Java code...

[Marc JACQUIN]

Hi all,

Don't know if you used this applet. This could be really interesting
specially with the feature that Steve mentioned : the image param can be a
CGI call.

Do you know how this works ? What should the CGI return : an URL to a GIF
(location: url) ?

thx

Marc

> -----Original Message-----
> From: Stephen Lime [mailto:steve.lime at dnr.state.mn.us]
> Sent: Wednesday, October 27, 1999 1:15 PM
> To: mapserver-users at lists.gis.umn.edu
> Subject: Java code...
>
>
> Ok. Here's my working version. It's Java 1.1 code and compiles fine
> under 1.2 except for a few "depricated methods" messages. If anyone
> is interested in porting to 1.2 and swing let me know.
>
> To install: Copy the mapimage.class file someplace on you system that
> is web accessible. If you need to rebuild from source you'll need to make
> sure that the Netscape java classes (either a .zip or a .jar) are in your
> CLASSPATH environment variable.
>
> To use:
>
>   1. Make sure your normal MapServer form has a name attribute
> (eg. name="mapserv")
>   2. Add the following javascript code to the HTML header section:
>
>     <script language="javascript">
>       function SetImageXY(i) { document.mapserv.imgxy.value = i; }
>       function SetImageBox(i) { document.mapserv.imgbox.value = i; }
>     </script>
>
>      These functions are called by the applet, so the names can't
> be changed. However, you
>      could change the function code itself to, for example:
>
>      - submit the form immediately
>      - update the status line of the browser
>
>   3.  Add a couple of hidden variables to the form:
>
>     <input type="hidden" name="imgbox" value="-1 -1 -1 -1">
>     <input type="hidden" name="imgxy" value="149.5 199.5">
>
>     imgbox allows the MapServer to process a pair of mouse clicks
> (ie. a box). It is ignored if the box is
>     simply a point, hence the initialization value. imgxy is a
> way to pass a single mouse click to the
>     MapServer. This mimics the standard forms based method. The
> initial value should be something
>     meaningful like the center of the image. Remember that the
> coordinates on the image start at 0
>     and end at nrows-1 or ncols-1. To compute center x use
> (ncols-1)/2 and y use (nrows-1)/2 and
>     keep the decimal value. This allows the user to zoom using a
> button rather than the image.
>
>   4. Add a call to the applet (this replaces the normal
> form-based call to the image <input type="image"...>).
>       Here's an example from a template file (note the [img]
> substitution):
>
>     <applet codebase="/java/mapimage" code="mapimage.class"
> width="300" height ="400" name="mapimage" MAYSCRIPT>
>         <param name="image" value="http://www.dnr.state.mn.us[img]">
>         <param name="jitter" value="1">
>         <param name="color" value="255 0 0">
>       </applet>
>
>      The parameters are:
>
>        image - fully qualified URL to the image. This can be a CGI call.
>        jitter - allowable slop in mouse clicking. Basically sets
> a minimum box size.
>        color - RGB triplet that sets the color of the box or cursor.
>
> That covers the basic use. There are 3 public methods that can be
> called from javascript that change
> the behavior of the applet.
>
> boxOn and boxOff toggle the applets ability to display a dragged
> box. Useful when adding features to
> an interface. For example, it doesn't make sense to drag a box
> when zooming out. No arguments.
>
> newMap(string image_url) allows you to swap images without
> changing the rest of the page. The function
> uses the java MediaTracker interface to delay image loading until
> the new image is completely loaded. This
> is useful with advanced interface setup. It's possible to manage
> extents, layers etc completely on the client
> using javascript requesting a new image only when necessary via
> the applet. It's actually pretty cool once
> it's set up that way. The string supplied to newMap must be a
> fully qualified URL for an image (can be a CGI
> call).
>
> Examples of this applet can be found at:
>
>   - http://deli.dnr.state.mn.us/
>   - http://www.dnr.state.mn.us/mis/gis/gislis99/example1.html
> (click "next step" until you hit example 5)
>   - http://www.ra.dnr.state.mn.us/
>
> Possible enhancements:
>
>   - displaying coordinates on the image as the mouse moves
>   - bubble attributes (eg. move mouse over feature label and
> display attributes or whatever)
>
> Hope this helps, have fun!
>
> Steve
>
> Stephen Lime
> Internet Applications Analyst
> MIS Bureau - MN DNR
>
> (651) 297-2937
> steve.lime at dnr.state.mn.us
>
>