<?php
/**
* round_corners
*
* Round the corners of an image. Transparency and anti-aliasing are supported.
*
* @version 0.2
* @author Contributors at eXorithm
* @link /algorithm/view/round_corners Listing at eXorithm
* @link /algorithm/history/round_corners History at eXorithm
* @license /home/show/license
*
* @param resource $image (GD image)
* @param number $radius Radius of the rounded corners.
* @param string $color (hex color code) Color of the background.
* @param mixed $transparency Level of transparency. 0 is no transparency, 127 is full transparency.
* @return resource GD image
*/
function round_corners($image=null,$radius=20,$color='ffffff',$transparency='127')
{
$width = imagesx($image);
$height = imagesy($image);
$image2 = imagecreatetruecolor($width, $height);
imagesavealpha($image2, true);
imagealphablending($image2, false);
imagecopy($image2, $image, 0, 0, 0, 0, $width, $height);
$full_color = allocate_color($image2, $color, $transparency);
// loop 4 times, for each corner...
for ($left=0;$left<=1;$left++) {
for ($top=0;$top<=1;$top++) {
$start_x = $left * ($width-$radius);
$start_y = $top * ($height-$radius);
$end_x = $start_x+$radius;
$end_y = $start_y+$radius;
$radius_origin_x = $left * ($start_x-1) + (!$left) * $end_x;
$radius_origin_y = $top * ($start_y-1) + (!$top) * $end_y;
for ($x=$start_x;$x<$end_x;$x++) {
for ($y=$start_y;$y<$end_y;$y++) {
$dist = sqrt(pow($x-$radius_origin_x,2)+pow($y-$radius_origin_y,2));
if ($dist>($radius+1)) {
imagesetpixel($image2, $x, $y, $full_color);
} else {
if ($dist>$radius) {
$pct = 1-($dist-$radius);
$color2 = antialias_pixel($image2, $x, $y, $full_color, $pct);
imagesetpixel($image2, $x, $y, $color2);
}
}
}
}
}
}
return $image2;
}
/**
* allocate_color
*
* Helper function to allocate a color to an image. Color should be a 6-character hex string.
*
* @version 0.2
* @author Contributors at eXorithm
* @link /algorithm/view/allocate_color Listing at eXorithm
* @link /algorithm/history/allocate_color History at eXorithm
* @license /home/show/license
*
* @param resource $image (GD image) The image that will have the color allocated to it.
* @param string $color (hex color code) The color to allocate to the image.
* @param mixed $transparency The level of transparency from 0 to 127.
* @return mixed
*/
function allocate_color($image=null,$color='268597',$transparency='0')
{
if (preg_match('/[0-9ABCDEF]{6}/i', $color)==0) {
throw new Exception("Invalid color code.");
}
if ($transparency<0 || $transparency>127) {
throw new Exception("Invalid transparency.");
}
$r = hexdec(substr($color, 0, 2));
$g = hexdec(substr($color, 2, 2));
$b = hexdec(substr($color, 4, 2));
if ($transparency>127) $transparency = 127;
if ($transparency<=0)
return imagecolorallocate($image, $r, $g, $b);
else
return imagecolorallocatealpha($image, $r, $g, $b, $transparency);
}
/**
* antialias_pixel
*
* Helper function to apply a certain weight of a certain color to a pixel in an image. The index of the resulting color is returned.
*
* @version 0.1
* @author Contributors at eXorithm
* @link /algorithm/view/antialias_pixel Listing at eXorithm
* @link /algorithm/history/antialias_pixel History at eXorithm
* @license /home/show/license
*
* @param resource $image (GD image) The image containing the pixel.
* @param number $x X-axis position of the pixel.
* @param number $y Y-axis position of the pixel.
* @param number $color The index of the color to be applied to the pixel.
* @param number $weight Should be between 0 and 1, higher being more of the original pixel color, and 0.5 being an even mixture.
* @return mixed
*/
function antialias_pixel($image=null,$x=0,$y=0,$color=0,$weight=0.5)
{
$c = imagecolorsforindex($image, $color);
$r1 = $c['red'];
$g1 = $c['green'];
$b1 = $c['blue'];
$t1 = $c['alpha'];
$color2 = imagecolorat($image, $x, $y);
$c = imagecolorsforindex($image, $color2);
$r2 = $c['red'];
$g2 = $c['green'];
$b2 = $c['blue'];
$t2 = $c['alpha'];
$cweight = $weight+($t1/127)*(1-$weight)-($t2/127)*(1-$weight);
$r = round($r2*$cweight + $r1*(1-$cweight));
$g = round($g2*$cweight + $g1*(1-$cweight));
$b = round($b2*$cweight + $b1*(1-$cweight));
$t = round($t2*$weight + $t1*(1-$weight));
return imagecolorallocatealpha($image, $r, $g, $b, $t);
}
?>