NAME

       Tk_GetPixelsFromObj, Tk_GetPixels, Tk_GetMMFromObj, Tk_GetScreenMM - translate between strings and screen
       units

SYNOPSIS

       #include <tk.h>

       int
       Tk_GetPixelsFromObj(interp, tkwin, objPtr, intPtr)

       int
       Tk_GetPixels(interp, tkwin, string, intPtr)

       int
       Tk_GetMMFromObj(interp, tkwin, objPtr, doublePtr)

       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.

       Tcl_Obj *objPtr (in/out)          String  value  specifies a distance on the screen; internal rep will be
                                         modified to cache converted distance.

       const char *string (in)           Same as objPtr except specification of distance is passed as a string.

       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.
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DESCRIPTION

       These  procedures  take  as  argument  a  specification  of distance on the screen (objPtr or string) and
       compute the corresponding distance either in integer pixels or  floating-point  millimeters.   In  either
       case,  objPtr  or  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_GetPixelsFromObj converts the value of objPtr to the nearest even number of  pixels  and  stores  that
       value  at  *intPtr.   It  returns  TCL_OK  under  normal  circumstances.  If an error occurs (e.g. objPtr
       contains a number followed by a character that is not one of the ones above) then TCL_ERROR  is  returned
       and  an  error  message  is  left  in  interp's result if interp is not NULL.  Tk_GetPixelsFromObj caches
       information about the return value in objPtr, which speeds up future calls  to  Tk_GetPixelsFromObj  with
       the same objPtr.

       Tk_GetPixels  is  identical  to  Tk_GetPixelsFromObj  except that the screen distance is specified with a
       string instead of an object.  This prevents Tk_GetPixels from caching the return value,  so  Tk_GetAnchor
       is less efficient than Tk_GetPixelsFromObj.

       Tk_GetMMFromObj  and  Tk_GetScreenMM  are  similar to Tk_GetPixelsFromObj and Tk_GetPixels (respectively)
       except that they convert the screen distance to millimeters and store a  double-precision  floating-point
       result at *doublePtr.

KEYWORDS

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