[SOLVED] Transparent GIF

[The Little Guy]

OK, I am trying to resize transparent GIF images, so I was reading, and they say to use fopen, fread, and read the first 13 bytes... OK, so I read in a transparent gif, and the first 13 bytes... and echo it out to the screen, and I get this:

 

GIF89a›�s�÷��

 

 

What am I supposed to do with that?

 

they then say "allocate that color as transparent, and use imagecopy(); to set the transparency back."

 

Can someone help me?? not exactly sure what to do

[cooldude832]

well the first 13 byes are the first 13 bytes of it.  I assume you are goign to read it as binary, but beyond that I dont have an idea.  All i know is transparent layers in gifs/pngs are not 100% compliiant.

[pocobueno1388]

Here is a function Barand helped me out with

 

<?php

   function uploadThumb($name, $filename, $new_w, $new_h, $ext) {
         
      if ($ext == 'jpg'){
         $src_img = imagecreatefromjpeg($name);
      } else if ($ext == 'gif'){
         $src_img = imagecreatefromgif($name);
      } else if ($ext == 'png'){
       $src_img = imagecreatefrompng($name);
      }
      
      $old_x=imageSX($src_img);
      $old_y=imageSY($src_img);
      
      if ($old_x > $old_y) {
      	$thumb_w=$new_w;
      	$thumb_h=$old_y*($new_h/$old_x);
      }
      if ($old_x < $old_y) {
      	$thumb_w=$old_x*($new_w/$old_y);
      	$thumb_h=$new_h;
      }
      if ($old_x == $old_y) {
      	$thumb_w=$new_w;
      	$thumb_h=$new_h;
      }
      
     $dst_img=ImageCreateTrueColor($thumb_w,$thumb_h);
     imagecopyresampled($dst_img,$src_img,0,0,0,0,$thumb_w,$thumb_h,$old_x,$old_y); 

     imagetruecolortopalette($dst_img,false,256);                                         // convert to palletted image
     $color_00 = imagecolorat($dst_img,0,0);                                              // get background color at 0,0
     imagecolortransparent($dst_img, $color_00);                                          // make it transparent
    	  
      if ($ext == 'jpg'){
         imagejpeg($dst_img,$filename);
      } else if ($ext == 'gif'){
         imagegif($dst_img,$filename);
      } else if ($ext == 'png'){
         imagepng($dst_img,$filename);
      }

     imagedestroy($dst_img); 
     imagedestroy($src_img); 
           
   }

?>

 

It works pretty good. The only problem with it is if you have a pure black area on the picture, it is going to make it transparent.

[The Little Guy]

Here is the one I found!!! IT WORKS TOO!

 

<?php
function transparentGif($imageDirectory,$thumbDirectory, $imageName, $thumbWidth){
$image = imagecreatefromgif("$imageDirectory/$imageName");
$details = getimagesize("$imageDirectory/$imageName");
$thumbHeight = $details[1] * ($thumbWidth / $details[0]);
$resized = imagecreatetruecolor($thumbWidth, $thumbHeight);
$colorTransparent = imagecolortransparent($image);
imagepalettecopy($image, $resized);
imagefill($resized, 0, 0, $colorTransparent);
imagecolortransparent($resized, $colorTransparent);
imagecopyresized($resized, $image, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $details[0], $details[1]);
imagegif($resized,"$thumbDirectory/$imageName");
}
?>

[pocobueno1388]

Awesome =] Don't forget to solve the topic.