I am stuck how to convert lat,long to bbox using WGS-84. Is there a formula or function code you could share.
e.g. lon=-79.80617638166511
lat=43.17565342984143
bbox?
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Raju,
My code snippet above is for a map click function where the event object passed is the map click event.
Here is a function to convert a lat lon to an extent.
<SPAN class="keyword token">function</SPAN> <SPAN class="token function">onSelDrawEnd</SPAN><SPAN class="punctuation token">(</SPAN>lat<SPAN class="punctuation token">,</SPAN> lon<SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN> <SPAN class="keyword token">var</SPAN> mapPnt <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">Point</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="token function">parseFloat</SPAN><SPAN class="punctuation token">(</SPAN>lon<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="token function">parseFloat</SPAN><SPAN class="punctuation token">(</SPAN>lat<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="keyword token">var</SPAN> scrPnt <SPAN class="operator token">=</SPAN> map<SPAN class="punctuation token">.</SPAN><SPAN class="token function">toScreen</SPAN><SPAN class="punctuation token">(</SPAN>mapPnt<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="comment token">//Expand the point by 5 pixels</SPAN> <SPAN class="keyword token">var</SPAN> xMin <SPAN class="operator token">=</SPAN> scrPnt <SPAN class="punctuation token">.</SPAN>x <SPAN class="operator token">-</SPAN> <SPAN class="number token">2.5</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="comment token">//value in pixels</SPAN> <SPAN class="keyword token">var</SPAN> yMin <SPAN class="operator token">=</SPAN> scrPnt <SPAN class="punctuation token">.</SPAN>y <SPAN class="operator token">-</SPAN> <SPAN class="number token">2.5</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="comment token">//value in pixels</SPAN> <SPAN class="keyword token">var</SPAN> xMax <SPAN class="operator token">=</SPAN> scrPnt <SPAN class="punctuation token">.</SPAN>x <SPAN class="operator token">+</SPAN> <SPAN class="number token">2.5</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="comment token">//value in pixels</SPAN> <SPAN class="keyword token">var</SPAN> yMax <SPAN class="operator token">=</SPAN> scrPnt <SPAN class="punctuation token">.</SPAN>y <SPAN class="operator token">+</SPAN> <SPAN class="number token">2.5</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="comment token">//value in pixels</SPAN> <SPAN class="keyword token">var</SPAN> mp1 <SPAN class="operator token">=</SPAN> map<SPAN class="punctuation token">.</SPAN><SPAN class="token function">toMap</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">Point</SPAN><SPAN class="punctuation token">(</SPAN>xMin<SPAN class="punctuation token">,</SPAN> yMin<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="keyword token">var</SPAN> mp2 <SPAN class="operator token">=</SPAN> map<SPAN class="punctuation token">.</SPAN><SPAN class="token function">toMap</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">Point</SPAN><SPAN class="punctuation token">(</SPAN>xMax<SPAN class="punctuation token">,</SPAN> yMax<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="keyword token">var</SPAN> ext <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">Extent</SPAN><SPAN class="punctuation token">(</SPAN>mp1<SPAN class="punctuation token">.</SPAN>x<SPAN class="punctuation token">,</SPAN> mp1<SPAN class="punctuation token">.</SPAN>y<SPAN class="punctuation token">,</SPAN> mp2<SPAN class="punctuation token">.</SPAN>x<SPAN class="punctuation token">,</SPAN> mp2<SPAN class="punctuation token">.</SPAN>y<SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">SpatialReference</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">{</SPAN> wkid<SPAN class="punctuation token">:</SPAN><SPAN class="number token">4326</SPAN> <SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="keyword token">return</SPAN> Polygon<SPAN class="punctuation token">.</SPAN><SPAN class="token function">fromExtent</SPAN><SPAN class="punctuation token">(</SPAN>ext<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN> <SPAN class="punctuation token">}</SPAN><SPAN class="line-numbers-rows"><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN></SPAN>
You working in 3.x or 4.x?
Thanks Rob for your response. Could you kindly provide an example for set of pixels toScreen and toMap. I have a deadline to meet.
Normally I would be adding/subtracting values with a set number of pixels using toScreen and toMap.
Thanks Rob for always being helpful. I am using simple math to get bbox from lat,long. It is not accurate for closest zoom scale.
var minxx = lon - 0.08999; var maxxx = lon + 0.08999; var minyy = lat - 0.08999; var maxyy = lat - 0.08999;
console.log("weblink/bbox?" + "xmin=" + minxx + "&ymin=" + minyy + "&xmax=" + maxxx + "&ymax=" + maxyy).
I have WGS-84 projection. Do I have to add condition for each scale. e.g.
If (scale =11)
elseif (scale =19)
var minxx = lon - ??; var maxxx = lon + ??; var minyy = lat - ??; var maxyy = lat - ??;
To get a bounding box from a single point you just need to do some math to add and subtract for that point to get the minx, miny, maxx and maxy for the extent class constructor.
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