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 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;  insertWidth 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 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