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Tk_GetPixelsFromObj(3)                      Tk Library Procedures                     Tk_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
                                         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  mil-limeters. millimeters.
                                         limeters.
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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_GetPixelsFro-mObj Tk_GetPixelsFromObj
       mObj 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_GetAn-chor Tk_GetAnchor
       chor 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 floatingpoint
       point result at *doublePtr.


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



Tk                                                   8.1                              Tk_GetPixelsFromObj(3)