PRODUCT  :  Borland C++                           NUMBER  :  1727
  VERSION  :  All
       OS  :  DOS
     DATE  :  October 25, 1993                         PAGE  :  1/2

    TITLE  :  Erasing test in a BGI Application




  A common question with BGI users is how to erase text from the
  screen. This is a very simple process, but not obvious at first.
  It is done by changing the drawing color to the background
  color, then redrawing the same text again.

  Below is a sample program that demostrates how this works.  The
  key to this process is:  setcolor(getbkcolor()). One line
  determines the background color and sets the drawing color to
  it.

  #include <graphics.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <conio.h>

  int main(void)
  {
     int gdriver = DETECT, gmode, errorcode;
     int midx, midy;

     initgraph(&gdriver, &gmode, "\\bc\\bgi");

     errorcode = graphresult();
     if (errorcode != grOk)  // an error occurred
     {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1); // terminate with an error code
     }
     midx = getmaxx() / 2;
     midy = getmaxy() / 2;
     moveto(midx, midy);

     //----------------------------------------------- output text
     outtext("This ");
     outtext("is ");
     outtext("a ");
     outtext("test.");
     getch();
     //---------------------------- move back to original position
     moveto(midx, midy);
     //--------------------- set drawing color to background color













  PRODUCT  :  Borland C++                           NUMBER  :  1727
  VERSION  :  All
       OS  :  DOS
     DATE  :  October 25, 1993                         PAGE  :  2/2

    TITLE  :  Erasing test in a BGI Application




     setcolor(getbkcolor());
     //-------------------------------- output the same text again
     outtext("This ");
     outtext("is ");
     outtext("a ");
     outtext("test.");
     getch();

     closegraph();
     return 0;
  }


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