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Tk_CanvasTextInfo(3)	     Tk	Library	Procedures	  Tk_CanvasTextInfo(3)

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NAME
       Tk_CanvasTextInfo  -  additional	information for	managing text items in
       canvases

SYNOPSIS
       #include	<tk.h>

       Tk_CanvasTextInfo *
       Tk_CanvasGetTextInfo(canvas)

ARGUMENTS
       Tk_Canvas canvas	(in)	      A	token  that  identifies	 a  particular
				      canvas widget.
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DESCRIPTION
       Textual canvas items are	somewhat more complicated to manage than other
       items, due to things like the selection and the input  focus.   Tk_Can-
       vasGetTextInfo  may  be	invoked	by a type manager to obtain additional
       information needed for items that display text.	The return value  from
       Tk_CanvasGetTextInfo is a pointer to a structure	that is	shared between
       Tk and all the items that display text.	The structure has the  follow-
       ing form:
	      typedef struct Tk_CanvasTextInfo {
		  Tk_3DBorder selBorder;
		  int selBorderWidth;
		  XColor *selFgColorPtr;
		  Tk_Item *selItemPtr;
		  int selectFirst;
		  int selectLast;
		  Tk_Item *anchorItemPtr;
		  int selectAnchor;
		  Tk_3DBorder insertBorder;
		  int insertWidth;
		  int insertBorderWidth;
		  Tk_Item *focusItemPtr;
		  int gotFocus;
		  int cursorOn;
	      }	Tk_CanvasTextInfo;
       The  selBorder  field  identifies a Tk_3DBorder that should be used for
       drawing the background under selected text.  selBorderWidth  gives  the
       width  of the raised border around selected text, in pixels.  selFgCol-
       orPtr points to an XColor that describes	the  foreground	 color	to  be
       used when drawing selected text.	 selItemPtr points to the item that is
       currently selected, or NULL if there is no item selected	or if the can-
       vas  does  not have the selection.  selectFirst and selectLast give the
       indices of the first and	last selected characters in selItemPtr,	as re-
       turned  by  the	indexProc  for that item.  anchorItemPtr points	to the
       item that currently has the selection anchor;  this is not  necessarily
       the  same  as selItemPtr.  selectAnchor is an index that	identifies the
       anchor  position	 within	 anchorItemPtr.	   insertBorder	  contains   a
       Tk_3DBorder  to	use  when  drawing  the	insertion cursor;  insertWidth
       gives the total width of	the insertion cursor in	pixels,	and insertBor-
       derWidth	 gives	the  width  of the raised  border around the insertion
       cursor.	focusItemPtr identifies	the item that currently	has the	 input
       focus,  or  NULL	if there is no such item.  gotFocus is 1 if the	canvas
       widget has the input focus and 0	otherwise.  cursorOn is	1 if  the  in-
       sertion	cursor	should be drawn	in focusItemPtr	and 0 if it should not
       be drawn;  this field is	toggled	on and off by Tk to  make  the	cursor
       blink.

       The structure returned by Tk_CanvasGetTextInfo is shared	between	Tk and
       the type	managers;  typically the type manager  calls  Tk_CanvasGetTex-
       tInfo  once  when  an item is created and then saves the	pointer	in the
       item's record.  Tk will update information  in  the  Tk_CanvasTextInfo;
       for  example,  a	 configure  widget  command might change the selBorder
       field, or a select widget command might change the  selectFirst	field,
       or Tk might change cursorOn in order to make the	insertion cursor flash
       on and off during successive redisplays.

       Type managers should treat all of the fields of	the  Tk_CanvasTextInfo
       structure as read-only, except for selItemPtr, selectFirst, selectLast,
       and selectAnchor.  Type managers	may  change  selectFirst,  selectLast,
       and  selectAnchor  to  adjust  for insertions and deletions in the item
       (but only if the	item is	the current owner of the selection or  anchor,
       as  determined by selItemPtr or anchorItemPtr).	If all of the selected
       text in the item	is deleted, the	item should set	selItemPtr to NULL  to
       indicate	that there is no longer	a selection.

KEYWORDS
       canvas, focus, insertion	cursor,	selection, selection anchor, text

Tk				      4.0		  Tk_CanvasTextInfo(3)

NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | KEYWORDS

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