use php to generate image, the background is always in wrong color

Question

The function is when users upload a picture, program will generate a new white background squre image, and put user's picture in the center of this image.

But the problem is, I set the background to white, it always shows black.

The code is

$capture = imagecreatetruecolor($width, $height);
$rgb = explode(",", $this->background); 
$white = imagecolorallocate($capture, $rgb[0], $rgb[1], $rgb[2]); 
imagefill($capture, 0, 0, $white); 

and the code that controls the color is protected $background = "255,255,255";

I've been tried to change $white = imagecolorallocate($capture, $rgb[0], $rgb[1], $rgb[2]); to $white = imagecolorallocate($capture, 255, 255, 255);. But the background still shows in black.

Thanks for any answer

Answer 1

From the manual imagecreatetruecolor() returns an image identifier representing a black image of the specified size. The first call to imagecolorallocate sets the background for palette based images but a true color image is not.

The way I set the background color on true color images is to just fill it with a solid rectangle.

imagefilledrectangle($capture, 0, 0, $width, $height, $white);

Answer 2

what about imagefill($im, x, y, $color) ?

$red = imagecolorallocate($im, 255, 0, 0);
imagefill($im, 0, 0, $red);

This will fill entire image with red color, and the x,y parameters are the starting point of rectangle fill.