[mapserver-users] help with dynamic layer

Fri Jul 26 15:16:44 EDT 2002

Thanks!  That did the trick.

One more question...It seems like the other way to add a dynamic layer 
is to actually generate a new shapefile (and dbf file) from the database 
query resultset, add it to a map object, and draw it.  Is one method 
more robust than the other?  Any reason to not do it the way I'm doing 
it, other than the "obscuring" problem you mentioned?

I think the shapefile-generation method is what Lowell was hinting at. 
In that case, you would need DATA defined for that layer in your map 
file (right?)

Thanks,
Dylan

woodbri at swoodbridge.com wrote:
> Dylan,
> 
> Try something like this:
> 
> // MapObj and ImageObj settings
> $map_path="/www/gis/mapfiles/";
> $map = ms_newMapObj($map_path."test.map");
> $img = $map->draw();
> 
> $layer = $map->getLayerByName("sites2");
> $layer->set('status', MS_ON);
> for ($i=0; $i<$rows; ++$i) {
>      $row = pg_fetch_row($result, $i);
>      // echo "Record $i: UTM_E $row[0], UTM_N $row[1]<br>";
>      $pt = ms_newPointObj();
>      $pt->setXY($row[0],$row[1]);
>      $pt->draw($map, $layer, $img, 0, "TEST");
>  }
> 
> $img_url=$img->saveWebImage(MS_PNG,1,1,0);
> 
> When you are using this style of adding objects to the map 
> dynamically you have to draw the map first THEN add you dynamic data 
> on top of the already rendered map.
> 
> This method has the problem that if you have a high density of 
> objects to add to the map it can obscure the underlining map. You 
> also might want to set LABELCACHE FALSE for the layer.
> 
> -Steve
> 
> On 26 Jul 2002 at 11:29, Lowell.Filak wrote:
> 
> 
>>I think there may be a couple of things missing.
>>I don't see where the "data" value is set for the layer & I don't see
>>where the addPoint is being done to add the point(s) to the data shapefile
>>before rendering the layer.
>>Lowell F.
>>
>>On Thu, 25 Jul 2002, Dylan Keon wrote:
>>
>>
>>>Hi,
>>>
>>>I'm trying to create a dynamic point layer using PHP Mapscript.  A
>>>simple query to a Postgres database returns the UTM coordinates.  That
>>>part works fine.  What isn't working is the rendering of the layer.  I
>>>read through the various "dynamic layer" posts in the archives, but
>>>still couldn't figure it out.  This is my first Mapscript attempt :-)
>>>I'm sure it's a simple error (or errors) on my part.
>>>
>>>The PHP code, map file, and error messages are below.  Any tips would be
>>>great.  Thanks!
>>>
>>>Dylan
>>>
>>>###################### PHP and HTML code ######################
>>><?php
>>>
>>>dl('php_mapscript.so');
>>>
>>>// db connect parameters
>>>$host = "localhost";
>>>$user = "xxxxx";
>>>$pass = "xxxxx";
>>>$db = "xxxxx";
>>>
>>>// open a connection to the db server
>>>$connection = pg_connect("host=$host dbname=$db user=$user password=$pass");
>>>
>>>if (!$connection) {
>>>         die("Could not open connection to database server");
>>>}
>>>
>>>// generate and execute the query
>>>$query = "SELECT utm_e, utm_n FROM sites";
>>>$result = pg_exec($connection, $query) or die("Error in query: $query. "
>>>. pg_last_error($connection));
>>>
>>>// get the number of rows in the resultset
>>>$rows = pg_numrows($result);
>>>
>>>// MapObj and ImageObj settings
>>>$map_path="/www/gis/mapfiles/";
>>>$map = ms_newMapObj($map_path."test.map");
>>>$img = $map->prepareImage();
>>>
>>>// get dummy layer
>>>$layer = $map->getLayerByName("sites2");
>>>
>>>// loop through resultset, generating points
>>>for ($i=0; $i<$rows; ++$i) {
>>>    $row = pg_fetch_row($result, $i);
>>>// echo "Record $i: UTM_E $row[0], UTM_N $row[1]<br>";
>>>    $pt = ms_newPointObj();
>>>    $pt->setXY($row[0],$row[1]);
>>>    $pt->draw($map, $layer, $img, 0, "TEST");
>>>    $layer->set('status', MS_ON);
>>>    $layer->draw($img);
>>>}
>>>
>>>// create web image
>>>$img=$map->draw();
>>>$img_url=$img->saveWebImage(MS_PNG,1,1,0);
>>>
>>>// close database connection
>>>pg_close($connection);
>>>
>>>?>
>>>
>>><html>
>>><head>
>>><title>Test Map</title>
>>></head>
>>><body>
>>><table align="center">
>>><tr><td>
>>><input type="image" name="test_map" src="<?php echo $img_url?>">
>>></td></tr>
>>></table>
>>></body>
>>></html>
>>>################################################################
>>>
>>>########################### map file ###########################
>>>NAME TEST
>>>SIZE 600 400
>>>STATUS ON
>>>SYMBOLSET "/www/gis/symbols/symbols.sym"
>>>EXTENT 370000 4640000 1011000 5130000 #minx miny maxx maxy
>>>UNITS METERS
>>>SHAPEPATH "/usr/local/gis_data/state"
>>>IMAGETYPE PNG
>>>
>>>WEB
>>>   IMAGEPATH "/www/tmp/"
>>>   IMAGEURL "/tmp/"
>>>END
>>>
>>>LAYER
>>>   NAME boundary
>>>   DATA bnd
>>>   TYPE polygon
>>>   STATUS DEFAULT
>>>   CLASS
>>>     NAME "State boundary"
>>>     OUTLINECOLOR 0 0 0
>>>     COLOR -1 -1 -1
>>>   END
>>>END
>>>
>>>LAYER
>>>   NAME sites2
>>>   TYPE POINT
>>>   STATUS OFF
>>>   CLASS
>>>     COLOR 255 255 0
>>>     OUTLINECOLOR 0 0 0
>>>     SYMBOL 7
>>>     SIZE 8
>>>   END
>>>END
>>>
>>>END
>>>################################################################
>>>
>>>####################### Error messages #########################
>>>Warning: MapServer Error in msGetBitmapFont(): Invalid bitmap font. Must
>>>be one of tiny, small, medium, large or giant. in
>>>/usr/local/etc/httpd/htdocs/test.php on line 47
>>>
>>>Fatal error: Call to a member function on a non-object in
>>>/usr/local/etc/httpd/htdocs/test.php on line 48
>>>################################################################
>>>
>>
>>
> 
> 

-- 
************************************************
  Dylan Keon
  GIS/Database Research Specialist
  Northwest Alliance for Computational
  Science and Engineering (NACSE)
  Oregon State University
  Corvallis, OR 97331
  keon at nacse.org        (541) 737-6608
************************************************