tk4.2 C API - GetPixels






NAME

     Tk_GetPixels, Tk_GetScreenMM - translate between strings and
     screen units


SYNOPSIS

     #include <tk.h>

     int
     Tk_GetPixels(interp, tkwin, string, intPtr)

     int
     Tk_GetScreenMM(interp, tkwin, string, doublePtr)


ARGUMENTS

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

     Tk_Window    tkwin      (in)      Window    whose     screen
                                       geometry   determines  the
                                       conversion  between  abso-
                                       lute units and pixels.

     char         *string    (in)      String  that  specifies  a
                                       distance on the screen.

     int          *intPtr    (out)     Pointer  to  location   in
                                       which  to  store converted
                                       distance in pixels.

     double       *doublePtr (out)     Pointer  to  location   in
                                       which  to  store converted
                                       distance in millimeters.





DESCRIPTION

     These two procedures take as  argument  a  specification  of
     distance  on the screen (string) and compute the correspond-
     ing distance either in integer pixels or floating-point mil-
     limeters.   In  either  case, string specifies a screen dis-
     tance as a floating-point number followed by one of the fol-
     lowing characters that indicates units:

     <none>
          The number specifies a distance in pixels.

     c    The number specifies a distance in centimeters  on  the
          screen.

     i    The number  specifies  a  distance  in  inches  on  the
          screen.

     m    The number specifies a distance in millimeters  on  the
          screen.

     p    The number specifies a  distance  in  printer's  points
          (1/72 inch) on the screen.

     Tk_GetPixels converts string to the nearest even  number  of
     pixels  and  stores  that  value at *intPtr.  Tk_GetScreenMM
     converts  string  to  millimeters  and  stores  the  double-
     precision floating-point result at *doublePtr.

     Both procedures return TCL_OK  under  normal  circumstances.
     If  an  error occurs (e.g. string contains a number followed
     by a character that  isn't  one  of  the  ones  above)  then
     TCL_ERROR  is  returned  and  an  error  message  is left in
     interp->result.



KEYWORDS

     centimeters, convert, inches, millimeters,  pixels,  points,
     screen units