[Users] Dynamic line between point and pop-up

[Matt Priour]

This an interesting problem, one which we have explored somewhat but never implemented.
CSS3 supporting browsers give you some nice possibities.
1. Anchor a div on one corner to the popup and on the other corner, the vector feature. Use a CSS background property for the div that includes an background image and background size with 'stretch stretch' or the actual pixel height width values.
2. Use a narrow div of variable height that you stretch and rotate to stay anchored to the popup

However, these are really just trying to mimic something that is already easily accomplished in Canvas, SVG, or VML. You could code the vector graphic yourself, OR just use the vector drawing API already implemented in OpenLayers.
What I would do is to add a linear feature in the vector layer you are already using.
You could create the vector feature and make it a property of the popup in the popup's afterrender event handler and then just reposition it in the move event handler.

for example here is a totally untested afterrender event handler, the move event handler could be somewhat similar:

//assumes that you set a vector feature as the location config option for the popup
onPopupRender(popup){
    var lyr = popup.location.layer;
    var cmpBox = popup.getBox();
    var brPopPixel = new OpenLayers.Pixel(cmpBox.x+cmpBox.width,cmpBox.y+cmpBox.height);
    var anchor = new OpenLayers.Feature.Vector(new OpenLayers.Geometry.LineString([lyr.getLonLatFromViewPortPx(brPopPixel),popup.location.geometry.getCentroid()]));
    lyr.addFeatures([anchor]);
    popup.anchor = anchor;
}

Matt Priour
Kestrel Computer Consulting



From: Òscar Vidal Calbet 
Sent: Tuesday, October 26, 2010 1:07 PM
To: users at geoext.org 
Subject: [Users] Dynamic line between point and pop-up


Hey everybody, 


I'm looking for some help



I'm new working with GeoExt, and I have a need that I don't know if GeoExt can resolve.


I want show a map where you can find different entities represented by points and lines. The user have to be allowed to make identify for each entity and have open several pop-up at the same time. The aims is that the user have to be allowed to move all the pop-up of the screen in a free way, but I don't want lost the reference between the pop-up and the entity, so I need show a dynamic line between the pop-up and the entity


thanks in advance,
Oscar 


sorry for my poor english






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