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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 isn't  one  of  the  ones  above)  then  TCL_ERROR  is |
       returned  and  an error message is left in interp's result if interp isn't NULL.  Tk_GetPixelsFromObj |
       caches information about the return value in objPtr, which speeds up future calls to Tk_GetPixelsFro- |
       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 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)