Re-size WordPress images on the fly using built-in WordPress functions.
使用vt_resize 功能可动态调整位于自定义字段、特色图像、上载目录、NextGen Gallery WordPress插件中的WordPress图像的大小，甚至可以调整到非现场图像的外部链接的大小它使用非常简单，只需将下面的代码复制/粘贴到WordPress主题中functions.php 当前激活的WordPress主题的文件。
然后，如果需要动态调整图像大小，只需按照函数注释中解释的参数用法调用该函数即可。
下面是一个自动获取帖子ID、帖子本身、帖子的自定义字段值的示例，以及从包含要动态调整大小的图像的自定义字段动态调整图像大小的示例。
<?php
# Place this in your functions.php
function get_postID() {
global $wp_query;
return $wp_query->post->ID;
}
?>
<?php
# Place the following lines where you want to perform this action.
$postID = get_postID(); // Obtain the current Post ID.
$post = get_post( $postID ); // Takes the current Post ID and returns the database record. (alternatively, `global $post`)
$custom = get_post_custom( $post->ID ); // Returns a multidimensional array with all custom fields of the Post.
$image = $custom[\'field-slug\'][0]; // Specify the array key of the Custom Field containing the image.
# The first parameter is 0. Meaning, will not use a Post Attachment.
# The second parameter is the image URL from Post\'s Custom Field value.
# The third and fourth parameters are the width and height of the image after the re-size is performed.
# The fifth parameter means crop this image.
$resizedImage = vt_resize( 0, $image, 190, 338, true ); // Dynamically re-size image on the fly.
echo \'<img src="\' . $resizedImage[ \'url\' ] . \'" width="\' . $resizedImage[ \'width\' ] . \'" height="\' . $resizedImage[ \'height\' ] . \'" title="\' . $post->post_title . \'" alt="\' . $post->post_title . \'" />\'; // The image properties are held in an array. (Use print_r($resizedImage) for array properties.)
?>
- Description: 使用WordPress内置函数动态调整图像大小
- Author: 维克托·泰泽拉Requirements: PHP 5.2+、WordPress 3.2+
我对源代码进行了重新格式化，以便于我自己阅读。如果您想要原始格式的源代码，请访问上面的链接。
<?php
if ( ! function_exists( \'vt_resize\' ) ) {
/**
* 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|void
*/
function vt_resize( int $attach_id = 0, string $img_url = \'\', int $width = 0, int $height = 0, bool $crop = false ) {
if ( $attach_id ) {
# this is an attachment, so we have the ID
$image_src = wp_get_attachment_image_src( $attach_id, \'full\' );
$file_path = get_attached_file( $attach_id );
} elseif ( $img_url ) {
# this is not an attachment, let\'s use the image url
$file_path = parse_url( $img_url );
$file_path = $_SERVER[\'DOCUMENT_ROOT\'] . $file_path[\'path\'];
# Look for Multisite Path
if ( file_exists( $file_path ) === false ) {
global $blog_id;
$file_path = parse_url( $img_url );
if ( preg_match( \'/files/\', $file_path[\'path\'] ) ) {
$path = explode( \'/\', $file_path[\'path\'] );
foreach ( $path as $k => $v ) {
if ( $v == \'files\' ) {
$path[ $k - 1 ] = \'wp-content/blogs.dir/\' . $blog_id;
}
}
$path = implode( \'/\', $path );
}
$file_path = $_SERVER[\'DOCUMENT_ROOT\'] . $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 );
# check if file exists
$base_file = $file_info[\'dirname\'] . \'/\' . $file_info[\'filename\'] . \'.\' . $file_info[\'extension\'];
if ( ! file_exists( $base_file ) ) {
return;
}
$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 ) {
# 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 or no height set
if ( $crop == false OR ! $height ) {
# 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;
}
}
# check if image width is smaller than set width
$img_size = getimagesize( $file_path );
if ( $img_size[0] <= $width ) {
$width = $img_size[0];
}
# Check if GD Library installed
if ( ! function_exists( \'imagecreatetruecolor\' ) ) {
echo \'GD Library Error: imagecreatetruecolor does not exist - please contact your webhost and ask them to install the GD library\';
return;
}
# 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;
}
# default output - without resizing
$vt_image = array(
\'url\' => $image_src[0],
\'width\' => $width,
\'height\' => $height
);
return $vt_image;
}
}
?>
