Post/Page Image was too generic a name. Post/Page Thumbnail is more clear, even if you can create very large thumbnail images if you so choose.

git-svn-id: https://develop.svn.wordpress.org/trunk@12351 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/post-thumbnail-template.php

@@ -0,0 +1,76 @@
+<?php
+/**
+ * WordPress Post Thumbnail Template Functions.
+ *
+ * Support for post thumbnails
+ * Themes function.php must call add_theme_support( 'post-thumbnails' ) to use these.
+ *
+ * @package WordPress
+ * @subpackage Template
+ */
+
+/**
+ * Check if post has an image attached.
+ * 
+ * @since 2.9.0
+ *
+ * @param int $post_id Optional. Post ID.
+ * @return bool Whether post has an image attached (true) or not (false).
+ */
+function has_post_thumbnail( $post_id = NULL ) {
+	global $id;
+	$post_id = ( NULL === $post_id ) ? $id : $popost-thumbnailst_id;
+	return !! get_post_thumbnail_id( $post_id );
+}
+
+/**
+ * Retrieve Post Thumbnail ID.
+ * 
+ * @since 2.9.0
+ *
+ * @param int $post_id Optional. Post ID.
+ * @return int
+ */
+function get_post_thumbnail_id( $post_id = NULL ) {
+	global $id;
+	$post_id = ( NULL === $post_id ) ? $id : $post_id;
+	return get_post_meta( $post_id, '_thumbnail_id', true );
+}
+
+/**
+ * Display Post Thumbnail.
+ * 
+ * @since 2.9.0
+ *
+ * @param int $size Optional. Image size.  Defaults to 'post-thumbnail', which theme sets using set_post_thumbnail_size( $width, $height, $crop_flag );.
+ * @param string|array $attr Optional. Query string or array of attributes.
+ */
+function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) {
+	echo get_the_post_thumbnail( NULL, $size, $attr );
+}
+
+/**
+ * Retrieve Post Thumbnail.
+ * 
+ * @since 2.9.0
+ *
+ * @param int $post_id Optional. Post ID.
+ * @param string $size Optional. Image size.  Defaults to 'thumbnail'.
+ * @param string|array $attr Optional. Query string or array of attributes.
+  */
+function get_the_post_thumbnail( $post_id = NULL, $size = 'post-thumbnail', $attr = '' ) {
+	global $id;
+	$post_id = ( NULL === $post_id ) ? $id : $post_id;
+	$post_thumbnail_id = get_post_thumbnail_id( $post_id );
+	$size = apply_filters( 'post_thumbnail_size', $size );
+	if ( $post_thumbnail_id ) {
+		do_action( 'begin_fetch_post_thumbnail_html', $post_id, $post_thumbnail_id, $size ); // for "Just In Time" filtering of all of wp_get_attachment_image()'s filters
+		$html = wp_get_attachment_image( $post_thumbnail_id, $size, false, $attr );
+		do_action( 'end_fetch_post_thumbnail_html', $post_id, $post_thumbnail_id, $size );
+	} else {
+		$html = '';
+	}
+	return apply_filters( 'post_thumbnail_html', $html, $post_id, $post_thumbnail_id, $size, $attr );
+}
+
+?>