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Fix Image block lightbox missing alt attribute and improve accessibil…
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…ity (#55010)

* Move lightbox open button after the image.

* Fix getting the lightbox image alt attribute.

* Improve docblocks.

* Do not render empty role attribute.

* Remove unnecessary aria-hidden attribute.

* Set aria-modal attribute dynamically.

* More meaningful and simpler modal dialog aria-label.

* Increase Close button target size.

* Add enlarged image base64 encoded placeholder.

* Better check for alt attribute as a string.

* Update changelog.

* Move changelog entry to the block library changelog.

* Set lightbox dialog aria-label dynamically.

* Hide background scrim container from assistive technology.

* Remove obsolete code

---------

Co-authored-by: Ricardo Artemio Morales <ric.morales22@gmail.com>
# Conflicts:
#	packages/block-library/CHANGELOG.md
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@afercia @mikachan
afercia authored and mikachan committed Oct 9, 2023
1 parent 11f6a6d commit 89f5e33
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Showing 6 changed files with 106 additions and 74 deletions.
49 changes: 25 additions & 24 deletions lib/block-supports/behaviors.php
View file
Original file line number Diff line number Diff line change
Expand Up @@ -84,35 +84,35 @@ function gutenberg_render_behaviors_support_lightbox( $block_content, $block ) {

$aria_label = __( 'Enlarge image', 'gutenberg' );

$processor->next_tag( 'img' );
$alt_attribute = $processor->get_attribute( 'alt' );

if ( null !== $alt_attribute ) {
// An empty alt attribute `alt=""` is valid for decorative images.
if ( is_string( $alt_attribute ) ) {
$alt_attribute = trim( $alt_attribute );
}

// It only makes sense to append the alt text to the button aria-label when the alt text is non-empty.
if ( $alt_attribute ) {
/* translators: %s: Image alt text. */
$aria_label = sprintf( __( 'Enlarge image: %s', 'gutenberg' ), $alt_attribute );
}
$content = $processor->get_updated_html();

// If we don't set a default, it won't work if Lightbox is set to enabled by default.
$lightbox_animation = 'zoom';
if ( isset( $lightbox_settings['animation'] ) && '' !== $lightbox_settings['animation'] ) {
$lightbox_animation = $lightbox_settings['animation'];
}

// We want to store the src in the context so we can set it dynamically when the lightbox is opened.
$z = new WP_HTML_Tag_Processor( $content );
$z->next_tag( 'img' );

// Note: We want to store the `src` in the context so we
// can set it dynamically when the lightbox is opened.
if ( isset( $block['attrs']['id'] ) ) {
$img_uploaded_src = wp_get_attachment_url( $block['attrs']['id'] );
$img_metadata = wp_get_attachment_metadata( $block['attrs']['id'] );
$img_width = $img_metadata['width'];
$img_height = $img_metadata['height'];
} else {
$img_uploaded_src = $z->get_attribute( 'src' );
$img_uploaded_src = $processor->get_attribute( 'src' );
$img_width = 'none';
$img_height = 'none';
}
Expand All @@ -123,7 +123,7 @@ function gutenberg_render_behaviors_support_lightbox( $block_content, $block ) {
$scale_attr = false;
}

$w = new WP_HTML_Tag_Processor( $content );
$w = new WP_HTML_Tag_Processor( $block_content );
$w->next_tag( 'figure' );
$w->add_class( 'wp-lightbox-container' );
$w->set_attribute( 'data-wp-interactive', true );
Expand Down Expand Up @@ -163,27 +163,28 @@ function gutenberg_render_behaviors_support_lightbox( $block_content, $block ) {
// Wrap the image in the body content with a button.
$img = null;
preg_match( '/<img[^>]+>/', $body_content, $img );
$button =
'<button
type="button"
aria-haspopup="dialog"
aria-label="' . esc_attr( $aria_label ) . '"
data-wp-on--click="actions.core.image.showLightbox"
data-wp-style--width="context.core.image.imageButtonWidth"
data-wp-style--height="context.core.image.imageButtonHeight"
data-wp-style--left="context.core.image.imageButtonLeft"
data-wp-style--top="context.core.image.imageButtonTop"
>
</button>'
. $img[0];

$button =
$img[0]
. '<button
type="button"
aria-haspopup="dialog"
aria-label="' . esc_attr( $aria_label ) . '"
data-wp-on--click="actions.core.image.showLightbox"
data-wp-style--width="context.core.image.imageButtonWidth"
data-wp-style--height="context.core.image.imageButtonHeight"
data-wp-style--left="context.core.image.imageButtonLeft"
data-wp-style--top="context.core.image.imageButtonTop"
></button>';

$body_content = preg_replace( '/<img[^>]+>/', $button, $body_content );

// We need both a responsive image and an enlarged image to animate
// the zoom seamlessly on slow internet connections; the responsive
// image is a copy of the one in the body, which animates immediately
// as the lightbox is opened, while the enlarged one is a full-sized
// version that will likely still be loading as the animation begins.
$m = new WP_HTML_Tag_Processor( $content );
$m = new WP_HTML_Tag_Processor( $block_content );
$m->next_tag( 'figure' );
$m->add_class( 'responsive-image' );
$m->next_tag( 'img' );
Expand All @@ -199,7 +200,7 @@ function gutenberg_render_behaviors_support_lightbox( $block_content, $block ) {
$m->set_attribute( 'data-wp-style--object-fit', 'selectors.core.image.lightboxObjectFit' );
$initial_image_content = $m->get_updated_html();

$q = new WP_HTML_Tag_Processor( $content );
$q = new WP_HTML_Tag_Processor( $block_content );
$q->next_tag( 'figure' );
$q->add_class( 'enlarged-image' );
$q->next_tag( 'img' );
Expand All @@ -219,7 +220,7 @@ function gutenberg_render_behaviors_support_lightbox( $block_content, $block ) {

$close_button_icon = '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" width="15" height="15" aria-hidden="true" focusable="false"><path d="M13 11.8l6.1-6.3-1-1-6.1 6.2-6.1-6.2-1 1 6.1 6.3-6.5 6.7 1 1 6.5-6.6 6.5 6.6 1-1z"></path></svg>';
$close_button_color = esc_attr( wp_get_global_styles( array( 'color', 'text' ) ) );
$dialog_label = $alt_attribute ? esc_attr( $alt_attribute ) : esc_attr__( 'Image', 'gutenberg' );
$dialog_label = esc_attr__( 'Enlarged image', 'gutenberg' );
$close_button_label = esc_attr__( 'Close', 'gutenberg' );

$lightbox_html = <<<HTML
Expand Down
1 change: 1 addition & 0 deletions lib/load.php
View file
Original file line number Diff line number Diff line change
Expand Up @@ -244,3 +244,4 @@ function () {
require __DIR__ . '/block-supports/duotone.php';
require __DIR__ . '/block-supports/shadow.php';
require __DIR__ . '/block-supports/background.php';
require __DIR__ . '/block-supports/behaviors.php';
7 changes: 7 additions & 0 deletions packages/block-library/CHANGELOG.md
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,13 @@

## Unreleased

### Bug Fix

- Fix Image block lightbox missing alt attribute and improve accessibility. ([#54608](https://github.com/WordPress/gutenberg/pull/55010))


## 8.20.0 (2023-10-05)

## 8.19.0 (2023-09-20)

## 8.18.0 (2023-08-31)
Expand Down
94 changes: 50 additions & 44 deletions packages/block-library/src/image/index.php
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,10 +9,11 @@
* Renders the `core/image` block on the server,
* adding a data-id attribute to the element if core/gallery has added on pre-render.
*
* @param array $attributes The block attributes.
* @param string $content The block content.
* @param WP_Block $block The block object.
* @return string Returns the block content with the data-id attribute added.
* @param array $attributes The block attributes.
* @param string $content The block content.
* @param WP_Block $block The block object.
*
* @return string The block content with the data-id attribute added.
*/
function render_block_core_image( $attributes, $content, $block ) {

Expand Down Expand Up @@ -76,12 +77,13 @@ function render_block_core_image( $attributes, $content, $block ) {
}

/**
* Add the lightboxEnabled flag to the block data.
* Adds the lightboxEnabled flag to the block data.
*
* This is used to determine whether the lightbox should be rendered or not.
*
* @param array $block Block data.
* @return array Filtered block data.
* @param array $block Block data.
*
* @return array Filtered block data.
*/
function block_core_image_get_lightbox_settings( $block ) {
// Get the lightbox setting from the block attributes.
Expand Down Expand Up @@ -113,43 +115,44 @@ function block_core_image_get_lightbox_settings( $block ) {
}

/**
* Add the directives and layout needed for the lightbox behavior.
* Adds the directives and layout needed for the lightbox behavior.
*
* @param string $block_content Rendered block content.
* @param array $block Block object.
*
* @param string $block_content Rendered block content.
* @param array $block Block object.
* @return string Filtered block content.
* @return string Filtered block content.
*/
function block_core_image_render_lightbox( $block_content, $block ) {
$processor = new WP_HTML_Tag_Processor( $block_content );

$aria_label = __( 'Enlarge image' );

$processor->next_tag( 'img' );
$alt_attribute = $processor->get_attribute( 'alt' );

if ( null !== $alt_attribute ) {
// An empty alt attribute `alt=""` is valid for decorative images.
if ( is_string( $alt_attribute ) ) {
$alt_attribute = trim( $alt_attribute );
}

// It only makes sense to append the alt text to the button aria-label when the alt text is non-empty.
if ( $alt_attribute ) {
/* translators: %s: Image alt text. */
$aria_label = sprintf( __( 'Enlarge image: %s' ), $alt_attribute );
}
$content = $processor->get_updated_html();

// Currently, we are only enabling the zoom animation.
$lightbox_animation = 'zoom';

// We want to store the src in the context so we can set it dynamically when the lightbox is opened.
$z = new WP_HTML_Tag_Processor( $content );
$z->next_tag( 'img' );

// Note: We want to store the `src` in the context so we
// can set it dynamically when the lightbox is opened.
if ( isset( $block['attrs']['id'] ) ) {
$img_uploaded_src = wp_get_attachment_url( $block['attrs']['id'] );
$img_metadata = wp_get_attachment_metadata( $block['attrs']['id'] );
$img_width = $img_metadata['width'];
$img_height = $img_metadata['height'];
} else {
$img_uploaded_src = $z->get_attribute( 'src' );
$img_uploaded_src = $processor->get_attribute( 'src' );
$img_width = 'none';
$img_height = 'none';
}
Expand All @@ -160,7 +163,7 @@ function block_core_image_render_lightbox( $block_content, $block ) {
$scale_attr = false;
}

$w = new WP_HTML_Tag_Processor( $content );
$w = new WP_HTML_Tag_Processor( $block_content );
$w->next_tag( 'figure' );
$w->add_class( 'wp-lightbox-container' );
$w->set_attribute( 'data-wp-interactive', true );
Expand All @@ -180,15 +183,17 @@ function block_core_image_render_lightbox( $block_content, $block ) {
"imageCurrentSrc": "",
"targetWidth": "%s",
"targetHeight": "%s",
"scaleAttr": "%s"
"scaleAttr": "%s",
"dialogLabel": "%s"
}
}
}',
$lightbox_animation,
$img_uploaded_src,
$img_width,
$img_height,
$scale_attr
$scale_attr,
__( 'Enlarged image' )
)
);
$w->next_tag( 'img' );
Expand All @@ -200,27 +205,28 @@ function block_core_image_render_lightbox( $block_content, $block ) {
// Wrap the image in the body content with a button.
$img = null;
preg_match( '/<img[^>]+>/', $body_content, $img );
$button =
'<button
type="button"
aria-haspopup="dialog"
aria-label="' . esc_attr( $aria_label ) . '"
data-wp-on--click="actions.core.image.showLightbox"
data-wp-style--width="context.core.image.imageButtonWidth"
data-wp-style--height="context.core.image.imageButtonHeight"
data-wp-style--left="context.core.image.imageButtonLeft"
data-wp-style--top="context.core.image.imageButtonTop"
>
</button>'
. $img[0];

$button =
$img[0]
. '<button
type="button"
aria-haspopup="dialog"
aria-label="' . esc_attr( $aria_label ) . '"
data-wp-on--click="actions.core.image.showLightbox"
data-wp-style--width="context.core.image.imageButtonWidth"
data-wp-style--height="context.core.image.imageButtonHeight"
data-wp-style--left="context.core.image.imageButtonLeft"
data-wp-style--top="context.core.image.imageButtonTop"
></button>';

$body_content = preg_replace( '/<img[^>]+>/', $button, $body_content );

// We need both a responsive image and an enlarged image to animate
// the zoom seamlessly on slow internet connections; the responsive
// image is a copy of the one in the body, which animates immediately
// as the lightbox is opened, while the enlarged one is a full-sized
// version that will likely still be loading as the animation begins.
$m = new WP_HTML_Tag_Processor( $content );
$m = new WP_HTML_Tag_Processor( $block_content );
$m->next_tag( 'figure' );
$m->add_class( 'responsive-image' );
$m->next_tag( 'img' );
Expand All @@ -236,7 +242,7 @@ function block_core_image_render_lightbox( $block_content, $block ) {
$m->set_attribute( 'data-wp-style--object-fit', 'selectors.core.image.lightboxObjectFit' );
$initial_image_content = $m->get_updated_html();

$q = new WP_HTML_Tag_Processor( $content );
$q = new WP_HTML_Tag_Processor( $block_content );
$q->next_tag( 'figure' );
$q->add_class( 'enlarged-image' );
$q->next_tag( 'img' );
Expand Down Expand Up @@ -268,20 +274,16 @@ function block_core_image_render_lightbox( $block_content, $block ) {
}

$close_button_icon = '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" width="15" height="15" aria-hidden="true" focusable="false"><path d="M13 11.8l6.1-6.3-1-1-6.1 6.2-6.1-6.2-1 1 6.1 6.3-6.5 6.7 1 1 6.5-6.6 6.5 6.6 1-1z"></path></svg>';
$dialog_label = $alt_attribute ? esc_attr( $alt_attribute ) : esc_attr__( 'Image' );
$close_button_label = esc_attr__( 'Close' );

$lightbox_html = <<<HTML
<div data-wp-body="" class="wp-lightbox-overlay $lightbox_animation"
data-wp-bind--role="selectors.core.image.roleAttribute"
aria-label="$dialog_label"
data-wp-bind--aria-label="selectors.core.image.dialogLabel"
data-wp-class--initialized="context.core.image.initialized"
data-wp-class--active="context.core.image.lightboxEnabled"
data-wp-class--hideAnimationEnabled="context.core.image.hideAnimationEnabled"
data-wp-bind--aria-hidden="!context.core.image.lightboxEnabled"
aria-hidden="true"
data-wp-bind--aria-modal="context.core.image.lightboxEnabled"
aria-modal="false"
data-wp-bind--aria-modal="selectors.core.image.ariaModal"
data-wp-effect="effects.core.image.initLightbox"
data-wp-on--keydown="actions.core.image.handleKeydown"
data-wp-on--touchstart="actions.core.image.handleTouchStart"
Expand All @@ -294,19 +296,21 @@ function block_core_image_render_lightbox( $block_content, $block ) {
</button>
<div class="lightbox-image-container">$initial_image_content</div>
<div class="lightbox-image-container">$enlarged_image_content</div>
<div class="scrim" style="background-color: $background_color"></div>
<div class="scrim" style="background-color: $background_color" aria-hidden="true"></div>
</div>
HTML;

return str_replace( '</figure>', $lightbox_html . '</figure>', $body_content );
}

/**
* Ensure that the view script has the `wp-interactivity` dependency.
* Ensures that the view script has the `wp-interactivity` dependency.
*
* @since 6.4.0
*
* @global WP_Scripts $wp_scripts
*
* @return void
*/
function block_core_image_ensure_interactivity_dependency() {
global $wp_scripts;
Expand All @@ -322,6 +326,8 @@ function block_core_image_ensure_interactivity_dependency() {

/**
* Registers the `core/image` block on server.
*
* @return void
*/
function register_block_core_image() {
register_block_type_from_metadata(
Expand Down
11 changes: 9 additions & 2 deletions packages/block-library/src/image/style.scss
View file
Original file line number Diff line number Diff line change
Expand Up @@ -154,6 +154,8 @@

.wp-lightbox-container {
position: relative;
display: flex;
flex-direction: column;

button {
border: none;
Expand Down Expand Up @@ -193,11 +195,16 @@

.close-button {
position: absolute;
top: calc(env(safe-area-inset-top) + 20px);
right: calc(env(safe-area-inset-right) + 20px);
top: calc(env(safe-area-inset-top) + 16px); // equivalent to $grid-unit-20
right: calc(env(safe-area-inset-right) + 16px); // equivalent to $grid-unit-20
padding: 0;
cursor: pointer;
z-index: 5000000;
min-width: 40px; // equivalent to $button-size-next-default-40px
min-height: 40px; // equivalent to $button-size-next-default-40px
display: flex;
align-items: center;
justify-content: center;

&:hover,
&:focus,
Expand Down
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