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<?php
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// $Id: imagerotate.inc,v 1.4 2009/02/13 00:06:02 drewish Exp $
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/**
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* @file
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* provides the imagerotate function for php-gd extensions compiled with the
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* upstream libgd instead of the libgd bundled with php.
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*/
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// Define as included.
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define('IMAGEAPI_IMAGEROTATE_PHP', 1);
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function imagerotate(&$im, $angle, $bgcolor) {
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if ($angle === 0) {
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return $im;
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}
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// imagerotate() in php's libgd rotates the image counterclockwise,
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// this implementation rotates clockwise. The angle needs to be
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// inverted to give the same behaviour between these implementations.
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$angle = 360 - $angle;
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$width = imagesx($im);
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$height = imagesy($im);
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// background color.
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list($r, $g, $b, $a) = imageapi_hex2rgba($bgcolor);
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switch ($angle) {
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case 270:
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case 90:
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// flip dimensions.
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$rot_width = $height;
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$rot_height = $width;
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break;
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case 180:
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// maintain dims.
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$rot_width = $width;
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$rot_height = $height;
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break;
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default:
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// well it won't be easy but we'll actually rotate this
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// puppy ourselves.. gonna require a little trig.
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// @todo: convert to a polar equation and use 1/2 length of hypoteneus.
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$center_x = floor($width/2);
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$center_y = floor($height/2);
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// convert to radians and precompute ...
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$cosangle = cos(deg2rad($angle+180));
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$sinangle = sin(deg2rad($angle+180));
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// caluculate new width and height.
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$corners=array(array(0, 0), array($width, 0), array($width, $height), array(0, $height));
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$max_x = $min_x = $max_y = $min_y = 0;
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foreach ($corners as $key => $value) {
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$value[0] -= $center_x; //Translate coords to center for rotation
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$value[1] -= $center_y;
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$x = $value[0] * $cosangle + $value[1] * $sinangle;
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$y = $value[1] * $cosangle - $value[0] * $sinangle;
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$max_x = max($x, $max_x);
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$min_x = min($x, $min_x);
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$max_y = max($y, $max_y);
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$min_y = min($y, $min_y);
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}
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$rot_width = (int)$max_x - $min_x;
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$rot_height = (int)$max_y - $min_y;
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$rot_center_x = floor($rot_width/2);
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$rot_center_y = floor($rot_height/2);
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}
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$rotate = imagecreatetruecolor($rot_width, $rot_height);
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$bg = imagecolorallocatealpha($rotate, $r, $g, $b, $a);
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imagefilledrectangle($rotate, 0, 0, $rot_width, $rot_height, $bg);
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imagealphablending($rotate, false);
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imagesavealpha($rotate, true);
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switch ($angle) {
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case 270:
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$rot_width--;
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for ($y = 0; $y < $height; ++$y)
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for ($x = 0; $x < $width; ++$x)
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imagesetpixel($rotate, $rot_width - $y, $x, imagecolorat($im, $x, $y));
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break;
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case 90:
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$rot_height--;
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for ($y = 0; $y < $height; ++$y)
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for ($x = 0; $x < $width; ++$x)
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imagesetpixel($rotate, $y, $rot_height - $x, imagecolorat($im, $x, $y));
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break;
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case 180:
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$rot_width--;
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$rot_height--;
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for ($y = 0; $y < $height; ++$y)
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for ($x = 0; $x < $width; ++$x)
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imagesetpixel($rotate, $rot_width - $x, $rot_height - $y, imagecolorat($im, $x, $y));
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break;
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default:
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for ($y = 0; $y < $rot_height; ++$y) {
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for ($x = 0; $x < $rot_width; ++$x) {
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$mod_y = $rot_center_y-$y;
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$mod_x = $rot_center_x-$x;
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$old_x = $mod_x * $cosangle + $mod_y * $sinangle + $center_x;
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$old_y = $mod_y * $cosangle - $mod_x * $sinangle + $center_y;
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if ($old_x >= 0 && $old_x < $width && $old_y >= 0 && $old_y < $height) {
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$color = imagecolorat($im, $old_x, $old_y);
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imagesetpixel($rotate, $x, $y, $color);
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}
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}
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}
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}
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return $rotate;
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}
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