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QWIK SCREEN UTILITIES USER'S GUIDE Version 5.x December 20, 1988 Copyright (C) 1988 Eagle Performance Software All Rights Reserved. _______ ____| _ | (tm) --| | |------------------- | ____|__ | Association of | | |_| Shareware |__| o | Professionals -----| | |--------------------- |___|___| MEMBER QWIK Screen Utilities User's Guide, Version 5.x T A B L E O F C O N T E N T S 1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 3 Features . . . . . . . . . . . . . . . . . . . . . . 3 Using the Manuals . . . . . . . . . . . . . . . . . . 3 Licensing . . . . . . . . . . . . . . . . . . . . . . 4 Customer Service . . . . . . . . . . . . . . . . . . 4 ASP . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. GETTING STARTED . . . . . . . . . . . . . . . . . . . . 6 Distribution Files . . . . . . . . . . . . . . . . . 6 Demonstration . . . . . . . . . . . . . . . . . . . . 6 Simple Programming . . . . . . . . . . . . . . . . . 6 Procedures and Functions . . . . . . . . . . . . . . 8 3. BASIC TECHNIQUES . . . . . . . . . . . . . . . . . . . 11 Number to String Conversion . . . . . . . . . . . . . 11 Cursor Mode Routines . . . . . . . . . . . . . . . . 11 Cursor Location Routines . . . . . . . . . . . . . . 13 EOS Marker . . . . . . . . . . . . . . . . . . . . . 13 Scrolling . . . . . . . . . . . . . . . . . . . . . . 14 Pop-Up Windows . . . . . . . . . . . . . . . . . . . 15 4. ADVANCED TECHNIQUES . . . . . . . . . . . . . . . . . . 17 Virtual Screens . . . . . . . . . . . . . . . . . . . 17 Video Pages . . . . . . . . . . . . . . . . . . . . . 18 Video Modes . . . . . . . . . . . . . . . . . . . . . 19 Multi-tasking Environments . . . . . . . . . . . . . 20 Interrupts . . . . . . . . . . . . . . . . . . . . . 20 5. HARDWARE DETECTION . . . . . . . . . . . . . . . . . . 21 Display Combination Code . . . . . . . . . . . . . . 21 Snow Checking . . . . . . . . . . . . . . . . . . . . 22 System Hardware . . . . . . . . . . . . . . . . . . . 23 Tips . . . . . . . . . . . . . . . . . . . . . . . . 23 APPENDIX A: Video Mode Table . . . . . . . . . . . . . . . 24 APPENDIX B: Cursor Mode Data . . . . . . . . . . . . . . . 26 Cursor Mode Tables . . . . . . . . . . . . . . . . . 26 Cursor Emulation . . . . . . . . . . . . . . . . . . 26 APPENDIX C: Performance . . . . . . . . . . . . . . . . . 29 Code Size . . . . . . . . . . . . . . . . . . . . . . 29 Speed . . . . . . . . . . . . . . . . . . . . . . . . 29 TP4 Usage . . . . . . . . . . . . . . . . . . . . . . 30 APPENDIX D: Application Products . . . . . . . . . . . . . 31 APPENDIX E: Revision History . . . . . . . . . . . . . . . 34 APPENDIX F: References and Credits . . . . . . . . . . . . 37 2 QWIK Screen Utilities User's Guide, Version 5.x 1. I N T R O D U C T I O N FEATURES Welcome to QWIK Screen Utilities! You have just obtained a copy of the highest performance screen writing tools available today for Turbo Pascal 5.0 (TP5). Both novice and professional programmers will appreciate these simple and very powerful utilities that gives you absolute control over your CRT displays in all text modes. Here are some of the features you will discover: . Writes on all IBM compatible computers, displays and adapters including the new PS/2 systems and Hercules. . Superior video detection routine. . Eliminates snow and flicker. . Writes directly to the screen in absolute coordinates. . Writes in all text modes and column modes. . Writes on all video pages. . Writes on virtual screens in RAM. . Writes text and attribute, text only, or attribute only. . Reads strings, characters and attributes. . Uses End-Of-String (EOS) marker for quick string chaining. . Provides standardized cursor control for all adapters. . Enhanced cursor movement. . 650% faster than TP5 direct screen writing. . Only 2.7k bytes of code if all 43 utilities are used. . Optimized by the compiler and drops unused code. . Used in all other Eagle products. QWIK is an enhancement unit providing capabilities not offered in the CRT unit that came with TP5. In contrast to the CRT unit which does window relative writing, QWIK knows how to write directly to the screen in absolute screen coordinates for any video configuration. | Version 5X - This version is simply a TP5 compiled version of QWIK42B. | QWIK50 will be out at a later date with other features specific to TP5. USING THE MANUALS Disk Based Guides - The manuals for QWIK are on disk so that you can conveniently scan for the topic you are seeking. You can do this with any list or search utility with a search function. You can also make a printed copy. If you have not already printed this manual, refer to the READ.ME file for instructions. At the present time, no bound manuals are being offered with registration. User's Guide - This manual, the one your are reading now, assumes that as a programmer you are already familiar with Turbo Pascal 4.0. And that you have a working knowledge of your disk operating system (DOS). It will provide you the basic principles of direct screen writing and powerful tips Chapter 1, Introduction Page 3 QWIK Screen Utilities User's Guide, Version 5.x on some previously unavailable techniques. Reference Guide - This manual describes in detail all procedures, functions and variables used in QWIK. It is a alphabetically arranged for easy access in a format similar to the TP5 manual. Use this manual when you have become familiar with the basic principles in the User's guide. LICENSING Registration - These utilities and the documentation have been released for distribution as Shareware. You have been given the chance to sample the full capability of QWIK without risk! If you find that QWIK is a valuable tool, then you are expected to register. You will find a reasonable licensing schedule found in LICENSE.ARC to meet private or commercial needs. When registering, be sure to specify the version for Turbo Pascal (such as TP4 or TP5) you wish to receive. Source Code - All registered users will receive source code when the signed license agreement is returned with the registration. CUSTOMER SERVICE If you have questions, comments, or suggestions, the Eagle can be contacted by three means - (1) CompuServe, (2) telephone, (3) The Eagle BBS, or (4) mail. CompuServe - The most dependable way to contact the Eagle is through CompuServe. James (Jim) H. LeMay has written the TP5 version of QWIK. He can be contacted on the Borland Forum by typing GO BPROGA from the CompuServe main menu. You will enter the Forum for Turbo Pascal. You can contact Jim with his PPN number of 76011,217. Messages can also be left through EasyPlex. Telephone - Jim can also be reached by phone at (817) 735-4833 on weekdays and Saturday from 9:00 a.m. to 8:00 p.m CST. The Eagle BBS - After 01-10-89, you can also contact us on our 24-hour BBS at (214) 539-9878, 1200 N81. Mail - For registration or problems, please write: Eagle Performance Software TP products P.O. Box 122237 Ft. Worth, TX 76121-2237 In your written request for resolving problems, be sure to include: . A 5 1/4 inch diskette of compilable source code of the problem. . The Eagle product and version number. . The computer make and model. . The type of video card, video monitor and keyboard. Chapter 1, Introduction Page 4 QWIK Screen Utilities User's Guide, Version 5.x For identical Turbo C products, write: Eagle Performance Software TC products P.O. Box 292786 Lewisville, TX 75029-2786 Or, contact Jim Gallagher at (214)-539-7855 ASP QWIK is a Shareware program conforming to the standards of the Association of Shareware Professionals (ASP). You can get more information about ASP by writing to: Association of Shareware Professionals 325 118th Ave. S.E., Suite 200 Bellevue, WA 98005. Chapter 1, Introduction Page 5 QWIK Screen Utilities User's Guide, Version 5.x 2. G E T T I N G S T A R T E D This section will acquaint you with the files on disk and show you a brief demonstration. You will also run your first program with QWIK and then become familiar with all of the utilities. DISTRIBUTION FILES In this version, QWIK5X.ARC contains: Qwik5x .tpu: Compiled unit of 2000 lines of assembly for TP5. Qwik5x .pas: Source code for QWIK5X.TPU. (MASM source code and object files are not included.) Qwik5x .doc: This document - a user's guide to QWIK. QwikDemo.pas: A demonstration program showing the features and speed of all procedures and is written primarily for color cards, but also works on mono cards. QwikRef .doc: QWIK Reference Guide document covering each procedure and variable in detail. Qinitest.pas: A program that verifies the equipment detected by the Qinit procedure. Qbench .pas: A timing program that shows "screens/second" for typical QWIK procedures. Strs .pas: Supplementary unit for number to string conversions. TimerD12.inc: Include file to measure elapsed time. License .arc: ARC file containing license agreements. DEMONSTRATION To get an overview of the speed and features of QWIK, let's run a demonstration program that came with the utilities. Do the following steps. 1. Copy QWIK5X.TPU to QWIK.TPU for TP5. 2. Make, compile and run QWIKDEMO.PAS to get a feel for features and speed. 3. Press return when the screen prompts you to continue with "... press any key". 4. Before running QINITEST.PAS, read the source code header to see if you want to test for a computer submodel ID. SIMPLE PROGRAMMING First Program - Let's write a short program to see how simple it is to write with QWIK. While in the TP editor, enter the following code: uses Crt,Qwik; begin TextAttr := Yellow+BlackBG; ClrScr; Qwrite (5, 1,Yellow+BlueBG,'QWIK writing'); Chapter 2, Getting Started Page 6 QWIK Screen Utilities User's Guide, Version 5.x Qwrite (5,13,Yellow+BlueBG,' is easy!'); end. Assuming you have already copied QWIK5X.TPU to QWIK.TPU, compile and run the code. You can then see the text "QWIK writing is easy!" starting on row 5, column 1. On color monitors, the text is a yellow foreground with a blue background while monochrome monitors show high intensity on black. Row/Col vs. X/Y - You probably noticed that the row parameter is first and the column parameter is second. Since QWIK is entirely for text modes, it is more intuitive to specify the row first and the column second just like any word processor. The X/Y scheme is better suited for graphics. Attributes - Notice that our example uses the constant "BlueBG". QWIK provides eight convenient background color constants to use along with Turbo's 16 foreground colors. The same names are used, but the "BG" suffix is added: BlackBG RedBG BlueBG MagentaBG GreenBG BrownBG CyanBG LightGrayBG These allow QWIK to make the most of Turbo's constant folding. By simply adding the foreground and background constants together, the compiler saves the result as a single word. And, by simply reading the Qwrite statement, what you see is what you get (WYSIWYG). Readable Code - As an added benefit, QWIK was designed with human factors in mind and was made so that it is very easy to read the code you create. With the row, column, and attribute parameters first and the string last, you can see that the two Qwrite statements were easily aligned. WYSIWYG to the rescue again! Chaining - Notice that we had to calculate the string length of "QWIK writing" before we could locate the string " is easy". Let's modify the last statement to indeed make it easier to locate the last string: uses Crt,Qwik; begin TextAttr := Yellow+BlackBG; ClrScr; Qwrite (5, 1,Yellow+BlueBG,'QWIK writing'); QwriteEos (Yellow+BlueBG,' is easy!'); end. Now that was really easy! How did QwriteEos know where to write? QWIK internally keeps track of an End-Of-String (EOS) marker so that any subsequent "Eos" procedure like QwriteEos will chain the next string right there - no rows or columns to calculate! And you can chain as many as you want on to any other QWIK procedure. Same Attribute - But suppose we did not want to change the attribute that was already on the screen and don't even know what it is. How is that done? Just modify the attributes to the following: Chapter 2, Getting Started Page 7 QWIK Screen Utilities User's Guide, Version 5.x uses Crt,Qwik; begin TextAttr := LightGray+BlackBG; ClrScr; Qwrite (5, 1,SameAttr,'QWIK writing'); QwriteEos (SameAttr,' is easy!'); end. The special constant SameAttr (which is negative) tells QWIK to simply enter the text on the screen without changing the attribute. The result of the program would show the text with LightGray on Black attributes. This special constant works on all QWIK utilities. When assigned to a variable, the attribute can even be switched at run time. Centering - Rather than having the text left justified, let's center the text on the screen by modifying a portion of the code: ... ClrScr; QwriteC (5, 1,80,SameAttr,'QWIK writing is easy!'); end. This will place the text on row 5 centered between columns 1 and 80 which is perfect for an 80 column text mode. But what if other text or column modes are used? How can we ensure that it is always centered? Only one simple change is needed: ... ClrScr; QwriteC (5, 1,CRTcols,SameAttr,'QWIK writing is easy!'); end. The variable CRTcols always has the value of the column width that is currently being used. How does it know? QWIK is initialized at startup by executing a procedure called Qinit. It detects a host of information about your video configuration, everything from the type of video card you are using to the shape of the cursor being used. You can see a list of all these variables available for your use in QWIKREF.DOC. PROCEDURES AND FUNCTIONS Now that you have a basic idea of what QWIK can do, let's make a brief survey of all the utilities in QWIK.TPU to just know what is available: One initializing procedure: Qinit - Initializing procedure executed by QWIK5X.TPU which sets the global variables for the QWIK procedures. It should be executed again after a change from one text mode to another. Three quick direct screen writing procedures, all work with or without attribute change: Chapter 2, Getting Started Page 8 QWIK Screen Utilities User's Guide, Version 5.x Qwrite - For any type string or character (char). QwriteC - For any type string or char; self-centering. QwriteA - For any type variable, arrays or substrings. Four quick direct screen filling procedures in Rows-by-Cols block parameters: Qfill - Repetitive filling with the same character; with or without attribute change. QfillC - Same as Qfill, but self-centering. Qattr - Repetitive filling with an attribute only. QattrC - Same as Qattr, but self-centering. Two quick screen storing procedures: QstoreToMem - Saves a Rows-by-Cols block to memory. QstoreToScr - Restores a Rows-by-Cols block to any screen page. Two quick screen storing procedures for copying blocks between a screen (Scr) and a virtual screen (Vscr - a screen in memory): QScrToVscr - Copies a Rows-by-Cols block from QWIK screen to virtual screen. QVscrToScr - Restores a Rows-by-Cols block from a virtual screen to the QWIK screen. Three quick screen reading functions for reading data from any screen: QreadStr - Reads a string of text. QreadChar - Reads a single character. QreadAttr - Reads an attribute. Two quick scrolling procedures work on any video page and also virtual screens without flicker or snow: QscrollUp - Scroll affected rows-by-cols block up. QscrollDown - Scroll affected rows-by-cols block down. Two quick video page changing procedures: QviewPage - Changes the page to be displayed - up to 8! QwritePage - Sets the page on which the QWIK procedures are writing. You don't have to write just on the displayed page! Three quick cursor procedures and functions which work on any video page. They now work on the page being written rather than viewed: GotoRC - Move cursor to absolute row and column coordinates rather than relative to a window. WhereR - Returns absolute cursor row. WhereC - Returns absolute cursor column. Chapter 2, Getting Started Page 9 QWIK Screen Utilities User's Guide, Version 5.x Eight quick EOS (End-Of-String) marker procedures and functions that alter its position and/or the cursor. The marker can be moved on the CRT and virtual screens, while the cursor movement is only on the page being written: GotoEos - Moves cursor to EOS marker (like TP write). EosR - Returns absolute row of EOS marker. EosC - Returns absolute col of EOS marker. EosToRC - Sets EOS to a given row and column. EosToRCrel - Relatively shifts EOS by a number of rows and columns, and can be negative or positive. EosToCursor - Matches EOS to the cursor position. EosLn - Moves EOS to column 1 of the next row. QEosLn - Like EosLn, but scrolls up if past last row. Three cursor routines alter the cursor mode: GetCursor - Get current cursor mode from low memory. SetCursor - Sets new cursor mode. ModCursor - Modifies cursor mode to on, off or erratic blink saving current scan lines. Four quick EOS writing procedures that chain write at the EOS marker: QwriteEos - like Qwrite. QwriteEosA - like QwriteA. QfillEos - like Qfill. QattrEos - like Qattr. A Submodel identification routine: GetSubModelID - Optional procedure to find IBM submodel ID. Five string functions that convert integers and reals to strings by using the supplementary STRS unit: StrL - converts LongInt to string StrLF - converts LongInt to string in a fixed Field StrR - converts Real to string StrRF - converts Real to string in a fixed Field StrRFD - converts Real to string in a fixed Field with a specified number of Decimals For a full description of each utility with its parameters, please refer to QWIKREF.DOC for a summary of details and examples. Chapter 2, Getting Started Page 10 QWIK Screen Utilities User's Guide, Version 5.x 3. B A S I C T E C H N I Q U E S NUMBER TO STRING CONVERSION Str Procedure - TP5 handily converts numbers into strings with the Str procedure. For example: var MyNumber: integer; MyString: string; begin Str (MyNumber:7,MyString); Qwrite ( 1, 1,SameAttr,MyString); end. But this means that a data area must be reserved and the code isn't as readable as it could be. Str Functions - Instead, QWIK and the supplementary STRS unit let you use a function form of Str: uses Qwik, Strs; var MyNumber: integer; begin Qwrite ( 1, 1,SameAttr,StrLF(MyNumber,7)); end. Just like WriteLn, this lets the number remain in the Qwrite statement. There are five functions in the STRS unit and they can be used just like any other function: StrL - converts LongInt to string StrLF - converts LongInt to string in a fixed Field StrR - converts Real to string StrRF - converts Real to string in a fixed Field StrRFD - converts Real to string in a fixed Field with a specified number of Decimals The suffixes mean: L - LongInt, but any scalar will work R - Real F - Field width that is right justified format D - Number of decimals in the format The Str* functions actually use the Str procedure from TP5 to do the conversion. But with an InLine code trick, functions were created that don't recopy the string for the greatest speed. The code useage is also reduced. CURSOR MODE ROUTINES Three Routines - If you have ever struggled with controlling the shape of the cursor, your life is about to be made easier. With just three Chapter 3, Basic Techniques Page 11 QWIK Screen Utilities User's Guide, Version 5.x routines, SetCursor, GetCursor, and ModCursor, you can consistently and reliably control the cursor mode (shape and visibility) on any video card! Four Standard Modes - To make it even easier, four standard cursor mode variables are initialized at startup to fit the exact requirements of the detected video card. They are: CursorUnderline - The standard underline cursor. CursorHalfBlock - The half block shape usually used for insert editing. CursorBlock - An easy to find full cell cursor. CursorInitial - The mode detected at start up. So, if we wanted a full block cursor, only one line of code is needed: SetCursor (CursorBlock); And that's it! There's nothing else to figure out - even if you are using something like 43-row mode on an EGA card. When ending your programs, you can get back to the original cursor mode by using: SetCursor (CursorInitial); Hidden Cursor - Many programs need to hide the cursor altogether. This can be done with ModCursor: ModCursor (CursorOff); Why use ModCursor instead of SetCursor? ModCursor leaves the shape of the cursor alone, and only alters bits 13 and 14 of the cursor mode to turn it on or off. In fact there are three constants that are useful with ModCursor: CursorOff ($2000) - To turn the cursor off. CursorOn ($0000) - To turn the cursor back on with the same shape. CursorBlink ($6000) - To create erratic blinking on MDA/CGA. (On EGA/VGA, it turns the cursor off.) Using your imagination, you can also mix and match the constants and variables by logically summing them. Let's say we want to change the shape of the cursor to a block while it is still turned off: SetCursor (CursorBlock or CursorOff); So, the next time ModCursor(CursorOn) is used, the cursor will be a full block. As a suggestion for terminating your program, be sure to restore the cursor in your exit procedure with: SetCursor (CursorInitial); GetCursor - This function simply returns the current cursor mode value stored in low memory allowing you to save it for later use. Chapter 3, Basic Techniques Page 12 QWIK Screen Utilities User's Guide, Version 5.x CURSOR LOCATION ROUTINES QWIK has three routines that complement the CRT unit - GotoRC, WhereR, and WhereC. They correspond with the familiar GotoXY, WhereX, and WhereY. However, there are some important differences: . The QWIK routines are absolute to the screen and are not restricted by the Turbo window. . The suffixes "R" and "C" mean row and column, so the parameters of GotoRC are reversed from GotoXY. . The QWIK routines will also work on any video page. This is explained in the Advanced Techniques section later. This is not the only way to move the cursor. The EOS marker is also a very powerful aid as you will see in the next topic. EOS MARKER Invisible Alternate Cursor - From the examples in the Simple Programming topic, we found that we could easily chain two strings together using the EOS marker. In fact, this marker is so versatile, the EOS marker utilities can be made interchangeable with the cursor, but much faster. You could think of it as an alternate cursor that is invisible. Keeping Track - Any time a QWIK writing procedure is used, the EOS marker is updated. It is actually saved as the global variable QEosOfs. Technically, the value is the offset from the screen base and is a 0-based byte count. For example, if the following procedure was executed: Qwrite (6,5,Yellow,'Important Data'); the EOS would be at row 6, column 19, right after the word "Data". The value of QEosOfs on an 80 column screen would be: QEosOfs = ((Row-1)*CRTcols + (Col-1)) * 2 = 836 QWIK does not need to calculate this value, but simply saves it after writing, so it is very efficient. From the overview, you are already aware of the four routines that will start writing at this marker - QwriteEos, QwriteEosA, QfillEos, and QattrEos. But what about changing the location of the marker itself? Keep reading. Moving the Marker - QWIK has four routines that will manually move the EOS marker: EosToRC - Sets EOS to a given row and column. EosToRCrel - Relatively shifts EOS by a number of rows and columns, and can be negative or positive. EosLn - Moves EOS to column 1 of the next row. QEosLn - Like EosLn, but scrolls up if past last row. The basic procedure EosToRC moves the EOS marker exactly like GotoRC does for the cursor. But there are also several ways to move the marker relatively. Let's test a short program: Chapter 3, Basic Techniques Page 13 QWIK Screen Utilities User's Guide, Version 5.x uses Crt,Qwik; begin TextAttr := Yellow; ClrScr; Qwrite ( 1, 1,Yellow+BlueBG,'First Row '); EosLn; { Jump to (2,1) } QwriteEos (Yellow+BlueBG,'Second Row '); EosToRC ( 3, 1); { Jump to (3,1) } QwriteEos (Yellow+BlueBG,'Third Row '); EosToRCrel ( 1,-4); { Jump to (4,8) } QwriteEos (Yellow+BlueBG, 'etc.'); EosToRC (succ(EosR),8); { Jump to (5,8) } QwriteEos (Yellow+BlueBG, 'etc.'); end. Compile and run the program. You should see "Row" and "etc." all aligned in one column. So, you can see that there are several simple ways to move the marker! EOS and the Cursor - You can also interface the EOS marker and the cursor with two procedures: GotoEos - Moves cursor to match the EOS marker. EosToCursor - Sets the EOS marker to match the cursor position. It can't get any simpler than that! Now you can see that: Qwrite (1,1,Yellow,'Test Line'); GotoEos; and, TextAttr := Yellow; GotoXY (1,1); Write ('Test Line'); produce identical results. But QWIK is much faster! SCROLLING Improved Control - With the CRT unit, you can only control the full screen size with WriteLn. But with the two QWIK routines, QscrollUp and QscrollDown, you can define any area to be scrolled: QscrollUp ( 2, 2,CRTrows-2,CRTcols-2,MyAttr); This example scrolls a portion of the screen starting at (2,2) leaving a one character border. In a 25x80 text mode, it clears row 24 from column 2 to 79. In addition, the cleared row attribute is MyAttr. Improved Performance - With QscrollDown and QscrollUp (called Qscroll* for brevity), your programs can overcome the BIOS problems on many machines. Transparent to you, these procedures work on all cards and machines without Chapter 3, Basic Techniques Page 14 QWIK Screen Utilities User's Guide, Version 5.x flicker or snow and operate at three speeds: Maximum - for video cards without snow Fast CGA - for CGA cards on 80286 machines or better Slow CGA - for CGA cards on 8086/8088 machines Qinit detects the CPU ID and video card to select the fastest algorithm. All speeds use 16-bit transfers rather than 8-bit. So, you can be assured of the highest performance. Cursor Location - These routines do not move the cursor. However, EOS is pointing to the first column of the blank line and GotoEos will move the cursor there if needed. QEosLn - This procedure is another alternative to full screen scrolling. It has the same function as EosLn, but will additionally scroll the screen up if the EOS marker is past the last row. Then it simply calls QscrollUp. The attribute of the cleared row is the global variable ScrollAttr. You must set this prior to using QEosLn. POP-UP WINDOWS QWIK has the basic tools to create and remove pop-up windows. Let's try to create one. While in the TP editor, enter the following code: uses Crt,Qwik; var MyWindow,MyUnderlay: array[1..250] of word; begin { -- Fill the screen with a hatch character. -- } Qfill ( 1, 1,CRTrows,CRTcols,LightGray+BlackBG,#176); { -- Create a pop-up window.-- } QstoreToMem ( 5,12,10,25,MyUnderlay); { Save area to be covered } Qfill ( 5,12,10,25,Black+LightGray,' '); { Clear the area } QwriteC (9,12,36,SameAttr,'Pop-Up Window'); { Label window } delay (1000); { Wait a sec } QstoreToMem ( 5,12,10,25,MyWindow); { Save a copy } QstoreToScr ( 5,12,10,25,MyUnderlay); { Restore screen } { -- Move window some where else. -- } QstoreToMem ( 8,25,10,25,MyUnderlay); { Save area to be covered } QstoreToScr ( 8,25,10,25,MyWindow); { Move window } delay (1000); { Wait a sec } { -- Remove window. -- } QstoreToScr ( 8,25,10,25,MyUnderlay); { Restore screen } end. Compile and run the code. You will see a 10 row by 25 column window located at (5,12) which is row 5, column 12 . After one second, it will be moved to (8,25). Then after another second, it is removed from the screen. We did a lot of work with very little code! Rows-by-Cols - QstoreToScr and QstoreToMem are screen saving and restoring procedures that conveniently work in row-by-column blocks. They accommodate any column mode, so there is no need to be concerned about Chapter 3, Basic Techniques Page 15 QWIK Screen Utilities User's Guide, Version 5.x screen width. Memory Requirements - Notice that QstoreToMem wrote the data direct to memory in MyWindow. It is important that the memory allocated to that variable is correct to prevent it from overwriting any other variables. The array size chosen was a 250 word array which is a perfect fit since one word is needed for each character and attribute on the screen. If you prefer, the heap can also be used such as: var MyUnderlay: pointer; begin GetMem (MyUnderlay,500); QstoreToMem ( 5,12,10,25,MyUnderlay^); { ... } FreeMem (MyUnderlay,500); end. Chapter 3, Basic Techniques Page 16 QWIK Screen Utilities User's Guide, Version 5.x 4. A D V A N C E D T E C H N I Q U E S This section will acquaint you with the powerful virtual screen writing features already built into QWIK. You will also find out easy it is to work on multiple video pages and how to accommodate video mode changes. VIRTUAL SCREENS This topic will show you how to create and use powerful virtual screens. Virtual Screen - Just what is a virtual screen? It is a screen maintained in RAM of any dimensions that can be reproduced on the CRT in full or in part. The advantages are: . Variable row-by-column screen . Large video buffer up to 64k . High speed in RAM . Unlimited number of screens Screen Record - QWIK uses seven variables to define any screen. At start up, QWIK initializes them to the video system detected: CRTrows - Number of rows CRTcols - Number of columns CRTsize - Byte allocation for screen Qsnow - True if snow checking needed QEosOfs - EOS offset QScrOfs - Screen offset QScrSeg - Screen segment To make data access even easier, all these variables are contained in the record QScrRec of VScrRecType. In addition, QScrPtr is absolute to QScrOfs and QScrSeg. This gives QWIK a true far pointer, so screens can be anywhere in memory and not just paragraph aligned! Creating Virtual Screens - In three easy steps, you can easily create a virtual screen: 1. Allocate memory for the screen. 2. Save the current screen record. 3. Modify the screen record for the virtual screen. Let's write some code that does just that: uses Qwik; var CRTrec,VScrRec: VScrRecType; begin with VScrRec do { create specs for virtual screen } begin Vrows := 80; { Let's choose 80 rows } Vcols := 100; { Let's choose 100 columns } Vsize := Vrows * Vcols shl 1; Vsnow := false; { Can always be false } VEosOfs := 0; { Be safe and start at the base } Chapter 4, Advanced Techniques Page 17 QWIK Screen Utilities User's Guide, Version 5.x GetMem (VScrPtr,Vsize); { Allocate heap space } end; CRTrec := QScrRec; { Save CRT specs } QScrRec := VScrRec; { Set virtual specs } { ... } { Write to the virtual screen } QScrRec := CRTrec; { Restore CRT specs when done! } end. Now, when you use any QWIK routine, they can be directed to the virtual screen - writing, reading, scrolling, wrapping, and everything you would expect. Qsnow can always be false when writing to virtual screens since RAM is used and not video card memory. Cursor Control - One thing not available to virtual screens is cursor movement, because the cursor location is reserved by DOS for just video pages. That means there is no cursor available for virtual screens. So, how can we get around this? The EOS marker comes to the rescue as an indispensable cursor! All EOS routines can still be used as before. Taking a Peek - At some time, we will need to take a look at all or a portion of the virtual screen by copying it to the CRT. Two inter-screen procedures do this by blocks at high speed - QScrToVscr and QVscrToScr. Here are the parameters of QVscrToScr: QVscrToScr (Row,Col,Rows,Cols,Vrow,Vcol,Vwidth,VScrPtr); Just like QstoreToScr, Row, Col, Rows, and Cols describe the position and size on the screen (Scr). This screen is specified by QScrRec which is usually the CRT. VScrPtr points to the virtual screen (Vscr). Now, where is the same size block on Vscr? It's at Vrow and Vcol. But the Vscr may have a different column width than CRTcols. So you specify that with Vwidth. Only the Scr side checks for possible snow. These procedures are extremely fast making virtual screens very practical. See QScrToVscr and QVscrToScr in QWIKREF.DOC for more examples. Multiple Virtual Screens - By changing QScrRec, you can even copy blocks from one virtual screen to another! These routines do not affect QEosOfs. VIDEO PAGES Multi-page Cards - TP5 procedures such as Write, Window, and GotoXY are dedicated to just page 0, but many video cards have more than one page. If you have a CGA or better, you already have memory on your card for 4 to 8 pages. Since the BIOS recognizes them as well, QWIK gives you access to these extra pages. Page Control - QwritePage and QviewPage give you the power to use QWIK on all video pages and display which ever you choose. On a multiple-video page card like CGA, you can simply code: QwritePage (MyPage); to make all QWIK routines be directed to your selected video page even though you could be viewing another page. To view a page, you can in turn Chapter 4, Advanced Techniques Page 18 QWIK Screen Utilities User's Guide, Version 5.x simply code: QviewPage (MyPage); Tips About Pages - Here are some tips to keep in mind when using several video pages: . The highest valid video page is detected by Qinit and saved in the variable MaxPage. . Invalid page parameters are just ignored. . The BIOS reserves a separate cursor location for each of up to 8 video pages. . There is only one possible cursor mode which is always displayed on the CRT. . The cursor location routines operate on the page being written rather than viewed. . The current video page viewed is found with VideoPage. . The current video page set by QwritePage is saved in QvideoPage. . Be sure to end your programs with "QviewPage (0);". VIDEO MODES CRT Unit - If you intend to use the CRT unit with QWIK, it is best to place the CRT unit first in the "USES" list. When the CRT runs its initialization code, it checks for the video mode to see if it is a valid text mode (0..3,7). If so, it remains in that mode. If not, it is in a graphics or extended column mode and is forced back into the