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:
OUTPUTFORMAT
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
OUTPUTFORMAT
NAME jpeg
DRIVER "GD/JPEG"
MIMETYPE "image/jpeg"
IMAGEMODE RGB
EXTENSION "jpg"
FORMATOPTION "QUALITY=100"
END
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="mapfile.map";
$map = ms_newMapObj($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
