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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  report-
					 ing.

       Tk_Window tkwin (in)		 Window	 whose	screen geometry	deter-
					 mines the conversion between absolute
					 units and pixels.

       Tcl_Obj *objPtr (in/out)		 String	value specifies	a distance  on
					 the screen; internal rep will be mod-
					 ified 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, ob-
       jPtr 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_GetPix-
       elsFromObj 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  pre-
       vents  Tk_GetPixels  from  caching the return value, so Tk_GetPixels 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 re-
       sult at *doublePtr.

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

Tk				      8.1		Tk_GetPixelsFromObj(3)

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