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TRACK and DIGITIZE Statements

 
The TRACK statement controls tracking of the input device. It enables and disables the graphic locator from following the input device position on the PLOTTER IS device during DIGITIZE statements. Tracking stops when a point is digitized, and the tracking cross is left at the location of the digitized point. When the display device is a plotter, the pen position tracks the input device. When it is the CRT, the tracking cross tracks the input device.
Use the arrow keys on the keyboard or the mouse to move the tracking cross around. Run the following two programs to get a feel for how the DIGITIZE and READ LOCATOR statements differ. Also look at how the TRACK and SET ECHO statements can be used to follow the input device on the output device. Press the ENTER key or one of the mouse buttons to read the current X,Y location in program #1. Enter the "STOP" command to terminate program #2.
Program #1                                                      Program #2                                              
10 GINIT                10 GINIT
20 PLOTTER IS CRT,"INTERNAL"                20 PLOTTER IS CRT,"INTERNAL"
30 GRAPHICS INPUT IS KBD,"KBD"                30 GRAPHICS INPUT IS KBD,"KBD"
40 FRAME                40 FRAME
50 TRACK CRT IS ON                50 READ LOCATOR X,Y,S$
60 DIGITIZE X,Y,S$                60 SET ECHO X,Y
70 PRINT X,Y,S$                70 GOTO 50
80 END                80 END