id,summary,reporter,owner,description,type,status,priority,milestone,component,version,severity,resolution,keywords,cc
15311,dynamic image resize (on the fly) using already available functions,vteixeira,,"The lack of a dynamic resize function in WordPress forces theme developers to register lots of image sizes for their themes to use.

One of the problems with this approach is that the server becomes full of image files that will be never used.

Another problem is that when someone changes their theme the image sizes simply doesn't match, forcing people to use a plugin to regenerate all image files, and once again lots of those files will never be used.

So theme developers right now are using some sort of image resizing script like timthumb that works outside of wp. I think it has many drawbacks comparing to a native implementation.

So I made a function that uses WordPress native image handling capabilities to resize and save those resized images for future use.

I use this for attached images as well as standalone files such as custom fields and other images.

What I want here is just to share my solution, and maybe we can someday put something like this into core (actually something better then this):

{{{
/*
 * Resize images dynamically using wp built in functions
 * Victor Teixeira
 *
 * php 5.2+
 *
 * Exemple use:
 * 
 * <?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 vt_resize( $attach_id = null, $img_url = null, $width, $height, $crop = false ) {

	// 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 = 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
	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
		if ( $crop == false ) {
		
			// 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' => $new_img_size[0],
					'height' => $new_img_size[1]
				);
				
				return $vt_image;
			}
		}

		// no cached 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;
	}

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



",enhancement,new,normal,Future Release,Media,3.1,normal,,dev-feedback has-patch,admin@… victorhteixeira@… anointed ian@… pross@… cais newkind navjotjsingh@… goto10 paulomagalhaes johnnytee pauldewouters dboulet aaron@… travis@… lol@… jeremy.felt@… admin@… jbrown510@… mercijavier@… dalton@… emzo techguytom bmonster99 webord.net@… willmot alexvornoffice@… jared@… mpretty@… aaron@… travis@… bk@… brady@… francesco.laffi@… code@… nashwan.doaqan@…