Not all of my featured images were larger than 620, so the default code to scale-down images didn't work like I wanted. I've updated the code to scale up the featured image to 620, then crop to fit the slice.

If people are interested I can post the modified code here.

Originally Posted by troyp

Not all of my featured images were larger than 620, so the default code to scale-down images didn't work like I wanted. I've updated the code to scale up the featured image to 620, then crop to fit the slice.

If people are interested I can post the modified code here.

Enhancements like this are mostly always worth having, troy. Please post the code. Thanks.

Yeah ... that was just what I was looking for! Please post the code! Thanks in advance.

Here is an updated includes/thumb.php file.

I added a function called bfa_image_crop_dimensions that does the resize up. Then had to modify the bfa_vt_resize function.

The code has my initials in comments around my modifications. I hope this helps others.

PHP Code:

<?php 
/*
 * Resize images dynamically using wp built in functions
 * Victor Teixeira
 *
 * php 5.2+
 *
 * Exemplo de uso:
 * 
 * <?php 
 * $thumb = get_post_thumbnail_id(); 
 * $image = vt_resize( $thumb, '', 140, 110, true );
 * ?>
 * <img src="<?php echo $image[url]; ?>" width="<?php echo $image[width]; ?>" height="<?php echo $image[height]; ?>" />
 *
 * @param int $attach_id
 * @param string $img_url
 * @param int $width
 * @param int $height
 * @param bool $crop
 * @return array
 */

function bfa_delete_thumb_transient( $post_id ) {
    delete_site_transient( 'bfa_thumb_' . $post_id );
}
add_action( 'edit_post', 'bfa_delete_thumb_transient' );

 /* TODO: Add parameter $link = 'fullsize' to link to full size image */
function bfa_thumb( $width, $height, $crop = false, $before = '', $after = '', $link = 'permalink' ) {

    global $post, $upload_dir;
    
    if( ! is_writable( $upload_dir['basedir'] ) ) {
      error_log("bfa_thumb non-writable basedir=".$upload_dir['basedir']);
        return;
    }
    
    $id = $post->ID;
    /* if the other fails : */
    /*
    global $wp_query;
    $id = $wp_query->post->ID;
    */
    
    #$bfa_thumb = get_site_transient( 'bfa_thumb_' . $id );
    
    #if ( false === $bfa_thumb ) {
        // It wasn't there, so regenerate the data and save the transient

        $bfa_thumb = '';
    
        $hasthumb = FALSE;
        $hassrc = FALSE;
        $has_thumbnail = FALSE;
        
        if( has_post_thumbnail() ) {
            $thumb = get_post_thumbnail_id(); 
            $hasthumb = TRUE;
        } elseif ( bfa_has_attachment() ) {
            $thumb = bfa_get_first_attachment_id(); 
            $hasthumb = TRUE;
        } elseif( bfa_has_img_src() ) {
            $thumb = bfa_get_first_img_src();
            $hassrc = TRUE;
        
        }
        
        if( $hasthumb == TRUE ) {
            $thumbimage = bfa_vt_resize( $thumb,'' , $width, $height, $crop );
            $has_thumbnail = TRUE;
        } elseif( $hassrc == TRUE ) {
            $thumbimage = bfa_vt_resize( '', $thumb , $width, $height, $crop );
            $has_thumbnail = TRUE;
        }    
        
        if( $has_thumbnail == TRUE ) { 
            $bfa_thumb .= $before;
            if( $link == 'permalink' ) 
                $bfa_thumb .= '<a href="' . get_permalink( $id ) . '">';
        
            $bfa_thumb .= '<img src="' . $thumbimage['url'] . '" width="' . $thumbimage['width'] . '" height="' . $thumbimage['height'] . '" />
            <span></span>';
        
            if( $link == 'permalink' ) 
                $bfa_thumb .= '</a>';
            $bfa_thumb .= $after;
        } 
    
        #set_site_transient( 'bfa_thumb_' . $id, $bfa_thumb, 60*60*1 );
    #} 
    
    echo $bfa_thumb;
}    

    
function bfa_has_attachment() {

    global $post;    
        
    $args = array( 'post_type' => 'attachment', 'numberposts' => -1, 'post_status' => null, 'post_parent' => $post->ID ); 
    $attachments = get_posts($args);
    if ($attachments) 
        return TRUE;
        
    return FALSE;
}

function bfa_get_first_attachment_id() {

    global $post;    
        
    $args = array( 'post_type' => 'attachment', 'numberposts' => -1, 'post_status' => null, 'post_parent' => $post->ID ); 
    $attachments = get_posts($args);
    return $attachments[0]->ID;
}


function bfa_has_img_src( $args = array() ) {

    global $post;

    $site_url = site_url();
    preg_match_all( '|<img.*?src=[\'"](.*?)[\'"].*?>|i', $post->post_content, $matches );

    foreach( $matches[1] as $match ) {
        if ( isset( $match ) && strpos( $match, $site_url ) !== FALSE )
        return TRUE;
    }
    return FALSE;
}

function bfa_get_first_img_src( $args = array() ) {

    global $post;
    $site_url = site_url();
    preg_match_all( '|<img.*?src=[\'"](.*?)[\'"].*?>|i', $post->post_content, $matches );

    foreach( $matches[1] as $match ) {
        if ( isset( $match ) && strpos( $match, $site_url ) !== FALSE )
            return $match;
    }
    
    return false;
        
}

//TRP -- insert this block to enable scaling images up to fit
function bfa_image_crop_dimensions($default, $orig_w, $orig_h, $new_w, $new_h, $crop){
    if ( !$crop ) return null; // let the wordpress default function handle this

    $aspect_ratio = $orig_w / $orig_h;
    $size_ratio = max($new_w / $orig_w, $new_h / $orig_h);

    $crop_w = round($new_w / $size_ratio);
    $crop_h = round($new_h / $size_ratio);

    $s_x = floor( ($orig_w - $crop_w) / 2 );
    $s_y = floor( ($orig_h - $crop_h) / 2 );

    return array( 0, 0, (int) $s_x, (int) $s_y, (int) $new_w, (int) $new_h, (int) $crop_w, (int) $crop_h );
}
add_filter('image_resize_dimensions', 'bfa_image_crop_dimensions', 10, 6);
// TRP end

function bfa_vt_resize( $attach_id = null, $img_url = null, $width, $height, $crop = false ) {

  $width=intval($width); $height=intval($height);//TRP - use only the integer value

    // this is an attachment, so we have the ID
    if ( $attach_id ) {
    
        $image_src = wp_get_attachment_image_src( $attach_id, 'full' );
        $file_path = get_attached_file( $attach_id );
    
    // this is not an attachment, let's use the image url
    } else if ( $img_url ) {
        
        $file_path = parse_url( $img_url );
        // $file_path = $_SERVER['DOCUMENT_ROOT'] . $file_path['path'];
        $file_path = str_replace( '//', '/', $_SERVER['DOCUMENT_ROOT'] . $file_path['path']);
        
        //$file_path = ltrim( $file_path['path'], '/' );
        //$file_path = rtrim( ABSPATH, '/' ).$file_path['path'];
        
        $orig_size = getimagesize( $file_path );
        
        $image_src[0] = $img_url;
        $image_src[1] = $orig_size[0];
        $image_src[2] = $orig_size[1];
    }
    
    $file_info = pathinfo( $file_path );
    $extension = '.'. $file_info['extension'];

    // the image path without the extension
    $no_ext_path = $file_info['dirname'].'/'.$file_info['filename'];

    $cropped_img_path = $no_ext_path.'-'.$width.'x'.$height.$extension;
  
    // checking if the file size is larger than the target size
    // if it is smaller or the same size, stop right here and return
    //TRP orig --- if ( $image_src[1] > $width || $image_src[2] > $height ) {

        // the file is larger, check if the resized version already exists (for $crop = true but will also work for $crop = false if the sizes match)
        if ( file_exists( $cropped_img_path ) ) {

            $cropped_img_url = str_replace( basename( $image_src[0] ), basename( $cropped_img_path ), $image_src[0] );
            
            $vt_image = array (
                'url' => $cropped_img_url,
                'width' => $width,
                'height' => $height
            );
            
            return $vt_image;
        }

        // $crop = false
        //TRP orig if ( $crop == false ) {
        if ($image_src[1] > $width) {  //TRP only scale down if it is wider
        
            // calculate the size proportionaly
            $proportional_size = wp_constrain_dimensions( $image_src[1], $image_src[2], $width, $height );
            $resized_img_path = $no_ext_path.'-'.$proportional_size[0].'x'.$proportional_size[1].$extension;            

            // checking if the file already exists
            if ( file_exists( $resized_img_path ) ) {
            
                $resized_img_url = str_replace( basename( $image_src[0] ), basename( $resized_img_path ), $image_src[0] );

                $vt_image = array (
                    'url' => $resized_img_url,
                    'width' => $proportional_size[0],
                    'height' => $proportional_size[1]
                );
                
                return $vt_image;
            }
        }

        // no cache files - let's finally resize it
        $new_img_path = image_resize( $file_path, $width, $height, $crop );
        $new_img_size = getimagesize( $new_img_path );
        $new_img = str_replace( basename( $image_src[0] ), basename( $new_img_path ), $image_src[0] );

        // resized output
        $vt_image = array (
            'url' => $new_img,
            'width' => $new_img_size[0],
            'height' => $new_img_size[1]
        );
        
        return $vt_image;
/*TRP this section not needed
    }

    // default output - without resizing
    $vt_image = array (
        'url' => $image_src[0],
        'width' => $image_src[1],
        'height' => $image_src[2]
    );
    
    return $vt_image;
    TRP */
}

troyp:
Thanks and kudos!

Originally Posted by troyp

Here is an updated includes/thumb.php file.

This is great, troy. I have been able to shrink pics to fit smaller spaces, but didn't have a way to make smaller pics fill bigger spaces. Nice enhancement. Thanks.

I added a function called bfa_image_crop_dimensions that does the resize up. Then had to modify the bfa_vt_resize function.

As far as naming conventions, consider this. Bytesforall prefaces all its custom functions with bfa_. To differentiate, and not to have them conflict with anything bfa or wp might have now or come out with at some time in the future, consider prefacing all your custom global variables and function names with custom_ or something like that. It also makes them easier to find on a search.

Keep up the great work, and thanks for sharing.

Best,

Jerry