Greetings,
I was wondering whether there is a way to provide a proj4 string or other method for specifying a projection where the units are in pixels and screen width and height are provided? My desire is to use the PointObj's project function for forward and reverse projecting an x,y screen coordinate. I find it odd that MapScript has great functions for zooming and panning based on pixel values and the whole shpxy functionality in the templating engine but lacks a way to convert a pixel to lat/lon or other projection values. It would be one thing if nothing in MapScript worked that way, but clearly something in the code-base knows how to do the conversion. I find this especially odd when the queryByPoint function requires a point object that explicitly states it should be in projected not screen values. My google searches thus far have pointed to useful formulae for doing the trick, but what's up with that?! I feel like I'm missing a less-than-obvious logic-leap that one is supposed to just know to make by understanding the object model. I have RTFM and I nothing I see suggests it is possible through php mapscript objects to convert screen units to a target projection. If there are tutorials or examples of how to do this I haven't yet discovered any. So, how does one, through php MapScript, get a lat/lon value for projecting into projection values if a PointObj cannot be defined with pixel values and the project functions take PointObj? Also, how would one go about requesting a special screen-projection as a projection to specify if something like that does not exist? ArtC Arthur Clifford
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