Xbase++ - Class XbpClipBoard()

Class function of the XbpClipBoard class.

The XbpClipBoard class provides objects that access the clipboard. The clipboard allows data to be easily exchanged between different processes.

Managing the clipboard is similar to managing a file. Both must be opened before reading or writing information and must later be closed. The unique aspect of the clipboard is that only one single process (more precisely: one single thread) at a time can access the clipboard. This is similar to a file being exclusively opened. As long as the Xbase++ application has the clipboard open, no other application or thread can access it. It is therefore extremely important to close the clipboard after it has been opened by an XbpClipBoard object.

The clipboard can simultaneously hold information that appears in different formats. For example, ASCII text can be stored in the clipboard along with a graphic in the metafile format. Access to different formats in the clipboard is controlled using the :getBuffer() method of the XbpClipBoard object. The formats that are currently available in the clipboard are determined using the :queryFormats() method. The following constants are defined in the XBP.CH file to identify the different clipboard formats:

Constant	Description
XBPCLPBRD_TEXT	Data in ASCII text format
XBPCLPBRD_BITMAP	Graphic data in a bitmap format
XBPCLPBRD_METAFILE	Graphic data in a meta file format
nFormat	User-defined format, see :registerFormat()

Objects of the XbpSLE and XbpMLE classes include methods that access the clipboard without using an XbpClipBoard object. ASCII text can be copied into the clipboard from the edit buffer of these objects and ASCII text in the clipboard can be retrieved by them.

Creates an instance of the XbpClipBoard class.

Requests system resources for the XbpClipBoard object.

Releases the system resources of the XbpClipBoard object.

Deletes the data currently in the clipboard.

Closes the clipboard.

Retrieves the data from the clipboard.

Retrieves the name of a clipboard data format.

Opens the clipboard.

Returns the data formats for which there is data currently available in the clipboard.

Registers an Xbase Part as recipient for "change" messages

Registers a user-defined data format

Writes data to the clipboard.

Data exchange using the clipboard


// This example demonstrates how data from the clipboard can 
// be imported into an Xbase++ application. An MLE is created 
// that receives the data. A text editor is started to 
// write data to the clipboard (write, mark, and copy text 
// to the clipboard using Ctrl+Insert). SetTimerEvent() is 
// used to start a thread that controls the clipboard. When 
// characters in the editor are copied to the clipboard, they 
// are imported into the edit buffer of the MLE in the 
// function MonitorClipBoard(). Later the data in the clipboard 
// is deleted. 

#include "Xbp.ch" 
#include "Appevent.ch" 

PROCEDURE Main 
   LOCAL nEvent, mp1, mp2, oXbp 
   LOCAL cText, oMle, oClipBoard 

   SetColor("N/W") 
   CLS 
   SetAppWindow():useShortCuts := .T. 

   // Create MLE 
   oMle := XbpMLE():new():create( , , {50,50}, {550,300} ) 

   // Create clipboard object 
   oClipBoard := XbpClipBoard():new():create() 

   // Create thread for controlling the clipboard 
   SetTimerEvent( 100, {|| MonitorClipBoard( oClipBoard, oMle ) } ) 

   #ifdef __OS2__ 
      // Editor E.EXE starten 
      RunShell('START "Editor called by Xbase++" /F E.EXE') 
   #else 
      // Editor Notepad.EXE starten 
      RunShell('START "Editor called by Xbase++" Notepad.EXE') 
   #endif 

   // Event loop 
   nEvent := 0 
   DO WHILE nEvent <> xbeP_Close 
      nEvent := AppEvent( @mp1, @mp2, @oXbp ) 
      oXbp:HandleEvent( nEvent, mp1, mp2 ) 
   ENDDO 
RETURN 

********************************************** 
PROCEDURE MonitorClipBoard( oClipBoard, oMLE ) 
   LOCAL cText, aFormats 

   // Open clipboard and determine the data formats 
   // contained in it 
   oClipBoard:open() 
   aFormats := oClipBoard:queryFormats() 

   // If text is available in the clipboard, import the 
   // text into the MLE and delete data in the clipboard 
   IF AScan( aFormats, XBPCLPBRD_TEXT ) > 0 
      cText := oClipBoard:getBuffer( XBPCLPBRD_TEXT ) 
      oClipBoard:clear() 
      oMLE:setData( cText ) 
      Tone(500) 
   ENDIF 

   oClipBoard:close() 
RETURN

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Class XbpClipBoard() Foundation