Question

我正在wordpress中显示第一个img帖子，如缩略图！但是我正在尝试将默认大小的拇指应用于此第一张图片，但没有成功：

我的默认尺寸是：

add_image_size('video-large', 565, 318, true);
add_image_size('video-single', 750, 330, true);
add_image_size('blog-single', 728, 288, true);
add_image_size('video-medium', 370, 208, true);
add_image_size('video-small', 175, 98, true);
add_image_size('widget-post', 55, 55, true);
add_image_size('term-listing', 170, 125, true);

我想将“视频大”尺寸应用于get_first_image，因为此过滤器裁剪了图像，并且我想要它。

我尝试：

<img src="<?php echo get_first_image('video-large');?>

但是，不起作用！

// Get first image
function get_first_image() {
    global $post, $posts;

    $first_image = '';
    ob_start();
    ob_end_clean();

    $output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches);
    $first_image = $matches[1][0];

    if ( empty($first_image) ) {
        // Defines a default image
        // Set the default image if there are no image available inside post content
        $first_image = "/img/default.jpg";
    }

    return $first_image;
}

Answer 1

如果我正确理解了您的问题，我认为您可以正确使用以下功能。

/*Find the image id from a URL*/

function url_get_image_id($image_url) {
    global $wpdb;
    $attachment = $wpdb->get_col($wpdb->prepare("SELECT ID FROM $wpdb->posts WHERE guid='%s';", $image_url ));
    return $attachment[0];
}

确定帖子中是否有特色图片，如果没有，请在帖子内容中查找第一张图片，$ size传递缩略图大小，$ url确定是返回URL还是完整图片标签

function checkImageType($size, $type) {

    global $post;
    $content = $post->post_content;                
    $first_img = '';
    ob_start();
    ob_end_clean();
    $output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $content, $matches);
    $first_img = $matches[1][0];

    /*If there's a featured image, show it*/

    if (get_the_post_thumbnail($post_id) != '' ) {
        if($type=='url') {
            the_post_thumbnail_url($size);
        } else {
            the_post_thumbnail($size);
        }
    } else {

        /*No featured image, so we get the first image inside the post content*/

        if ($first_img) {

            //let's get the correct image dimensions

            $image_id = url_get_image_id($first_img);
            $image_thumb = wp_get_attachment_image_src($image_id, $size);

            // if we've found an image ID, correctly display it

            if($image_thumb) {
                if($type=='url') {
                    echo $image_thumb[0];
                } else {

                    echo '<img src="'.$image_thumb[0].'" alt="'.get_the_title().'"/>';
                }
            } else {

                //if no image (i.e. from an external source), echo the original URL

                if($type=='url') {
                    echo $first_img;
                } else {

                    echo '<img src="'.$first_img.'" alt="'.get_the_title().'"/>';
                }

            }
        }
    }
}

一些示例使用：

checkImageType('full', 'url'); 

// Returns: http://your-domain/image-url.jpg)

checkImageType('post-thumb');

// Returns: <img src="http://your-domain/image-url.jpg" alt="Alt text">

Answer 2

在function.php中添加WordPress自定义图像大小

// Make sure featured images are enabled
add_theme_support( 'post-thumbnails' );

// Add featured image sizes
add_image_size( 'featured-large', 640, 294, true ); // width, height, crop
add_image_size( 'featured-small', 320, 147, true );

// Add other useful image sizes for use through Add Media modal
add_image_size( 'medium-width', 480 );
add_image_size( 'medium-height', 9999, 480 );
add_image_size( 'medium-something', 480, 480 );

// Register the three useful image sizes for use in Add Media modal
add_filter( 'image_size_names_choose', 'wpshout_custom_sizes' );
function wpshout_custom_sizes( $sizes ) {
    return array_merge( $sizes, array(
        'medium-width' => __( 'Medium Width' ),
        'medium-height' => __( 'Medium Height' ),
        'medium-something' => __( 'Medium Something' ),
    ) );
}

如何向get_first_image函数添加默认图像尺寸过滤器？

2 个答案: