gazchap

By default, WooCommerce will only show thumbnails for categories if the category has a thumbnail set.
This plugin changes this behaviour so that WooCommerce will hunt for a product thumbnail in the category being displayed, and use that instead.
Upon activation, the plugin will configure itself with the basic settings. Any categories that you have on your WooCommerce store that do not have a thumbnail set will then start displaying any available product thumbnails inside the category.
There are a number of options, these can be found in WooCommerce -> Settings -> Products -> Auto Category Thumbnails.
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Thumbnail Size sets the image size that the plugin should use when displaying the thumbnails. Defaults to shop_thumbail, but shop_catalog may be a better option for some themes.
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Go into Child Categories makes the plugin look in child categories too, useful if you have products buried in quite a deep category structure.
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Random Thumbnail tells the plugin to pick a random product thumbnail from those it finds every time the page loads – otherwise it always uses the first one it finds.
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Use Transients tells the plugin to save the thumbnail it picks for a category as a transient in WordPress, so that it won’t have to do it again while the transient is still active. This can hugely increase performance on sites with many categories, so is enabled by default.
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Transient Expiry is the length of time each transient is active for before the site picks another thumbnail for the category. By default it is set to 1 day.
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Custom Transient Expiry can be used to define your own transient expiry period (in seconds) if none of the pre-defined options are suitable.
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Exclude Thumbnail IDs accepts a comma-separated list of attachment IDs from the WordPress Media Library. The plugin will never use any thumbnail with one of these IDs for a category.
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<h3>License</h3>
Licensed under the <a href="http://www.gnu.org/licenses/gpl-2.0.html" rel="nofollow ugc">GNU General Public License v2.0</a>

GazChap's WooCommerce Auto Category Product Thumbnails

Pick WooCommerce category thumbnails automatically from products contained within those categories.

maff

The plugin is actually just a port of a plugin/snippet I wrote for <a href="http://www.modxcms.com" rel="nofollow ugc">MODx</a> a while ago (<a href="http://modxcms.com/phpThumb-Package-1522.html" rel="nofollow ugc">see here</a>). It scans your content’s source code for <img> tags with width and height attributes and passes them to <a href="http://phpthumb.sourceforge.net/" rel="nofollow ugc">phpThumb</a>, a great PHP image editing library, which handles the resizing and editing of the image. Additionally, by passing parameters to phpThumb using a query string, it’s possible to edit the image in several ways (take a look at <a href="http://phpthumb.sourceforge.net/demo/demo/phpThumb.demo.demo.php" rel="nofollow ugc">phpThumb’s demos</a>).
The simplest way to get resized images is to specify width/height attibutes in your HTML. AutoThumb will use the given values and remove the attributes from your page’s output. When you take a look at the URLs of the example images found on the plugin home page, you will see that the <img>-tag’s src-attribute points to a file called image.php in the plugin’s directory. This file takes the image source and several other parameters and passes them to phpThumb, which will generate and output the final image (of course images will be cached).
To prevent evil people playing with the query string and letting your server generate tons of different images, the plugin generates a hash which is a combination of the query string and a secret password you set in phpThumb’s config file. So every call with different parameters (even the same image with different sizes) has another unique hash and it’s not possible to generate new images without knowing the secret password.
See the <a href="http://ailoo.net/projects/autothumb/" rel="nofollow ugc">plugin page</a> for more details on the plugin.
All development is done on <a href="https://github.com/maff/wp-autothumb" rel="nofollow ugc">GitHub</a>. If you have ideas, enhancements, etc. feel free to fork the project and send a pull request.
For any issues please use the <a href="https://github.com/maff/wp-autothumb/issues" rel="nofollow ugc">Issue Tracker</a>.

AutoThumb

The plugin is actually just a port of a plugin/snippet I wrote for MODx a while ago (see here). It scans your content's source code for <img&g …

GazChap's WooCommerce Auto Category Product Thumbnails vs AutoThumb