Custom post type with a forced fixed aspect ratio image crop

Question

What I am looking for is similar to a couple other questions. The links are:

Creating an Image-Centric Custom Post Type?

Using Default WordPress Custom Header Image Crop Feature in a Post Type / MetaBox

I am looking for a sort of combination of the two. I'll explain so you don't have to look up these other questions.

I would like a user to be able to upload a picture into a custom post type and be prompted to crop the image with a set aspect ratio before saving. I am trying to keep users from needing to crop images outside WordPress just to make them fit into a slideshow with a set image size.

The custom header functionality is pretty much what I'd like to use, but I am at a loss on how to pull that into either a plugin or a theme and have it execute in a custom post type. The fact that the user is asked to crop the image at a set ratio before proceeding is key.

I am fairly comfortable with custom post types if anyone can just give me a pointer on how to get WordPress to force a custom cropping of an image before saving the custom post.

Thanks in advance to whichever one of you coding geniuses knows/figures out how to do this.

Answer 1

Don,

You will have to add support for thumbnails in your functions.php/plugin-file.php

//Add Support for Thumbs
if ( function_exists( 'add_theme_support' ) ) {
  add_theme_support( 'post-thumbnails' );
        set_post_thumbnail_size( 960, 276, true ); // default Post Thumbnail dimensions   
}
//Add Thumbnail sizes   
if ( function_exists( 'add_image_size' ) ) { 
  add_image_size( 'large-thumb', 960, 276, true ); //960 pixels wide x 276 height and cropping
  add_image_size( 'medium-thumb', 605, 174 ); //No crop
  add_image_size( 'small-thumb', 288, 83, true ); 
}

From here you can modify this output in your loop to work for your needs:

<?php if ( has_post_thumbnail() ) {

          echo '<a href="' . get_permalink( $post->ID ) . '" title="' . esc_attr( $post->post_title ) . '">';
          echo get_the_post_thumbnail($thumbnail->ID, 'small-thumb', array( 'alt' => esc_attr( $post->post_title ), 'title' => esc_attr( $post->post_title ) ));
          echo '</a>';  //Change the 'small-thumb' to whichever size you would like.
          } 

Hope this helps you figure out what you're doing - if you need any help building a Query for this I you should look into this page.