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<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=407031609-20082010>Hi,</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=407031609-20082010></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=407031609-20082010>you have to calculate your offset for every zoomlevel.
I do it by use of a styleMap with context. The code below should give you an
idea, how to get it work.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=407031609-20082010></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial>function
layerContext()<BR>{<BR> theXOffset =
10;<BR> theYOffset =
10;<BR> theResolution = map.getResolution();</FONT></DIV>
<DIV> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial>
var context = {<BR> getXO :
function(){<BR>
return theXOffset * theResolution /
map.getResolution();<BR>
},<BR> getYO :
function(){<BR>
return theYOffset * theResolution /
map.getResolution();<BR>
}<BR> };<BR> var template =
{<BR>
...<BR> graphicXOffset :
"${getXO}",<BR> graphicYOffset :
"${getYO}",<BR>
...<BR> pointRadius
: 0<BR> };<BR> yourLayer.styleMap = new
OpenLayers.StyleMap(new OpenLayers.Style(template, {context:context})
);<BR>}<BR></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=407031609-20082010>I use this approach to display georeferenced images as
externalGraphic.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><A
href="http://gis.ibbeck.de/ginfo/apps/OLExamples/OL27/examples/ExternalGraphicOverlay/ExternalGraphicOverlay.asp">http://gis.ibbeck.de/ginfo/apps/OLExamples/OL27/examples/ExternalGraphicOverlay/ExternalGraphicOverlay.asp</A></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2
face=Arial></FONT> </DIV>
<DIV dir=ltr align=left><SPAN class=407031609-20082010><FONT color=#0000ff
size=2 face=Arial>Arnd</FONT></SPAN></DIV><BR>
<DIV dir=ltr lang=de class=OutlookMessageHeader align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>Von:</B> users-bounces@openlayers.org
[mailto:users-bounces@openlayers.org] <B>Im Auftrag von </B>ilias
kanellos<BR><B>Gesendet:</B> Donnerstag, 19. August 2010 11:03<BR><B>An:</B>
Users@openlayers.org<BR><B>Betreff:</B> [OpenLayers-Users] External Graphic of
features positioning<BR></FONT><BR></DIV>
<DIV></DIV>Dear List,<BR><BR>I am trying to create markers as point features of
a vector layer. I do this by using the following
code:<BR><BR>
var markerStyle = OpenLayers.Util.extend({},
OpenLayers.Feature.Vector.style['default','select']);<BR>
markerStyle.graphicWidth = 21;<BR>
markerStyle.graphicHeight = 25;<BR>
markerStyle.graphicOpacity =
1;<BR>
markerStyle.externalGraphic = ""; // I put the url of the image
here<BR>
markerStyle.graphicTitle = displayName; // displayName is a string previously
defined<BR>
var
markerCoordPoint = new
OpenLayers.Geometry.Point(markerCoords.lon,markerCoords.lat); // markerCoords is
a LonLat object<BR>
var newMarker
= new
OpenLayers.Feature.Vector(markerCoordPoint,null,markerStyle);
<BR><BR>When I add the above feature to a vector layer and
put in on my map it displays the image I want in the correct coordinates,
<BR>however the center of the image is put to the Lon/Lat coordinates I specify
for the newMarker variable. <BR>What I would like to do is to set a specific
point (such as the center of the bottom, or the bottom left corner) of the image
to be put on the determined coordinates.<BR>I tried to add the following to the
markerStyle object:<BR><BR>
markerStyle.graphicXOffset =
-(markerStyle.graphicWidth/2);<BR>
markerStyle.graphicYOffset =
-markerStyle.graphicHeight;<BR><BR>However if I understood this correctly, the
above offset concerns pixels, and the result is that the marker image gets
placed in a completely wrong position, <BR>especially in low zoom levels. Is
there some way to 'anchor' the externalGraphic the way I want to?<BR>Thank
you<BR><BR><BR></BODY></HTML>