Dave Ligthart

A simple way to choose a default thumbnail for your post.
Works alongside the featured image core functionality.
For theme usage:
<h4>Add this function where you want the thumbnail to appear</h4>
<pre><code><?php if(function_exists('wct_thumb')){ wct_thumb(); } ?>
</code></pre>

WP-Choose-Thumb

A simple way to add a default thumbnail to your post.

sebastianbarria

This plugin is made for developers.
It creates a function named thumbGen() that allows to show any image in the specified size. Additionally you can specify values like crop, center, rotation and effects.
It saves all generated thumbs in a cache folder, so it won’t overload your server at all.
<h3>Usage</h3>
To use this function you just need to use this line code:
<pre><code><?php thumbGen(image,width,height,additional_parameters); ?>
</code></pre>
[image:] the URL of the original image you need to create a thumbnail from (needed).
[width:] the width you need for the generated thumbnail (default=0 – if not specified it gets the 
proportional value from the specified height).
[height:] the height you need for the generated thumbnail (default=0 – if not specified it gets the proportional value from the specified width).
note: if you don’t specify the with AND height (or if you set both to 0), the image will be generated in the source size.
<h4>Additional parameters</h4>
[filename:] some people have troubles with duplicated names, so I’ve added this parameter for you to specify a new filename (or ID or something like that) in order to differentiate each file (if not set it will use the source filename).
[md5:] by default, the images are generated with an md5 encode filename. If you don’t want the generated file to have an encoded name set this to 0
[force:] force thumb creation, even if it already exists (default=0) (NOT RECOMENDED! – use it just for testing or debugging)
[crop:] if you want the thumbnail to be cropped (no image deformation) if the width and height are different from the original image, set this value as 1 or true. If you want the content of the thumbnail to be resized to fit the space (image deformation) set this to 0 or false (default=1).
[halign:] horizontal align of the croped image. You can set it to left, center or right (default=center)
[valign:] vertical align of the croped image. You can set it to top, center or bottom (default=center)
[effect:] you can apply two effects: grayscale and sephia
[rotate:] you can specify a rotation angle
[background:] hex color (like #ffffff) to apply on the background ONLY when you rotate the image. If you don’t want a color applied you can set this to transparent (default=transparent)
[return:] if set to 1 (or true) the image name will be returned instead of printed (default=0).
[preserveAnimation:] if set to 1 (or true) it will show animated gif’s with motion but without applying other parameters. Otherwise, it will show the first frame of the animated gif resized.
[quality:] you can chooos from 0 to 9, where 0 is the worst quality (lower file size) and 9 is the best (bigger file size). The default value is 7.
<h3>Examples of usage</h3>
In this example I will not explain detailed how this WordPress code works, but I will show this as an example of this plugin usage:
<pre><code><?php
$img="";
$args = array(
'post_parent' => $post->ID,
'post_type' => 'attachment',
'numberposts' => 1,
'post_mime_type' => 'image'
);
$attachs = get_posts($args);
if ($attachs) {
$img=wp_get_attachment_image_src($attachs[0]->ID,'full');
}
if(!empty($img)){
?>
<img src='<?php thumbGen($img[0],171,56,"effect=grayscale&halign=left&valign=top"); ?>' alt='' />
<?php
}
?>
</code></pre>
This example reads the first attached image of a post and save it’s information in a variable called $img. In the thumbGen function the first parameter is $img[0] and that’s the image URL. The second and third parameters are the width and height of the generated thumbnail we need. The rest of the parameters are defined in the string in the format parameter=value, concatenated with an &. the values not specified will use their default value.

thumbGen

This plugin creates a function named thumbGen() that allows to show any image in the specified size (plus many other things).

WP-Choose-Thumb vs thumbGen