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    <p>So you want to take latitude/longitude coordinates and find out the pixel coordinates on your image of that location?</p> <p>The main GMap2 class provides transformation to/from a pixel on the displayed map and a lat/long coordinate:</p> <pre><code>Gmap2.fromLatLngToContainerPixel(latlng) </code></pre> <p>For example:</p> <pre><code>var gmap2 = new GMap2(document.getElementById("map_canvas")); var geocoder = new GClientGeocoder(); geocoder.getLatLng( "1600 Pennsylvania Avenue NW Washington, D.C. 20500", function( latlng ) { var pixel_coords = gmap2.fromLatLngToContainerPixel(latlng); window.alert( "The White House is at pixel coordinates (" + pixel_coodrs.x + ", " + pixel_coords.y + ") on the " + "map image shown on this page." ); } ); </code></pre> <p>So assuming that your map image is a screen grab of the Google Map display, then this will give you the correct pixel coordinate on that image of a lat/long coordinate.</p> <p>Things are trickier if you're grabbing tile images and stitching them together yourself since the area of the complete tile set will lie outside the area of the displayed map.</p> <p>In this case, you'll need to use the left and top values of the top-left image tile as an offset from the coordinates that fromLatLngToContainerPixel(latlng:GLatLng) gives you, subtracting the left coordinate from the x coordinate and top from the y coordinate. So if the top-left image is positioned at (-50, -122) (left, top), and fromLatLngToContainerPixel() tells you a lat/long is at pixel coordinate (150, 320), then on the image stitched together from tiles, the true position of the coordinate is at (150 - (-50), 320 - (-122)) which is (200, 442).</p> <p>It's also possible that a similar GMap2 coordinate translation function:</p> <pre><code>GMap2.fromLatLngToDivPixel(latlng:GLatLng) </code></pre> <p>will give you the correct lat/long to pixel translation for the stitched-tiles case - I've not tested this, nor is it 100% clear from the API docs.</p> <p>See here for more: <a href="http://code.google.com/apis/maps/documentation/reference.html#GMap2.Methods.Coordinate-Transformations" rel="noreferrer">http://code.google.com/apis/maps/documentation/reference.html#GMap2.Methods.Coordinate-Transformations</a></p>
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    1. POConvert long/lat to pixel x/y on a given picture
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    1. USAlan Donnelly
    1. USAlan Donnelly
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