Power-Programmierung/CD1.mdf/lan/spy/source/screen.pas

Pascal/Delphi Source File | 1989-10-02 | 6KB | 176 lines

{$A+,B-,D-,E-,F+,I-,L-,N-,O-,R-,S-,V+}
Unit Screen;
{
  Screen supports fast, adapter independent movement of data to and from page
  zero of a text-mode screen.

  Author: Edwin T. Floyd [76067,747]
          9 Adams Park Court
          Columbus, GA 31909
          404-322-0076 (home)
          404-576-3305 (work)

  Thanks to Jeff Dunteman and Brian Foley who pioneered much of the code for
  these routines.

  This unit is contributed to the public domain.
}
Interface

Type
  AdapterType = (None, MDA, CGA, EGAMono, EGAColor, VGAMono, VGAColor,
    MCGAMono, MCGAColor, HercMono, HercPlus, HercInColor);
  FontSize = (Font8, Font14, Font16);
  ScreenSaveHeader =
  { Format of data area used by SaveScreenArea and RestoreScreenArea }
  Record
    Cursor : Word;                 { CursorPosition }
    RowCol1 : Word;                { Upper-left corner }
    RowCol2 : Word;                { Lower-right corner }
    Mode : Byte;                   { Video mode }
    Compressed : Boolean;          { True if screen area is compressed }
    Size : Word;                   { Size of data area that follows }
    { The header is followed by screen data }
  End;

Var
  ScreenOfs : Word;                { *Offset of video buffer }
  ScreenSeg : Word;                { *Segment of video buffer }
  DesqViewVersion : Word;          { *0 if DesqView not active }
  ScreenCols : Byte;               { *Number of columns on screen }
  ScreenRows : Byte;               { *Number of rows on screen }
  ScreenAdapterType : AdapterType; { *Adapter type }
  ScreenVideoMode : Byte;          { *Video mode }
  ScreenFontSize : FontSize;       { *Font size }
  BiosVideoMode : Byte Absolute $0040:$0049; { Video Mode byte in Bios data }
  CheckSnow : Boolean;             { If True, wait for retrace on CGA }
  DirectVideo : Boolean;           { If False, use BIOS }
  {
    Fields marked with "*" are set by GetBiosInfo. In a TSR, if
    ScreenVideoMode <> BiosVideoMode, you should GetBiosInfo again.
  }

Procedure GetBiosInfo;
{ Get information on current video adapter }

Procedure FillWord(Var Dest; Count, Value : Word);
{ Like FillChar, only with words (faster than FillChar) }

Function CursorPosition : Word;
{ Returns current cursor position on page 0.  Hi=Row, Lo=Col base 1. }

Procedure SetCursorPosition(RowCol : Word);
{ Sets cursor position }

Procedure PutWord(RowCol, Value : Word);
{ Write a word (Hi=Attribute, Lo=Character) to screen at indicated position }

Procedure PutWords(Var Source; RowCol, Count : Word);
{ Copy words to screen beginning at indicated position up to end of row }

Procedure GetWords(Var Dest; RowCol, Count : Word);
{ Copy words from screen beginning at indicated position up to end of row }

Function ScreenAreaSize(X1, Y1, X2, Y2 : Byte) : Word;
{ Returns the number of bytes required by SaveScreenArea. }

Procedure SaveScreenArea(Var Dest; X1, Y1, X2, Y2 : Byte);
{ Save a rectangular area of screen.  Coordinates set 1 defines upper-left
  corner, 2 defines lower right corner, top row: X1=1, left col: Y1=1.
  Save area format is described by ScreenSaveHeader above. }

Procedure RestoreScreenArea(Var Source);
{ Restore a previously saved rectangular area of screen }

Implementation
Type
  ScreenSaveArea = Record
    Header : ScreenSaveHeader;
    Data : Array[0..30000] Of Word;
  End;

Procedure GetBiosInfo;
External;

Procedure FillWord(Var Dest; Count, Value : Word);
External;

Function CursorPosition : Word;
External;

Procedure SetCursorPosition(RowCol : Word);
External;

Procedure PutWord(RowCol, Value : Word);
External;

Procedure PutWords(Var Source; RowCol, Count : Word);
External;

Procedure GetWords(Var Dest; RowCol, Count : Word);
External;

{$L SCREEN.OBJ }

Function ScreenAreaSize(X1, Y1, X2, Y2 : Byte) : Word;
Begin
  If X2 > ScreenCols Then X2 := ScreenCols;
  If Y2 > ScreenRows Then Y2 := ScreenRows;
  If (X1 > X2) Or (Y1 > Y2) Then ScreenAreaSize := SizeOf(ScreenSaveHeader)
  Else ScreenAreaSize := SizeOf(ScreenSaveHeader)
    + Succ(X2-X1) * Succ(Y2-Y1) * 2;
End;

Procedure SaveScreenArea(Var Dest; X1, Y1, X2, Y2 : Byte);
Var
  SaveArea : ScreenSaveArea Absolute Dest;
  LenPerRow, RowCount, i, j : Word;
Begin
  If X2 > ScreenCols Then X2 := ScreenCols;
  If Y2 > ScreenRows Then Y2 := ScreenRows;
  If X1 > X2 Then LenPerRow := 0 Else LenPerRow := Succ(X2-X1);
  If Y1 > Y2 Then RowCount := 0 Else RowCount := Succ(Y2-Y1);
  With SaveArea, Header Do Begin
    Cursor := CursorPosition;
    RowCol1 := Y1 Shl 8 + X1;
    RowCol2 := Y2 Shl 8 + X2;
    Mode := ScreenVideoMode;
    Compressed := False;
    Size := LenPerRow * RowCount * 2;
    If Size > 0 Then Begin
      j := 0;
      For i := Y1 To Y2 Do Begin
        GetWords(Data[j], i Shl 8 + X1, LenPerRow);
        Inc(j, LenPerRow);
      End;
      If Not DirectVideo Then SetCursorPosition(Cursor);
    End;
  End;
End;

Procedure RestoreScreenArea(Var Source);
Var
  SaveArea : ScreenSaveArea Absolute Source;
  LenPerRow, X1, Y1, Y2, i, j : Word;
Begin
  With SaveArea, Header Do Begin
    If Size > 0 Then Begin
      X1 := Lo(RowCol1);
      Y1 := Hi(RowCol1);
      Y2 := Hi(RowCol2);
      LenPerRow := Succ(Lo(RowCol2) - X1);
      j := 0;
      For i := Y1 To Y2 Do Begin
        PutWords(Data[j], i Shl 8 + X1, LenPerRow);
        Inc(j, LenPerRow);
      End;
    End;
    SetCursorPosition(Cursor);
  End;
End;

Begin
  DirectVideo := True;
  GetBiosInfo;
  CheckSnow := (ScreenAdapterType = CGA) And (ScreenSeg = $B800);
End.