从ImageMagick for PHP中的二进制字符串解码图像对象

Question

I have a script that downloads favicons and turns them in to PNGs.

To handle the conversion, I am using ImageMagick. My current approach involves downloading the data, writing it to a file, converting the file, then deleting the originally downloaded file. Here's what I mean:

$source = 'http://google.com/favicon.ico';
$image = file_get_contents($source);

// I'd like to skip these lines
$favicon = fopen('favicon.ico', 'w');
fwrite($favicon, $image);
fclose($favicon);

$im = new Imagick();
$im->readimage('favicon.ico');
$im = $im->flattenImages();
$im->setImageFormat('png');
$im->writeImage('favicon.png');
unlink('favicon.ico');

This works, but ideally I could do it without writing the $image variable to the file favicon.ico and instead I might just convert the data within the $image variable and then $im->writeImage('favicon.png') on that.

I checked out the method getImageBlob but when I tried that I got this error:

PHP Fatal error:  Uncaught exception 'ImagickException' with message 'no decode delegate for this image format `' @ error/blob.c/BlobToImage/364' in /home/vagrant/test/test_image.php:73
Stack trace:
#0 /home/vagrant/test/test_image.php(73): Imagick->readimageblob('\x00\x00\x01\x00\x02\x00\x10\x10\x00\x00\x01\x00 \x00h...')
#1 {main}
  thrown in /home/vagrant/test/test_image.php on line 73

Any ideas?

Answer 1

You'll need to invoke Imagick::setFormat before reading blob.

<?php
$source = 'http://google.com/favicon.ico';
$image = file_get_contents($source);

$im = new Imagick();
$im->setFormat('ICO');
$im->readImageBlob($image);
$im = $im->flattenImages();
$im->setImageFormat('PNG');
$im->writeImage('favicon.png');

Update

Flattening the .ico image may have negative effects on files containing more than one image. Simplest solution would be to iterate over all the images, and determine which sub-image to use.

$im = new Imagick();
$im->setFormat('ICO');
$im->readImageBlob($image);
for( $idx = 0, $len = $im->getNumberImages(); $idx < $len; $idx++ ) {
    // If this is the sub-image you want, do the following, else skip
    $im->setImageFormat('png');
    $im->setImageIndex($idx);
    $im->writeImage(sprintf('favicon_%d.png', $idx));
}