phpmapscript imagemap creation

Rodrigo Martín LÓPEZ GREGORIO rodrigomlg at GMAIL.COM
Wed Jul 4 10:16:59 EDT 2007


Thanks. That's great and it was very clear. I think that will be great if
you put this in a how-to in mapserver site, cause as you said, there are no
enough information about the imagemap creation with mapserver.

Thanks again.

On 7/4/07, Doug Williams <williams at> wrote:
> Rodrigo,
> Here is what I did to make the imagemap work using phpmapscript.  This is
> my first go round trying
> to create an imagemap, so others may have more sensible methods or more
> extended methods, but I
> never did get any specific information from anyone, nor could I find any
> complete information about
> FORMATOPTIONs which would be very helpful!!.  I had to feel my way through
> trying to piece
> together bits and pieces of scattered information,  found luckily by
> google searching which turned
> up one interesting old message from the list from someone that also did
> not have it working.  I never
> did find any response to that person that showed a working
> example.  Anyhow, I have also not ever
> tried to describe this process so bear with my rambling, long-winded
> description.
> First I added a OUTPUTFORMAT to my mapfile.  I already had one
> OUTPUTFORMAT in my mapfile to
> improve the quality of images generated by mapserver.  Whichever
> OUTPUTFORMAT comes first in
> the map file is used when generating images, unless the script resets
> this, which has to be done in
> order to generate both the imagemap (which is not an actual image, but
> just some html code) and
> the map (which is the actual visual image that is displayed).  It would be
> possible to use more than
> one mapfile rather than resetting the outputformat used, but it is not
> necessary.  More on
> outputformats in a minute.  Also it is necessary to define a CLASSITEM for
> the layer that you want to
> use to define your imagemap.  The classitem is the attribute that is
> stuffed into the html and
> displayed when the mouse is held over map polygons (in this example, a
> simple one layer example).
> The other important connection between the map file and the script is that
> the image shown in the
> html output has to be the same dimensions as the IMAGESIZE defined in the
> map file.  The other
> necessary steps take place in the php script.  So hear is the mapfile
> stuff:
>      NAME imagemap
>      DRIVER imagemap
>      FORMATOPTION "MAPNAME=map_test"
>      FORMATOPTION "TITLE=''  # this gets stuffed properly, you do not need
> to reference anything
>                                                        # on the right side
> of the = sign
>                                                        # in fact, you do
> not need this option at all.  But maybe
>                                                        # someday you will?
>      MIMETYPE "text/html"          # this option is also not needed!
>   END
>   NAME jpeg
>   MIMETYPE "image/jpeg"
>   EXTENSION "jpg"
> The first output format is used to generate the imagemap, the second is
> used to generate the actual
> map.  The script resets the format that is used.  Show you that in a
> second.  I don't really think the
> mimetype statement is necessary, but I have seen it used so I include it
> here.  I myself will actually
> end up using the FORMATOPTIONs for mouseover and mouseout shown in my
> earlier message, but I
> am not going to go into how I am going to take good advantage of them here
> because it will
> apparently be necessary for me to do some additional coding to get the
> effect I want, which I find
> works much better (immediate response on the web page with more inclusive
> attribute data detail),
> but is more complicated programmatically... more scripting on the server
> side and a script on the
> client side as well which is not needed with this method.  I won't
> describe the second output format,
> but the first defines a reference name for the outputformat; the driver
> which tells mapserver what to
> generate in terms of output, in this case the html code defining the areas
> of the imagemap with the
> coords; the name of the generated <map>, you use this name when declaring
> the usemap; and the
> formatoption to add a title for each defined area of the imagemap which is
> stuffed with the attribute
> data from the shapefile specified by the layer classitem (not really
> needed).  (Don't formatoption
> suppress="yes", or you will not get the areas in your <map>.)
> So hear is my layer definition in my map file:
>     LAYER
>       NAME "lakes"   # this is a bad layer example because the polygons
> are small and so
>                                   # the imagemap driver generates some bad
> <map> areas.  I'll process these
> out.
>                                   # Typically one would likely be using
> this with maps that produce
>                                   # larger features than a few worldwide
> lakes that are being squished to mere
> dots
>                                   # in an image the size and way I am
> doing here.
>       DATA esri/world/lakes
>       STATUS on
>       TYPE polygon
>       CLASSITEM "NAME"  # this is the attribute field to list in the
> 'title' for each <map> area
>       CLASS
>         NAME "Lakes"
>         COLOR -1 -1 -1
>         OUTLINECOLOR 200 200 50
>       END
>     END
> Well, it is something like that anyway, but the important part is the
> CLASSITEM line, which tells the
> imagemap driver what information you want stuffed in the map area
> title.  Again, the title
> formatoption above is not even needed, the imagemap driver just stuffs the
> classitem values into the
> title for each area.  It would be much nicer if all the attributes were
> made available with a reference
> mechanism so that one would have to declare something like formatoption
> "TITLE=[NAME]" with a
> way to escape characters like quotes ... maybe that is coming in the
> future.
> The map file will also have the SIZE defined, such as:
>   SIZE 600 300
> which we will use in the script to define the width and height of the
> image returned to the browser.
> So those are the mapfile necessities.  Easy enough.
> The php script is not so bad either.
> If you have created and displayed a map, then you know how to create your
> map object for creating
> the actual map:
> $map_path="/path/to/mapfile/directory";
> $map_file="";
> $map = ms_newMapObj($map_path.$map_file);
> You may want to create another map object to deal with the imagemap,
> though you could just use
> the same object.
> $imagemap = ms_newMapObj($map_path.$map_file);
> I draw the imagemap first, and the imagemap driver is set first in my map
> file, so draw() is using that
> driver.  It will be necessary to change this to the jpeg outputformat
> before drawing the other map (or
> png or gif or whatever you may be doing):
> $htmlmap = $imagemap->draw();
> $htmlmap->saveImage("/path/to/someplace/the/script/can/write/test.html",
> $imagemap);
> This will generate a text file on the server.
> test.html will be the:
> <map name="map_test">
>   with areas and coords and titles
> </map>
> I use the php require() command to write this into the html that I return
> to the browser.
> To change the ouputdriver use the phpmapscript command:
> $map->selectOutputFormat("jpeg");
> and draw as before:
> $image=$map->draw();
> $image_url=$image->saveWebImage(MS_PNG,1,1,0);
> I have mixed jpeg and png here ... probably not what you want, png is
> better for vector/line type
> stuff, jpeg is better for more real world type images (in my
> understanding).
> So now you have an image of your map as before, and you have the imagemap
> information in a file
> that was written to the server.  I add the imagemap to the html output
> like this:
> <body>
> <? require "/path/to/somplace/the/script/can/write/test.html" ?>
> I just plop it in right after I send the html <body> tag. Then you need to
> display the image in an
> <img> tag.  The standard mapserver way is to place the image in a form
> <input> tag, but I have not
> tried this as I read stuff stating that imagemaps do not work in form
> <input type=image> elements
> (makes sense since there is no place to associate the needed
> usemap).  Fortunately I had already
> moved away from displaying my images in those elements because I wanted to
> be able to click on
> the map without sending the form automatically.  Not using the form
> element means you will have to
> send the img.x and img.y coordinates that get sent automatically when
> using the form element by
> some other method, but that goes beyond the scope of this discussion.
> So display the image like this:
> <img src=<? echo $image_url; ?> usemap="#map_test" width=<? echo
> $map->width; ?> height=<?
> echo $map->height; ?> border=0>
> or however you like to code.  If things turn out correctly, when you place
> the cursor over a polygon
> and leave it still for a couple of seconds, the title will appear by the
> cursor showing you the attribute
> data.  View the page source to see if the <map> looks like what you expect
> it to look like.
> Those are the basic pieces.  Sorry it is not a very well laid out
> description.  If you have any questions,
> feel free to ask.  I am using a slightly more recent version of mapserver,
> but believe this has been
> around a while.  If the mapserver folks would like, I would be willing to
> produce something more in
> line with some of the howtos.
> Best,
> Doug
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