overlay(3XCURSES)					  X/Open Curses Library Functions					 overlay(3XCURSES)

NAME

       overlay, overwrite - copy overlapped windows

SYNOPSIS

       cc [ flag... ] file... -I /usr/xpg4/include  -L	/usr/xpg4/lib 
	-R  /usr/xpg4/lib  -lcurses  [ library... ]

       c89 [ flag... ] file... -lcurses [ library... ]

       #include <curses.h>

       int overlay(const WINDOW *srcwin, WINDOW *dstwin);

       int overwrite(const WINDOW *srcwin, WINDOW *dstwin);

PARAMETERS

       srcwin	 Is a pointer to the source window to be copied.

       dstwin	 Is a pointer to the destination window to be overlayed or overwritten.

DESCRIPTION

       The  overwrite() and overlay() functions overlay srcwin on top of destwin. The srcwin and dstwin arguments do not have to be the same size;
       only text where the two windows overlap is copied.

       The overwrite() function copies characters as though a sequence of win_wch(3XCURSES) and wadd_wch(3XCURSES) were performed with the  desti-
       nation window's attributes and background attributes cleared.

       The  overlay()  function does the same thing, except that, whenever a character to be copied is the background character of the source win-
       dow, overlay() does not copy the character but merely moves the destination cursor the width of the source background character.

       If any portion of the overlaying window border is not the first column of a multi-column character, then all the column positions  will	be
       replaced  with  the  background	character  and rendition before the overlay is done. If the default background character is a multi-column
       character when this occurs, then these functions fail.

RETURN VALUES

       Upon successful completion, these functions return OK. Otherwise, they return ERR.

ERRORS

       No errors are defined.

EXAMPLES

       Example 1 Implement a pop-up dialog

       The following example demonstrates the use of overwrite() to implement a pop-up dialog box.

	 #include <curses.h>
	 /*
	  *   Pop-up a window on top of curscr.  If row and/or col
	  *   are -1 then that dimension will be centered within
	  *   curscr.  Return 0 for success or -1 if malloc() failed.
	  *   Pass back the working window and the saved window for the
	  *   pop-up.  The saved window should not be modified.
	  */
	 int
	 popup(work, save, nrows, ncols, row, col)
	 WINDOW **work, **save;
	 int nrows, ncols, row, col;
	 {
	      int mr, mc;
	      getmaxyx(curscr, mr, mc);
	      /* Windows are limited to the size of curscr. */
	      if (mr < nrows)
		   nrows = mr;
	      if (mc < ncols)
		   ncols = mc;
	      /* Center dimensions. */
	      if (row == -1)
		   row = (mr-nrows)/2;
	      if (col == -1)
		   col = (mc-ncols)/2;
	      /* The window must fit entirely in curscr. */
	      if (mr < row+nrows)
		   row = 0;
	      if (mc < col+ncols)
		   col = 0;
	      *work = newwin(nrows, ncols, row, col);
	      if (*work == NULL)
		   return (-1);
	      if ((*save = dupwin(*work)) == NULL) {
		   delwin(*work);
		   return (-1);
	      }
	      overwrite(curscr, *save);
	      return(0);
	 }
	 /*
	  * Restore the region covered by a pop-up window.
	  * Delete the working window and the saved window.
	  * This function is the complement to popup().  Return
	  * 0 for success or -1 for an error.
	  */
	 int
	 popdown(work, save)
	 WINDOW *work, *save;
	 {
	      (void) wnoutrefresh(save);
	      (void) delwin(save);
	      (void) delwin(work);
	      return(0);
	 }
	 /*
	  * Compute the size of a dialog box that would fit around
	  * the string.
	  */
	 void
	 dialsize(str, nrows, ncols)
	 char *str;
	 int *nrows, *ncols;
	 {
	      int rows, cols, col;
	      for (rows = 1, cols = col = 0; *str != ''; ++str) {
		   if (*str == '
') {
			if (cols < col)
			    cols = col;
			col = 0;
			++rows;
		   } else {
			++col;
		   }
	       }
	       if (cols < col)
		    cols = col;
	       *nrows = rows;
	       *ncols = cols;
	 }
	 /*
	  * Write a string into a dialog box.
	  */
	 void
	 dialfill(w, s)
	 WINDOW *w;
	 char *s;
	 {
	      int row;
	      (void) wmove(w, 1, 1);
	      for (row = 1; *s != ''; ++s) {
		   (void) waddch(w, *((unsigned char*) s));
		   if (*s == '
')
			wmove(w, ++row, 1);
	      }
	      box(w, 0, 0);
	 }
	 void
	 dialog(str)
	 char *str;
	 {
	      WINDOW *work, *save;
	      int nrows, ncols, row, col;
	      /* Figure out size of window. */
	      dialsize(str, &nrows, &ncols);
	      /* Create a centered working window with extra */
	      /* room for a border. */
	      (void) popup(&work, &save, nrows+2, ncols+2, -1, -1);
	      /* Write text into the working window. */
	      dialfill(work, str);
	      /* Pause.  Remember that wgetch() will do a wrefresh() */
	      /* for us. */
	      (void) wgetch(work);
	      /* Restore curscr and free windows. */
	      (void) popdown(work, save);
	      /* Redraw curscr to remove window from physical screen. */
	      (void) doupdate();
	 }

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       copywin(3XCURSES), libcurses(3XCURSES), wadd_wch(3XCURSES), win_wch(3XCURSES), attributes(5), standards(5)

SunOS 5.11							    5 Jun 2002							 overlay(3XCURSES)