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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_CanvasGetTextInfo may be invoked by a type manager to obtain addi-tional additional
       tional 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  struc-ture structure
       ture 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 background 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 currently 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 cursor;  inser-tWidth insertWidth
       tWidth gives the total width of the insertion cursor in pixels, and insertBorderWidth 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_CanvasTextInfo;  for example, a configure
       widget  command might change the selBorder field, or a select widget command might change the select-First selectFirst
       First field, or Tk might change cursorOn in order to make the insertion cursor flash on and off  dur-ing during
       ing 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)