Pie Charts in PHP

Rendair · 12-04-2007, 07:44 PM

Hey all i thought i would write this tutorial on how to create a simple pie chart in PHP.

You can view a demo HERE

Ok firsts thing first we must place a header and set the page to an image type.

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header ("Content-type: image/pjpeg"); //define the page to be a image

Next we need to work out the values to fit the by chart we can do this by adding all the values together and deviding each value by the total result and then times by 360. So (value / totalofall) * 360. This will give us the size of all the peieces to fit in the pie chart.

PHP Code:


			


$value1 = 240;

$value2 = 1540;

$value3 = 698;

$value4 = 150;

$total = $value1 + $value2 + $value3 +  $value4;

    

$result1 = $value1 / $total * 360; //Work out piece size for value1

$result2 = $value2 / $total * 360;  //Work out piece size for value2

$result3 = $value3 / $total * 360; //Work out piece size for value3

$result4 = $value4 / $total * 360;  //Work out piece size for value4

Next we need to start defining colours we can use for the pie chart. First off we need to create the actual base of the chart or background

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$im = imagecreate(500,600);

PHP Code:


			
imagecreate(width, height) //Will create a simple rectangle.

Here we can start creating colours to use for the piechart peices themself

PHP Code:


			
$colour2 = imagecolorallocate ($im, 200,200,200); //Get colour using the RGB 

$colour3 = imagecolorallocate ($im, 242,225,231); //Get colour using the RGB 

$colour4 = imagecolorallocate ($im, 120,255,210); //Get colour using the RGB 

$colour5 = imagecolorallocate ($im, 152,110,150); //Get colour using the RGB 

$colour = imagecolorallocate ($im, 0,0,0); //Get colour using the RGB

Now we have actually got some colours to use for our pieces of the pie. We can now start constructing the pie pieces.

PHP Code:


			


// Will be start constructing the pie pieces using the colours above



imagefilledarc ($im, 250, 230,400,400,0,$result2+$result1+$result3+$result4,$colour, IMG_ARC_PIE); 

imagefilledarc ($im, 250, 230,400,400,0,$result1+$result2+$result3,$colour3, IMG_ARC_PIE); 

imagefilledarc ($im, 250, 230,400,400,0,$result2+$result1,$colour4, IMG_ARC_PIE); 

imagefilledarc ($im, 250, 230,400,400,0,$result1,$colour5, IMG_ARC_PIE);

As you can see above we have used 4 lines this will create four pieces.

PHP Code:


			
imagefilledarc  ( resource image, center X axis , center y axis , arc width , arc height ,start position in degrees , finish position, arc background colour, arc style )

When dealing with the arc start position if you set it to 0 it will start at 3 o clock and go around clockwise from that point.

Now we have have done the actual pie we can add some text to it.

PHP Code:


			
imagestring($im,10,60,460,"Value 1: $value1",$colour);

imagestring($im,10,60,475,"Value 2: $value2",$colour);

imagestring($im,10,60,490,"Value 3: $value3",$colour);

imagestring($im,10,60,505,"Value 4: $value4",$colour);

imagestring($im,2,10,580," Coded By: Dale ( Rendair ) ",$colour);

That will give us some text one below the other with the results and the coded by text.

PHP Code:


			
imagestring  ( resource image  , font size  , x  , y  , string  , colour  )

The x and y means from the top left hand corner so if x = 50 and y = 200 then move in 50pixels from top left corner, then move down 200pixels from that position.

Ok now we can tidy it up a bit by adding some lines around the values and a border around the whole thing.

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imagerectangle($im,20,550,380,450,$colour);

imagerectangle($im,0,0,498,598,$colour);

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imagerectangle  ( resource image,Upper left x coordinate,Upper left y coordinate,Bottom right x coordinate,Bottom right y coordinate,colour)

Upper left y coordinate 0, 0 is the top left corner of the image. We are done all we have to do now is display the final image

PHP Code:


			
imagejpeg($im);

All this can be easily converted for use with MySQL database results, be it number of hits in certain months.

I have included the final full code below.

PHP Code:


			
<?php



    header ("Content-type: image/pjpeg"); //define the page to be a image

    

    

    //Next we need to work out the values to fit the by chart we can do this by adding

    //all the values together and deviding each value by the total result and then times by 360

    //So (value / totalofall) * 360. This will give us the size of all the peieces to fit in the

    //pie chart

    

    $value1 = 240;

    $value2 = 1540;

    $value3 = 698;

    $value4 = 150;

    $total = $value1 + $value2 + $value3 +  $value4;

    

    $result1 = $value1 / $total * 360;

    $result2 = $value2 / $total * 360;

    $result3 = $value3 / $total * 360;

    $result4 = $value4 / $total * 360;

    

    //Next we need to start defining colours we can use for the pie chart

    //First off we need to create the actual base of the chart or background

    

    $im = imagecreate(500,600);

    

    //Here we can start creating colours to use for the piechart peices themself

    $colour2 = imagecolorallocate ($im, 200,200,200);

    $colour3 = imagecolorallocate ($im, 242,225,231);

    $colour4 = imagecolorallocate ($im, 120,255,210);

    $colour5 = imagecolorallocate ($im, 152,110,150);

    $colour = imagecolorallocate ($im, 0,0,0);

    

    

    //Here we can start by creating the acutal pieces

    imagefilledarc ($im, 250, 230,400,400,0,$result2+$result1+$result3+$result4,$colour, IMG_ARC_PIE); 

    imagefilledarc ($im, 250, 230,400,400,0,$result1+$result2+$result3,$colour3, IMG_ARC_PIE); 

    imagefilledarc ($im, 250, 230,400,400,0,$result2+$result1,$colour4, IMG_ARC_PIE); 

    imagefilledarc ($im, 250, 230,400,400,0,$result1,$colour5, IMG_ARC_PIE); 

    

    //Add the text

    imagestring($im,10,60,460,"Value 1: $value1",$colour);

    imagestring($im,10,60,475,"Value 2: $value2",$colour);

    imagestring($im,10,60,490,"Value 3: $value3",$colour);

    imagestring($im,10,60,505,"Value 4: $value4",$colour);

    imagestring($im,2,10,580," Coded By: Dale ( Rendair ) ",$colour);

    

    //Add lines around the main thing and around values

    imagerectangle($im,20,550,380,450,$colour);

    imagerectangle($im,0,0,498,598,$colour);



    imagejpeg ($im);



?>

Swordbeta · 12-04-2007, 07:50 PM

Wow,that's cool :)
Nice tutorial,helps me and explains me a lot about images in PHP.

Wildhoney · 12-04-2007, 08:25 PM

Exceedingly useful! I was dabbling with GD the other day - more specifically, using the Windows COM component in PHP to take a screen-shot of a given website. It's something I've wanted to do for a while but finally got around to taking a closer look on how to do it without diving into the C world.

Can I be a bit of a pig though and point out an easier way to do the values at the start? Not that it makes much difference, just an easier way to do it. If you add the values to an array, you can then use array_sum to plus them all together:

php Code:

$aValue[] = 45;
$aValue[] = 78;
$aValue[] = 121;
$aValue[] = 255;

var_dump(array_sum($aValue));

Rendair · 12-04-2007, 09:03 PM

O yes of course that is a good way, but you know i feel displaying whats going on with all the adding can show people what process is taking place.

ReSpawN · 12-04-2007, 09:59 PM

Wildhoney, give this dude a medal. Oh hell man! I've been looking all over the WEB for this! Thanks!

++Tutorial!

Rendair · 12-04-2007, 11:14 PM

Your very welcome

glad it helped