PHP Imagick setImageCompression

Question

I'm just starting to write some PHP using the Imagick / ImageMagick library, and have seen several examples regarding setImageCompression which appear to implement things differently.

For example I've seen it used like this:

$image->setImageCompression(Imagick::COMPRESSION_LZW);

and also like this:

$image->setImageCompression(\Imagick::COMPRESSION_UNDEFINED);

So, what is the relevance of the backslash before declaring the compression type? Is this specific to the compression type? A typo in examples I've seen or something else?

May be it is something about namespaces. – HddnTHA Mar 07 '15 at 12:24 — HddnTHA, Mar 07 '15 at 12:24

score 3 · Accepted Answer · answered Mar 07 '15 at 12:27

3

The backslash is only necessary when using namespaces.

For instance, the former won't work in namespace Foo because it will look for a class Foo\Imagick:

namespace {
    var_dump(Imagick::COMPRESSION_LZW); // int(11)
}

namespace Foo {
    var_dump(Imagick::COMPRESSION_LZW); // Class 'Foo\Imagick' not found
}

The second will work in all cases:

namespace {
    var_dump(\Imagick::COMPRESSION_LZW); // int(11)
}

namespace Foo {
    var_dump(\Imagick::COMPRESSION_LZW); // int(11)
}

answered Mar 07 '15 at 12:27

cmbuckley

40,217
9
77
91

Ok, so if I understand correctly, the 2nd -with the backslash is better practice since it will work with or without namespaces? – Phill Healey Mar 07 '15 at 12:30
Arguably yes, but also maybe overkill if you have no intention of using namespaces for your code. – cmbuckley Mar 07 '15 at 12:31
Thanks for the clarity, but is a single backslash really overkill? Or am I missing something? – Phill Healey Mar 07 '15 at 12:33
Only in the strictest sense, in that it's not necessary to do so; it's up to you :-) – cmbuckley Mar 07 '15 at 12:37

PHP Imagick setImageCompression

1 Answers1