Drawing points and lines dynamically

[Camden Daily]

I would guess that this is a projection problem.  Your layers and
output are using one projection with one type of unit (feet? meters?),
but then you are trying to place a point on the map using decimal
degrees units.  To check this, try placing a point with an x value
between -994934.821920 and 322333.423383 and a y value between
5173124.716504 and 6431993.097353.  I'd image it would show up just
fine.

What you'll need to do is define a projection block in your layer
definitions.  Mapserver has no trouble mixing different layers of
different projections, but it can be difficult at first to figure out
what projections are and how you need to set them up.  I would suggest
doing some looking through mapserver examples and listserv archives
regarding projections and then asking specific questions you may have
to the group.

-Camden Daily

On 4/15/05, sc <sc at bytron.com> wrote:
> Hi Camden
> 
> I have altered my code to use your function but I still cannot see my
> 'point',  I have also switched
> off all other layers and it is still not visible.  Following is an extract
> of the code I am using and
> part of the map file.
> 
> My other layers are all in Lambert Conformal Conic projection, could this be
> where the problem lies?
> 
> The EXTENTs were arrived at by using ogrinfo -so on my shapefile.
> 
> regards
> 
> Simon
> 
> # Code Extract
> 
> $layer = ms_newLayerObj($map);
> $layer->set("name","Route");
> $layer->set("type",MS_LAYER_POINT);
> $layer->set("status", MS_ON);
> add_point_to_layer($layer, 0.0, 54.0);
> $image = $map->draw();
> 
> # Map file extract
> 
> MAP
>     NAME UK
>     STATUS ON
>     SIZE 800 600
>     IMAGETYPE PNG
>     IMAGECOLOR 170 210 250
>     SHAPEPATH "/usr/local/apache/htdocs/map/data/conic"
>     EXTENT -994934.821920 5173124.716504 322333.423383 6431993.097353
>     #UNITS MILES
> 
> 
> -----Original Message-----
> From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU]On
> Behalf Of Camden Daily
> Sent: 15 April 2005 14:06
> To: MAPSERVER-USERS at LISTS.UMN.EDU
> Subject: Re: [UMN_MAPSERVER-USERS] Drawing points and lines dynamically
> 
> If you turn off all of the other layers, can you see the point then?
> It might be a matter of extents or projections.  Are your extents in
> latitude/longitude degrees as well?
> 
> > One thing that I am confused about is to whether or not the layer that I
> > want to create the point
> > on has to be already defined in the map file or whether the code below
> > actually creates a 'dynamic'
> > layer.
> 
> It creates a dynamic layer.  You do not need to pre-define the layer
> in the .map file.  Althought I've not actually tried it, I believe
> that you could make your entire .map file definition through
> mapscript.
> 
> I'm not sure why else the point might not show up, but I would suggest
> looking at the layer->addFeature() function.  I think it's much more
> straightforward than drawing the map, and then calling point->draw()
> over it.  Just do something like this to add a point to a layer:
> 
> function add_point_to_layer($layer, $longitude, $latitude) {
>   // create and initialize new point object
>   $point = ms_newPointObj();
>   $point->setXY($longitude, $latitude);
>   // create and initialize new line object
>   $line = ms_newLineObj();
>   $line->add($point);
>   // create and initialize new shape object
>   $shape = ms_newShapeObj(MS_SHAPE_POINT);
>   $shape->add($line);
>   // add our shape
>   $layer->addFeature($shape);
> }
> 
> Then, once you've added the points, just call $image = $map->draw();
> and everything should draw nicely.
> 
> -Camden
> 
> > regards
> > Simon
> >
> > $layer = ms_newLayerObj($map);
> > $layer->set("name", "Route");
> > $layer->set("type", MS_LAYER_POINT);
> > $layer->set("status", MS_DEFAULT);
> > $layer->set("transform", TRUE);
> >
> > $class = ms_newClassObj($layer);
> > $class->label->set("font", "arial");
> > $class->label->color->setRGB(255, 0, 0);
> >
> > $symbol = $map->getSymbolByName("circle");
> > $style = ms_newStyleObj($class);
> > $style->set("symbol", $symbol);
> > $style->set("size", 8);
> > $style->color->setRGB(255, 0, 0);
> >
> > $image = $map->draw();
> >
> > $point = ms_newPointObj();
> > $point->setXY(0.0, 54.0);
> > $point->draw($map, $layer, $image, 0, "test");
> > $image_url=$image->saveWebImage();
> > --
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