules integrity, and to reuse UI layouts already developed. Moreover, several tools integratealso more or less complete graphic class libraries.The advantages of using GUI tools in a software development process can be classified into twomain groups: The quality of the interfaces will be higher; The user interface code will be easier and more economical to create and maintain.1.1 GUI BuildersGUI builders are interactive tools for building graphical user interfaces. Widgets used as buildingblocks can come from different graphics standards (X, OSF/Motif, Athena, etc.). The most importantevaluation’s criteria we considered in order also to fit with our project’s requirements are: simplicity of use; compatibility and standards; completeness and extensibility; code generation and C++ solutions.1.2 Graphics class librariesGraphics class libraries provide a set of graphic primitives, resources, graphic objects and methodsto handle them, which should be used and integrated to compose the interface in the final application.These objects share many common traits and form a natural hierarchy and therefore can be consideredas the units of an object-oriented design. These are the criteria we took into account in our evaluation: Compatibility and Portability across APIs Extensibility and Completeness– primitive drawing functions– geometrical functions– transformation functions– events handling and interactors– graphics objects/gadgets, persistency and efficiency Evaluations of three commercial GUI tools Object-oriented design– polymorphism– class hierarchy - Protocols and Containers– external objects encapsulation– active values Maintenance and other more technical features ...2 EvaluationsThe commercial software packages evaluated and presented in this paper are the following: X-Designer 3.2 ILOG Views 2.1 XVT Development Solutions C++ 3.22.1 X-Designer 3.2X-Designer is an interactive tool for building graphical user interfaces (GUIs), using the widgets ofthe standard OSF/Motif toolkit as building blocks.Using X-Designer it is possible to design a hierarchy of widgets simply by clicking on icons andobtaining simultaneously on the screen the tree structure of the hierarchy and an active prototypeas dynamic display, showing what the current interface looks like and how it behaves.How to create an X-Designer application:1. Building the widget hierarchy;2. Settings resources;3. Adjusting the interface-layout using the built-in Layout Editor;4. Designating callbacks to be associated with individual widgets;5. Generating code (C, C++ or UIL): code-files for each hierarchy, header files and stubs filescontaining the function declarations necessary to connect the interface code to theapplication code;6. Linking, running and testing.2.1.1 FeaturesThe tool offers a very clean and intuitive Design Hierachy representation. There’s the possibilityto fold/unfold subsets of widgets, to highlight with colors those widgets defined as C++ classes,structures or functions, to split the design in more than one shell.The Standard OSF/Motif widgets are directly represented on a widget palette and the user can adddirectly into the palette user-defined widgets or set of widgets. It is possible to integrate class widgetsdifferent from standard OSF/Motif, like XRT or Athena widgets. X-Designer offers a very powerfulcontrol of widgets’ resources. The use of inheritance is exploited for managing common resourcesand methods among widgets. The tool provides built-in Pixmap Editor, Compound String Editor,Layout Editor and a Dynamic display. It is possible to map, unmap, declare, create, destroy callbacksand user-defined methods, adding user-defined method declarations directly at design-level. It isalso possible to apply same callbacks to different widgets.The tool automatically generates code specifications for callbacks and puts the code to be filled bythe user in a separated file (stub-file). It can generate C, C++ or UIL source code, XPM and UILPixmap files, X resource files, Makefile and a main procedure. The code is well structured andcommented where needed.The user always has an exact control of resources for each widget (resources can be inserted ornot inside the code). It is possible to import pixmap data from external files. X-Designer can beintegrated with other packages (e.g.XRunner) for testing the generated interface.2.1.2 X-Designer 3.2, globallyX-Designer 3.2 globally gives a positive impression. It appears to be reliable and complete. Itsstrong points are: Good assembly and intuitive grouping of command types; Complete on-line help and text documentation even in matter of error recovery;The support from the company is good and quite fast. On the other side: No possibility to load more than one design at a time; Not very easy to understand how to setup and manage inherited resources and methods forwidgets defined as C++ classes; Compatibility: supporting only X or X/Motif; It’s nothing more than a GUI-builder !2.2 ILOG Views 2.1ILOG Views is an advanced C++ graphics class library; it handles graphics tasks, ranging from basicgraphical user interfaces to complex real-time vectorial applications. Interfaces built with ILOGViews are portable across systems including X, X with Motif, Windows, and Presentation Manager.The package is supplied with an auxiliary editing tool called ilvedit to help the user designing hisinterface. The editor itself is written making use of the ILOG Views class library and its source code isdelivered with the package, so it is useful to the user for possible customizations or coding templates.Everything is written in pure exemplary C++ style emphasizing code reuse through inheritance.Classes can be grouped into 7 different domains more or less linked to each other through the useof derived objects or inherited methods: Primitives, a collection of drawing member functions realizing a sort of connection layerenabling the user to communicate transparently with different display systems (X, Motif orMS-Windows); Resources, whose class directly interacts with most of the primitives cited above; Views, the objects directly associated to windows on the screen; Graphics Objects and Containers, a class hierarchy to create and manage graphics objectsand containers where to put them in; Gadgets, the set of classes enabling the user to create interface graphics objects, theirinteractors and their special containers; Charts, Scales & Gauges, graphics objects designed to represent data; Management, the main class which is responsible of the interactions between graphicsobjects, views and storage places (layers).2.2.1 FeaturesIn ILOG-Views, the drawing member primitives handle every aspect of the connection with theused display system. Elementary drawing classes includes: point, point with fp coordinates, vector,rectangle, region (list of rectangles), curves, strings, arcs, arrows, polylines, Bezier curves, labels,bitmaps ... . There are primitives dealing with resources: colors, line styles, patt., fonts. and Mouse& keyboard events handling primitives. It is possible to manage any bitmap format (GIF, BPM,BMP), to record events, store them and play back at any speed, to redirect the output on screen orPS file. The package includes 2D transformation, strings, timer and error handling.A View is the real place where graphics objects are drawn on the screen, a window is an associatedset of one or several views; visibility, scrolling, drawing, sizing are managed at this level. A graphicsobject is displayed associating its coordinates with the coordinate system of a particular container.The Containers coordinate the storage and the display of graphics objects inside a window; it is akind of view with predefined Callbacks handling system/user events and the automatic refresh ofgraphics objects it stores. Functionalities provided by Containers are: object management, drawingfunctions, geometrical transformations, buffering, I/O operations, accelerators.It’s possible to set look & feel of graphics objects. Object Interactors are defined to manage userevents on objects. For each gadget there’s a predefined object interactor for containers. At managerlevel the user can handle large sets of objects. The Manager coordinates the interactions betweenthe display of graphics objects in multiple views and the organization of graphics objects in multiplelayers.2.2.2 The graphics editorILOG Views provides Ilvedit as a tool to build graphical user interfaces using ILOG Views gadgets.Ilvedit is an extensible GUI builder, it provides special panels displaying predefined gadgets andgraphics objects; the user must simply pick and drag the object from the panel to the work space tographically configure his own panel.It gives the possibility to handle all graphics objects and gadgets supported with the library in agraphic and intuitive way. Attachment and alignment of objects is very easy and practical. It’s veryeasy to extend the editor with user-defined gadgets and graphics resources can be set in a practicalway. The tool generates C++ code, defining a class for each panel being built. Generated code isclean, well structured and commented where needed; it is possible to generate callbacks as virtualmember functions (just redefine them in a derived class). Resource data can be included or not insidethe code. The tool can also generate a main procedure.2.2.3 ILOG Views 2.1, globallyILOG Views 2.1 is provided as a C++ class library where classes are complete, efficient and extensible.Its power is that it is based on a true object-oriented architecture separating visual aspects from objects’behavior. Benefits of this are class reusability and programming flexibility.Predefined drawing primitives assure portability accross different window systems (X, X/Motif,Microsoft Windows) making the system independent of platform and graphics standards. Docu-mentation and tutorial on classes and code description are good and sufficiently deep. The possibilityto handle the gadget editor source code, which is freely delivered within the package, is very useful.The GUI builder or gadget editor is provided as a tool. By means of the editor it is possible to handlethe most important features and tools provided within ILOG Views. Some solutions adopted withthe editor are really successful such as the way to set attachments and alignment for objects and theeasiness to extend the editor itself.On the other hand: There’s no on-line help or error-recovery; Ilvedit lacks a sort of dynamic-display; A hierarchy display is missing.2.3 XVT DSC++ 3.2XVT Development Solution for C++ (DSC++) is a set of products whose aim is to form a productiveC++ development workbench. The software components of DSC++ are: XVT-Power++ (release 3.2) - a portable C++ application framework, including the RogueWave Tools.h++ class library; XVT-Portability Toolkit (release 4.0) - a portable API library that enables XVT-Power++ toeasily move across platforms. XVT-Architect (release 1.0) - a visual object-oriented GUI development tool andapplication generator.XVT DSC++ is portable across most major GUI environments including: Motif/X11R5, OPENLOOK, MS-Windows, MS-Windows NT, OS/2 and Macintosh.2.3.1 Application FrameworkXVT-Power++ incorporates an application framework and encapsulates several hierarchies of objectclasses to feature an object-oriented design within the field of GUI programming. These objects areused by the designer as building blocks to assemble into the application. The application frameworkconsists of three levels: Application - program control, application startup and cleanup handling, providing globalobjects/data and getting access to them, finding out global definitions and creatingdocuments, message propagation between classes. Document - The document is the link between the application level and the view level.CDocument is the abstract class for accessing and managing files and internal data,creating windows or variations. View - Views allow the user to interact with the application and reflect the state of theapplication. Views draw themselves on the screen. A Draw() method is defined for eachview, providing automatic clipping.2.3.2 FeaturesIn an application built using XVT-Power++ there’s one CApplication object which controls theprogram once started: it’s the first object to be instantiated and the last to be destroyed. The CBossclass manages the events and message-passing among classes. Data can be propagated in two differentways:1. through the DoCommand chain mechanism: the document acts as a server to all of itsclient windows. Windows can ask for a change or pass messages to other windows bysimply generating a DoCommand.2. through the ADP (Automatic Data Propagation) system: it plays around the concept ofnotifiers: providers and dependents.Views can be built up of other views and a view can contain several other views. Enclosures areprovided to ensure clipping on included views. Among the predefined shapes are: Rectangle (Square),Oval (Circle), Arc, Polygon (Regular Polygon), Line. They are all derived from CSubView andcan act as enclosures for other objects, receive and communicate events, be moved/sized, or alsogenerate commands. The package offers helper views providing stickiness properties, data structuresto manage attributes, helper objects for enabling a view to be moved and sized. It provides classesfor inserting, removing, moving objects on cells and sizing grids; classes for handling strings/texts(from Rogue Wave); classes for run-time type checking of objects and debugging utilities; classes toautomatically handle traversals of menubar hierarchy; methods to read and write several differentimage file formats: BMP, PICT, xpm, xbm.Program resources on UNIX platforms are coded using the URL (Universal Resource Language).It is possible to store resources in a separate file (read at launch time by the application) or storethem in a separate code-file.2.3.3 XVT-ArchitectBuilt on top of XVT-DSC++, it offers most of the functionalities of XVT-Power++ to graphicallydesign and build an application. XVT-Architect supports different editors for managing global dataand refining the application: Menu, Command, Accelerators, etc. It is possible to import/exportand cut/paste projects. XVT-Architect consists of three main visual components: the Blueprint, theDrafting Board and the Strata Interface. Blueprint module, to establish the primary object hierarchy and inter-objectcommunication for the application; Drafting Board module, to lay out views and subviews making up the GUI interface of theapplication; Strata Interface, the attribute editor.2.3.4 XVT-DSC++ 3.2, globallyXVT Development Solution for C++ seems to be globally a very good product for developing GUIapplications within an object-oriented application framework. It can assure portability across themost important hardware platforms and graphics environments by means of a robust and completeAPI library provided by the XVT-Portability Toolkit component. XVT-Power++ integrates the RogueWave’s Tools.h++ data structures and its class hierarchy is based on Rogue Wave Collectable classes.That’s really a strong advantage of this package, since Rogue Wave class library provides a robustand rich set of collections, utility classes and data structures. Templates are not used within XVT-Power++, however it can benefit from the use of Rogue Wave template classes. Very interesting andpowerful is the Automatic Data Propagation (ADP) system to propagate changes of data from objectsto objects, as well as the possibility to perform run-time type checking on objects. XVT-PortabilityToolkit realizes a robust and reliable interface to operate on UI graphics objects independently fromthe underlying graphics system or hardware platform, providing in addition a flexible and powerfulhypertext-based help system. By means of XVT-Architect, the user can make use of all featuresand functionalities provided by the XVT-Power++ class library in a very ease and intuitive way.The possibility of import/export and cut/paste projects files becomes very useful to structure thedevelopment for a team-oriented organization. The ”Factory”-system method is a skilful solution forapplication maintenance and for reducing efforts when updating or refining parts of the applicationbeing developed. Documentation and tutorial on classes and API library as well as XVT-Architecton-line help are good and well organized. Strong point: The user always has under control the general structure of the project and the classhierarchy of objects he is working on; it’s very ease to skip among them to visualize orchange current settings and/or inherited attributes.On the other hand: RW persistence feature is not supported by XVT-Power++ (it will be in a future release); Resources management is quite complex, since on UNIX platforms it makes use of theURL language and the final generated application has to be delivered together with aseparated binary file containing all specific resource settings (which will be loaded inmemory once at launch-time).References1 G. Cosmo et al., GEANT 4 : an Object-Oriented toolkit for simulation in HEP,CERN/LHCC/95-70 (1995).2 B.A. Myers and M.B. Rosson Survey on User Interface Programming. Human Factors inComputing Systems, Proceedings SIGCHI’92, Monterey, CA, pp. 195-202 (1992).

Graphical user interface tools

Abstract

Similar works

Full text

Available Versions

CERN Document Server