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Tk_GetDash(3) Tk Library Procedures Tk_GetDash(3) 





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 converted.

  
Tk_Dash *dashPtr (out)

  
Points to place to store the dash pattern value converted from
      string. Must not be NULL.
    
    

    

  








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 “.,-_” and spaces. If all goes
    well, TCL_OK is returned and a dash descriptor is stored in the
    variable pointed to by dashPtr. If string does not have the
    proper syntax then TCL_ERROR is returned, an error message is left in
    the interpreter's result, and nothing is stored at *dashPtr.


The first possible syntax is a list of integers. Each element
    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 in the
    first position of the string. Some examples:








    -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 between this syntax and the numeric is that it
    is shape-conserving. This means that all values in the dash list will be
    multiplied by the line width before display. This ensures 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 pattern 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 to the first
    one.






SEE ALSO


canvas(n), Tk_CreateItemType(3)






KEYWORDS


dash, conversion







  

    8.3
    Tk