PNG Transparency

[The Little Guy]

OK... I have this as my code, it seems to work, but it doesn't make my PNG images have a transparent background, it just makes the background black.

In the last 9 lines is where the PNG portion is located
[code]<?php
// The file
session_start();
$img_id = $_GET['image_id'];
include"db.php";
$img = mysql_query("SELECT * FROM files where file_id='$img_id'")or die(mysql_query());
$imgs = mysql_fetch_array($img);
//$imgname = $_GET['image_id'];
$filename = "users/".$_SESSION['user']."/$imgs[file_name]";
#$filename = "users/ryan/screen2.jpg";
//$filename = 'images/user_images/geoff.jpg';


$percent = $_GET['percent'];
switch($percent){
case ".25";
$percent = .25;
break;
case ".50";
$percent = .50;
break;
case ".75";
$percent = .75;
break;
case "1";
$percent = 1;
break;
default:
$percent = .5;
break;
}
function getext($file) {
$pos = strrpos($file,'.');
$str = substr($file, $pos);
return strtolower($str);
}

// Content type
if(getext($filename)=='.jpg'){
header('Content-type: image/jpeg');
}elseif(getext($filename)=='.gif'){
header('Content-type: image/gif');
}elseif(getext($filename)=='.png'){
header('Content-type: image/png');
}

// Get new sizes
list($width, $height) = getimagesize($filename);
$newwidth = $width * $percent;
$newheight = $height * $percent;

// Load
$thumb = imagecreatetruecolor($newwidth, $newheight);

if(getext($filename)=='.jpg'){
$source = imagecreatefromjpeg($filename);
}elseif(getext($filename)=='.gif'){
$source = imagecreatefromgif($filename);
}elseif(getext($filename)=='.png'){
$source = imagecreatefrompng($filename);
imageAlphaBlending($source, true);
imageSaveAlpha($source, true);
}
// Resize
imagecopyresized($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);

// Output
imagejpeg($thumb);
?>[/code]

So how do I make it transparent? If I do this:

[b]$source = imagecreatefrompng($filename);
$source = imageAlphaBlending($source, true);
$source = imageSaveAlpha($source, true);[/b]

It doesn't even work.

[monkey_05_06]

If it's a PNG...why the hell are you using [b]imagejpeg[/b]:

[code]// Output
imagejpeg($thumb);
?>[/code]

:o

[b][EDIT:][/b]

Wait...you're using imagejpeg for ALL your images? It won't work that way. You'll have to use imagejpeg for your JPEGs imagegif for your GIFs and imagepng for your PNGs.

[The Little Guy]

OK, I changed that line to this:
[code]
// Output
if(getext($filename)=='.jpg'){
imagejpeg($thumb);
}elseif(getext($filename)=='.gif'){
imagegif($thumb);
}elseif(getext($filename)=='.png'){
imagepng($thumb);
}[/code]

It still doesn't do anything useful, it is still non-transparent

I'm using FF 2 btw.

It worked just fine even with imgjpeg on gif, and png images.

[monkey_05_06]

Hmmm...as for that...I don't know. Are you sending the proper headers?

i.e.,

[code]header("Content-type: image/" . (getext($filename) === ".jpg" ? "jpeg" : (getext($filename) === ".gif" ? "gif" : "png"))); // send the appropriate image header since you are printing the image's contents directly to the browser[/code]

Notice I've used === instead of == I'm not sure why but you should use it instead. Also just make sure you're sending the headers (since you're printing the raw image data to the screen)...either that or write it to a file first and print out the image from the file using HTML tags.

However it appears to me you're just trying to resize your images to make thumbnails. If this is the case, why not just set the WIDTH/HEIGHT attributes of your IMG tags? Unless you really want to just want/need a script that will make thumbnails of your images...

[The Little Guy]

I don't know it that matters, but anyways, I got the code from here: http://us2.php.net/manual/en/function.imagecopyresized.php
so basically it is the exact same way that PHP.net has it, only this has my own modifications.

[monkey_05_06]

Well that makes sense of some of it. Sorry if I seemed harsh before...I just thought you had written the entire code snippet which would have made it a rather stupid mistake. ;)

I've noticed that you are indeed sending the proper headers...my mistake for not taking the time to read over your code properly.

However I'm fairly certain that using == won't work properly with strings. At least I think I read that somewhere. In any case, try using === instead. If nothing else it will make for better coding practice.

Also, have you tried using [url=http://us2.php.net/manual/en/function.imagecopyresampled.php]imagecopyresampled[/url] instead? I don't know if it would make a difference, but it could be worth a try.

P.S. you can make links by putting [ url=http://link.com ]link.com[ /url ] (without the spaces) ;)

[The Little Guy]

the === thing didn't do anything. Any other suggestions?

Once again here is the code:
[code=php:0]
<?php
// The file
session_start();
$img_id = $_GET['image_id'];
include"db.php";
$img = mysql_query("SELECT * FROM files where file_id='$img_id'")or die(mysql_query());
$imgs = mysql_fetch_array($img);
//$imgname = $_GET['image_id'];
$filename = "users/".$_SESSION['user']."/$imgs[file_name]";
#$filename = "users/ryan/screen2.jpg";
//$filename = 'images/user_images/geoff.jpg';


$percent = $_GET['percent'];
switch($percent){
case ".25";
$percent = .25;
break;
case ".50";
$percent = .50;
break;
case ".75";
$percent = .75;
break;
case "1";
$percent = 1;
break;
default:
$percent = .5;
break;
}
function getext($file) {
$pos = strrpos($file,'.');
$str = substr($file, $pos);
return strtolower($str);
}

// Content type
if(getext($filename)=='.jpg'){
header('Content-type: image/jpeg');
}elseif(getext($filename)=='.gif'){
header('Content-type: image/gif');
}elseif(getext($filename)=='.png'){
header('Content-type: image/png');
}

// Get new sizes
list($width, $height) = getimagesize($filename);
$newwidth = $width * $percent;
$newheight = $height * $percent;

// Load
$thumb = imagecreatetruecolor($newwidth, $newheight);

if(getext($filename)=='.jpg'){
$source = imagecreatefromjpeg($filename);
}elseif(getext($filename)=='.gif'){
$source = imagecreatefromgif($filename);
}elseif(getext($filename)=='.png'){
$source = imagecreatefrompng($filename);
imageAlphaBlending($source, true);
imageSaveAlpha($source, true);
}
// Resize
imagecopyresized($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);

// Output
if(getext($filename)=='.jpg'){
imagejpeg($thumb);
}elseif(getext($filename)=='.gif'){
imagegif($thumb);
}elseif(getext($filename)=='.png'){
imagepng($thumb);
}
?>
[/code]

[monkey_05_06]

Just to see what's going on...why not throw a die in there somewhere...

i.e.:

[code]if (getext($filename) === ".jpg") die("JPEG");
else if (getext($filename) === ".gif") die("GIF");
else if (getext($filename) === ".png") die("PNG");[/code]

I'm telling you...you really need to use triple equal signs here. You said it didn't make a difference, but you should still change it.

[The Little Guy]

This is my alt text in the img tag when I run yours:

The image “http://71.82.126.113:6251/tzfiles/resize.php?image_id=43” cannot be displayed, because it contains errors.

When I run mine, It outputs the image, only it has a black background instead of a transparent one.

[The Little Guy]

anyone help?