Site screenshot: Add responsive image support to the screenshot block

source/wp-content/themes/wporg-showcase-2022/functions.php

@@ -62,6 +62,17 @@ function setup_theme() {
 	add_image_size( 'screenshot-desktop', 2044, 1150, array( 'center', 'top' ) );
 	add_image_size( 'screenshot-mobile', 750, 1334, array( 'center', 'top' ) );
 
+	// More desktop sizes to support responsive images in the grid.
+	// In production these will be generated using Photon CDN, but we can set
+	// them up as real sizes for local support too.
+	// Images in the grid are display from 340-740px wide. This set of sizes
+	// should cover 1x and 2x resolution.
+	$desktop_ratio = 1150 / 2044;
+	add_image_size( 'screenshot-desktop-1400', 1400, 1400 * $desktop_ratio, array( 'center', 'top' ) );
+	add_image_size( 'screenshot-desktop-1100', 1100, 1100 * $desktop_ratio, array( 'center', 'top' ) );
+	add_image_size( 'screenshot-desktop-800', 800, 800 * $desktop_ratio, array( 'center', 'top' ) );
+	add_image_size( 'screenshot-desktop-500', 500, 500 * $desktop_ratio, array( 'center', 'top' ) );
+
 	// Add tonesque support so that Jetpack loads the class.
 	add_theme_support( 'tonesque' );
 
@@ -470,7 +481,7 @@ function jetpack_related_posts_display( $markup, $post_id, $related_posts, $bloc
 <!-- wp:query {"queryId":2,"query":{"perPage":3,"include":<?php echo esc_attr( wp_json_encode( $ids ) ); ?>,"inherit":false},"align":"wide","layout":{"type":"constrained","wideSize":"1760px"}} -->
 <div class="wp-block-query alignwide">
 	<!-- wp:post-template {"align":"wide","style":{"spacing":{"blockGap":"var:preset|spacing|40"}},"layout":{"type":"grid","columnCount":3},"className":"wporg-related-posts"} -->
-		<!-- wp:wporg/site-screenshot {"isLink":true,"lazyLoad":true} /-->
+		<!-- wp:wporg/site-screenshot {"isLink":true,"lazyLoad":true,"location":"row"} /-->
 
 		<!-- wp:group {"style":{"spacing":{"margin":{"top":"var:preset|spacing|10"}}},"layout":{"type":"flex","flexWrap":"nowrap","justifyContent":"space-between"}} -->
 		<div class="wp-block-group" style="margin-top:var(--wp--preset--spacing--10)">

source/wp-content/themes/wporg-showcase-2022/patterns/_site-grid-featured.php

@@ -39,7 +39,7 @@
 	<!-- /wp:heading -->
 
 	<!-- wp:post-template {"align":"wide","style":{"spacing":{"blockGap":"var:preset|spacing|40"}},"layout":{"type":"grid","columnCount":3}} -->
-		<!-- wp:wporg/site-screenshot {"isLink":true,"lazyLoad":true} /-->
+		<!-- wp:wporg/site-screenshot {"isLink":true,"lazyLoad":true,"location":"grid"} /-->
 
 		<!-- wp:group {"style":{"spacing":{"margin":{"top":"var:preset|spacing|10"}}},"layout":{"type":"flex","flexWrap":"nowrap","justifyContent":"space-between"}} -->
 		<div class="wp-block-group" style="margin-top:var(--wp--preset--spacing--10)">

source/wp-content/themes/wporg-showcase-2022/patterns/_site-grid.php

@@ -38,7 +38,7 @@
 	<!-- wp:query-title {"type":"archive","className":"screen-reader-text"} /-->
 
 	<!-- wp:post-template {"align":"wide","style":{"spacing":{"blockGap":"var:preset|spacing|40"}},"layout":{"type":"grid","columnCount":3}} -->
-		<!-- wp:wporg/site-screenshot {"isLink":true,"lazyLoad":true} /-->
+		<!-- wp:wporg/site-screenshot {"isLink":true,"lazyLoad":true,"location":"grid"} /-->
 
 		<!-- wp:group {"style":{"spacing":{"margin":{"top":"var:preset|spacing|10"}}},"layout":{"type":"flex","flexWrap":"nowrap","justifyContent":"space-between"}} -->
 		<div class="wp-block-group" style="margin-top:var(--wp--preset--spacing--10)">

source/wp-content/themes/wporg-showcase-2022/patterns/_site-hero.php

@@ -42,7 +42,7 @@
 					<span aria-hidden="true" class="wp-block-cover__background has-background-dim-0 has-background-dim"></span>
 					<img class="wp-block-cover__image-background" alt="" src="<?php echo esc_url( get_theme_file_uri( 'images/dots-hero.svg' ) . '?v=' . time() ); ?>" style="object-position:0% 0%" data-object-fit="contain" data-object-position="0% 0%"/>
 					<div class="wp-block-cover__inner-container">
-						<!-- wp:wporg/site-screenshot {"isLink":true} /-->
+						<!-- wp:wporg/site-screenshot {"isLink":true,"location":"hero"} /-->
 					</div>
 				</div>
 				<!-- /wp:cover -->

source/wp-content/themes/wporg-showcase-2022/patterns/screenshot-auditor.php

@@ -41,15 +41,15 @@
 <h3 class="has-small-font-size"><?php esc_attr_e( 'Desktop', 'wporg' ); ?></h3>
 <!-- /wp:heading -->
 
-<!-- wp:wporg/site-screenshot {"isLink":true,"type":"desktop"} /--></div>
+<!-- wp:wporg/site-screenshot {"isLink":true,"type":"desktop","location":"header"} /--></div>
 <!-- /wp:column -->
 
 <!-- wp:column {"width":"25%"} -->
 <div class="wp-block-column" style="flex-basis:25%"><!-- wp:heading {"level":3,"fontSize":"small"} -->
 <h3 class="has-small-font-size"><?php esc_attr_e( 'Mobile', 'wporg' ); ?></h3>
 <!-- /wp:heading -->
 
-<!-- wp:wporg/site-screenshot {"isLink":true,"type":"mobile"} /--></div>
+<!-- wp:wporg/site-screenshot {"isLink":true,"type":"mobile","location":"header"} /--></div>
 <!-- /wp:column --></div>
 <!-- /wp:columns --></div>
 <!-- /wp:group -->

source/wp-content/themes/wporg-showcase-2022/src/site-screenshot/block.json

@@ -21,6 +21,11 @@
 			"type": "string",
 			"default": "desktop",
 			"enum": [ "desktop", "mobile" ]
+		},
+		"location": {
+			"type": "string",
+			"default": "grid",
+			"enum": [ "grid", "hero", "header", "row" ]
 		}
 	},
 	"supports": {

source/wp-content/themes/wporg-showcase-2022/src/site-screenshot/index.php

@@ -30,14 +30,14 @@ function init() {
  *
  * @param WP_Post $post
  * @param string  $type
+ * @param string  $size
  * @return string
  */
-function get_site_screenshot_src( $post, $type = 'desktop' ) {
+function get_site_screenshot_src( $post, $type = 'desktop', $size = 'screenshot-desktop' ) {
 	$screenshot_url = false;
 	$media_id = get_post_meta( $post->ID, 'screenshot-' . $type, true );
 	$cache_key = '20230913'; // To break out of cached image.
 
-	$size = 'screenshot-' . $type;
 	$all_sizes = wp_get_registered_image_subsizes();
 	if ( ! isset( $all_sizes[ $size ] ) ) {
 		return null;

source/wp-content/themes/wporg-showcase-2022/src/site-screenshot/readme.md

@@ -0,0 +1,41 @@
+# Site Screenshots
+
+Display the screenshot for the current post (site). This uses the uploaded image if available, otherwise falls back to using the `domain` to take and load a screenshot from mshots.
+
+The mshots behavior uses the [Interactivity API](https://github.com/WordPress/gutenberg/blob/trunk/packages/interactivity/docs/1-getting-started.md) to provide a CSS-controlled loading state.
+
+When a local image is used, the block may use responsive images, depending on the location.
+
+This block also controls loading the panel into the Document Settings sidebar for uploading the desktop & mobile images, and setting the custom background color.
+
+## Attributes
+
+### `isLink`: boolean
+
+- Default: false
+
+If true, will wrap the screenshot in a link to the current post.
+
+### `lazyLoad`: boolean
+
+- Default: false
+
+Controls the `loading` attribute on the `img` tag. This is currently not used for mshots images.
+
+### `type`: "desktop" | "mobile"
+
+- Default: "desktop"
+
+Controls which image to show/capture. When `desktop`, it uses the image saved as `screenshot-desktop` or captures from mshots at 1920x1080. When `mobile`, it uses the image saves as `screenshot-mobile` or captures from mshots at 375x667.
+
+### `location`: "grid" | "hero" | "header" | "row"
+
+- Default: "grid"
+
+This indicates to the block where in the layout this will be rendered. This is used to control the responsive image hints.
+
+- grid: the main site grid, on homepage or archives, which displays at 3, 2, or 1 column depending on screen size.
+- hero: the homepage header, does not use responsive images.
+- header: single site page header, does not use responsive images.
+- row: the "related sites" section, which displays at 3 or 1 column depending on screen size.
+

source/wp-content/themes/wporg-showcase-2022/src/site-screenshot/render.php

@@ -13,14 +13,45 @@
 $has_link = isset( $attributes['isLink'] ) && true == $attributes['isLink'];
 $is_lazyload = isset( $attributes['lazyLoad'] ) && true === $attributes['lazyLoad'];
 
-$screenshot = get_site_screenshot_src( $current_post, $attributes['type'] );
+$img_size = ( 'desktop' === $attributes['type'] ) ? 'screenshot-desktop' : 'screenshot-mobile';
+$screenshot = get_site_screenshot_src( $current_post, $attributes['type'], $img_size );
 $is_mshots = str_contains( $screenshot, 'mshots' );
 
 $classname = 'is-size-' . esc_attr( $attributes['type'] );
 if ( $has_link ) {
 	$classname .= ' is-linked-image';
 }
 
+$has_responsive_images = ! $is_mshots && 'desktop' === $attributes['type'] && ( 'grid' === $attributes['location'] || 'row' === $attributes['location'] );
+
+// If the block needs responsive images, set up more image URLs & sizes attribute.
+if ( $has_responsive_images ) {
+	$screenshot = get_site_screenshot_src( $current_post, $attributes['type'], 'screenshot-desktop-1100' );
+	$screenshot_srcset = get_site_screenshot_src( $current_post, $attributes['type'], 'screenshot-desktop-500' ) . ' 500w, ';
+	$screenshot_srcset .= get_site_screenshot_src( $current_post, $attributes['type'], 'screenshot-desktop-800' ) . ' 800w, ';
+	$screenshot_srcset .= get_site_screenshot_src( $current_post, $attributes['type'], 'screenshot-desktop-1100' ) . ' 1100w, ';
+	$screenshot_srcset .= get_site_screenshot_src( $current_post, $attributes['type'], 'screenshot-desktop-1400' ) . ' 1400w';
+
+	// Set up the sizes attribute. The value here should reflect the width of
+	// the column, i.e., the displayed with of the image.
+	// On very large screens, columns are a fixed size.
+	$sizes = '(min-width: 1920px) 533px,';
+	// Handle dynamic column sizes. This math is not really reflective of the
+	// layout, but it works well. Real math would be tricky due to the scaling
+	// column gap value (--wp--preset--spacing--40).
+	// See https://css-tricks.com/a-guide-to-the-responsive-images-syntax-in-html/#aa-being-more-chill-about-sizes
+	if ( 'grid' === $attributes['location'] ) {
+		$sizes .= '(min-width: 1601px) calc(25vw + 30px),';
+		$sizes .= '(min-width: 801px) calc(50vw - 125px),';
+	} else {
+		// In "row", this stays 3-column until flipping to one-column.
+		$sizes .= '(min-width: 801px) calc(25vw + 30px),';
+	}
+	// One column—this one's actually accurate! At one column, we only need to
+	// account for site padding & border width.
+	$sizes .= 'calc(100vw - 60px)';
+}
+
 // Initial state to pass to Interactivity API.
 // This handles the image data (used to load image from mshots) and current
 // state information (like errors).
@@ -56,6 +87,10 @@ class="wporg-site-screenshot__mshot-container"
 	<?php else : ?>
 		<img
 			src="<?php echo esc_url( $screenshot ); ?>"
+			<?php if ( $has_responsive_images ) : ?>
+				srcset="<?php echo esc_attr( $screenshot_srcset ); ?>"
+				sizes="<?php echo esc_attr( $sizes ); ?>"
+			<?php endif; ?>
 			alt="<?php echo the_title_attribute( array( 'echo' => false ) ); ?>"
 			loading="<?php echo $is_lazyload ? 'lazy' : 'eager'; ?>"
 		/>

source/wp-content/themes/wporg-showcase-2022/src/style/style.scss

@@ -152,7 +152,7 @@ a:where(:not(.wp-element-button)):focus-visible {
 	}
 }
 
-@media (max-width: 1440px) {
+@media (max-width: 1600px) {
 	.wp-block-post-template.is-layout-grid.columns-3:not(.wporg-related-posts) {
 		grid-template-columns: repeat(2, minmax(0, 1fr));
 	}

source/wp-content/themes/wporg-showcase-2022/templates/single.html

@@ -6,9 +6,9 @@
 	<div class="wp-block-group alignfull has-feature-color-background has-background" style="border-bottom-color:var(--wp--preset--color--light-grey-1);border-bottom-style:solid;border-bottom-width:1px;background-color:#f6f6f6;margin-bottom:var(--wp--preset--spacing--50);padding-top:var(--wp--preset--spacing--60);padding-right:var(--wp--preset--spacing--edge-space);padding-left:var(--wp--preset--spacing--edge-space)">
 		<!-- wp:group {"style":{"spacing":{"blockGap":"var:preset|spacing|60"}},"layout":{"type":"flex","flexWrap":"nowrap","justifyContent":"center","verticalAlignment":"bottom"}} -->
 		<div class="wp-block-group">
-			<!-- wp:wporg/site-screenshot /-->
+			<!-- wp:wporg/site-screenshot {"location":"header"} /-->
 
-			<!-- wp:wporg/site-screenshot {"type":"mobile"} /-->
+			<!-- wp:wporg/site-screenshot {"type":"mobile","location":"header"} /-->
 		</div>
 		<!-- /wp:group -->
 	</div>