[mapserver-users] How TO: Flashing / Blinking Polygon?

[Daniel Morissette]

"Hankley, Chip" wrote:
> 
> I'd like to figure out a way to make the polygon "blink" or "flash" a number
> of times in rapid succession, but have absolutely no idea how to do it.
> 
> Anyone have any suggestions / examples?
> 
> Thanks!
> 
> Chip
> 
> (MapServer 3.4, PHP MapScript for PHP Version 4.0.4pl1, WIN NT 4, PWS)

You could use animated GIFs... I never tried this specifically, but did
similar things before so it should work:

1- You'll need to download and install the whirlgif executable in your
path.  Get it from http://www.danbbs.dk/~dino/whirlgif/

2- In your script, draw the map once with default layers, and once with
the highlighted polygon.  Make sure background is opaque.  Then combine
the images into an animated GIF using whirlgif:

   // Draw the 2 map slides to the imagepath directory
   $img1 = $map->draw();
   $img2 = $map->drawQuery();
   $imgURL1 = $img1->saveWebImage(...);
   $imgURL2 = $img2->saveWebImage(...);
   $filePath1 = map->web->imagepath . substr(strrchr($imgURL1, "/"),1);
   $filePath2 = map->web->imagepath . substr(strrchr($imgURL2, "/"),1);

   // Create a unique filename and URL for the animated GIF output
   $animName = "anim".substr(strrchr($imgURL1, "/"),1);
   $animPath = $map->web->imagepath . $animName;
   $animURL = $map->web->imageurl . $animName;

   // Run whirlgif to generate the animated GIF
   system("whirlgif -o $animPath -loop -time 500 $filePath1 -time 500
$filePath2");

   // $animURL now points to an animated GIF with the flashing polygon
   print "<IMG SRC=\"$animURL\" WIDTH=... HEIGHT=...>\n";


Note: a possible optimization could be to draw only the layer containing
the polygon to highlight with a transparent background in the second
pass.  I let you figure out how to do that.

-- 
------------------------------------------------------------
 Daniel Morissette               morissette at dmsolutions.ca
 DM Solutions Group              http://www.dmsolutions.ca/
------------------------------------------------------------
  Don't put for tomorrow what you can do today, because if 
      you enjoy it today you can do it again tomorrow.