Tk_GetPixelsFromObj(3)

Tk_GetPixelsFromObj(3)Tk Library ProceduresTk_GetPixelsFromObj(3)

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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  abso-
                                       lute units and pixels.

     Tcl_Obj *objPtr (in/out)          String value  specifies  a
                                       distance  on  the  screen;
                                       internal rep will be modi-
                                       fied  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

Tk                      Last change: 8.1                        1

Tk_GetPixelsFromObj(3)Tk Library ProceduresTk_GetPixelsFromObj(3)

     These procedures take as argument a  specification  of  dis-
     tance  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  informa-
     tion  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 *doub-
     lePtr.

KEYWORDS

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

Tk                      Last change: 8.1                        2