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 dis-
					 tance.

       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

Tk									8.1						    Tk_GetPixelsFromObj(3)