I wrote a simple image randomizer on PHP that picks a random image from a list using the rand() function. The code works perfectly, and a random image is generated when I include it on my html as a picture.
The problem comes when I try to include it twice in the same html. A random image WILL be generated and displayed for both times I included it, but it will be the same image. In other words, I get a repeated random image on my page.
An easy way to solve this is to simply copy the randomizer.php, give it a new name, and include both images in HTML. The reason I don't want to do this is because my final HTML will have about 25 pictures, and I simply feel like there should be a better way to do this. Keep in mind that I CANNOT add any PHP functions into my HTML, given that my files are hosted in different servers, and my HTML server does not support PHP.
If anyone know of a better fix other than creating 25 copies of my randomizer.php file (or creating 25 different files that include it), please let me know. I will most definitely appreciate your input!!
Thank you very, very much!!
Here's a snippet of the code:
if (count($fileList) > 0) {
do { //do-while loop will get a new random image until that image has not been used yet in this session
$imageNumber = rand( 0 , ( count($fileList) - 1) ); //get random image from fileList
$iterations++;
} while( !(empty($_SESSION['img' . $imageNumber])) && iterations < 200);
$_SESSION['img' . $imageNumber] = True; //this image number has been displayed
$_SESSION['shown']++; //increments the number of shown pictures in this signature
$img = $folder.$fileList[$imageNumber];
}
It may be that the browser thinks it is the same image and is caching, try setting the name of the image (emit a header with content-disposition/filename IIRC) and/or adding a unique tag to the end of the image name with a random string, ( e.g. image.jpg?e0.6613725793930488 )
My guess is that rand() either didn't reseed, or is seeded with the same value.
Have you considered calling srand() - or "the better random number generator" combination of mt_srand() and mt_rand()?
Related
This is an odd question but I'm stuck on how I would achieve this and I am unable to find any methods of doing so.
I have a simple php script that takes variables (containing file names) from the URL, cleans then and then uses them to generate a single image from the inputted values. This works fine and outputs a new png to the webpage using:
imagepng($img);
I also have a facebook sharing script in PHP that takes a filepath as an input and then shares the image on the users feed where this statement is used to define the image variable:
$photo = './mypic.png'; // Path to the photo on the local filesystem
I don't know how I can link these two together though. I would like to use my generation script as the image to share.
Can anyone point me in the right direction of how to do this? I am not the master of PHP so go easy please.
-Tim
UPDATE
If it helps, here are the links to the two pages on my website containing the outputs. They are very ruff mind you:
The php script generating the image:
http://the8bitman.herobo.com/Download/download.php?face=a.png&color=b.png&hat=c.png
The html page with the img tag:
http://the8bitman.herobo.com/Share.html
Treat it as a simple image:
<img src="http://yourserve/yourscript.php?onlyImage=1" />
yourscript.php
if($_GET['onlyimage']) {
header('Content-type:image/png'); //or your image content type
//print only image
} else {
//print image and text too
}
Hi I have searched the web for 2 days but did not accomplish what I am looking for.
I have an apache server which will be accessed by 146 students. the user picks an angle from dropdown lets say 45 degress, then user clicks CALCULATE button. Then user clicks DIAGRAM button to see how the sine graph looks like.
Works like charm when i write the image to a file e.g: imagepng($img,"diagram.png");
Now the problem is that the diagram.png will always get overwritten by the last user. So for example if another user logs in and calculates the Sin 135. Both users will see Sine 135 because filename is hardcoded since there is conflict of filename.
I have searched the web on how to create the image dynamically instead of writing to a file and then reading the file. I have come across the following but not working:
base64_encode and decode
What would I have to do to my code of imagepng(...., ...) mentioned above to make use of base64 so I can actually draw the picture of already processed data. Let assume if I comment out the imagepng(..) code, then what do I replace it with. I hope I don't have to change my code a whole lot.
Please help
thanks
Amit
The filename argument to imagepng is optional. From the manual:
filename
The path to save the file to. If not set or NULL, the raw image stream will be outputted directly.
You would just need to send a png header at the top of the script and you would get the image as output for that script.
It's hard to tell without seeing you code how it is structured
but if once the user submits the form all you do is show the image by itself, then you can do something like this.
// make sure nothing else is out put before this otherwise it will stuff up the header
header('Content-Type: image/png);
imagepng($img);
If you embed the image into an html page as the result, then your best best would be to change the url of the image on the success page to something like this.
<img src="/path/to/file.php?deg=45" />
Then in the file.php
$deg = $_GET['deg'] + 0; // make sure it is a number
$img= function_render_graph($deg);
// make sure nothing else is out put before this otherwise it will stuff up the header
header('Content-Type: image/png);
imagepng($img);
By using a GET request, rather then a POST request then the image will likely be cached by the browser, so it doesn't need to be rendered each time. (Given that you have a drop list of angles, there must be a limited number of graphs that can actually be drawn)
Draw_Resultant_Prism_Graph (parameters)
{
$img = imagecreatetruecolor(800,750);
....
....
...
the following lines captures the data from output buffer and displays on same screen
***some version of IE have some issues mostly the dumb terminals where IE update is ADMIN
***restricted
ob_start();
header("Content-type: image/jpeg");
imagepng($img);
$output = ob_get_contents();
ob_end_clean();
imagedestroy($img);
echo img src="data:image/jpeg;base64,'.base64_encode($output).'"
user tags around img above and semicolon af
}
I am using PHP to generate images and this works fine. I am having trouble displaying these images however:
My image generator is a PHP file that takes tons of parameters and loads of data to generate the image. Because of the excessive amounts that has to be passed to the generator, using the GET container does not work for me, so the data is sent via a POST request. The result of this request is the raw image data.
I am using
$result = post_request('http://myurl.com/graphx/generator.php', $data);
if($result['status'] == 'ok') {
echo "<img src=\"data:image/png;base64,".
base64_encode($result['content'])."\"/>\n";
}
to display my image. This works for very small images, but as they get bigger (300px*300px for example), the image is not displayed anymore (it seems to be cut somewhere).
Is my approach reasonable?
Is there any workaround for the size issue?
Update:
When I let the generator save the image to a file, the created file contains the image as I want it to be. Also, if convert my generator into a GET-generator, the following code works properly as well:
$data = http_build_query($data);
echo "<img src=\"http://myurl.com/graphx/get_generator.php?{$data}\"/>\n";
So it definitely seems to be a problem with either the POST request, or the conversion into the base64 format. I'm using the POST request as shown here.
I'd suggest having your page be structured like this:
main page:
<img src="imageproxy.php" />
imageproxy.php:
<?php
$result = post_request('http://myurl.com/graphx/generator.php', $data);
header('Content-type: image/png');
if($result['status'] == 'ok') {
echo $result['content']);
} else {
readfile('error_message_image.png');
}
instead of trying to work with data uris and length limits, just have your proxy script output the actual raw image data and treat it as an image in your client-side html.
According to http://en.wikipedia.org/wiki/Data_URI_scheme IE 8 (and presumably below if they support it) "limits data URIs to a maximum length of 32 KB". This could be what you are seeing if it only reads the first 32k of whatever you are sending it.
Why don't you base64 the parameters and put THAT in the GET request, and do a simple:
<img src="/path/to/php.php?p=eyJ0aGlzIjoiaXMiLCJhIjoiYmVhdXRpZnVsIiwic2V0Ijoib2YiLCJwYXJhbWV0ZXJzIjoiISEifQ==" />
Then on the php.php base64_decode($p) and return the image.
Even better on php.php, use X-Sendfile mod of apache (https://tn123.org/mod_xsendfile/) and perhaps cache the image as well locally so that you don't have to recreate it all the time
Edit:
I don't know exactly how many parameters we are talking about here. If you go and see What is the maximum length of a URL in different browsers? you will see that experience has shown that a URI is pretty much around 2000 characters.
So it depends if your base64 encoded string is less that that you are safe. Otherwise you could think of alternative ways of encoding. Perhaps yEnc or base85?
Even further you could do store a serialized object (containing the parameters needed) on a local storage (ie RDBMS), link it with an id and pass that id around. When php.php get's the id, looks it up on the storage retrieves the parameters creates the image and so on.
I'm building a site that depends on bookmarklets. These bookmarklets pull the URL and a couple of other elements. However, I need to select 1 image from the page the user bookmarks. Currently I'm trying to use the PHP Simple HTML DOM Parser http://simplehtmldom.sourceforge.net/
It pulls the HTML as expected, and returns the tags as expected. However, I want to take this a step further and only return images with a min width of 40px. I know about the function getimagesize() but from what I understand, this is resource heavy. Is there a better method available to pre-process the image and achieve the results I'm looking for?
Thanks!
First check if the image HTML tag has a width attribute. If it's above 40, skip over it. As Matthew mentioned, it will get false positives where people sized down a large image to 40px wide, but that's no big deal; the point of this step is to quickly weed out the first dozen or so images that are obviously too big.
Once the script catches an image that SAYS it's under 40px wide, check the header information to deduce a general width based on the size of the file. This is faster than getimagesize because you don't have to download the image to get the info.
function get_image_kb($path) {
$headers = get_headers($path);
$len = explode(" ",$headers[6]);
return $len[1];
}
$imageKb = get_image_kb('test1.jpg');
// I'm going to gander 40x80 is about 2000kb
$cutoffSize = 2000;
if ($imageKb < $cutoffSize) {
// this is the one!
}
else {
// it was a phoney, keep scraping
}
Setting it at 2000kb will also let through images that are 100x30, which isn't good.
However, at this point, you've weeded out most of the huge 800kb files that would really slow you down, and because we know it's under 2kb, it's not too taxing to test this one with getimagesize() to get an accurate width.
You can tweak the process depending on how picky you are for the 40px mark, as usual higher accuracy takes more time, and vice versa.
Okay, I have a question guys. I want to remote upload (copy an image from a site to my server) MULTIPLE images by putting links into a TEXTAREA and hitting submit. I just don't know how to make this possible with multiple images.
I am able to make it with an single image using the copy(); function, but not for multiple entries in a TEXTAREA.
I also want to limit the remote uploading feature up to 30 remote links and one image should not exceed 10MB - But I don't know how to start. I heard cURL is able to make this and I also heard that file_get_contents(); with file_put_contents(); can make a similar thing, but I still cannot figure out how to do it myself.
Help anyone? :)
You can use the same procedure as you do now with a single image, but do it in a loop.
$lines = explode("\n", $_POST['textarea']);
if(count($lines) > 30) {
die('Too many files');
}
foreach($lines as $line) {
$srcfile = trim($line);
//copy $srcfile here
//check size of the file with filesize()
}
You need to parse the URLs out of the textarea. You could with this PHP side with a regular expression.
You could then examine the parsed URLs and array_slice() the first 30, or error if more than 30.
You'd then need to copy the files from the remote server. You could inspect the Content-Length header to ensure the file is under 10mb. You could get just the headers using HEAD instead of GET.
I am not familiar with PHP but I suggest the following:
Solving the multiple files upload issue:
splitting the content in the text area by the carriage return
then iterate them to get image
preserve the size of each file in a variable, but how to get the size?
you can do exec (system) call to know the file size (this requires a full image download but its the most convenient way ), or you can make use of Content-Length header value, if the content length is more than 10 MG then skip it and move to the next item.
How to download the image?
use the file put content but make sure to put the encoding as binary encoding to preserve the content type.