DMS display on MouseMove

[Puneet Kishor]

On Feb 9, 2006, at 7:57 AM, william paul wrote:

> I replay to the email, I didn't thing that the list will not receive 
> the email!!!
>  
> My problem isn't how you transform from DD to DMS. I already know this.
>  
> I want to make the transformation in such manner that the DMS are 
> displayed ON MOUSEMOVE over the map, which means that the coordinates 
> are changing with position of the cursor on the map
>  
> I did that for DD using a script found on the list, but I can't make 
> it work for DMS
>  
> My code looks like:
>  
> var x2 = event.offsetX; // mouse coordinates in pixels
> var y2 = event.offsetY; // mouse coordinates in pixels
> var res_dd = ([maxlon] - [minlon]) / [mapwidth]; // resolution in DD
> var x_dd = [minlon];
> var y_dd = [minlat];
> x1_dd = Math.round(((x2*res_dd) + x_dd)*1000000)/1000000; 
> //coordinates in DD to be displayed on mousemove
> y1_dd = Math.round(((([mapheight] - y2)*res_dd) + 
> y_dd)*1000000)/1000000; //coordinates in DD to be displayed on 
> mousemove
>
> window.status="Latitude DD: " + y1_dd + " " + "Longitude DD: " + y1_dd;
>  
> I tried for DMS:
>  
> //for longitude in DMS
>
> var dd = Math.floor(x1_dd);
> var m = Math.floor((x1_dd - dd) * 60);
> var s = Math.ceil((((x1_dd - dd) * 60) - m) *60);
>  
> I also have tried to break the resolution in DMS, but I don't know how 
> to multiply the resolution with the coordinates in pixel and then add 
> to minlon


I am not sure what the problem is. Do for DMS exactly the way you are 
doing for DD. There is nothing conceptually different between DD and 
DMS. They express the same thing in different ways -- it is like saying 
1 lb of tomatoes versus 454 gms of tomatoes. Figure out your min, max 
in DMS, and add them to your current mouse coordinates.

That said, look at Clint Johnson's email from yesterday. He recommends 
reading about projections at 
http://fisher.lib.virginia.edu/reference/help/esri/esri_pdfs_9.html, 
and that should be the first thing that all MapServer users should read 
before setting out making mapping websites. Ed McNierny also has 
elaborated on this several times (in fact, I have been thinking of 
taking all of Ed's emails and compiling them into a "must read"... note 
to Ed -- if you save your MapServer-list emails, forward them to me and 
I will do the rest).

Remember, that the pixel space is a rectangle, in that, opposite sides 
are equal, while Lat/Long space is more like a trapezoid, in that, the 
horizontal opposite sides are not equal, and in fact, at the poles, it 
becomes a triangle. If you really want to be exact with your coordinate 
display, project your map into a rectangular coordinate system and then 
you will get what you want.


>  
> william paul wrote:
> > Hi:
> >
> > I know this, my problem is other, but...I will solve it
>
> Please send all replies to the list as well. In the meantime, would
> the following help  --
>
> //(0) Grab the dd value
> var dd = obj.value;
>
> // (1) The Degrees are simply the numbers to the left of the decimal
> // (using 42.36824 as an example, the degrees would be 42)
> var d = Math.floor(dd);
>
> // (2) To determine the Minutes, multiply the number to the right of
> // the decimal point by 60 (example: .36824 x 60 = 22.0944)
> // (3) The Minutes are the numbers to the left of the decimal point
> // (in this example, 22)
> var m = Math.floor((dd - d) * 60);
>
> // (4) To determine the Seconds, multiply the number to the right of
> // the decimal point by 60 (example: .0944 x 60 = 5.664)
> // (5) The Seconds are the numbers to the left of the decimal point,
> // rounded up (in this example, 06)
> var s = Math.ceil((((dd - d) * 60) - m) * 60);
>
> // display it
> var dms = d + ' deg, ' + m + ' min, ' + s + ' sec';
>
> >
> > */Puneet Kishor <punkish at EIDESIS.ORG>/* wrote:
> >
> >     william paul wrote:
> >      > Hi:
> >      >
> >      > I display the coordinates on mousemove over the map. The
> >     coordinates are
> >      > in DD and UTM, but I would like display them also in DMS.
> >      >
> >
> >      From the very first hit on Google --
> >
> >     (1) The Degrees are simply the numbers to the left of the decimal
> >     (using 42.36824 as an example, the degrees would be 42)
> >     (2) To determine the Minutes, multiply the number to the  right 
> of
> >     the decimal point by 60 (example: .36824 x 60 = 22.0944)
> >     (3) The Minutes are the numbers to the left of the decimal point
> >     (in this example, 22)
> >     (4) To determine the Seconds, multiply the number to the right of
> >     the decimal point by 60 (example: .0944 x 60 = 5.664)
> >     (5) The Seconds are the numbers to the left of the decimal point,
> >     rounded up (in this example, 06)
> >
> >     Implementing it in Js is left as an exercise for the reader...
> >
> >
>
>
> --
> Puneet Kishor
>
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--
Puneet Kishor