Re: [UMN_MAPSERVER-USERS] 4.10 GEOS Fuctions with PHP Mapscipt

Thu, 26 Oct 2006 07:32:09 -0700 

Chris,
The within function returns true or false so tests should be done like this if ($oProvShape->within($oDistShape)) echo "1" else echo "0". The blank page in your case simple means that the within function returned false. 


 Is it possible that the test you are doing is inversed? : by looking 
at the name of the layers, I am assuming that districts are inside 
provinces so a call $oProvShape->within($oDistShape) would return false 
and the $oDistShape->within($oProvShape); would return true.



 I have checked the documentation of php mapscript and it was stated 
incorrectly leading to the confusion. It is now updated and reflects the 
correct syntax.


 Let me know if that solves your problem.

Best Regards,

CamKhmer wrote:

Hi Steve,

Thanks for your response. I am not receiving the response I was expecting
from the shapeObj->within() method when I pass to it a shapeObj from a
separate layer. I was expecting that GEOS would compare the geometry of
shape A and shape B then determine whether one was within the other, if this
was the case I thought that this method could take any valid shape object
regardless of its source, but this appears not to be the case. Here's a
thinned down version of what I'm trying to do (apologies for posting an
elongated chunk of code up):

<?php
$oMap = ms_newMapObj($szMapFile);

function getShapeByName($oMap, $sLayerName, $sColumnName, $sShapeName){
        $oLayer = $oMap->getLayerByName($sLayerName);
        $oLayer->open();

        //returns all the shapes in the layer
        $status = $oLayer->whichShapes($oMap->extent);

        //Loop through each of the shapes

	while ($shape = $oLayer->nextShape()) 
		   {

                           $shapeIndex = $shape->index;
                           $oShape = $oLayer->getShape(-1,$shapeIndex);
                           $sName = $oShape->values[$sColumnName];

                           //return if we have the shape we're after
                           if($sName == $sShapeName) {
                                        return $oShape;

			   }		   		   
		   }
	return null; 	   
	//$oLayer->close();	

}

//Get the province shape obj
$oProvShape = getShapeByName($oMap, 'provinces_fill', 'NAME','KHAMMUANE');

//Get the district shape obj
$oDistShape = getShapeByName($oMap, 'districts', 'NAME', 'NAKAI');

//This shows I have the shape object so we know there are no problems prior
to this
print_r($oProvShape);
print_r($oDistShape);

//See if one shape is within another
$inside = $oProvShape->within($oDistShape);

//Should return true or false
echo $inside;
?>

The above code just returns a blank screen, if I replace:

$inside = $oProvShape->within($oDistShape);

with:

$inside = $oProvShape->within($oProvShape);

It returns 1 as expected, which indicated to me that shape objects from one
shape file can't be passed as an argument for the within() method of a shape
object from a different shape file. Is this the case? If so is there any
work around you can think of that doesn't involve dumping all the layers in
a single shape file.

Thanks for any input you can give me.

Chris



Steve Lime wrote:


Chris: The GEOS operators work at the shapeObj level and have no

connection to 
parent layers (you can create shapeObj's without mapfiles).


Are you seeing strange behavior?

Steve



CamKhmer <[EMAIL PROTECTED]> 10/24/2006 7:27:14 AM >>>


Hi Guys,

I have just begun experimenting with the GEOS functions now available in
4.10 via mapscript and have a question.

Can shape objects from layer object A be passed as arguments to shape
object
methods in layer object B? (Each layer has a separate shape file)

I am trying to create a function that determines if shape A (district) is
within shape B (province), as stated above both layers are separate layers
in separate shape files.

I know I have the objects needed as both can be output using print_r(), I
know the method is working as if I pass a shape object from the same layer
I
get the results as expected.

Is it just the case that shape objects from different layers or shape
files
can’t be passed as objects to shapeObj methods? If so it there any
feasible
way around this or am I just going to have to put both districts and
provinces in the same layer and output them through class references?

Thanks for your ideas,

Chris

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