CD Actual 15/CDACTUAL15.iso/cdactual/program/pascal/PASLIBR.ZIP/CH2_2.DOC

Text File | 1991-03-15 | 26.9 KB | 1,154 lines

..pgno26
..foot60A2-##
..head02L──────────────────────────────────────────────────────────────────────
..head04L──────────────────────────────────────────────────────────────────────
..head03AGetScrn
■ Description

  Read the character and attribute bytes starting from specified
  position on the screen into the buffer.


■ Summary

  Procedure GetScrn( x, y, NWords : Integer; Var Buffer );


  x           column to begin reading data from the screen.

  y           row to begin reading data from the screen.

  NWords      number of words to read from the display screen.

  Buffer      data area where the data from the display screen will be
              placed.


■ Remarks

  This procedure provides additional checks for vertical and
  horizontal retrace periods on a CGA video adapter.  This is to
  eliminate the snow effect that is produced from direct moves to or
  from the video display.  These checks may be turned off through the
  global variable CheckSnow.


■ See Also

  PutScrn

■ Example

  Program Example;
  Uses FPVideo;
  Var
     Buffer : Array[1..160] Of Char;
  Begin
     GetScrn( 1, 1, 80, Buffer );
  End.

  In the above example the size of Buffer must be at least 160 bytes
  long. A copy of row one on the screen will be placed into Buffer.
  Buffer will contain both the character and attribute byte values for
  each cell on the video display.
..page
..head03AGetVideoCols
■ Description

  Get the number of columns per line for the current display mode.


■ Summary

  Function GetVideoCols : Integer;


■ See Also

  GetVideoInfo


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     Writeln( 'Total number of columns = ', GetVideoCols:1 );
  End.

  GetVidoCols should return either 40 or 80 depending on the video
  mode the system is in.
..page
..head03AGetVideoInfo
■ Description

  Gets general video display informtion.


■ Summary

  Procedure GetVideoInfo( Var BaseSeg, Cols, Pg, Mode : Integer );

  BaseSeg     returns the base segment address of the current video
              page.

  Cols        returns the number of display columns available for the
              current video mode.

  Pg          returns the active display page for the video display.
              This will always be zero for the monochrome display
              adapter.

  Mode        returns the current video display mode.


■ See Also

  GetVideoCols, GetVideoMode, GetVideoPage


■ Example

  Program Example;
  Uses FPVideo;
  Var
      BaseSeg,Mode,NCols,Pg : Integer
  Begin
     ClrWin( 1, 1, 80, 25, 7 );
     GotoxyAbs( 1, 1 );

     GetVideoInfo( BaseSeg, NCols, Pg, Mode );

     Writeln('BaseSeg             = ', BaseSeg:1 );
     Writeln('Number of columns   = ', NCols:1   );
     Writeln('Active display page = ', Pg:1      );
     Writeln('Current video mode  = ', Mode:1    );
  End.

  This example will display the video information to the screen.  The
  current video mode should return a value from 0-15, the number of
  columns will be either 40 or 80, and the active video display page
  will be a value from 0-7.
..page
..head03AGetVideoMode
■ Description

  Gets the current video mode.


■ Summary

  Function GetVideoMode : Integer;


■ Remarks

  Returns an integer giving the current video mode the system is in.
  Use the guide on video modes under InitVideo.


■ See Also

  GetVideoInfo


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     Writeln( 'Current video mode  = ', GetVideoMode:1 );
  End.

  This example will display the current video mode the system is in.
..page
..head03AGetVideoPage
■ Description

  Gets the active display page currently in use.


■ Summary

  Function GetVideoPage : Integer;


■ Remarks

  On monochrome displays GetVideoPage will always return a zero.


■ See Also

  GetVideoInfo


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     Writeln( 'Current video page  = ', GetVideoPage:1 );
  End.

  This example will display the current video page on the system.  It
  should be a value in the range of 0-7.
..page
..head03AGotoxyAbs
■ Description

  Position the cursor at the specified position on the screen without
  regards to the global variables WindMin and WindMax.


■ Summary

  Procedure GotoxyAbs( x, y : Integer );

  x           column number to place the cursor in.

  y           row number to place the cursor in.


■ Remarks

  This procedure will place the cursor at the specified x,y
  coordinates on the screen.  GotoxyAbs is NOT sensitive to the global
  variables WindMin and WindMax.

■ See Also

  WhereXAbs, WhereYAbs


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     WindowFP( 10, 10, 50, 24 );
     GotoxyAbs( 1, 1 );
  End.

  Even though the upper left corner of the defined window is row 10,
  column 10, GotoxyAbs will still place the cursor in row 1 column 1
  on the screen.
..page
..head03AHideCursor
■ Description

  Hides the cursor from view of the video display.


■ Summary

  Procedure HideCursor;


■ Remarks

  This function turns on the fifth bit of the current cursor size.


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     HideCursor();
   End.

  This example will hide the cursor from view of the video display.
..page
..head03AInitVideo
■ Description

  Initialize the video mode.


■ Summary

  Procedure InitVideo( Mode : Integer );

  Mode        gives the video mode to initialize.


■ Remarks

  To set the screen to the appropriate video mode use the following
  table as a guide.

     Mode           Type            Colors   Adapter
   ───────────────────────────────────────────────────
  |    0  |  Text - 40 x 25 B/W   |  b/w   |   CGA    |
  |    1  |  Text - 40 x 25 COLOR |  16    |   CGA    |
  |    2  |  Text - 80 x 25 B/W   |  b/w   |   CGA    |
  |    3  |  Text - 80 x 25 COLOR |  16    |   CGA    |
  |    4  |  Graphics - 320 x 200 |   4    |   CGA    |
  |    5  |  Graphics - 320 x 200 | 4 grey |   CGA    |
  |    6  |  Graphics - 640 x 200 |  b/w   |   CGA    |
  |    7  |  Text - 80 x 25       |  16    |   MDA    |
  |    8  |  Graphics - 160 x 200 |  16    |   PCjr   |
  |    9  |  Graphics - 320 x 200 |  4,64  |   PCjr   |
  |   10  |  Graphics - 640 x 200 |  16    | PCjr,EGA |
  |   13  |  Graphics - 320 x 200 |  16    |   EGA    |
  |   14  |  Graphics - 640 x 200 |  16    |   EGA    |
  |   15  |  Graphics - 640 x 350 |   4    |   EGA    |
   ───────────────────────────────────────────────────


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     InitVideo( 3 );
   End.

  This example will initialize the video mode to 80 x 25 color text.
..page
..head03APutFrameAttr
■ Description

  Write the data in the buffer to the attribute byte in the specified
  area on the screen.


■ Summary

  Procedure PutFrameAttr( x1, y1, x2, y2 : Integer; Var Buffer );

  x1          left column of window.

  y1          top row of window.

  x2          right column of window.

  y2          bottom row of window.

  Buffer      data buffer that contains the information to display on
              the screen.


■ See Also

  GetFrameAttr, PutFrameCell, PutFrameChar


■ Example

  Program Example;
  Uses FPVideo;
  Var
     Buffer : Array[1..2000] Of Char;
  Begin
     FillChar( Buffer, sizeof( Buffer ), 7 );
     PutFrameAttr( 1, 1, 80, 25, Buffer );
  End.

  In this example the first statment fills the buffer array with the
  value of 7.  This will be the attribute character placed on the
  screen for each attribute position.  Then the PutFrameAttr statement
  places each byte in the buffer on the display screen.

  Normally PutFrameAttr is used as the inverse or complement of the
  procedure GetFrameAttr.  Using GetFrameAttr would save the attribute
  bytes for a section of the screen to be later restored with
  PutFrameAttr.
..page
..head03APutFrameCell
■ Description

  Write the data in the buffer to the character and attribute bytes in
  the specified area on the screen.


■ Summary

  Procedure PutFrameCell( x1, y1, x2, y2 : Integer; Var Buffer );

  x1          left column of window.

  y1          top row of window.

  x2          right column of window.

  y2          bottom row of window.

  Buffer      data buffer that contains the information to display on
              the screen.


■ See Also

  GetFrameCell, PutFrameAttr, PutFrameChar


■ Example

  Program Example;
  Uses FPVideo;
  Var
     Buffer : Array[1..2100] Of Char;
     i      : Integer;
  Begin
     For i := 1 To 25 Do
        FillRowCell( 1, i, 80, (i+64) Shl 8 + i );
     GetFrameCell( 10, 10, 80, 25, Buffer );
     ClrWin( 1, 1, 80, 25, 7 );
     ColorMsg( 1, 1, 7, 'Press any key to continue...' );
     i := GetKey;
     PutFrameCell( 1, 1, 71, 16, Buffer );
  End.

  In this example the first statment retrieves a section of the
  display screen and places 2100 bytes in the data variable Buffer.
  The screen is then cleared to remove the display data from the
  screen.  PutFrameCell restores the data saved from GetFrameCell and
  places the data onto another portion of the display screen.
..page
..head03APutFrameChar
■ Description

  Write the data in the buffer to the character byte in the specified
  area on the screen.


■ Summary

  Procedure PutFrameChar( x1, y1, x2, y2 : Integer; Var Buffer );

  x1          left column of window.

  y1          top row of window.

  x2          right column of window.

  y2          bottom row of window.

  Buffer      data buffer that contains the information to display on
              the screen.


■ See Also

  GetFrameChar, PutFrameAttr, PutFrameChar


■ Example

  Program Example;
  Uses FPVideo;
  Var
     Buffer : Array[1..2000] Of Char;
  Begin
     FillChar( Buffer, sizeof( Buffer ), 'A' );
     PutFrameChar( 1, 1, 80, 25, Buffer );
  End.

  In this example the first statment fills the buffer array with the
  letter A.  This will be the character to be placed on the screen for
  each character position. Then the PutFrameChar statement places each
  character from the buffer to the display screen.

  Normally PutFrameChar is used as the inverse of the GetFrameChar
  procedure.  Using GetFrameChar would allow the character bytes for a
  section of the screen to be saved and later restored with
  PutFrameChar.
..page
..head03APutScrn
■ Description

  Displays the data in the buffer to the specified screen position in
  character attribute byte form.


■ Summary

  Procedure PutScrn( x, y, NWords : Integer; Var Buffer );

  x           column to begin display of screen data.

  y           row to begin display of screen data.

  NWords      number of words to read from the display screen.

  Buffer      data buffer to place the screen information.


■ Remarks

  This procedure provides additional checks for vertical and
  horizontal retrace periods on a CGA video adapter.  This is to
  eliminate the snow effect that is produced from direct moves to or
  from the video display.  These checks may be turned off through the
  global variable CHECKSNOW.


■ See Also

  GetScrn
..page
■ Example

  Program Example;
  Uses FPVideo;
  Var
     Buffer : Array[1..1920] Of Char;
     i      : Integer;
  Begin

     ClrWin( 1, 1, 80, 25, 7 );

     { place screen divider line in middle of screen }
     FillRowChar( 1, 13, 80, '-' );

     { place characters and attributes to the screen }
     For i := 14 To 25 Do
        FillRowCell( 1, i, 80, (i+64) Shl 8 + i );

     { save the screen data }
     GetScrn( 1, 14, 960, Buffer );

     ColorMsg( 1, 1, 7, 'Press any key to continue...' );
     i := GetKey();

     { restore screen data to a different location }
     PutScrn( 1, 1, 960, Buffer );
  End.

  In this example the size of Buffer is 1920 bytes long. The 960 words
  in the lower half of the screen are placed into the data buffer with
  the call to GetScrn.  The call PutScrn will then place the data
  buffer information on the screen starting at row one column one.
  Both the attribute and character bytes will be written to the
  screen.  The Buffer variable may be subscripted to use a different
  starting point for the buffers contents.
..page
..head03ARvsAttr
■ Description

  Reverses the video attribute byte passed.

■ Summary

  Function RvsAttr( Attr : Integer ) : Integer;

  Attr        value in the range 0-255 giving the screen color to be
              reversed.


■ Remarks

  RvsAttr exchanges the three foreground and background attribute bits
  of the parmaeter value passed in.  The blink and intensity bits of
  the byte remain unchanged.


■ Example

  Foreground color --> white.
  Background color --> black.

  If the above is true for the foreground and background colors then
  after calling RvsAttr the foreground and background colors will be
  as follows:

  Foreground color --> black.
  Background color --> white.


  Program Example;
  Uses FPVideo;
  Begin
     Writeln( 'Attribute value 7 reversed = ', RvsAttr( 7 ):1 );
  End.
..page
..head03AScrollDown
■ Description

  Scroll the specified portion of the screen down N lines filling in
  new lines with spaces and the specified attribute.


■ Summary

  Procedure ScrollDown( x1, y1, x2, y2, Attr, NRows : Integer );

  x1          left column of window.

  y1          top row of window.

  x2          right column of window.

  y2          bottom row of window.

  Attr        value in the range 0-255. It defines the display
              attribute to be used when filling in the blank lines at
              the top of the window.

  NRows       number of lines the specified portion of the screen is
              to be scrolled.


■ Remarks

  If you use a value of zero for the number of lines to scroll, the
  window area defined by the x1,y1,x2,y2 coordinates will be cleared
  to the color defined by the Attribute variable.


■ See Also

  ScrollLeft, ScrollRight, ScrollUp
..page
■ Example

  Program Example;
  Uses FPVideo;
  Var
     i : Integer;
  Begin
     ClrWin( 1, 1, 80, 25, 7 );
     For i := 1 To 25 Do
        FillRowChar( 1, i, 80, Chr( 64+i ) );

     ScrollDown( 4, 5, 15, 20, 48, 1 );
  End.

  In this example one line will be scrolled down in the window with
  the top row being filled in with cyan on a Color/Graphics Adapter.
..page
..head03AScrollLeft
■ Description

  Scroll the specified portion of the screen left N columns filling in
  new columns with spaces and the specified attribute.


■ Summary

  Procedure ScrollLeft( x1, y1, x2, y2, Attr, NCols : Integer );

  x1          left column of window.

  y1          top row of window.

  x2          right column of window.

  y2          bottom row of window.

  Attr        value in the range 0-255. It defines the display
              attribute to be used when filling in the blank columns
              on the right side of the window.

  NCols       number of columns the specified portion of the screen is
              to be scrolled.


■ Remarks

  If you use a value of zero for the number of lines to scroll, the
  window area defined by the x1,y1,x2,y2 coordinates will be cleared
  to the color defined by the Attribute variable.


■ See Also

  ScrollDown, ScrollRight, ScrollUp
..page
■ Example

  Program Example;
  Uses FPVideo;
  Var
     i : Integer;
  Begin
     ClrWin( 1, 1, 80, 25, 7 );
     For i := 1 To 25 Do
        FillRowChar( 1, i, 80, Chr( 64+i ) );
     ScrollLeft( 4, 5, 15, 20, 48, 1 );
  End.

  In this example one column will be scrolled left in the window with
  the right column being filled in with cyan on a Color/Graphics
  Adapter.
..page
..head03AScrollRight
■ Description

  Scroll the specified portion of the screen right N columns filling
  in new columns with spaces and the specified attribute.


■ Summary

  Procedure ScrollRight( x1, y1, x2, y2, Attr, NCols : Integer );

  x1          left column of window.

  y1          top row of window.

  x2          right column of window.

  y2          bottom row of window.

  Attr        value in the range 0-255.  It defines the display
              attribute to be used when filling in the blank columns
              on the left side of the window.

  NCols       number of columns the specified portion of the screen is
              to be scrolled.


■ Remarks

  If you use a value of zero for the number of lines to scroll, the
  window area defined by the x1,y1,x2,y2 coordinates will be cleared
  to the color defined by the Attribute variable.


■ See Also

  ScrollDown, ScrollLeft, ScrollUp
..page
■ Example

  Program Example;
  Uses FPVideo;
  Var
     i : Integer;
  Begin
     ClrWin( 1, 1, 80, 25, 7 );
     For i := 1 To 25 Do
        FillRowChar( 1, i, 80, Chr( 64+i ) );
     ScrollRight( 4, 5, 15, 20, 48, 1 );
  End.

  In this example one column will be scrolled right in the window with
  the left column being filled in with cyan on a Color/Graphics
  Adapter.
..page
..head03AScrollUp
■ Description

  Scroll the specified portion of the screen up N lines filling in new
  lines with spaces and the specified attribute.


■ Summary

  Procedure ScrollUp( x1, y1, x2, y2, Attr, NRows : Integer );

  x1          left column of window.

  y1          top row of window.

  x2          right column of window.

  y2          bottom row of window.

  Attr        value in the range 0-255. It defines the display
              attribute to be used when filling in the blank lines at
              the bottom of the window.

  NRows       number of lines the specified portion of the screen is
              to be scrolled.


■ Remarks

  If you use a value of zero for the number of lines to scroll, the
  window area defined by the x1,y1,x2,y2 coordinates will be cleared
  to the color defined by the Attribute variable.


■ See Also

  ScrollDown, ScrollLeft, ScrollRight
..page
■ Example

  Program Example;
  Uses FPVideo;
  Var
     i : Integer;
  Begin
     ClrWin( 1, 1, 80, 25, 7 );
     For i := 1 To 25 Do
        FillRowChar( 1, i, 80, Chr( 64+i ) );
     ScrollUp( 4, 5, 15, 20, 48, 1 );
  End.

  In this example one line will be scrolled up in the window with the
  bottom row being filled in with cyan on a Color/Graphics Adapter.
..page
..head03ASetCursorSize
■ Description

  Set the size of the cursor.


■ Summary

  Procedure SetCursorSize( StScan, SpScan : Integer );

  StScan      starting scan line to be used for the cursor.

  SpScan      ending scan line to be used for the cursor.


■ Remarks

  The scan lines are numbered from zero at the top (StScan) to N at
  the bottom (SpScan) where N applies to the following video adapters:

                7 - Color/Graphics Adapter
               14 - Monochrome Adapter

               - 0 --
               - 1   |
               - 2   |
               - 3   |---> Scan lines for a Color/Graphics
               - 4   |     display adapter.
               - 5   |
               - 6   |
               - 7 --


■ See Also

  GetCursorSize
..page
■ Example

  The following examples are for the Color/Graphics Adapter:


  Program Example;
  Uses FPVideo;
  Begin
     SetCursorSize( 32, 32 );    { hides the cursor          }
     SetCursorSize( 0 ,  7 );    { cursor covers entire cell }
     SetCursorSize( 6 ,  7 );    { cursor size normal        }
  End.

  The first SetCursorSize statment makes the cursor invisible on the
  screen.  The second SetCursorSize will cover the entire character
  cell on a color/graphic display and will cover half of the cell on a
  monochrome display.  If the display was a monochrome display and the
  entire character cell was to be covered by the cursor then the
  parameters should be (0,13).
..page
..head03ASetVideoPage
■ Description

  Set the active display page.


■ Summary

  Procedure SetVideoPage( PageNo : Integer );

  PageNo      active display page to use.


■ Remarks

  Active display pages available for various display cards.

     0    - Monochrome
     0-7  - Color/Graphics 40 column text mode
     0-3  - Color/Graphics 80 column text mode
     0    - Color/Graphics Hi Resolution Graphics mode


■ See Also

  GetVideoPage


■ Example

  The following examples are for the Color/Graphics Adapter because
  the monochrome display only has one page available.

  Program Example;
  Uses FPVideo;
  Begin
     SetVideoPage( 0 );  { default video page - page 1 }
     SetVideoPage( 1 );  { another page       - page 2 }
  End.

  The first statement will set the video display to the default
  display page and the second statement will switch the video
  display to page one.  This function is not intended for use with a
  monochrome display adapter.
..page
..head03AShowCursor
■ Description

  Shows the cursor on the video display.


■ Summary

  Procedure ShowCursor;


■ Remarks

  This function turns off the fifth bit of the current cursor size.


■ Example

  Program Example;
  Uses FPVideo;
  Var
     i : Integer;
  Begin
     HideCursor();
     Writeln( 'Press any key to display the cursor' );
     i := GetKey();
     ShowCursor();
   End.

  This example will hide the cursor from view of the video display
  and then wait until the user presses a key.  Once a key has been
  pressed the program will then turn the cursor back on.
..page
..head03AVioInit
■ Description

  Initializes the Video units global variables.


■ Summary

  Procedure VioInit;


■ Remarks

  This function must be executed once before any video functions can
  be used.  If at some time you wish to reset the global variables to
  their default settings you may use this procedure to complete that
  task.


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     VioInit;      { do only if global video variables need }
                   { to be reset.                           }
  End.

  This example initializes the video display variables needed for the
  video library routines.
..page
..head03AWhereXAbs
■ Description

  Returns the column the cursor is in.


■ Summary

  Function WhereXAbs : Integr;


■ Remarks

  This function will return an integer giving the column number the
  cursor is on.  This routine is not sensitive to the currently
  defined window.


■ See Also

  GotoxyAbs, WhereYAbs


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     Writlen( 'The cursor is in column ', WhereXAbs:1 );
  End.

  The column number of the cursor when WhereXAbs was called will be
  displayed to the screen.
..page
..head03AWhereYAbs
■ Description

  Returns the row the cursor is on.


■ Summary

  Function WhereYAbs : Integer;


■ Remarks

  This function will return an integer giving the row number the
  cursor is on.  This routine is not sensitive to the currently
  defined window.


■ See Also

  GotoxyXAbs, WhereXAbs


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     Writeln( 'The cursor is in row ', WhereYAbs:1 );
  End.

  The row number of of the cursor when WhereYAbs was called will be
  displayed to the screen.
..page
..head03AWindowFP
■ Description

  Set the window coordinate variables WindMin and WindMax.


■ Summary

  Procedure WindowFP( x1, y1, x2, y2 : Integer );

  x1          left column of window.

  y1          top row of window.

  x2          right column of window.

  y2          bottom row of window.


■ Remarks

  This function sets the window coordinates in the WindMin and WindMax
  global variables which FrameWin uses for framing windows on the
  display screen.


■ See Also

  FrameWin


■ Example

  Program Example;
  Uses FPVideo;
  Begin
     WindowFP( 1, 1, 80, 25 );
     FrameWin( 'L', 'R', 'l', 'r', 'h', 'v', 7 );
  End.

  This example will set the window coordinates to the upper left and
  lower right corners of the video display.
..page
..head03AWriteSt
■ Description

  Display a string on the screen


■ Summary

  Procedure WriteSt( St : String );

  St          string expression to display on screen.


■ Remarks

  WriteSt positions the cursor after the newly displayed string.
  WriteSt is NOT sensitive to the currently defined window and will
  wrap around to the next row of column one of the physical screen
  when necessary. WriteSt will not scroll the screen if the data to be
  displayed is to extend beyond the last row of the screen.  WriteSt
  uses the attribute byte defined by the global variable TextAttr.


■ See Also

  WriteStLn


■ Example

  Program Example;
  Uses FPVideo;
  Var
     i : Integer;
  Begin
     GotoxyAbs( 1, 1 );      { position curor in upper left corner }
     For i := 1 To 49 Do
        WriteSt( 'test string ');
  End.

  This example will position the cursor in the upper left corner of
  the display screen and then will proceed to display the string "test
  string" fifty times.  Example of the intented output follows:

  test string test string test string test string ...
..page
..head03AWriteStln
■ Description

  Display a string on the screen

■ Summary

  Procedure WriteStln( St : String );

  St          string expression to display on screen.


■ Remarks

  WriteStln positions the cursor in column one on the next line of the
  display screen after the data has been displayed.  WriteStln is NOT
  sensitive to the currently defined window and will wrap around to
  the next row of column one of the physical screen when necessary.
  WriteStln will not scroll the screen if the data to be displayed is
  to extend beyond the last row of the screen.  WriteStln uses the
  attribute byte defined by the global variable TextAttr.


■ See Also

  WriteSt


■ Example

  Program Example;
  Uses FPVideo;
  Var
     i : Integer;
  Begin
     GotoxyAbs( 1, 1 );      { position curor in upper left corner }
     For i := 1 To 24 Do
        WriteSt( 'test string ');
  End.

  This example will position the cursor in the upper left corner of
  the display screen and then on each line will display the string
  "test string" on the first 24 lines of the display.
..page