Ah, sorry about that, I misunderstood the problem you were having!
J. Cliff Dyer wrote: > Thanks. That's definitely a cleaner setup, but it didn't really solve > the problem I was having. Before the box would look like it was being > drawn properly, but then the persistent copy would be vertically offset. > Now it's offset from the time I start drawing. Which is an improvement, > because at least it will be easier for users to draw the box they want. > Here's a screenshot to show what I mean: > > http://imgur.com/5cJ4H > > The Box was drawn exactly from Cape Fear to Cape Hatteras, marked with > little black dots on the screenshot. However, the box itself starts > drawing a bit above the location of the cursor. It seems the further I > get from the top of the display, the further displaced the box is. It > is impossible to get closer than ~2cm from the bottom of the map. There > also seems to be a very slight horizontal displacement. > > Any thoughts on what might cause this displacement? At this point, no > transformation is being done--at least not in any of my code. > > Cheers, > Cliff > > > > On Fri, 2009-11-13 at 09:58 -0700, Scott Lewis wrote: >> I did something like this using one of the examples on the OpenLayers >> site, modified slightly. Here's what I used: >> >> boxControl = new OpenLayers.Control(); >> OpenLayers.Util.extend(boxControl, { >> draw: function() { >> this.box = new OpenLayers.Handler.RegularPolygon(boxControl, >> {"done": this.notice}, {sides:4, irregular:true, persist:true}); >> this.box.activate(); >> }, >> >> notice: function(geom) { >> // whatever you want it to do after the box has been drawn >> } >> }); >> >> // then add the boxControl to the map >> >> This works pretty nicely. Note that "geom" will be in the same >> projection as the map, so if you want the output to be in another >> projection (like a latitude/longitude display) you will have to go >> through the geometry and transform the points. Also, you may have to go >> through the geometry to determine which point is which (it doesn't >> always start with the upper-left corner, and it's not always clockwise >> or counter-clockwise). If interested, I can post some of the functions >> I do for that. >> >> I hope this helps, >> >> Scott Lewis >> NSIDC >> >> J. Cliff Dyer wrote: >>> I'm trying to draw a box on a map, have it persist until another box >>> gets drawn, and submit the coordinates of the box to a form. I'm doing >>> this to allow the user to search for objects within a given area. >>> >>> I'm doing this by using an OpenLayers.Handler.Box tool in a custom >>> OpenLayers.Control, which then uses to the "done" callback of the draw >>> method to create (or recreate) an OpenLayers.Feature.Vector and populate >>> (or repopulate) a search form. >>> >>> My immediate problem is that the persistent box is not in quite the same >>> location as the box the user just drew. I suspect this has something to >>> do with projections, but since I never explicitly set projections, I'm >>> not sure where the error sneaked in. >>> >>> More generally, I'm not sure I'm taking the optimal route from the >>> bounds passed to the callback to the Vector feature. Currently, I do >>> the following: >>> >>> 1) Take the incoming OpenLayers.Bounds object, >>> 2) Get an OpenLayers.Pixel from the the corners >>> 3) Get the coordinates of each pixel using map.getLonLatFromPixel >>> 4) Create a new OpenLayers.Bounds >>> 5) Extend it to my new coordinates >>> 6) Convert it to a geometry >>> 7) Convert it to an OpenLayers.Feature.Vector >>> >>> Then I take the coordinates from step 3) and populate a form with them, >>> which I then submit to my application server side. >>> >>> The code for this is pasted here: http://pastebin.com/m300c24a5 >>> >>> Any pointers on how to do this more cleanly would be much appreciated. >>> >>> Cheers, >>> Cliff >>> >>> >>> >>> _______________________________________________ >>> Users mailing list >>> [email protected] >>> http://openlayers.org/mailman/listinfo/users > > > _______________________________________________ > Users mailing list > [email protected] > http://openlayers.org/mailman/listinfo/users _______________________________________________ Users mailing list [email protected] http://openlayers.org/mailman/listinfo/users
