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16 years ago
I was quite surprised to see that no one had done any working rotate function. And since I needed one for my web hotel, I whipped this one up. Someone might want to expand it so that it matches imagerotate.

Also, does imagerotate really rotate things counter clockwise? Otherwise this should also be changed.

<?php
if(!function_exists("imagerotate")) {
    function imagerotate(&$srcImg, $angle, $bgcolor, $ignore_transparent = 0) {
        return imagerotateEquivalent(&$srcImg, $angle, $bgcolor, $ignore_transparent);
    }
}

/*
    Unfinished imagerotate replacement. ignore_transparent is, well, ignored. :)
    Also, should have some standard functions for 90, 180 and 270 degrees, since they are quite 
    easy to implement faster.
*/
function imagerotateEquivalent(&$srcImg, $angle, $bgcolor, $ignore_transparent = 0) 
{
    function rotateX($x, $y, $theta){
        return $x * cos($theta) - $y * sin($theta);
    }
    function rotateY($x, $y, $theta){
        return $x * sin($theta) + $y * cos($theta);
    }
    
    $srcw = imagesx($srcImg);
    $srch = imagesy($srcImg);
  
    if($angle == 0) return $srcImg;
    
    // Convert the angle to radians
    $theta = deg2rad ($angle);

    
    // Calculate the width of the destination image.
    $temp = array (    rotateX(0,     0, 0-$theta),
                    rotateX($srcw, 0, 0-$theta),
                    rotateX(0,     $srch, 0-$theta),
                    rotateX($srcw, $srch, 0-$theta)
                );
    $minX = floor(min($temp));
    $maxX = ceil(max($temp));
    $width = $maxX - $minX;
    
    // Calculate the height of the destination image.
    $temp = array (    rotateY(0,     0, 0-$theta),
                    rotateY($srcw, 0, 0-$theta),
                    rotateY(0,     $srch, 0-$theta),
                    rotateY($srcw, $srch, 0-$theta)
                );
    $minY = floor(min($temp));
    $maxY = ceil(max($temp));
    $height = $maxY - $minY;
    
    $destimg = imagecreatetruecolor($width, $height);
    imagefill($destimg, 0, 0, imagecolorallocate($destimg, 0,255, 0));

    // sets all pixels in the new image
    for($x=$minX;$x<$maxX;$x++) {
        for($y=$minY;$y<$maxY;$y++) 
        {
            // fetch corresponding pixel from the source image
            $srcX = round(rotateX($x, $y, $theta));
            $srcY = round(rotateY($x, $y, $theta));
            if($srcX >= 0 && $srcX < $srcw && $srcY >= 0 && $srcY < $srch)
            {
                $color = imagecolorat($srcImg, $srcX, $srcY );
            }
            else
            {
                $color = $bgcolor;
            }
            imagesetpixel($destimg, $x-$minX, $y-$minY, $color);
        }
    }
    
    return $destimg;
}
?>
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