[wp-trac] [WordPress Trac] #18951: A function to add default images for themes

[WordPress Trac]

#18951: A function to add default images for themes
-----------------------------+-----------------------------
 Reporter:  F J Kaiser       |      Owner:
     Type:  feature request  |     Status:  new
 Priority:  normal           |  Milestone:  Awaiting Review
Component:  Themes           |    Version:  3.2.1
 Severity:  normal           |   Keywords:
-----------------------------+-----------------------------
 Adding default images to themes is not an easy task. They have to play
 nicely with different image sizes that are built-in and/or added via
 {{{add_image_size();}}}. If they don't, then they will simply break the
 layout or won't change with user changes. Sadly we can't simply use most
 of the core media/image functions as those functions check if the image is
 an attachment image and - if not - abort.

 So I want to introduce {{{wp_default_img();}}}. It works with an input
 array of attributes and offers two filters (wp_default_img_attr &
 wp_default_img). So setting up default images is as easy as using a filter
 (if the theme developer isn't satisfied with the functions default args)
 and finally just adding

 {{{
 // functions.php during init:
 add_image_size( 'default_img', 80, 80, true );

 // Inside some template
 $placeholder = get_site_url( null, 'your_path' ).'/some_img.jpg';
 echo wp_default_img( array( 'url' => $placeholder, 'size' => 'default_img'
 ) );
 }}}

 The function also cares about cropping images if 4th argument set to
 {{{true}}} when registering the size using {{{add_image_size();}}}.

 The actual function (documented as far as possible).

 {{{
 /**
  * Default image
  *
  * Builds an default <img> for use in themes or plugins before any other
 images are added.
  * Resizes & crops the image using the built-in (retireved via
 `get_intermediate_image_sizes();`)
  * or custom image (added via `add_image_size();`) sizes.
  *
  * Retrieves calculated resize dimension @uses image_resize_dimensions();
  * Builds the width and height string @uses image_hwstring();
  *
  * @param $args (array)
  *              string $url URl to the given default image.
  *              string $size Optional. Default is 'medium'.
  *              string (optional) $alt Image Description for the alt
 attribute.
  *              string (optional) $title Image Description for the title
 attribute.
  *              string (optional) $align Part of the class name for
 aligning the image.
  *              string (optional) $echo Wheter to return or echo the
 $image
  * @return string HTML IMG element for given image attachment
  */
 function wp_default_img( $attr = array( 'url', 'size' => 'medium',
 'classes' => false, 'alt' => false, 'title' => false, 'align' => 'none',
 'echo' => true ) )
 {
         // Sizes registered via add_image_size();
         global $_wp_additional_image_sizes;

         if ( 'thumb' === $attr['size'] )
                 $attr['size'] = 'thumbnail';

         // Size in built in sizes - call size setting from DB
         # behavoir in here dependent on @link
 http://core.trac.wordpress.org/ticket/18947
         if ( ! in_array( $attr['size'], array_keys(
 $_wp_additional_image_sizes ) ) )
         {
                 $sizes                          =
 get_intermediate_image_sizes();
                 // Get option - gladly autoloaded/can use wp_cache_get();
                 $size_data['width']     = intval( get_option(
 "{$attr['size']}_size_w") );
                 $size_data['height']= intval( get_option(
 "{$attr['size']}_size_h") );
                 // Not sure how this will behave if cropped is false
 (autoloaded option not added)
                 $size_data['crop']      = get_option(
 "{$attr['size']}_crop" ) ? get_option( "{$attr['size']}_crop" ) : false;
         }
         // Size array from global registered additional/custom sizes array
         else
         {
                 $size_data = $_wp_additional_image_sizes[ $attr['size'] ];
         }

         // Retrieve image width & height
         $img_info       = @getimagesize( $attr['url'] );

         // Calculate final dimensions - if "crop" was set to true during
 add_image_size(), the img will get ... cropped
         $end_sizes      = image_resize_dimensions( $img_info[0],
 $img_info[1], $size_data['width'], $size_data['height'],
 $size_data['crop'] );

         // defaults to px units - can't get changed, as applying units is
 not possible
         $hwstring       = ' '.trim( image_hwstring( $end_sizes[4],
 $end_sizes[5] ) );

         // Attributes:
         // Not made required as users tend to do funky things (...and lock
 screen readers out)
         $attr['alt'] = $attr['alt'] ? ' alt="'.esc_attr( $attr['alt']
 )."'" : '';

         if ( ! $attr['title'] )
                 $attr['title'] = sprintf( __('default image of type:
 %1$s'), explode( "/", $img_info['mime'] ) );
         $attr['title'] = $attr['title'] ? ' title="'.esc_attr(
 $attr['title'] )."'" : '';

         $attr['classes'] = "wp-img-default ".esc_attr( $attr['classes'] ?
 $attr['classes'] : '' );
         $attr['align'] = $attr['align'] ? "align".esc_attr( $attr['align']
 ) : '';
         $attr['size'] = "size-".esc_attr( $attr['size'] );

         // Allow filtering of the default attributes
         $attributes     = apply_filters( 'wp_default_img_attr', $attr );

         // Build class attribute, considering that maybe some attribute
 was unset via the filter
         $classes  = ' class="';
         $classes .= 'wp-img-default'.esc_attr( $attr['classes'] ? '
 '.$attr['classes'] : '' );
         $classes .= $attr['align'] ? ' '.esc_attr( $attr['align'] ) : '';
         $classes .= $attr['size'] ? ' '.esc_attr( $attr['size'] ).'" ' :
 '" ';

         $image          = "<img
 src='{$url}'{$hwstring}{$classes}{$alt}{$title} />";
         $image          = apply_filters( 'wp_default_img', $image );

         if ( ! $attr['echo'] )
                 return $image;

         return print $image;
 }
 }}}

 Related ticket that pops the whole image size data into
 [http://core.trac.wordpress.org/browser/branches/3.2/wp-
 includes/media.php#L580 get_intermediate_image_sizes();], can be found
 here #18947.

-- 
Ticket URL: <http://core.trac.wordpress.org/ticket/18951>
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