Different size user pictures (avatars) in different pages

A while back, we need to do display different sized user pictures (avatars) in Drupal 5.x on a client site. They wanted the user picture on the user profile page to be 100x100 pixels, but be displayed only as 25x25 on blog comments.

This is fairly easily achieved by creating this function in template.php. This function creates 25x25 size images from the original 100x100, and takes an argument of size so either can be used in different places.

function phptemplate_user_picture($account, $size = '25x25') {
if (!variable_get('user_pictures', 0))  {
// Nothing to do, user pictures are not enabled
return NULL;
}
if ($account->picture && file_exists($account->picture)) {
if ($size == '100x100') {
$maxsize_icon = array('w'=>100, 'h'=>100);
$info = image_get_info($account->picture);
if ($info['height'] < $maxsize_icon['h']) {
$maxsize_icon['h'] = $info['height'];
}
if ($info['width'] < $maxsize_icon['w']) {
$maxsize_icon['w'] = $info['width'];
}
$newpicture = dirname($account->picture) . '/picture-' . $account->uid . '.' . $info['extension'];
if (!file_exists($newpicture) || (filectime($newpicture) < filectime($account->picture))) {
image_scale($account->picture, $newpicture, $maxsize_icon['w'], $maxsize_icon['h']);
}
$picture = file_create_url($newpicture);
}
else if ($size == '25x25')  {
$maxsize_tile = array('w'=>25, 'h'=>25);
$info = image_get_info($account->picture);
$newpicture = dirname($account->picture) . '/picture-small-' . $account->uid . '.' . $info['extension'];
if (!file_exists($newpicture) || (filectime($newpicture) < filectime($account->picture))) {
image_scale($account->picture, $newpicture, $newpicture, $maxsize_tile['w'], $maxsize_tile['h']);
}
$picture = file_create_url($newpicture);
}
else {
$picture = file_create_url($account->picture);
}
}
else if (variable_get('user_picture_default', '')) {
$picture = variable_get('user_picture_default', '');
}
if (isset($picture)) {
$alt = t('@user\'s picture', array('@user' => $account->name ? $account->name : variable_get('anonymous', 'Anonymous')));
$picture = theme('image', $picture, $alt, $alt, '', false);
if (!empty($account->uid) && user_access('access user profiles')) {
$picture = l($picture, "user/$account->uid", array('title' => t('View user profile.')), NULL, NULL, FALSE, TRUE);
}
return "<div class=\"avatar\">$picture</div>";
}
} 

Once you have that in the theme, you can select the small size like this:

<?php if ($picture) { print theme('user_picture', $node, '25x25'); }?> 

Or the normal size like this:

<div class="picture"><?php print theme('user_picture', $user, '100x100'); ?></div>

Now, all you need to do is select the size you want in the various places you need to display the user picture.