I need a script which makes rounded transparent corners on supplied image. I've found one and it works good except the one thing: the applied corners do not look smooth. The imageantialias() throws Fatal Error since PHP is running on Debian and re-compiling it is not an option.
The trick I've found to make those corners look smooth is resizing the image with imagecopyresampled() as the following:
- prepare the image;
- imagecopyresample it to 10x size;
- draw corners with a special colour;
- make that color transparent;
- decrease the image to it's original size
But here comes the problem: the corners of the result image (after step 5) are smooth, but not transparent. When sending to output the image after step 4 (i.e. before decreasing it's size) – everything's as it should be.
Here's the part of the code responsible for making corners rounded:
// $dest = image resource
$q=10;
// making everything 10x bigger
$new_width=$width*$q;
$new_height=$height*$q;
$radius=$radius*$q;
$magnified=imagecreatetruecolor($new_width, $new_height);
imagecopyresampled($magnified, $dest, 0,0, 0,0, $new_width,$new_height, ($new_width/$q),($new_height/$q));
// picking the unique colour
$found = false;
while($found == false) {
$r = rand(0, 255);
$g = rand(0, 255);
$b = rand(0, 255);
if(imagecolorexact($magnified, $r, $g, $b) != (-1)) {
$found = true;
}
}
$colorcode = imagecolorallocate($magnified, $r, $g, $b);
// drawing corners
imagearc($magnified, $radius-1, $radius-1, $radius*2, $radius*2, 180, 270, $colorcode);
imagefilltoborder($magnified, 0, 0, $colorcode, $colorcode);
imagearc($magnified, $new_width-$radius, $radius-1, $radius*2, $radius*2, 270, 0, $colorcode);
imagefilltoborder($magnified, $new_width-1, 0, $colorcode, $colorcode);
imagearc($magnified, $radius-1, $new_height-$radius, $radius*2, $radius*2, 90, 180, $colorcode);
imagefilltoborder($magnified, 0, $new_height-1, $colorcode, $colorcode);
imagearc($magnified, $new_width-$radius, $new_height-$radius, $radius*2, $radius*2, 0, 90, $colorcode);
imagefilltoborder($magnified, $new_width-1, $new_height-1, $colorcode, $colorcode);
// making the unique colour transparent
imagecolortransparent($magnified, $colorcode);
// scaling down the enlarged image to it's original size
// expecting corners to remain transparent
imagecopyresampled($dest, $magnified, 0,0, 0,0, ($new_width/$q),($new_height/$q), $new_width,$new_height);
// but they're not
// sending $magnified to output for testing purposes
$dest=$magnified;
// outputting $dest as image/png
So as you can see, the problem occurs when enlarged image is being imagecopyresampled to it's original size. The transparent corners get filled with the $colorcode colour. I've been playing with imagesavealpha() and imagealphablending() as advised, but no result.
Please help me to make this work.
P.S. This may be useful: when uploaded the large PNG to imgur.com it had it converted to JPG and as you can see all corners got filled with that very restored $colorcode.
P.S. Hope I won't get banned for overusing the word "enlargement" :)
