Making a Speedometer!?

[strberg]

Hello!

 

Allright so i want taken upon a task were i should make a gauge. But i don't know how. I've been googleing alot about this and i found this:

 

http://jpgraph.net/download/manuals/chunkhtml/ch20s02.html

 

But for my it only says how to make it. Which is a great start but i want the gauge to look into a database to see what precent the meter should point on.

Example:

 

The question is, Do you watch the olympics?

Two answers, Yes and No.

 

The database saves these and when you press View results, the speedometers arrow should point at, lets say 60%. The you know that 60% watches the olympics and 40% doesn't. (it is a half circle)

If you have any better guides than the one i linked please enlighten me.

 

If you haven't notice i'm new to PHP so use your easy words.

[Barand]

Rather than have your gauge look into the database so that it performs only a single function it is much better to have a gauge that just lets you pass a percentage figure and draw itself accordingly.

 

That way it becomes reusable on many other occasions. Query the database to get the percentage.

 

Another approach would be a basic gauge class which you can then subclass for your olympics question.

[strberg]

You mean i should go another design? Because the whole point of making this is that i want the speedometer look, and that the arrow moves according to the database vaulues.

[Barand]

If you separate the gauge from the question you can then have dozens of questions all utilizing the same gauge to show the results.

[strberg]

Oh okay. I have bad english as you may have noticed thats why i didin't get it from the beginning.

 

And how do I do that?

[Barand]

Create a php script to draw your gauge using the GD library, say "gauge.php". This would expect the percentage to be passed to it so it can draw the pointer in the right position.

 

guage.php

$percent = $_GET['percent'];         // get the percentage to be displayed

// draw gauge and output

 

Query the database and calc the percentage to be displayed, say $pcent.

 

Display the gauge using an img tag

 

<img src='gauge.php?percent=$pcent' />

 

You can repeat this for as many questions as you like.

 

 

[strberg]

I don't quite understand, is there any way you could expand your guide?

[xyph]

There are many tutorials on how to use GD with PHP to create custom images. Chances are no one here is going to write another one just for your issue.

 

If you can be more specific as to what you're having problems with, we might be able to help. As of now, the questions you're asking are too generic.

 

Are you having problems getting the percentage from the database? Once you have that number, the class you listed should do the rest for you quite easily.

 

$odo->needle->Set($percent);

[Barand]

Here's an example using one of my image php files to draw a bar graph (you would substitute your gauge image).

 

I am attaching the code for img_bar.php to get you started.

 

<style type='text/css'>
th {background-color: #369; color:#FFF; font-family: arial; font-size: 10pt;}
td {background-color: #ccc; color:#000; font-family: arial; font-size: 9pt;}
</style>
<?php
/***
* Suppose you had these questions and reults
*/
$questions = array (
     array (
        'q' => 'Do you watch the Olympic Games?',
        'pcent' => 70
        ),
        
     array (
        'q' => 'Do you normally watch sport?',
        'pcent' => 55
        ),
        
     array (
        'q'  => 'Do you watch soaps?',
        'pcent' => 80
        )
);

/***
* and you want to display them
*/

echo "<table border='0' cellpadding='4' cellspacing='2'><tr><th>Question</th><th colspan='2'>Percent</th>";
foreach ($questions as $qarr) {
    echo "<tr><td>{$qarr['q']}</td>
        <td>{$qarr['pcent']}</td>
        <td><img src='img_bar.php?val={$qarr['pcent']}&max=100' /></td></tr>";
}
echo "</table>";
?>

18829_.php

[strberg]

Thanks for that barand it gave me alot more understanding!

 

Just how have one question at the moment, how do i collect the value in the database and how do i make it work with this?

[Barand]

That would depend on your database.

 

Assuming you have a table of questions and a table of responses

 

question -> qid, question_text

response-> rid, userid, qid, answer

 

SELECT q.qid, q.question_text, COUNT(*) as total, SUM(IF(r.answer='yes', 1, 0) as yes
FROM response r
INNER JOIN question q USING (qid)
GROUP BY qid

[strberg]

The value is decided here right?

 

$questions = array (
     array (
        'q' => 'Do you watch the Olympic Games?',
        'pcent' => 70
        ),
        
     array (
        'q' => 'Do you normally watch sport?',
        'pcent' => 90
        ),
        
     array (
        'q'  => 'Do you watch soaps?',
        'pcent' => 80
        )

 

How do i get so the "pcent" is decided by the code you replied with for getting the database value?

[Barand]

You calculate the percents from the yes counts and the totals

[jazzman1]

It's a pretty cool img_bar.php file.

I'm going to use it in the future 

[Barand]

Just send me a note of thanks on the back of a $50.00 bill 

[jazzman1]

Just send me a note of thanks on the back of a $50.00 bill 

No problem