I've been trying to get transparency to work with my application (which dynamically resizes images before storing them) and I think I've finally narrowed down the problem after much misdirection about imagealphablending and imagesavealpha. The source image is never loaded with proper transparency!
// With this line, the output image has no transparency (where it should be
// transparent, colors bleed out randomly or it's completely black, depending
// on the image)
$img = imagecreatefromstring($fileData);
// With this line, it works as expected.
$img = imagecreatefrompng($fileName);
// Blah blah blah, lots of image resize code into $img2 goes here; I finally
// tried just outputting $img instead.
header('Content-Type: image/png');
imagealphablending($img, FALSE);
imagesavealpha($img, TRUE);
imagepng($img);
imagedestroy($img);
It would be some serious architectural difficulty to load the image from a file; this code is being used with a JSON API that gets queried from an iPhone app, and it's easier in this case (and more consistent) to upload images as base64-encoded strings in the POST data. Do I absolutely need to somehow store the image as a file (just so that PHP can load it into memory again)? Is there maybe a way to create a Stream from $fileData that can be passed to imagecreatefrompng?
you can use this code :
$new = imagecreatetruecolor($width, $height);
// preserve transparency
imagecolortransparent($new, imagecolorallocatealpha($new, 0, 0, 0, 127));
imagealphablending($new, false);
imagesavealpha($new, true);
imagecopyresampled($new, $img, 0, 0, $x, 0, $width, $height, $w, $h);
imagepng($new);
imagedestroy($new);
It will make a transparent image for you. Good Luck !
Blech, this turned out to ultimately be due to a totally separate GD call which was validating the image uploads. I forgot to add imagealphablending and imagesavealpha to THAT code, and it was creating a new image that then got passed to the resizing code. Which should probably be changed anyway. Thanks very much to goldenparrot for the excellent method of converting a string into a filename.
Do I absolutely need to somehow store the image as a file (just so that PHP can load it into memory again)?
No.
Documentation says:
You can use data:// protocol from php v5.2.0
Example:
// prints "I love PHP"
echo file_get_contents('data://text/plain;base64,SSBsb3ZlIFBIUAo=');
Related
this is my first question and I'm planning to hang around in this forum. I'm very new to programming since I'm studying but I'm making great progress. So, with this in mind I'll try to be as detailed as possible.
The project I am working with is about creating a png-image using GD PHP. The script recieves data, calculates image WIDTH/HEIGHT according to these. From this data I then print out pixels on the image in different spots. Everything works great, it displays the image and saves it on the server, there's nothing wrong with that. But when I run the script, it outputs the image to the browser. I don't want that. I just want the script to process the image and save it to the server. I have searched plenty but haven't found anything about it.
Code for creating the image: I have to remove some code though, but it's not needed to answer my question. I suspect it's something with the header and imagecreatetruecolor. This is all the data I can give.
<?php
//Some calculations before
// --- START: CREATE IMAGE ---
$png = imagecreatetruecolor($WIDTH, $HEIGHT);
imagesavealpha($png, true);
$trans_colour = imagecolorallocatealpha($png, 0, 0, 0, 127);
imagefill($png, 0, 0, $trans_colour);
//Here's just a loop to print pixels
header("Content-type: image/png");
imagepng($png);
save($png); //Function used for saving
//Erase from memory
imagedestroy($png);
?>
I am trying to create an employee poster for a website that I develop. My goal is to take an image from a directory on the server of any file type (.png, .gif, .jpeg, etc.) and copy it onto another generate imaged that will then be outputted to the browser.
The problem is that I use:
$final_image = imagecreatefrompng("large_background.png");
for making the final image and for some reason if I add profile images with the type jpeg's, gif's, etc, (any type that isn't a jpeg) it doesn't work. The images never show up in the output. However, if I use png's it does work.
To solve this problem I tried converting the image to a png and then creating a png from it as shown in the code below. Unfortunately it doesn't work. Profile images still do not show up on the background.
// get image from database
$image_from_database = could be a .png, .jpeg, .gif, etc.
// get the image from the profile images directory
$path = "profile_images/".$image_from_database;
// create a png out of the image
$image = imagecreatefrompng(imagepng($path));
// add the $image to my larger $final_image (which is a png)
imagecopy($final_image, $image, $x, $y, 0,0, $height, $width);
imagepng($final_image, $ouput_url);
...
Can anybody tell me why this won't work? My profile images do not show up in the output of the final image.
My questions,
Is this line imagecreatefrompng(imagepng(...)); even possible? Essentially I want to convert an image of any type into a png and then create a png from it.
I'm just running a few local tests... The following works:
$src = imagecreatefromgif('test.gif');
$dest = imagecreatefrompng('test.png');
imagecopy($dest, $src, 0, 0, 0, 0, 100, 100);
header('Content-Type: image/png');
imagepng($dest);
imagedestroy($src);
imagedestroy($dest);
So does this:
$src = imagecreatefromstring(file_get_contents('test.gif'));
If you're still having trouble after trying the latter example, please update your question. The actual images you're using would be helpful, in addition to a functional code example.
After you read an image with a imagecreatefrom* function, it doesn't matter what format the original was.
imagecreatefrom* functions return an image resource. When the image is loaded you are using internal representation of the images and not PNG, JPEG or GIF images.
If the images are successfully loaded imagecopy should have no problems with them.
This code uses images in different formats and works without a problem:
$img = imagecreatefrompng('bg.png');
$png_img = imagecreatefrompng('img.png');
$jpeg_img = imagecreatefromjpeg('img.jpeg');
$gif_img = imagecreatefromgif('img.gif');
/* or use this, so you don't need to figure out which imagecreatefrom* function to use
$img = imagecreatefromstring(file_get_contents('bg.png'));
$png_img = imagecreatefromstring(file_get_contents('img.png'));
$jpeg_img = imagecreatefromstring(file_get_contents('img.jpeg'));
$gif_img = imagecreatefromstring(file_get_contents('img.gif'));
*/
imagecopyresampled($img, $png_img, 10, 10, 0,0, 100, 100, 200, 200);
imagecopyresampled($img, $jpeg_img, 120, 10, 0,0, 100, 100, 200, 200);
imagecopyresampled($img, $gif_img, 230, 10, 0,0, 100, 100, 200, 200);
header('Content-Type: image/png');
imagepng($img);
Your example
$image = imagecreatefrompng(imagepng($path));
is wrong.
imagepng is used to output an image resource as a PNG image. If you provide a path as a second argument a PNG image file is created, otherwise it's printed to the output like echo does.
What imagepng actually returns is a boolean, indicating, if the output was successful.
You are then passing that boolean to imagecreatefrompng which expects a filepath. This is obviously wrong.
I suspect you have a problem with loading images.
imagecreatefrom* functions return FALSE on failure and you should check, if you have any problems with that.
Maybe your image paths are relative to doc root and your working directory is different.
Or you have permission problem.
Or your images are just missing.
It's impossible to tell from your question.
UPDATE:
now I learned more I looked alot and modified I got this:
function show_image($image, $new_width, $new_height) {
//$this->helper('file'); why need this?
//$image_content = read_file($image); We does not want to use this as output.
list($old_width,$old_height) = getimagesize("$image");
//resize image
$image = imagecreatefromjpeg($image);
$thumbImage = imagecreatetruecolor($new_width, $new_height);
imagecopyresized($thumbImage, $image, 0, 0, 0, 0, $new_width, $new_height, $old_width, $old_height);
imagedestroy($image);
//imagedestroy($thumbImage); do not destroy before display :)
ob_end_clean(); // clean the output buffer ... if turned on.
header('Content-Type: image/jpeg');
imagejpeg($thumbImage); //you does not want to save.. just display
imagedestroy($thumbImage); //but not needed, cause the script exit in next line and free the used memory
exit;
}
when using this function I get a file, but I need to get a URL
I wanna be able to use:
<img src=" ... ">
Since you can't use GD on the server, a good option might be to handle it on the client side.
One idea that comes to mind is loading the image into an html5 canvas, and using that to manipulate the image characteristics before uploading it to the server.
This post talks about how you'd go about uploading image data straight from a canvas and saving it as an image on your server.
How to save a HTML5 Canvas as an image on a server
You also will likely need to take a look at the JavaScript File API to load the image into the canvas on the client side.
It's not necessarily an easy solution, but it might be your best shot without access to GD and stuff.
I posted earlier about another resizing script not working and I got a little farther with this script which does things a little differently.
I got a little farther, only now there is a new problem. The first three lines of the code successfully place three identical files in the target directory with the file and it's two thumbnail files named accordingly. I then want to load the thumbnails, which are still full-size, and resize them but the script stops at imagecreatefromjpeg() and I can't seem to figure out why because $src has a value.
I thought that I could possibly remove that line and replace $source with $src in my imagecopyresized() function, and that gets me even closer. But it then returns a thumbnail of the target size, but the thumbnail is black.
move_uploaded_file($tmpFilePath, $newFilePath);
copy($newFilePath, $thumb500);
copy($newFilePath, $thumb200);
function thumbImage($src, $dest, $newheight) {
list($width, $height) = getimagesize($src);
$newwidth = $width * ($newheight / $height);
// Load
$thumb = imagecreatetruecolor($newwidth, $newheight);
header('Content-type: image/jpeg');
$source = imagecreatefromjpeg($src);
// Resize
imagecopyresized($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
// Output
imagejpeg($thumb, $dest);
}
thumbImage($thumb500, $thumb500, 500);
thumbImage($thumb200, $thumb200, 200);
I feel as if this must be a common issue. Any suggestions anyone?
For me the supplied code block works if I use a JPEG image as source.
The problem may be that you use a PNG image that uses transparency. As JPEG can not handle transparencies, the transparent background colour will be filled. Maybe that is the problem. If not, please provide a sample image that has the problematic behaviour.
5
imagecopyresized takes an image resource as its second parameter, not a file name. You'll need to load the file first. If you know the file type, you can use imagecreatefromFILETYPE to load it. For example, if it's a JPEG, use imagecreatefromjpeg and pass that the file name - this will return an image resource.
If you don't know the file type, all is not lost. You can read the file in as a string and use imagecreatefromstring (which detects file types automatically) to load it as follows:
{$oldImage = imagecreatefromstring(file_get_contents($_FILES['image']['tmp_name']));
}
enter code here
I've got a problem making alpha PNGs with PHP GD. I don't have imageMagik etc.
Though the images load perfectly well in-browser and in GFX programs, I'm getting problems with Flash AS3 (actionscript) understanding the files. It complains of being an unknown type. But, exporting these files from Fireworks to the same spec works fine. So I'm suggesting it's something wrong with the formatting in PHP GD.
There seems to be a number of ways of doing this, with several similar functions; so maybe this isn't right?
$image_p = imagecreatetruecolor($width_orig, $height_orig);
$image = imagecreatefrompng($filename);
imagealphablending($image_p, false);
ImageSaveAlpha($image_p, true);
ImageFill($image_p, 0, 0, IMG_COLOR_TRANSPARENT);
imagealphablending($image_p, true);
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width_orig, $height_orig, $width_orig, $height_orig);
imagepng($image_p, "new2/".$filename, 0);
imagedestroy($image_p);
This just takes files it's given and puts them into new files with a specified width/height - for this example it's same as original but in production it resizes, which is why I'm resampling.
To keep the transparency you should do
imagealphablending($image_p, false);
instead of "true". Maybe that will solve the format problem too.