Qt + OpenGL Code Example
I wanted to develop a game using OpenGL but I was having trouble deciding on a windowing library. Somebody suggested I try Qt, so I decided to give it another shot. I heard it was good, but the editor it came with was so foreign and unintuitive. Unfortunately, this overshadowed what a beautiful library Qt really is! It takes a little getting used to, but it really is well designed.
array_map_recursive
Not much needs to be said here.
$ret = array();
foreach($arr as $key => $val) {
if(is_array($val)) $ret[$key] = array_map_recursive($callback, $val);
else $ret[$key] = $callback($val);
}
return $ret;
}
I wrote this so that I could do this...
foreach($filters as $filter) $view_vars = array_map_recursive($filter, $view_vars);
Which just sanitizes my variables before I print them.
All I want is a drag-and-drop CD burner
I know I've mostly been posting code snippets here, but I originally started this site to post more in-depth tutorials. This isn't going to be one of those. I'm taking a spin and would like to say a few words on the design of good software -- the second half of this site that's been neglected.
My brother's girlfriend asked me to burn some files for her using her laptop the other day, so I tried. I didn't think it would be so difficult.
So I popped in the blank disc, and iTunes came up, exclaiming that it could burn stuff for me. Fine, I'll try that. It told me I had to create a new playlist (Why? I'm just going to delete it in 5 seconds). So I did. And then I tried to drag and drop my videos onto the playlist. Nothing. Okay. Let's dig through the menus: "Add to playlist"? No. "Import files"? No. It looks to me like I have to add the files to my library, then search for those files that I just added, figure out how to add them to my newly created playlist, burn them, and then delete the playlist I didn't want in the first place. Brilliant. Except I couldn't figure that out, and I still haven't the faintest idea how to use iTunes. Call me idiot, iTune-lovers, but software really shouldn't take more than about 3 minutes to figure out how to do what you want with it.
Next I tried ImgBurn, something a friend recommended to me, which was indeed great for burning images, as the name suggests, but pretty horrid at burning a list of files. Fail.
I eventually just went into "My Computer" and dragged some files on it. Windows told me I had to format the CD (it was rewriteable) first. Fine. That took an extraordinarily long time, and then finally when it started burning it told me it would be finished in 0 seconds, but it literally took between thirty minutes and an hour. I know her drive isn't that slow, it's a new computer.
CDBurnerXP has worked great in the past for me, but apparently it's a failure on Windows 7. The "used space" bar was just plain wrong, and when I tried telling it that it was an idiot, it threw a fit and crashed.
Nero was good, back in the day, until they figured out they were getting popular and thought they could get away with adding whatever crapware they wanted. Now I just refuse to support their bullshit.
All I wanted to do was to drag-and-drop some files onto a program window, list them for me, and tell me how much space I've got left. Click burn, and that's it. Don't touch my files, don't convert them, don't move, copy, sort, cache or archive them. Don't install useless crap on my computer, and don't have me six thousand features I don't need.
Give me what I want. Make it big, bold, obvious, easy to find. And make it do what it's supposed to do when I click it. No more, no less. Is that so hard? Why can't people develop nice, clean, simple, intuitive UIs? We're not asking you to invent anything new, just take what's already been done, and works, and use that. There's frameworks for it. Use them!
jQuery Select Table Column or Row
Table rows are pretty easy to work as all the td elements are contained within one tr, but how would you grab all the tds in a single column? Why, by using these selectors of course!
return $('tr:nth-child('+(i+1)+') td', this);
}
$.fn.column = function(i) {
return $('tr td:nth-child('+(i+1)+')', this);
}
// example - this will make the first column of every table red
$(document).ready(function() {
$('table').column(0).css('background-color','red');
});
I like my selectors zero-based, but you can get rid of the +1 if you don't like it.
SQL Injection Safe Queries Redux
if(is_numeric($value)) return $value;
elseif(empty($value)) return 'NULL';
elseif(is_string($value)) return '\''.mysql_real_escape_string($value).'\'';
elseif(is_array($value)) return implode(',',array_map('mysql_safe_string',$value));
}
function mysql_safe_query($format) {
$args = array_slice(func_get_args(),1);
$args = array_map('mysql_safe_string',$args);
$query = vsprintf($format,$args);
$result = mysql_query($query);
if($result === false) echo '<div class="mysql-error"><strong>Error: </strong>',mysql_error(),'<br/><strong>Query: </strong>',$query,'</div>';
return $result;
}
// example
$result = mysql_safe_query('SELECT * FROM users WHERE username=%s', $username);
Just use mysql_safe_query in place of mysql_query and you should be safe from SQL injection attacks. Use %s in place of any variables, and append them as arguments. Don't quote your strings, it'll be done for you automatically. Arrays will be flattened for you automatically and concatenated with commas. You can delete the error-echoing line if you want, but I find it useful for development.
Facebook PHP API: Get the names of all your friends
If you didn't already know, Facebook has an API that exposes quite a darn bit information. You can easily query this data using their API, but each request takes a fair bit of time. Typically, to get the names of all your friends, first you have to grab a list of the user ids of all your friends, and then query each and every single one to get their names. For me, that's about 300 cross-server requests, which will almost certainly cause my server to time out, and probably force Facebook to reject me. Fortunately, Facebook has also created their own MySQL-like language, FQL (I pronounce it feequel), which lets you do some of these "complicated" queries in a single call. Here's a simple example I wrote:
require_once 'facebook-platform/php/facebook.php';
$appapikey = 'yourapikeyhere';
$appsecret = 'yoursecretkey';
$facebook = new Facebook($appapikey, $appsecret);
$user_id = $facebook->require_login();
$result = fql_query('SELECT name FROM user WHERE uid IN (SELECT uid2 FROM friend WHERE uid1=%s)', $user_id);
pr($result);
function fql_query($query) {
global $facebook;
$args = array_slice(func_get_args(), 1);
return $facebook->api_client->fql_query(vsprintf($query, $args));
}
function pr($arr) {
echo '<pre>';
print_r($arr);
echo '</pre>';
}
You'll notice I've included two of my favorite wrapper functions. You can unroll them if you want. Anyway, just thought I'd share 
I prefer writing FQL than trying to remember all their API calls anyway.
Oh... and just FYI, this prints out something like this:
Array
(
[0] => Array
(
[name] => Mark Zuckerberg
)
[1] => Array
(
[name] => Tom Riddle
)
I hate it when people leave it a mystery what exactly their example is doing!
Get Domain & Subdomain from URL
define('PROTOCOL', strtolower(substr($_SERVER['SERVER_PROTOCOL'],0,strpos($_SERVER['SERVER_PROTOCOL'],'/'))).'://');
define('SUBDOMAIN', $matches[1]);
define('DOMAIN', $matches[2]);
define('HERE', $_SERVER['REQUEST_URI']);
If you're at http://www.sub.domain.com/page, then:
PROTOCOL = http://
SUBDOMAIN = sub
DOMAIN = domain.com
HERE = /page
Insert into MySQL datetime column from PHP
You can use this simple function to convert a unix timestamp (like the one obtained from time()) to MySQL datetime format:
if(!isset($timestamp)) $timestamp = time();
return date('Y-m-d H:i:s', $timestamp);
}
I'm using this instead of MySQL's NOW() function because my MySQL server isn't localized to my timezone, but my PHP is by usage of date_default_timezone_set.
Edit: And you can use this function to convert back the other way (you can do this directly in the SQL too, but just in case)
list($date, $time) = explode(' ', $datetime);
list($year, $month, $day) = explode('-', $date);
list($hour, $minute, $second) = explode(':', $time);
return mktime($hour, $minute, $second, $month, $day, $year);
}
Human-readable file size in JavaScript
"size" is in bytes, the rest you should be able to figure out.
var units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
var i = 0;
while(size >= 1024) {
size /= 1024;
++i;
}
return size.toFixed(1) + ' ' + units[i];
}
PHP code for handling recursive categories/hierarchical data
I'm just going to paste the code I wrote here... you can read some other tutorial to understand what it's doing, but for some reason they have really incomplete examples, so here's the whole shabang. It will even keep your nodes in alphabetical order. It has a function for displaying a drop down list too; wrap it in <select> tags.
class Category {
function getParent($id) {
return mysql_safe_query('SELECT parent.* FROM categories AS child, categories AS parent WHERE parent.id = child.parent_id AND child.id = %s LIMIT 1', $id);
}
function getChildren($id, $direct = false) {
if($direct) {
return mysql_safe_query('SELECT * FROM categories WHERE parent_id = %s ORDER BY left_val ASC', $id);
} else {
return mysql_safe_query('SELECT child.* FROM categories AS child, categories AS parent WHERE child.left_val >= parent.left_val AND child.right_val <= parent.right_val AND parent.id = %s ORDER BY child.left_val ASC', $id);
}
}
function insert($name, $parent_id) {
$result = mysql_safe_query('SELECT * FROM categories WHERE parent_id <=> %s AND name < %s ORDER BY name DESC LIMIT 1', $parent_id, $name);
if(mysql_num_rows($result) > 0) {
// insert between children
$row = mysql_fetch_assoc($result);
mysql_safe_query('UPDATE categories SET left_val = left_val + 2 WHERE left_val > %s', $row['right_val']);
mysql_safe_query('UPDATE categories SET right_val = right_val + 2 WHERE right_val > %s', $row['right_val']);
mysql_safe_query('INSERT INTO categories (parent_id, left_val, right_val, name) VALUES (%s, %s, %s, %s)',
$parent_id, $row['right_val'] + 1, $row['right_val'] + 2, $name);
} else {
$result = mysql_safe_query('SELECT * FROM categories WHERE id <=> %s LIMIT 1', $parent_id);
if(mysql_num_rows($result) > 0) {
// insert first child
$row = mysql_fetch_assoc($result);
mysql_safe_query('UPDATE categories SET left_val = left_val + 2 WHERE left_val > %s', $row['left_val']);
mysql_safe_query('UPDATE categories SET right_val = right_val + 2 WHERE right_val > %s', $row['left_val']);
mysql_safe_query('INSERT INTO categories (parent_id, left_val, right_val, name) VALUES (%s, %s, %s, %s)',
$parent_id, $row['left_val'] + 1, $row['left_val'] + 2, $name);
} else {
// insert at beginning of tree
mysql_safe_query('UPDATE categories SET left_val = left_val + 2, right_val = right_val + 2');
mysql_safe_query('INSERT INTO categories (parent_id, left_val, right_val, name) VALUES (%s, %s, %s, %s)',
null, 1, 2, $name);
}
}
}
function delete($id) {
$result = mysql_safe_query('SELECT * FROM categories WHERE id = %s LIMIT 1', $id);
$row = mysql_fetch_assoc($result);
mysql_safe_query('DELETE FROM categories WHERE id = %s LIMIT 1', $id);
mysql_safe_query('UPDATE categories SET parent_id = %s WHERE categories.parent_id = %s', $row['parent_id'], $id); // relink parent
mysql_safe_query('UPDATE categories SET left_val = left_val - 1, right_val = right_val - 1 WHERE left_val > %s AND right_val < %s', $row['left_val'], $row['right_val']); // update children
mysql_safe_query('UPDATE categories SET left_val = left_val - 2 WHERE left_val > %s', $row['right_val']); // update left values of nodes to right
mysql_safe_query('UPDATE categories SET right_val = right_val - 2 WHERE right_val > %s', $row['right_val']); // update right values of encompassing nodes and nodes to right
}
function incPostCount($id, $amount=1) {
$result = mysql_safe_query('SELECT * FROM categories WHERE id = %s', $id);
$row = mysql_fetch_assoc($result);
return mysql_safe_query('UPDATE categories SET num_posts = num_posts + %s WHERE left_val <= %s AND right_val >= %s',
$amount, $row['left_val'], $row['right_val']);
}
function decPostCount($id, $amount=1) {
return self::incPostCount($id, -$amount);
}
function getPath($id) {
$result = mysql_safe_query('SELECT * FROM categories WHERE id = %s', $id);
$row = mysql_fetch_assoc($result);
return mysql_safe_query('SELECT * FROM categories WHERE left_val <= %s AND right_val >= %s ORDER BY left_val ASC',
$row['left_val'], $row['right_val']);
}
function printOptions($selected=null, $format=null, $mult=null, $add=null) {
if(!isset($format)) $format = '<option value="%s" style="padding-left:%spx"%s>%s</option>';
if(!isset($mult)) $mult = 15;
if(!isset($add)) $add = 3;
$depth = 0;
$result = mysql_safe_query('SELECT * FROM categories ORDER BY categories.left_val ASC');
while($row = mysql_fetch_assoc($result)) {
if(isset($last)) {
if($row['left_val'] == $last['left_val'] + 1) {
++$depth;
$next_right = $last_right + 1;
} elseif($row['left_val'] > $last['right_val'] + 1) {
$levels = $row['left_val'] - $last['right_val'] - 1;
$depth -= $levels;
}
}
$last = $row;
if($row['id'] == $selected) $selected_str = ' selected="selected"';
else $selected_str = '';
echo sprintf($format, $row['id'], $depth*$mult+$add, $selected_str, $row['name'], $row['num_posts'], $depth);
}
}
function printTree($format=null) {
if(!isset($format)) $format = '<li><a href="index.php?cat=%s">%s</a> (%s)';
$depth = 0;
$result = mysql_safe_query('SELECT * FROM categories ORDER BY categories.left_val ASC');
echo '<ul>';
while($row = mysql_fetch_assoc($result)) {
if(isset($last)) {
if($row['left_val'] == $last['left_val'] + 1) {
echo '<ul>';
++$depth;
$next_right = $last_right + 1;
} elseif($row['left_val'] > $last['right_val'] + 1) {
$levels = $row['left_val'] - $last['right_val'] - 1;
echo str_repeat('</li></ul></li>', $levels);
$depth -= $levels;
} else {
echo '</li>';
}
}
$last = $row;
echo sprintf($format, $row['id'], $row['name'], $row['num_posts'], $depth);
}
echo str_repeat('</li></ul>', $depth+1);
}
function printAdminTree() {
self::printTree('<li><a href="index.php?cat=%s">%s</a> (<a href="category_delete.php?id=%1$s">Delete</a>)');
}
}
Please leave a comment if you found this useful!