getpixels(3Tk)

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 absolute 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 corresponding distance either in integer
     pixels or floating-point millimeters.  In either case, string specifies a
     screen distance as a floating-point number followed by one of the
     following 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