The XParam interface provides utilities for handling X-style -display and -geometry command-line arguments. If your application installs a single top-level window, the XTrestle interface may be more appropriate than this interface.
INTERFACE XParam; IMPORT Point, Rect, Trestle, TrestleComm;
Here are routines for manipulating the -display argument:
TYPE Display = RECORD hostname: TEXT := ""; display : CARDINAL := 0; screen : CARDINAL := 0; DECnet : BOOLEAN := FALSE END; PROCEDURE ParseDisplay (spec: TEXT): Display RAISES {Error}; <* LL = arbitrary *>
For example, if spec contains the string myrtle.pa.dec.com:0.2, the record returned would be
Display{hostname := "myrtle.pa.dec.com", display := 0, screen := 2, DECnet := FALSE}
PROCEDURE UnparseDisplay (READONLY d: Display): TEXT; <* LL = arbitrary *>
Return the text-version of the -display argument d.
Here are routines for manipulating the -geometry argument:
CONST Missing = Point.T{-1, -1}; TYPE Geometry = RECORD vertex := Rect.Vertex.NW; (* corner for displacement *) dp := Point.Origin; (* displacement *) size := Missing; (* width, height *) END; PROCEDURE ParseGeometry (spec: TEXT): Geometry RAISES {Error}; <* LL = arbitrary *>
Return a parsed version of the -geometry argument in spec.
For example, if spec contains the string 1024x800-0-10, the returned record would be
Geometry {Rect.Vertex.SE, Point.T {0, 10}, Point.T {1024, 800}}
The size field defaults to Missing. The horizontal and vertical displacements default to Point.Origin (no displacement). The displacements are always positive values; use the vertex field to find out from which corner they are to be offset.
PROCEDURE UnparseGeometry (READONLY g: Geometry): TEXT; <* LL = arbitrary *>
Return the text-version of the -geometry argument g.
PROCEDURE Position ( trsl: Trestle.T; id : Trestle.ScreenID; READONLY g : Geometry ): Point.T RAISES {TrestleComm.Failure}; <* LL.sup = VBT.mu *>
Return the position specified by g in the screen coordinates for the screenID id on the window system connected to trsl (cf. Trestle.GetScreens). The value of g.size must not be Missing, unless g.vertex is the northwest corner.
Here is the definition of the Error exception:
TYPE Info = OBJECT spec : TEXT; index: CARDINAL END; GeometryInfo = Info BRANDED OBJECT END; DisplayInfo = Info BRANDED OBJECT END; EXCEPTION Error(Info);
Parsing errors are reported with the text (spec) and position (index) of the first illegal character in the text.
END XParam.
Here is an example of how to use this interface to install a VBT v as a top level window, obeying the display and geometry arguments given to the application. It relies on the Params interface, which provides the number of arguments passed to the program, Params.Count, and a procedure to retrieve the value of the nth argument, Params.Get(n).
EXCEPTION Error (TEXT); VAR display, geometry: TEXT := NIL; d: XParam.DisplayRec; g: XParam.Geometry; i: CARDINAL := 1; BEGIN LOOP IF i >= Params.Count - 1 THEN EXIT END; WITH argument = Params.Get (i) DO IF Text.Equal (argument, "-display") THEN display := Params.Get (i + 1); TRY d := XParam.ParseDisplay (display) EXCEPT XParam.Error (info) => RAISE Error ("Illegal -display argument: " & info.spec) END; INC (i, 2) ELSIF Text.Equal (argument, "-geometry") THEN geometry := Params.Get (i + 1); TRY g := XParam.ParseGeometry (geometry); IF g.size = XParam.Missing THEN WITH shapes = VBTClass.GetShapes (v, FALSE) DO g.size.h := shapes [Axis.T.Hor].pref; g.size.v := shapes [Axis.T.Ver].pref END END EXCEPT XParam.Error (info) => RAISE Error ("Illegal -geometry argument: " & info.spec); END; INC (i, 2) ELSE INC (i) END (* IF *) END (* WITH *) END; (* LOOP *)
At this point, if display is non-NIL, then d contains the information from the -display argument. Similarly, if geometry is non-NIL, then g contains the information from the -geometry argument. If the window-size specificiation was missing, the preferred shape of the window is used.
Finally, we now process the display and geometry information:
VAR trsl := Trestle.Connect (display); screen: CARDINAL; BEGIN TrestleImpl.SetDefault (trsl); Trestle.Attach (v, trsl); Trestle.Decorate (v, ...); IF geometry = NIL THEN Trestle.MoveNear (v, NIL) ELSE StableVBT.SetShape (v, g.size.h, g.size.v) IF d = NIL THEN screen := Trestle.ScreenOf (v, Point.Origin).id ELSE screen := d.screen END; Trestle.Overlap ( v, screen, XParam.Position(trsl, screen, g)) END (* IF *) END (* BEGIN *) END; (* BEGIN *)
The call to TrestleImpl.SetDefault establishes the value of the -display argument as the default Trestle connection. The call to StableVBT.SetShape is used to control the size of a top-level window. The TrestleImpl and StableVBT interfaces are part of Trestle.
Return a parsed version of the -display argument in spec.