CONVERT

    Given the coordinates of a point in one coordinate system, CONVERT
    returns the corresponding coordinates for the point in another
    coordinate system.  The converted coordinates are returned using the
    "to_x_integer" and "to_y_integer" parameters.

 Syntax

    CONVERT ({DECW_ROOT_WINDOW | SCREEN | window},
             {CHARACTERS | COORDINATES},
             from_x_integer, from_y_integer,
             {DECW_ROOT_WINDOW | SCREEN | window},
             {CHARACTERS | COORDINATES},
             to_x_integer, to_y_integer)


 Parameters

    DECW_ROOT_WINDOW     Specifies the coordinate system being used by the
                         root window of the screen on which VAXTPU is
                         running.

    SCREEN               Specifies the coordinate system being used by the
                         DECwindows window associated with VAXTPU's
                         top-level widget.

    window               Specifies the coordinate system being used by the
                         VAXTPU window.

    CHARACTERS           Specifies a character-cell system for measuring
                         screen distance.  In a character-based system, the
                         point in the top row and the left-most column has
                         the coordinate (1,1).

    COORDINATES          Specifies a DECwindows-style coordinate system in
                         which coordinate units correspond to pixels.  The
                         pixel in the top row and the leftmost column has
                         the coordinates (0,0).

    from_x_integer and from_y_integer   Specify a a point in the coordinate
                                        system and units specified by the
                                        first two parameters.

    to_x_integer and to_y_integer       Receive the two integers specifying
                                        a point in the coordinate system
                                        and units specified by the fifth
                                        and sixth parameter.  The point
                                        specified by these integers
                                        corresponds to the point specified
                                        by the first four parameters.

 Example

    The following procedure converts a point's location from the current
    window's coordinate system (with the origin in the upper left-hand
    corner of the window) to the VAXTPU screen's coordinate system (with
    the origin in the upper left-hand corner of the VAXTPU screen).  If the
    current window is not the top window, CONVERT changes the value of the
    y-coordinate to reflect the difference in the VAXTPU screen's
    coordinate system.

    PROCEDURE user_convert

    LOCAL source_x,
          source_y,
          dest_x,
          dest_y;

    source_x := 1;
    source_y := 1;
    dest_x := 0;
    dest_y := 0;

    CONVERT (CURRENT_WINDOW, COORDINATES, source_x, source_y, SCREEN,
             COORDINATES, dest_x, dest_y);

    ENDPROCEDURE;