Tk_CanvasTextInfo(3tk)

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 background under selected text.  sel-
     BorderWidth 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

Tk                      Last change: 4.0                        1

Tk_CanvasTextInfo(3)  Tk Library Procedures  Tk_CanvasTextInfo(3)

     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 exam-
     ple,  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 selI-
     temPtr, selectFirst,  selectLast,  and  selectAnchor.   Type
     managers  may  change selectFirst, selectLast, and selectAn-
     chor 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                      Last change: 4.0                        2