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Text File | 1992-01-18 | 20.0 KB | 751 lines

* * * * * * * * * * * * * * * * * ***************** VICON ***************** * * * * * * * * * * * * * <Version 1.9> * * * * * * * * * * * * * Programmed by * * * * * * * * *Khai-Wei CHOONG* * * * * * * * * * * This essay was written on 20th June 1991. Correspondence Address: Permanent address: 11 Ray Street Wilston QLD 4051 Australia Current address ( valid till end of 1991 ) : 3/242 Carmody Road St Lucia QLD 4067 Australia ================================================================ (1) Conception After reading through an article in DR DOBB'S JOURNAL in July 1989 which presented the techniques to create simple icons, I could not resist the temptation of flashing out a much more functional icon editor. Thence I was addicted to these catchy little pictures even before Microsoft Windows 3.0 immortalized them in the PC world. ================================================================ (2) Who needs icons? Iconolaters cannot worship without them. Neither can the modern men whose technological flair has resulted in the endless need to compress a thousand words into little pictures of instant appeal and meaning. Icons have invaded our lives. They are on the streets, in the courts, and now they are on our screens. Imagine yourself pointing and clicking at them to switch TV channels ten years from now! Or imagine using Microsoft Windows without them..... ================================================================ (3) The neglected BGI programmers Reverend Borland has provided more than 50 graphics routines for Turbo Pascal, C and C++ users. As a result, we have seen a flood of graphics applications previously unachievable in text mode. However, I have yet to see even a handful of icon-oriented programs. This is not because of inability on the part of programmers, for an icon is a relatively simple thing in the world of OOP (object-oriented programming). It is the lack of facilities to create icons that has stunted the growth and proliferation of icons in graphics applications. Unlike many graphical objects, an icon is a symbolic bit map image that cannot be preprogrammed into an application and must be manually created, pixel by pixel, in advance. Hence VICON to the rescue..... ================================================================ (4) How good is it? See for yourself. VICON is similar to many drawing packages in various ways, but strives for the much needed ease of use. For example, in a few other drawing utilities, you are "locked" into the rubber banding mode in order to draw an object, during which you can only stretch the rubberband, click to anchor a pivot or quit. You are not allowed to change colors, stroke sizes or even select a menu. Another major problem is in color selection: either the color palette is not immediately available and has to be selected via a menu or the palette is far away and the user has to constantly move the mouse cursor across the screen to click on the desired color. VICON addresses these problems to alleviate the tedious editing, and provides additional features for special effects and high productivity. ================================================================ (5) Bonus Add-Ons Since the use of colors is so extensive and important I have provided several tools to enhance and coordinate it. These include Video Emulation, Palette Editor and Palette Rotator. For those of you who like to grab your icon on a piece of paper, you can print out your favourite ones on a dot matrix printer, a LaserJet printer or a Hewlett- Packard Color Plotter via any parallel or COM port. A word of advice: if your mouse has been installed on COM port 1 and you choose to print via this port, VICON will oblige you, with the loss of use of your mouse during the printing process. You can still respond to VICON via the keyboard. The mouse will be faithfully restored when the printing is finished. ================================================================ (6) What?! A file manager in an icon editor? Yes, I know you are probably so used to your own file manager that you won't even bother with it. Nevertheless, if you do happen to need it, you will have to shell out, quit VICON or use a TSR, won't you. Ah! speaking of TSRs, they don't coexist well with graphics. If you have to use a TSR in VICON, be certain to run Video Emulation to restore the screen later. Anyway, a handy file manager right at your finger tips is always great. Moreover, this is one dressed in a stunning graphical user interface! ================================================================ (7) The future of VICON This depends on whether I get enough incentive in the form of constructive criticisms and user registrations. It will be frustrating indeed not to receive any response or reward after 18 months of intense effort. I would like people to be honest and trustworthy, even to the author of an icon editor. I have not built in enough intelligence in VICON for this task. If only VICON could read the human mind! ================================================================ (8) Support for other graphics formats This is not difficult provided I know the formats. However I have a hard time obtaining the information. Meanwhile, I have already worked out the Microsoft Windows Icon format the hard way. Anyone who is interested in seeing VICON support other graphics formats such as PCX, TIFF (etc.) may send the complete information to me by mail. Once it is successfully implemented, that version of VICON will be sent to the person free. Any code examples included in the information should preferably be written in PASCAL. Unless it is well commented, I do not enjoy the task of reading or translating C++, much less the cryptic old fashioned C. I am also looking for BGI drivers that cater for 256 colors at super VGA resolution(s). Please advise me if you know of any. What about porting VICON to Microsoft Windows 3 ? This will be another story..... Remember, I am anxious to hear from you. And good luck in your future graphics programming. May the GUI and VICON be with you !!! ================================================================ (9) Writing text to screen in graphics mode From a programmer's point of view, the similarity between an application in text mode and another in graphics mode begins and ends in the way text is written to the screen. Programming in graphics mode is largely a different ball game. Gone are all the comforts of the 80 x 25 cells supported by BIOS. As soon as you leave text mode, you are responsible for the color and intensity of each of the 640 x 480 pixels you inherit from a VGA screen. The contemporary MS-DOS systems do not permit mapping the ROM-based character set(s) directly into a graphics display. Since text is more important than anything else, Borland has supplied a few scalable fonts to overcome that problem. Writing text to a graphics screen is a laborious programming task. When new text is written to the screen in conventional text modes, the existing text is simply written over, vanishing automatically as the new characters are assigned to each row/column position. In graphics modes, however, text output is drawn rather than written. The new text does not replace; rather, it overlaps with the old, confusing the text display. To erase the appropriate text before writing new text to the screen, you would have to remove the block of graphics background that otherwise would interfere with the text image. The following prerequisites must be satisfied in order to accomplish this task: a) The text style, fonts and justification must be identical as when the text was originally written. b) The original drawing color must be in effect. c) The screen coordinates where the original text was written must be known. (This in turn may need to be viewport-adjusted.) d) The original text itself must be known. e) The original color and fill style of the background in which the text was written. (The background may not even have a uniform color and fill style.) So much for erasing text alone. You also need to attend to the following when writing text to the screen: a) Temporarily turn off the mouse cursor if it is present, otherwise the refreshing of the cursor will destroy some portions of the text. b) Assuming that the text is being drawn horizontally, you must make sure that the starting X-coordinate is never less than zero, or nothing will be written to the screen. This is one of the idiosyncrasies of the Borland Graphics Interface (BGI). Once you have mastered the basics, you can then pitch your talent against creating a fully-fledged graphics editor. You will need to overcome at least a few of these formidable barriers: a) Present the user with a blinking cursor so much taken for granted in text mode. You will need to keep track of the cursor's position, and its size according to the font size and proportional width. b) The screen can not be scrolled up or down and left or right in the usual manner. While it is possible to use GetImage() and PutImage() to move a major portion of the screen image, the operation is slow and the memory requirements can be excessive. c) There is no way to read a character from the screen. Neither is it easy to find the screen position of any character, especially when a proportional font is used. Essentially, you have to invent most of the features found in the CRT unit and many, many more to get reasonable results. Tough! Tough! Tough! ================================================================ (10) The Graphical User Interface (GUI) The subject of GUI could easily fill a thick book. Here, I shall show you what you should pay attention to as a programmer and what you should look for in a program with a GUI from an end user's viewpoint. 1) An application will benefit the user if it is SAA compliant. SAA stands for Systems Application Architecture, which is a collection of selected software interfaces, conventions and protocols that collectively provides the framework for the development and execution of consistent applications. Programmers interested in developing their own GUI will also reap much benefit if they follow the SAA guide-lines set by IBM. Current examples of powerful SAA compliant environments are Microsoft Windows and the OS/2 Presentation Manager. The SAA Common User Access (CUA) Advanced Interface Design Guide is available from IBM representatives or branch offices. 2) If you are going to produce a graphics application armed with a decent GUI, then learn object oriented programming by all means. This programming methodology promises to reduce the complexity of your task much more than the ubiquitous structured programming. 3) The next phase is to make your application event- driven. An event may be a mouse click, a mouse move or a key pressed that an application responses to. Instead of coding an event loop into every routine or subroutine that interacts with a user, you code one event manager to dispatch events to appropriate routines. Hence the majority of your routines do not bother themselves with the repetitive tasks of reading user inputs or interacting with a scroll bar and so on.... ================================================================ (11) The limitations of Borland Graphics Interface (BGI) BGI provides more than 50 primitives for various graphics driver supports, line drawing, circle, ellipse, rectangle, pie slice, sector, text and viewport. On the whole, BGI is a rather complete and flexible graphics package for most general applications. However, you need to do a great deal of work to create a pipeline of graphics elements such as buttons, scroll bars, menus and windows required by GUI. BGI only provides the drawing primitives. The rest is all up to you. There are also a few insurmountable obstacles presented by BGI. Unless Borland further improves BGI, the increasing availability and acceptance of Microsoft Windows or even OS/2 might cast BGI to oblivion. Hey! Borland, are you listening? Here is a list of features absent, inadequately or incorrectly implemented in BGI, together with some general problems: a) Easier text handling and display are strongly recommended. b) Greater range of fonts, including bit-mapped, stroked and Adobe-type fonts are desirable. We would like fonts created from Bezier curves. c) Rotatable text is required. d) Multiple scrollable graphics windows or viewports should be implemented. e) Methods to extend the graphics image beyond the display limits are desirable. f) Provide an interactive program to facilitate the creation of customized BGI drivers. Borland has already produced a font editor to create CHR files. An equivalent editor for the BGI files would be a welcome addition. g) VGA256.BGI is pretty useless with its 640 x 200 resolutions. Give us BGI drivers for SVGA, XVGA etc., with resolutions up to 1024 x 768 and 256 colors. h) Currently only a few graphics modes support multiple video pages. I have one megabytes of video memory to be tapped, yet only one page is supported in the VGA high resolution mode. i) FloodFill() and those palette manipulation routines should work in all graphics modes, including IBM8514. j) Fix the bug that prevents loading of any external font whose source file is larger than 16K bytes. k) PutImage() will not work if the whole image does not fit inside the screen. l) OutText() and OutTextXY() will not work if the starting point does not lie inside the screen. m) The BGI device driver routines are accessed via the vector table. All but one vector in the table have their equivalent routines in Turbo Pascal or C. That unsupported vector is SYMBOL. We would like to see it implemented by Borland. n) Lastly, but not the least, increase the speed of execution of all graphics routines. I hope that Borland will release a version of TURBO VISION written for BGI. Even though TURBO VISION is a masterpiece, I am reluctant to use it for serious DOS applications simply because text mode is too restrictive. Borland has been accused of neglecting the once popular TURBO PASCAL GRAPHICS TOOLBOX. Let's hope that BGI will not suffer the same fate. To be fair, Borland has no obligation to offer follow-up supports for any of their products. But then those of us who have invested heavily on BGI and Turbo Vision etc. are truly living dangerously at the mercy of Borland. I do like Turbo Pascal for Windows. However, I also want freedom of choice. Not everybody wants to develop graphics programs that run in Microsoft Windows. BGI clearly fits the appetites of those who want a solid DOS-based graphics foundation to work on. ================================================================ (12) Conclusions (a) Icons are no longer just gimmicks and elaborations used to fancily dress otherwise conventional programs. Icons are pictures without words, conveying messages without unnecessarily cluttering the screen with text. Icons represent portholes into an application's internals, encapsulating latent actions with easy access by the user. Icons serve as screen symbols and as buttons to summon or control applications or subprocedures. (b) Undoubtedly, graphics programming incurs man-months of efforts and exacts tremendous demand and dedication from the programmer. However, through the use of object oriented and event driven programming, the results can be very rewarding indeed. (c) Current computer science courses in universities do not stress the importance of software engineering and user interface enough. The upshot is many poorly designed applications with crummy user interface, low level of usability and consistency. Moreover, since our education stresses engineering, few of us have formal and proper training in design. Most of us spend hours after hours writing codes without giving much thought to program organization, abstraction and interaction. With the advent of object oriented programming, which places more weight on design than any previous programming approaches, the problems are aggravated. As a result, much of the design work occurs during the phase of implementation. Many programmers are finding that, although they have a working program, they are forced to redesign and rewrite to truly reap the benefits of reusability, extensibility and consistency. ================================================================ I invite you to judge and comment on all aspects of VICON. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + Please read Register.DOC, ReadMe.DOC, BGIuser.DOC, Licence.DOC + ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++