Tk_GetDash(3tk)

Tk_GetDash(3)         Tk Library Procedures         Tk_GetDash(3)

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NAME

     Tk_GetDash - convert from string to valid dash structure.

SYNOPSIS

     #include <tk.h>

     int
     Tk_GetDash(interp, string, dashPtr)

ARGUMENTS

     Tcl_Interp *interp (in)        Interpreter to use for  error
                                    reporting.

     const char * string (in)       Textual  value  to  be   con-
                                    verted.

     Tk_Dash *dashPtr (out)         Points to place to store  the
                                    dash  pattern value converted
                                    from string.
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DESCRIPTION

     These procedure parses the string and fills in the result in
     the  Tk_Dash structure. The string can be a list of integers
     or a character string containing only ".,-_" or  spaces.  If
     all  goes  well, TCL_OK is returned. If string does not have
     the proper syntax then TCL_ERROR is returned, an error  mes-
     sage  is  left  in  the interpreter's result, and nothing is
     stored at *dashPtr.

     The first possible syntax is a list of integers.  Each  ele-
     ment represents the number of pixels of a line segment. Only
     the odd segments are drawn using the  "outline"  color.  The
     other segments are drawn transparent.

     The second possible syntax is a  character  list  containing
     only  5  possible characters ".,-_ ".  The space can be used
     to enlarge the space between other line  elements,  and  can
     not  occur  as  the first position in the string. Some exam-
     ples:
              -dash .     = -dash {2 4}
              -dash -     = -dash {6 4}
              -dash -.    = -dash {6 4 2 4}
              -dash -..   = -dash {6 4 2 4 2 4}
              -dash {. }  = -dash {2 8}
              -dash ,     = -dash {4 4}

     The main difference of this syntax with the previous is that
     it  is  shape-conserving.  This means that all values in the

Tk                      Last change: 8.3                        1

Tk_GetDash(3)         Tk Library Procedures         Tk_GetDash(3)

     dash list will  be  multiplied  by  the  line  width  before
     display. This assures that "." will always be displayed as a
     dot and "-" always as a dash regardless of the line width.

     On systems where only a limited set of  dash  patterns,  the
     dash  pattern  will be displayed as the most close dash pat-
     tern that is available. For example,  on  Windows  only  the
     first  4  of  the  above  examples are available. The last 2
     examples will be displayed identically as the first one.

KEYWORDS

     dash, conversion

Tk                      Last change: 8.3                        2