Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Maintain transparency of PNG image during upload

Posted on 2009-04-01
5
Medium Priority
?
419 Views
Last Modified: 2012-06-22
I have a php scrip to upload PNG files but I am losing the transparency during the upload and it is giving the images by default a black BG. I am attaching a snippet of code I am using. I need to know how to modify the code to maintain the transparency of the images being uploaded. Thanks and any help will be appreciated.
if ($mimetype=="image/png") {
$i = imagecreatefrompng($temporary_name);
imagealphablending($i, true); // setting alpha blending on
imagesavealpha($i, true); // save alphablending setting (important)
$dest_x = $tx;
$dest_y = $ty;
if (imagesx($i) > $dest_x or imagesy($i) > $dest_y) {
if (imagesx($i) >= imagesy($i)) {
$thumb_x = $dest_x;
$thumb_y = imagesy($i)*($dest_x/imagesx($i));
} else {
$thumb_x = imagesx($i)*($dest_y/imagesy($i));
$thumb_y = $dest_y;
}
} else {
$thumb_x = imagesx($i);
$thumb_y = imagesy($i);
}
$thumb = imagecreatetruecolor($thumb_x,$thumb_y);
imagecopyresampled($thumb, $i ,0, 0, 0, 0, $thumb_x, $thumb_y, imagesx($i), imagesy($i));
imagejpeg($thumb, $upload."/".$name."_".$un.".png", 9);
chmod($upload."/".$name."_".$un.".png", 0777);
$image_name=$name."_".$un.".png";
}

Open in new window

0
Comment
Question by:sulentho
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
5 Comments
 
LVL 5

Expert Comment

by:-null-
ID: 24036969
Hi

What browser are you using as <IE6 doesn't support transparent pngs and that might be throwing you off

-null-
0
 
LVL 5

Expert Comment

by:-null-
ID: 24036982
um and you're jpeging a png:

imagejpeg($thumb, $upload."/".$name."_".$un.".png", 9);


Jpegs don't do transparency
0
 
LVL 14

Accepted Solution

by:
shobinsun earned 1600 total points
ID: 24037090
Hello,

Here is an example code to create .png image with transparent effect.

Hope this code will help you.

Regards.
<?php
header("Content-type: image/png");
$image="powered_by.png";//this image is uloaded from the form
$im = imagecreatefrompng($image);
$bg_color = imagecolorat($im,1,1);
imagecolortransparent($im, $bg_color);
imagepng($im,"pics.png");
//ImagePNG($pic,"pics45.png");
imagedestroy($im);
 
?>

Open in new window

0
 

Author Comment

by:sulentho
ID: 24037573
Hi Shobinsun,
I have attached the code that I am currently using but  what is happening is there is now a very slight whitish layer behind the image so it is actually not a 100% transparent. Can anyone let me know if there is anything I need to tweak in the code. I am attaching a file created from this script as an example.
function setTransparency($new_image,$image_source)
{
$transparencyIndex = imagecolortransparent($image_source);
$transparencyColor = array('red' => 255, 'green' => 255, 'blue' => 255);
if ($transparencyIndex >= 0) {
$transparencyColor    = imagecolorsforindex($image_source, $transparencyIndex);   
}
$transparencyIndex    = imagecolorallocate($new_image, $transparencyColor['red'], $transparencyColor['green'], $transparencyColor['blue']);
imagefill($new_image, 0, 0, $transparencyIndex);
imagecolortransparent($new_image, $transparencyIndex);
} 
 
function createUniqueImage($imagefile,$imagename,$tx,$ty,$upload) {
$token = md5(uniqid(rand(),1));
$un = substr($token, 0, 5);
$filename = $imagefile['name'];
$temporary_name = $imagefile['tmp_name'];
$mimetype = strtolower($imagefile['type']);
$split = explode(".", $filename);
$name=$imagename;
 
// .png file format
 
if ($mimetype=="image/png") {
$i = imagecreatefrompng($temporary_name);
$dest_x = $tx;
$dest_y = $ty;
if (imagesx($i) > $dest_x or imagesy($i) > $dest_y) {
if (imagesx($i) >= imagesy($i)) {
$thumb_x = $dest_x;
$thumb_y = imagesy($i)*($dest_x/imagesx($i));
} else {
$thumb_x = imagesx($i)*($dest_y/imagesy($i));
$thumb_y = $dest_y;
}
} else {
$thumb_x = imagesx($i);
$thumb_y = imagesy($i);
}
$thumb = imagecreatetruecolor($thumb_x,$thumb_y);
setTransparency($thumb,$i);
imagecopyresampled($thumb, $i ,0, 0, 0, 0, $thumb_x, $thumb_y, imagesx($i), imagesy($i));
imagepng($thumb, $upload."/".$name."_".$un.".png", 9);
chmod($upload."/".$name."_".$un.".png", 0777);
$image_name=$name."_".$un.".png";
}
}

Open in new window

fcvbweather-860b5.png
0

Featured Post

On Demand Webinar: Networking for the Cloud Era

Did you know SD-WANs can improve network connectivity? Check out this webinar to learn how an SD-WAN simplified, one-click tool can help you migrate and manage data in the cloud.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I imagine that there are some, like me, who require a way of getting currency exchange rates for implementation in web project from time to time, so I thought I would share a solution that I have developed for this purpose. It turns out that Yaho…
Since pre-biblical times, humans have sought ways to keep secrets, and share the secrets selectively.  This article explores the ways PHP can be used to hide and encrypt information.
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…
The viewer will learn how to dynamically set the form action using jQuery.

715 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question