_gtBoxD()
 Draw a double-line box on the screen
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 C Prototype

     #include "gt.api"
     ERRCODE _gtBoxD(
                      USHORT uiTop,
                      USHORT uiLeft,
                      USHORT uiBottom,
                      USHORT uiRight
                    )

 Arguments

     uiTop, uiLeft, uiBottom, and uiRight define the coordinates
     of the box.  Allowable row values are from zero to _gtMaxRow() and
     allowable column values are from zero to _gtMaxCol().  Specifying
     coordinates that are not within this range will result in that area
     being drawn off the screen.

 Returns

     _gtBoxD() returns zero if successful.  Any other value indicates an
     error.

 Description

     _gtBoxD() draws a double-line box at the specified coordinates on the
     screen.  Existing text and color remain unchanged.

     After _gtBoxD() executes, the cursor is located in the upper corner of
     the boxed region (uiTop + 1 and uiLeft + 1).  The internal row and
     column coordinates are updated so the CA-Clipper functions, ROW() and
     COL(), will reflect the new cursor position.

 Examples

     .  This example draws text framed by a double-line box on the
        screen:

        #include "gt.api"

        void boxTextD( USHORT uiRow, USHORT uiCol, BYTEP fpStr );

        void boxTextD( USHORT uiRow, USHORT uiCol, BYTEP fpStr )
        {
           _gtBoxD( uiRow, uiCol, uiRow + 2,
                    uiCol + strlen( fpStr ) + 2 );
           _gtWrite( fpStr, strlen( fpStr ) );
        }

 Files  Library is CLIPPER.LIB, header file is Gt.api.