PHP create image question

[ashrobbins87]

I have created an image in php and the size of it gets updated depending on a variable from my DB. I want to use it as a kind of totaliser, as it is displaying the amount of money that has been raised to date, therefore I want the image to start at the bottom and grow upwards. I know how to start it at the bottom of the canvas but I want to know how to draw the height of the image upwards, instead of it going down the page and off the bottom of the canvas.

 

Sorry if that explanation isnt very clear!!

//create the canvas
$image = ImageCreate(30, 400);

//set up colours
$blue = ImageColorAllocate($image, 0, 0, 255);
$red = ImageColorAllocate($image, 255, 0 , 0);

//draw rectangle
ImageFilledRectangle($image, 1, 299, 28, $figure, $red);

//output image to browser
header ("Content-type: image/png");
ImagePng($image);

//clean up 
ImageDestroy($image);

 

$figure is the variable that sets the height of the image.

 

[GingerRobot]

Well it's just simple maths, right?

 

If 0 is the top of the canvas, x is the bottom of it and we need the top of the image to be drawn with height h, it's just x-h.

[ashrobbins87]

i really dont understand that