Accessibility: Media: Add a "Copy URL" button to the attachment File URL fields.

For a number of years, various screens in the WordPress admin provided users with a readonly input field to copy the attachment file URL. Manually copying from a readonly field is an annoying task at best even for mouser users. It's a usability and accessibility issue at the same time. 
These fields now have a new "Copy URL" button that is easy to use and accessible to everyone.

Props theolg, markdubois, vabrashev, sajjad67, xkon, nrqsnchz, melchoyce, audrasjb, afercia.
See #41612, #50322, #50335.
Fixes #48463.

Built from https://develop.svn.wordpress.org/trunk@48232


git-svn-id: http://core.svn.wordpress.org/trunk@48001 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/css/media-rtl.css

@@ -798,6 +798,16 @@ border color while dragging a file over the uploader drop area */
 	text-decoration: none;
 }
 
+.copy-to-clipboard-container {
+	display: flex;
+	align-items: center;
+	margin-top: 8px;
+	clear: both;
+}
+
+.copy-to-clipboard-container .success {
+	margin-right: 8px;
+}
 
 /*------------------------------------------------------------------------------
   14.2 - Image Editor
@@ -1216,6 +1226,10 @@ audio, video {
 		width: auto;
 		max-width: none;
 	}
+
+	.copy-to-clipboard-container .success {
+		font-size: 14px;
+	}
 }
 
 /**

wp-admin/css/media.css

@@ -797,6 +797,16 @@ border color while dragging a file over the uploader drop area */
 	text-decoration: none;
 }
 
+.copy-to-clipboard-container {
+	display: flex;
+	align-items: center;
+	margin-top: 8px;
+	clear: both;
+}
+
+.copy-to-clipboard-container .success {
+	margin-left: 8px;
+}
 
 /*------------------------------------------------------------------------------
   14.2 - Image Editor
@@ -1215,6 +1225,10 @@ audio, video {
 		width: auto;
 		max-width: none;
 	}
+
+	.copy-to-clipboard-container .success {
+		font-size: 14px;
+	}
 }
 
 /**

wp-admin/includes/media.php

@@ -3268,6 +3268,10 @@ function attachment_submitbox_metadata() {
 	<div class="misc-pub-section misc-pub-attachment">
 		<label for="attachment_url"><?php _e( 'File URL:' ); ?></label>
 		<input type="text" class="widefat urlfield" readonly="readonly" name="attachment_url" id="attachment_url" value="<?php echo esc_attr( $att_url ); ?>" />
+		<span class="copy-to-clipboard-container">
+			<button type="button" class="button copy-attachment-url edit-media" data-clipboard-target="#attachment_url"><?php _e( 'Copy URL' ); ?></button>
+			<span class="success hidden" aria-hidden="true"><?php _e( 'Copied!' ); ?></span>
+		</span>
 	</div>
 	<div class="misc-pub-section misc-pub-filename">
 		<?php _e( 'File name:' ); ?> <strong><?php echo $filename; ?></strong>

wp-admin/js/post.js

@@ -4,7 +4,7 @@
  * @output wp-admin/js/post.js
  */
 
- /* global postL10n, ajaxurl, wpAjax, setPostThumbnailL10n, postboxes, pagenow, tinymce, alert, deleteUserSetting */
+ /* global postL10n, ajaxurl, wpAjax, setPostThumbnailL10n, postboxes, pagenow, tinymce, alert, deleteUserSetting, ClipboardJS */
  /* global theList:true, theExtraList:true, getUserSetting, setUserSetting, commentReply, commentsBox */
  /* global WPSetThumbnailHTML, wptitlehint */
 
@@ -297,7 +297,10 @@ jQuery(document).ready( function($) {
 		$postVisibilitySelect = $('#post-visibility-select'),
 		$timestampdiv = $('#timestampdiv'),
 		$postStatusSelect = $('#post-status-select'),
-		isMac = window.navigator.platform ? window.navigator.platform.indexOf( 'Mac' ) !== -1 : false;
+		isMac = window.navigator.platform ? window.navigator.platform.indexOf( 'Mac' ) !== -1 : false,
+		copyAttachmentURLClipboard = new ClipboardJS( '.copy-attachment-url.edit-media' ),
+		copyAttachmentURLSuccessTimeout,
+		__ = wp.i18n.__;
 
 	postboxes.add_postbox_toggles(pagenow);
 
@@ -1217,7 +1220,38 @@ jQuery(document).ready( function($) {
 			window.history.replaceState( null, null, location );
 		});
 	}
-});
+
+	/**
+	 * Copies the attachment URL in the Edit Media page to the clipboard.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param {MouseEvent} event A click event.
+	 *
+	 * @returns {void}
+	 */
+	copyAttachmentURLClipboard.on( 'success', function( event ) {
+		var triggerElement = $( event.trigger ),
+			successElement = $( '.success', triggerElement.closest( '.copy-to-clipboard-container' ) );
+
+		// Clear the selection and move focus back to the trigger.
+		event.clearSelection();
+		// Handle ClipboardJS focus bug, see https://github.com/zenorocha/clipboard.js/issues/680
+		triggerElement.focus();
+
+		// Show success visual feedback.
+		clearTimeout( copyAttachmentURLSuccessTimeout );
+		successElement.removeClass( 'hidden' );
+
+		// Hide success visual feedback after 3 seconds since last success.
+		copyAttachmentURLSuccessTimeout = setTimeout( function() {
+			successElement.addClass( 'hidden' );
+		}, 3000 );
+
+		// Handle success audible feedback.
+		wp.a11y.speak( __( 'The file URL has been copied to your clipboard' ) );
+	} );
+} );
 
 /**
  * TinyMCE word count display