mapObj.zoomRectangle from Java Mapscript.

[Rodrigo Del C. Andrade]

    Hello Javier, thanks for the info.

    We have been struggling for some time now with the zoomRectangle and 
every piece of info is appreciated.
    Concerning the swap of MinY with MaxY in your code, I gotta say this 
caught me off guard.
     I couldn't get past a "miny >= maxy" error while trying to  use 
zoomRectangle before and went as far as changing and recompiling 
mapzoom.i where there is a consistency check that looks like:

	if (poPixRect->maxy >= poPixRect->miny) { -- insert nasty error here -- }


    thinking I found a bug. I got past the error after that change, 
however the zoom behavior was what could best be described as "all over 
the place". Like zooming to the wrong hemisphere and the like.
    So I changed mapzoom.i back to the original code and swapped the 
order of arguments on my code following your example, and it worked 
better than the last behavior, however the zoom isn't still quite 
working in a predictable manner.
    Sometimes when zooming the map will remain at the same zoom factor, 
and just pan a little to the sides or actually zooming out instead of 
going zooming to the passed coordinates. I am running out of ideas as to 
what could be causing this behavior.
    Here is what I am doing:

      //Current map geo extent
      String[] extents = ((String) params.get("extent")).split(" ");
       rectObj extent = new rectObj(Double.parseDouble(extents[0]), 
Double.parseDouble(extents[1]),
                                     Double.parseDouble(extents[2]), 
Double.parseDouble(extents[3]), mapscript.MS_FALSE);
       mapa.setExtent(extent);

        //rectangle Pic coords
        String[] pxCoordZoom = ((String) 
params.get("coordenadas")).split(" ");
        Double minx = Double.parseDouble(pxCoordZoom[0]);
        Double miny = Double.parseDouble(pxCoordZoom[1]);
        Double maxy = Double.parseDouble(pxCoordZoom[2]);
        Double maxx = Double.parseDouble(pxCoordZoom[3]);

       /*We are using a cropper javascript class and the order the 
rectangle coordinates where being passed was kind of unpredictable and 
causing errors                while trying to create the rectangle with 
the eventual minX > maxX /*
        double transport;
        if(minx > maxx){
            transport = minx;
            minx = maxx;
            maxx = transport;
        }         
        if(miny > maxy){
            transport = miny;
            miny = maxy;
            maxy = transport;
        }

        rectObj zoomArea = new rectObj(minx, maxy, maxx, miny, 
mapscript.MS_TRUE);   //with MaxY and MinY swapped
        mapa.zoomRectangle(zoomArea, mapa.getWidth(), mapa.getHeight(), 
extent, getMaxGeorefExtent(mapa));

    Do you see any glaring mistakes that could cause the zoom to behave 
wrongly?
    What confuses me is the fact that you mentioned that the rectangle 
should be constructed with bottom-left and top-right defined, but isn't 
the MinX and MaxY pair actually top-left?
  
    Thanks in advance, any scrap of information helps immensely.

    Rod.

-- 


*Rodrigo Del C. Andrade*
/Estagiário Nível Superior/
/SIC - SSE - Soluções Segurança Pública/

*DÍGITRO TECNOLOGIA*
*E-mail:* rodrigo.andrade at digitro.com.br 
<mailto:rodrigo.andrade at digitro.com.br>
*Fone:* +55 48 3281- / +55 48 3281-7000
*Fax:* +55 48 3281-7299
*Site:* www.digitro.com <http://www.digitro.com>

Javier Caicedo wrote:
> According to the Mapscript API mapObj.zoomRectangle first parameter must
> be in  image coordinates, so you should set the last parameter of the
> rectObj constructor to TRUE. Here goes an example from my current project:
>
>   //vMap is an instance of mapObj
>   rectObj rect = vMap.getExtent(); //map coordinates
>   String [] box = getCurrentRequest().getParameter("box").split(" ");
>   //box is something like this: 10 10 200 200
>   //0,0 is at top left, so box defines top left and bottom right corners
>   double mx = Double.parseDouble(box[0]);
>   double my = Double.parseDouble(box[1]);
>   double mxx = Double.parseDouble(box[2]);
>   double mxy = Double.parseDouble(box[3]);
>
>   //bunch of validation code ommitted
>
>   rectObj rbox = new rectObj(mx,mxy,mxx,my,mapscriptConstants.MS_TRUE);
>   //notice the switch of mxy and my
>   //rectObj constructor requires you define bottom left and top right
>   //corners. rbox is in image coordinates
>   vMap.zoomRectangle(rbox,w,h,rect,null);
>
> Hopefully this will help you out a little.
>
> Regards,
> Javier Caicedo Espinoza
> CTI - ESPOL
> Guayaquil, Ecuador
>
>
>   



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