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CentOS 7.0 - man page for tk_canvastextinfo (centos section 3)

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_CanvasGetTextInfo 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 following 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 back-
       ground under selected text.  selBorderWidth gives the width of the  raised  border  around
       selected text, in pixels.  selFgColorPtr points to an XColor that describes the foreground
       color to be used when drawing selected text.  selItemPtr points to the item that  is  cur-
       rently  selected,  or NULL if there is no item selected or if the canvas does not have the
       selection.  selectFirst and selectLast give the indices of the  first  and  last  selected
       characters  in  selItemPtr,  as	returned  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 cur-
       sor;   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  insertion  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_CanvasGetTextInfo once when an item is created and
       then saves the pointer in the item's record.  Tk will update information in the Tk_Canvas-
       TextInfo;   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  deter-
       mined  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)


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