Jan
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| Posted: 03/08/2005, 2:49 PM |
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I am currently doing my final year project at University using perl cgi.
I have used a cgi script to output data onto the web browser, but have also included code to generate a graph using gd:graph. The problem is that on submit of my form the graph appears as a string of wierd characters onto the browser window. The user input appears as text onto the browser window as specified. If I run the graph as a separate script then it outputs fine.
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Ozum
Posts: 57
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| Posted: 03/08/2005, 2:58 PM |
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If I get right your problem, you can't see both text and image at the same time with one script. They have different file headers.
You can use <img src="your_image_script.cgi"> to render and send your image below the message.
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Jan
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| Posted: 03/11/2005, 6:03 AM |
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Hi Ozzum
Thanx for your reply. I am still a bit confused what you mean?
I have put all the code on one cgi script including the graph code. The idea is that on submit of the form - if there are no errors with the form, then the users data will be output in text format together with a graph.
Thsi code has been put in a loop. I can get the text output, with the graph output - except that the graph appears as a string of characters/lines. I dont understand why the graph appears as lines?
Thanks
J
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Ozum
Posts: 57
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| Posted: 03/11/2005, 12:51 PM |
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Hi,
I try to explain,
According to HTTP standards Internet Browsers or any other client expect a file header. These requests are usually handled via Perl CGI module or GD::Graph
WEB BROWSER -----request(get)-------> WEB SERVER
WEB BROWSER <-------response--------------|
Below are two imaginary get requests for a jpg file and an html file
For jpg file: GET /car.jpg ....
For html file: GET /description.html .....
Web server responses for these requests like these.
...
Content-Length: 141
Content-Type: text/html
Or
...
Content-Length: 4500
Content-Type: image/jpeg
So your browser expect to see a html file (text based) stream in the first one, and a jpeg file stream (binary) in the second one.
In your case you print a HTML file header to write your message and browser capture this text and prints it to screen, but after that your image stream continue to flow as a binary data to the browser. Since browser assumes it is a text stream it tries to print them as its text, and you see strange characters. These strange characters are the same when you look at your jpeg file via a hex editor.
You can combine these two in a script checking it via parameters. Example:
Assume file is named as "combine.cgi"
use CGI qw(:all);
use GD::Graph;
if ( param('give') eq 'message' )
{
print header;
print "Hello this is image: <br> <img src='combine.cgi?give=photo'>";
}
elsif ( param('give') eq 'photo' )
{
# Here print a jpeg file header. (I don't remember exactly)
# And here print your image file with GD
}
When you call this file as combine.cgi?give=message this does what you want.
Regards Ozum
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