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copied!<p>Array access in PHP can certainly be slow. PHP uses hash tables to implement arrays, i.e. in order to access an element in an array it has to calculate a hash and traverse a linked list. Using a compiled language with real arrays will definitely improve performance, because there a direct memory access is made. For the interested: Code for <a href="http://lxr.php.net/xref/PHP_5_3/Zend/zend_hash.c#zend_hash_find">hash access with string</a> and <a href="http://lxr.php.net/xref/PHP_5_3/Zend/zend_hash.c#zend_hash_index_find">with integer</a>.</p> <p>Concerning your code, there are several points I would optimize:</p> <ul> <li><code>return</code> directly, don't <code>break</code> twice.</li> <li>put <code>$file->get_width()</code> and <code>$file->get_height</code> into simple variables. I assume that the height or width doesn't change throughout the process. Remember: Functions in PHP are slow.</li> <li><del>Use a one-dimensional array, instead of nested arrays. You save one hash lookup per iteration that way.</del> Actually a one-dimensional array is only marginally faster or even slightly slower. <a href="https://gist.github.com/813289">Comparison of several ways of saving the data concerning performance and memory usage</a>.</li> </ul> <p>.</p> <pre><code>function fits($bin, $x, $y, $w, $h) { $w += $x; $h += $y; for ($i = $x; $i < $w; ++$i) { for ($j = $y; $j < $h; ++$j) { if ($bin[$i][$j] !== 0) { return false; } } } return true; } </code></pre> <p>Though I'm not sure, why you add <code>$x</code> to the <code>$width</code> / <code>$y</code> to the <code>$height</code>. Don't you want to iterate from the current coordinates to the image boundaries?</p>

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