DispOutAt

DispOutAt

Displays a value on the screen

Syntax

      DispOutAt( <nRow>      , ;
                    <nCol>      , ;
                    <expression>, ;
                    [<cColor>]  , ;
                    [<lSetPos>]   ) --> NIL

Arguments

<nRow> : Row number of screen to <expression> write

<nCol> : Column number of screen to <expression> write

<expression> : Any expression to write to the screen.

<cColor> : Color string for display

<lSetPos> : Specifies whether or not to update the screen cursor positions ( Row(), Col() after writing

Return

DispOutAt() returns always NIL.

Description

This function write the value of <expression> at the specified cursor position on the screen, using the color <cColor>, if specified.

Note

DispOutAt() don’t obey SET DEVICE setting and write always to the screen

Example

      DispOutAt( 0, 0, "Here upper left corner of screen", "W+/R" )

         is equvalent to :

         @ 0,0  SAY ""Here upper left corner of screen" COLOR  "W+/G"

Seealso

@ … SAY, Col(), DevOut(), DispBegin(), DispCount(), DispEnd(), DispOutAt(), OutStd(), QOut() | QQOut(), Row(), SetPos()

DispOut

DispOut

Displays a value on the screen

Syntax

      DispOut( <expression>, [<cColor>] ) --> NIL

Arguments

<expression> : Any expression to write to the screen.

<cColor> : Color string for display

Return

DispOut() returns always NIL.

Description

This function write the value of <expression> at the current cursor position on the screen, using the color <cColor>, if specified.

Note

DispOut() don’t obey SET DEVICE setting and write always to the screen

Example

      SetPos( 0, 0 )
         DispOut( "Here upper left corner of screen", "W+/R" )

         is equvalent to :

          @ 0,0  SAY ""Here upper left corner of screen" COLOR  "W+/G"

Seealso

@ … SAY, Col(), DevOut(), DispBegin(), DispCount(), DispEnd(), DispOutAt(), OutStd(), QOut() | QQOut(), Row(), SetPos()

DispEnd

DispEnd

Display buffered screen updates

Syntax

      DispEnd() --> NIL

Returns

DispEnd() always returns NIL.

Description

DispEnd() is a screen function that informs the Harbour display output system that the application has finished performing a series of display operations.

DispEnd() is used with DispBegin() so the display output system can buffer display updates. This can be important for applications in which complex screen displays are slow and the appearance of performance is desired.

Examples

      .  This example buffers screen output, updates the screen, and
      then displays the buffered screen output:

      DispBegin()            // Start screen buffering
      //
      SetPos(10, 10)
      DispOut("A display update")
      SetPos(11, 10)
      DispOut("Another display update")
      //
      DispEnd()               // Display buffered screen data

Seealso

DispBegin(), DispCount()

DispBegin

DispBegin

Begin buffering screen output

Syntax

      DispBegin() --> NIL

Returns

DispBegin() always returns NIL.

Description

DispBegin() is a screen function that informs the Harbour display output system that the application is about to perform a series of display operations.

Use DispBegin() with DispEnd() to allow the display output system to buffer display updates. Display output which occurs after DispBegin() but before DispEnd() is allowed to accumulate in internal buffers. When DispEnd() executes, any pending updates appear on the physical display. This is useful in applications where complex screen displays are slow and the appearance of performance is desired.

DispBegin() and DispEnd() calls are optional. They are not required for normal output.

Notes

. Nested calls: DispBegin() calls are nested internally. If several DispBegin() calls occur, buffering is allowed until a corresponding number of DispEnd() calls occur.

. Guaranteed operations: Display updates performed between DispBegin() and DispEnd() are not guaranteed to be buffered–some updates may become visible before DispEnd() is called. However, all updates are guaranteed to be visible after the closing call to DispEnd().

. Terminal operations: Terminal input operations such as INKEY() or READ should not be performed between DispBegin() and DispEnd(). Doing this may cause input or display output to be lost.

. Incompatible operations: Display output by other than the Harbour display functions (e.g., by add-on libraries or by DOS via OUTSTD(), etc.) may not be compatible with DispBegin() and DispEnd(). Output may be lost.

Examples

      .  This example buffers screen output, updates the screen, and
      then displays the buffered screen output:

      DispBegin()            // Start screen buffering
      //
      SETPOS(10, 10)
      DISPOUT("A display update")
      SETPOS(11, 10)
      DISPOUT("Another display update")
      //
      DispEnd()               // Display buffered screen data

Seealso

DispCount(), DispEnd()

C5_DISPCOUNT

 DISPCOUNT()
 Return the number of pending DISPEND() requests
------------------------------------------------------------------------------
 Syntax

     DISPCOUNT() --> nDispCount

 Returns

     DISPCOUNT() returns the number of DISPEND() calls required to restore
     the original display context.

 Description

     You can use DISPCOUNT() to determine the current display context.
     Clipper uses display contexts to buffer and to supervise screen
     output operations.

     Each call to DISPBEGIN() defines a new display context.  Output to the
     display context is suppressed until a matching DISPEND() statement
     executes.

     Since you may nest DISPBEGIN() calls, use DISPCOUNT() to determine
     whether there are pending screen refresh requests.

 Examples

     .  This example saves the setting of DISPCOUNT(), then releases
        all pending display contexts before writing to the screen:

        PROCEDURE ForceDisplay(cExp)
           LOCAL nSavCount

        nSavCount := DISPCOUNT()

        //  Discard pending display contexts
        DO WHILE ( DISPCOUNT() > 0)
           DISPEND()

        ENDDO

        DISPOUT(cExp)

        //  "Rewind" the current display context
        DO WHILE (DISPCCOUNT() < nSavCount )
           DISPBEGIN()
        ENDDO

        RETURN

 Files   Library is CLIPPER.LIB.

See Also: DISPBEGIN() DISPEND()