Re: GD transparency problem

I've always found transparency to be crap with 24-32 bit pngs, try converting the pings down to 8bit and the transparency should stay. One other thing you should consider doing is putting the GD stuff as an image, this way you can load the page , text etc and call the complicated map process as an image which will "look" better atleast :) <img src="myDynamicImage.php?this=that" width=100 height=100> You can this kind of thing from the geo mapping system i built here: http://www.londontown.com/londonmaps/index.php?ID=7643&IV_Type=TotalLondon&I V_RunByMethod=VBGC&IV_GeoHorizontal=529451&IV_GeoVertical=180462&type=transp ort&PlotGeoH=529451&PlotGeoV=180462 This was a nightmare to build, hundreds of tiles, dynamically trying to find out which tiles should be obtained to create a single image and then trying to join them and all the rest of it, yuk! "Steve M" <steve.m@wanadoo.fr> wrote in message news:20030511200950.6492.qmail@pb1.pair.com... > Just when I thought I was getting a grip on PHP I decide to take on the GD > library. -sigh- I have two problems which I'll put in two postings, so > here's the first and here's what I'm trying to do: > > I want to display a map and overlay it with highlight sections according to > the results of a database search. I tried doing this with floating boxes and > GIFs, but had some issues with positioning the whole shebang on the page, so > I thought I'd try some GD routines. And it's working to a degree. Having > converted the files to PNG format, I now use the following code: > > $backimg = imagecreatefrompng('deptmaps/bckgrnd.png'); > for ($i = 1; $i <= $dbrows ; $i++) { > $overlay[$i] = imageCreateFromPNG("deptmaps/".$deptcode[$i].".png"); > imageCopyMerge($backimg,$overlay[$i],0,0,0,0,350,394,10); > } > imagepng($backimg,"deptmaps/result.png"); > echo "<IMG SRC='deptmaps/result.png'>"; > > (the $deptcode array holds values from '01' to '95' and there are files in > the deptmaps folder named 01.png etc...) > > The problem is that I don't get a clear image overlaid by other clear > images. The whole thing is rather murky (you can see what I mean at > http://www.webvivant.com/features/deptfndr.php . Type > 'or' into the 'Search > by name' box and hit 'Find'). > > I think the problem lies with the PNG files not retaining their > transparency. They look fine when I view them in Photoshop, but if I use a > 'pct' value of 100 I see the last overlay as the desired image on a grey, > rather than transparent, background. (BTW, I don't really understand that > 'pct' value - I just tried experimenting with different values). > > So here's where I need help from wiser heads. I need a pointer to help me > investigate this further. Is this a problem with the PNG files? Do I need to > edit the colour map, maybe choosing a different transparency value? > > Or do I need to play with imagecolortransparent to try to set a new > transparency value for the image created with imagecreatefrompng? > > Any pointers would be appreciated. > >