dynamic (inline) PHP images

artg

I have a table that is generated out of a datbase. Many of the cells need to have a dynamically generated image containing a tag from the database. The image is supposed to have a background color with a few characters of text from the database superimposed (black text on yellow background or black on lightblue, or black on green).

I'm generating the images with a call to a function that creates the image in a .png file. The cell images seem correct but the text is not. It's obvious the PNG file is getting overwritten before HTML can pick up the image and stream it out.

I need to generate each image in-line, e.g. with no file being written. Over a hundred images are being created and writing to a single file is not only inefficient, it doesn't work correctly. But I can't seem to come up with a syntax that PHP likes to try to generate each image in-line - on the fly.

Especially troubling is when I put a header() command in the image generation function. The browser (properly) complains about already having sent HTML headers.

Here's part of my image generation code. It's a function that's included in the PHP file that generates the table:

// header("Content-Type: image/png");

// ID label passed in as $loc

// create the image
$im = ImageCreate(20,80);

// allocate colors
$green = ImageColorAllocate($im,0,255,0);
$black= ImageColorAllocate($im,0,0,0);
$yellow = ImageColorAllocate($im,255,255,0);
$pblue = ImageColorAllocate($im,0,255,255);

// determine background color
switch($avail) {
case 0:
ImageFilledrectangle($im,0,0,20,80,$green);
break;
case 1:
ImageFilledrectangle($im,0,0,20,80,$yellow);
break;
case 2:
ImageFilledrectangle($im,0,0,20,80,$pblue);
break;
}

ImageStringUp($im,4,0,50,"A99",$black);
ImagePNG($im,"vtable_image.png");
ImageDestroy($im);
return;

Any ideas?

Thanks,
Art G.

diego25

If your script outputs HTML, the content-type header is going to be text/html, but if you output an image, the content-type needs to be image/png (or something like that). But a script can only output one type of content, so you can't output the images in the same script as you output the table.

To fix it, separate the scripts that output the table and the image. And then, in your table script, you'll output:

print "<img src=\"image.php?text=$valueFromDB\">";

And then image.php will generate the image with the text.

Diego

artg

Originally posted by diego25
If your script outputs HTML, the content-type header is going to be text/html, but if you output an image, the content-type needs to be image/png (or something like that). But a script can only output one type of content, so you can't output the images in the same script as you output the table.

To fix it, separate the scripts that output the table and the image. And then, in your table script, you'll output:

print "<img src=\"image.php?text=$valueFromDB\">";

And then image.php will generate the image with the text.

Diego

Ok, I tried that. I have two scripts that generate either vertical or horizontal table cell images. each is called as you suggest above.
But when I send a jpeg header out of the image script, the only thing that displays in the browser is one jpeg image. It looks good - text on the proper background -- but there is nothing else. There is no HTML at all. Only the jpeg image. When I comment out the image/jpeg header command, the output is total trash, and includes a warning that headers have already been sent. So that doesn't seem right.

Is there some kind of buffering that I need to invoke?

Weedpacket

Just checking: the HTML file that contains the <img> tag is being sent with a text/html type; while the jpeg image that's being sent out by image.php is being set with an image/jpeg type? And that the HTML script isn't outputting images and the image.php page isn't outputting HTML?

artg

That's correct. The main PHP script builds a large HTML table. Some of the cells have an image tag that looks like: <img src="htable.php?tag1=$tid&tag2=0">

htable.php generates the image. It's sized to fit the table cell. The source code is similar to my original posting (I changed to using jpeg). It outputs an image/jpeg header.

when I run the script from the browser (currenly mozilla under redhat 8) either of two things happen. If I output an image/jpeg header in the htable.php script, the browser shows only one image in the top left corner of the screen. Apparently, all other HTML data and all other images get thrown away leaving only the last image sent.

If I comment out the header("Content-Type: image/jpeg"); line, the HTML is there, and some of the images are there, but they are severely messed up, and usually I get a warning message about the htable.png script outputting HTML. I can't see why that would be because it consists only of a set of <?php ?> tags with PHP script between. And there is no blank space before or after the tags.

Hope this helps.

diego25

You have to output the content-type header, otherwise the browser won't know if it's a JPEG, GIF, PNG, or even Flash movie, or etc...

Can out post here the relevant code for the main PHP script that outputs the table?

Diego

artg

PROBLEM SOLVED!

I wondered about how the image generation code could have been issuing any HTML code, and then remembered I was originally calling functions located within the image generating scripts, and so I was including the script code in my main routine.

When I removed the includes, it worked.

Thanks one and all for your assistance!

Have a great New Year!

Art G.