note 83547 added to function.imagerotate

Shortly after posting I was informed about a very nice algorithm for calculating the new pixel position for a rotation and thought it would be a nice improvement. Hopes this helps anyone needing a full implementation. Note: I tested the function on a 3Mb photo and it seemed to work perfectly with no quality loss. <?php if(!function_exists("imagerotate")) { function imagerotate(&$srcImg, $angle, $transparentColor = null) { $srcw = imagesx($srcImg); $srch = imagesy($srcImg); if($angle == 0) return $srcImg; // Convert the angle to radians $pi = 3.141592654; $theta = $angle * $pi / 180; // Get the origin (center) of the image $originx = $srcw / 2; $originy = $srch / 2; // The pixels array for the new image $pixels = array(); $minx = 0; $maxx = 0; $miny = 0; $maxy = 0; $dstw = 0; $dsth = 0; // Loop through every pixel and transform it for($x=0;$x<$srcw;$x++) { for($y=0;$y<$srch;$y++) { list($x1, $y1) = translateCoordinate($originx, $originy, $x, $y, false); $x2 = $x * cos($theta) - $y * sin($theta); $y2 = $x * sin($theta) + $y * cos($theta); // Store the pixel color $pixels[] = array($x2, $y2, imagecolorat($srcImg, $x, $y)); // Check our boundaries if($x2 > $maxx) $maxx = $x2; if($x2 < $minx) $minx = $x2; if($y2 > $maxy) $maxy = $y2; if($y2 < $miny) $miny = $y2; } } // Determine the new image size $dstw = $maxx - $minx + 1; $dsth = $maxy - $miny + 1; // Create our new image $dstImg = imagecreatetruecolor($dstw, $dsth); // Fill the background with our transparent color if($transparentColor == null) $transparentColor = imagecolorallocate($dstImg, 1, 2, 3); imagecolortransparent($dstImg, $transparentColor); imagefilledrectangle($dstImg, 0, 0, $dstw + 1, $dsth + 1, $transparentColor); // Get the new origin $neworiginx = -$minx; $neworiginy = -$miny; // Fill in the pixels foreach($pixels as $data) { list($x, $y, $color) = $data; list($newx, $newy) = translateCoordinate($neworiginx, $neworiginy, $x, $y); imagesetpixel($dstImg, $newx, $newy, $color); } return $dstImg; } /** * Translates from mathematical coordinate system to computer coordinate system using * origin coordinates from the computer system or visa versa * * @param int $originx * @param int $originy * @param int $x * @param int $y * @param bool $toComp * @return array(int $x, int $y) */ function translateCoordinate($originx, $originy, $x, $y, $toComp=true) { if($toComp) { $newx = $originx + $x; $newy = $originy - $y; } else { $newx = $x - $originx; $newy = $originy - $y; } return array($newx, $newy); } } ?> ---- Server IP: 66.207.199.35 Probable Submitter: 24.78.45.213 ---- Manual Page -- http://www.php.net/manual/en/function.imagerotate.php Edit -- https://master.php.net/note/edit/83547 Del: integrated -- https://master.php.net/note/delete/83547/integrated Del: useless -- https://master.php.net/note/delete/83547/useless Del: bad code -- https://master.php.net/note/delete/83547/bad+code Del: spam -- https://master.php.net/note/delete/83547/spam Del: non-english -- https://master.php.net/note/delete/83547/non-english Del: in docs -- https://master.php.net/note/delete/83547/in+docs Del: other reasons-- https://master.php.net/note/delete/83547 Reject -- https://master.php.net/note/reject/83547 Search -- https://master.php.net/manage/user-notes.php