How to draw barchart in php

[dinesh1985singh]

Hello everybody,

I am trying to create barchart in php,but i am little bit confused about how does

imagefilledrectangle() works actually.

<?php
// Create a 55x30 image
$im = imagecreatetruecolor(55, 30);
$white = imagecolorallocate($im, 255, 255, 255);
 
// Draw a white rectangle
imagefilledrectangle($im, 4, 4, 50, 25, $white);
 
// Save the image
imagepng($im, './imagefilledrectangle.png');
imagedestroy($im);
?>
 

in this code I saw that the second co-ordinates(x2,y2) always would be (imagewidth-(x1 co-ordinates+1)) ,(imageheight-(x1 co-ordinates+1))

could anyone explain the logic behind this please.

Thank you

[zorgi]

I am not looking at your code but reading that you want to create bar chart. Instead of doing it from scratch you might want to look at ready made pChart. Easy to use and fairly well documented:

http://pchart.sourceforge.net/

Hope this helps :)

[yobtar]

While talking about graphing libraries, I personally use jpgraph myself.

[dinesh1985singh]

@zorgi
Thank you yobtar and zorg you too.

But as I am newbie,so i guess it would be better to understand the logic behind bar chart,because once I got the logic behind its working I can draw any chart by myself.

So if you have any link from where I could understand the same in better way ,please let me know.I myself search it out on net ,I got almost every thing from there but just stuck behind why the second co-coordinates in

imagefilledrectangle($im,x1,y1, x2-1, y2-1, $white),
always would be (imagewidth-(x1 co-ordinates+1)) ,(imageheight-(x1 co-ordinates+1))

Thank you