TkGetPixelsFromObj(3) Tk Library Procedures TkGetPixelsFromObj(3)

NAME
       TkGetPixelsFromObj,  TkGetPixels,  TkGetMMFromObj,  TkGetScreenMM -
       translate between strings and screen units

SYNOPSIS
       ##iinncclluuddee <>

       int                                                                     |
       TTkkGGeettPPiixxeellssFFrroommOObbjj((interp, tkwin, objPtr, intPtr))                      |

       int
       TTkkGGeettPPiixxeellss((interp, tkwin, string, intPtr))

       int                                                                     |
       TTkkGGeettMMMMFFrroommOObbjj((interp, tkwin, objPtr, doublePtr))                       |

       int
       TTkkGGeettSSccrreeeennMMMM((interp, tkwin, string, doublePtr))

AARRGGUUMMEENNTTSS
       TclInterp   *interp    (in)      Interpreter to use for error  report-
                                         ing.

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

       TclObj      *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.



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:

        The number specifies a distance in pixels.

       cc      The number specifies a distance in centimeters on the screen.

       ii      The number specifies a distance in inches on the screen.

       mm      The number specifies a distance in millimeters on the screen.

       pp      The number specifies a distance in printer's points (1/72  inch)
              on the screen.

       TTkkGGeettPPiixxeellssFFrroommOObbjj  converts  the  value of objPtr to the nearest even |
       number of pixels and stores that value at *intPtr.  It  returns  TTCCLLOOKK |
       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 |
       TTCCLLEERRRROORR  is  returned and an error message is left in interp's result |
       if interp isn't NULL.  TTkkGGeettPPiixxeellssFFrroommOObbjj caches information about the |
       return  value  in objPtr, which speeds up future calls to TTkkGGeettPPiixxeellss- |
       FFrroommOObbjj with the same objPtr.                                           |

       TTkkGGeettPPiixxeellss is identical to TTkkGGeettPPiixxeellssFFrroommOObbjj except that the screen |
       distance  is  specified  with a string instead of an object.  This pre- |
       vents TTkkGGeettPPiixxeellss from caching the return value,  so  TTkkGGeettAAnncchhoorr  is |
       less efficient than TTkkGGeettPPiixxeellssFFrroommOObbjj.                                |

       TTkkGGeettMMMMFFrroommOObbjj  and  TTkkGGeettSSccrreeeennMMMM are similar to TTkkGGeettPPiixxeellssFFrroommOObbjj |
       and TTkkGGeettPPiixxeellss (respectively) except that  they  convert  the  screen |
       distance  to  millimeters  and  store a double-precision floating-point |
       result at *doublePtr.


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



Tk                                    8.1               TkGetPixelsFromObj(3)