Improve UI of previews

- Remove margins around thumbnails and images, increase radius, etc. for a fresher look overall
- Increase preview body contrast just enough to pass AA standards
- Add a `More`/`Less` button to expand previews that take more than one line. Button is added only when necessary
- Use a zoom-in cursor on hover for thumbnails
- Improve preview message errors

client/css/style.css

@@ -238,6 +238,7 @@ kbd {
 #chat .nick .from::before,
 #chat .action .from::before,
 #chat .toggle-button::after,
+#chat .toggle-content .more-caret::before,
 #version-checker::before,
 .context-menu-item::before,
 #help .website-link::before,
@@ -1332,75 +1333,112 @@ kbd {
 	color: #f00;
 }
 
+#chat .toggle-content.opened .more-caret, /* Expand/Collapse link previews */
 #chat .toggle-button.opened, /* Thumbnail toggle */
 #chat .msg.condensed:not(.closed) .toggle-button { /* Expanded status message toggle */
 	transform: rotate(90deg);
 }
 
 #chat .toggle-content {
-	background: #f5f5f5;
-	border-radius: 2px;
+	background: #f6f6f6;
+	border-radius: 5px;
 	display: none;
-	color: #222;
 	max-width: 100%;
 	margin: 0;
 	margin-top: 6px;
 	overflow: hidden;
+	box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
+	contain: content; /* This fixes a display bug where border-radius stopped working on image link hover */
 }
 
-#chat .toggle-type-error {
-	background: transparent;
-}
-
+/* This applies to images of preview-type-image and thumbnails of preview-type-link */
 #chat .toggle-content img {
 	max-width: 100%;
 	max-height: 128px;
 	display: block;
+	cursor: zoom-in;
 }
 
-#chat .prefetch-error {
+#chat .toggle-content pre.prefetch-error {
+	padding: 0;
+	margin: 0;
+	color: inherit;
+	background-color: transparent;
+}
+
+#chat .toggle-content .prefetch-error {
 	display: none;
 }
 
+#chat .toggle-content.opened .prefetch-error {
+	display: inline;
+}
+
+/* This applies to thumbnails of preview-type-link only */
 #chat .toggle-content .thumb {
-	max-width: 48px;
-	max-height: 38px;
+	max-height: 54px;
+	max-width: 96px;
 }
 
-#chat .toggle-thumbnail {
-	padding: 6px;
+#chat .toggle-type-error,
+#chat .toggle-content .toggle-text {
+	padding: 8px 10px;
 }
 
-#chat .toggle-text {
-	padding: 6px;
-	min-width: 0;
-	display: flex;
-	flex-direction: column;
+#chat .toggle-content .toggle-text {
 	white-space: nowrap;
-	color: inherit;
-}
-
-#chat .toggle-text:not(:first-child) {
-	padding-left: 0;
-}
-
-#chat .toggle-content .head,
-#chat .toggle-content .body {
-	text-overflow: ellipsis;
 	overflow: hidden;
-	color: inherit;
+}
+
+#chat .toggle-content.opened .toggle-text {
+	white-space: normal;
 }
 
 #chat .toggle-content .head {
+	display: flex;
+	align-items: flex-start;
 	font-weight: bold;
+	color: #222;
 }
 
-#chat .toggle-content .body {
-	color: #999;
+#chat .toggle-type-error,
+#chat .toggle-text .body {
+	color: #717171;
+}
+
+#chat .toggle-text a {
+	color: inherit;
+}
+
+#chat .toggle-text .overflowable {
+	text-overflow: ellipsis;
+	overflow: hidden;
+	flex-grow: 1;
+}
+
+#chat .toggle-content .more {
+	color: #50a656;
+	font-weight: normal;
+	margin-left: 10px;
+	flex-shrink: 0;
+}
+
+#chat .toggle-content .more::after {
+	content: attr(aria-label);
+}
+
+#chat .toggle-content .more-caret {
+	display: inline-block;
+	transition: transform 0.2s;
+}
+
+#chat .toggle-content .more-caret::before {
+	content: "\f0da"; /* https://fontawesome.com/icons/caret-right?style=solid */
 }
 
 #chat .toggle-content.show {
 	display: inline-flex !important;
+	align-items: flex-start;
 }
 
 #chat audio {
@@ -2322,6 +2360,11 @@ part/quit messages where we don't load previews (adds a blank line otherwise) */
 	#chat .header .title {
 		padding-left: 6px;
 	}
+
+	#chat .toggle-content .thumb {
+		max-height: 58px;
+		max-width: 104px;
+	}
 }
 
 @media (max-width: 479px) {

client/js/lounge.js

@@ -49,6 +49,7 @@ $(function() {
 
 		slideoutMenu.toggle(isOpen);
 		storeSidebarVisibility("thelounge.state.sidebar", isOpen);
+		utils.togglePreviewMoreButtonsIfNeeded();
 	});
 
 	viewport.on("click", ".rt", function() {
@@ -57,6 +58,7 @@ $(function() {
 		viewport.toggleClass("rt", isOpen);
 		chat.find(".chan.active .chat").trigger("keepToBottom");
 		storeSidebarVisibility("thelounge.state.userlist", isOpen);
+		utils.togglePreviewMoreButtonsIfNeeded();
 
 		return false;
 	});
@@ -252,6 +254,8 @@ $(function() {
 			if (!keepSidebarOpen && $(window).outerWidth() < utils.mobileViewportPixels) {
 				slideoutMenu.toggle(false);
 			}
+
+			utils.togglePreviewMoreButtonsIfNeeded();
 		}
 
 		const lastActive = $("#windows > .active");

client/js/renderPreview.js

@@ -66,6 +66,26 @@ function appendPreview(preview, msg, template) {
 
 	previewContainer.append(template);
 
+	const moreBtn = previewContainer.find(".more");
+	const previewContent = previewContainer.find(".toggle-content")[0];
+
+	const showMoreIfNeeded = () => {
+		if (preview.type === "link") {
+			const isVisible = moreBtn.is(":visible");
+			const shouldShow = previewContent.offsetWidth >= previewContainer[0].offsetWidth;
+
+			if (!isVisible && shouldShow) {
+				moreBtn.show();
+			} else if (isVisible && !shouldShow) {
+				togglePreviewMore(moreBtn, false);
+				moreBtn.hide();
+			}
+		}
+	};
+
+	$(window).on("resize", showMoreIfNeeded);
+	window.requestAnimationFrame(showMoreIfNeeded);
+
 	if (activeChannelId === channelId) {
 		container.trigger("keepToBottom");
 	}
@@ -97,6 +117,24 @@ $("#chat").on("click", ".text .toggle-button", function() {
 	}
 });
 
+$("#chat").on("click", ".toggle-content .more", function() {
+	togglePreviewMore($(this));
+	return false;
+});
+
+function togglePreviewMore(moreBtn, state = undefined) {
+	moreBtn.closest(".toggle-content").toggleClass("opened", state);
+	const isExpanded = moreBtn.closest(".toggle-content").hasClass("opened");
+
+	moreBtn.attr("aria-expanded", isExpanded);
+
+	if (isExpanded) {
+		moreBtn.attr("aria-label", moreBtn.data("opened-text"));
+	} else {
+		moreBtn.attr("aria-label", moreBtn.data("closed-text"));
+	}
+}
+
 /* Image viewer */
 
 const imageViewer = $("#image-viewer");

client/js/utils.js

@@ -23,6 +23,7 @@ module.exports = {
 	toggleNickEditor,
 	toggleNotificationMarkers,
 	requestIdleCallback,
+	togglePreviewMoreButtonsIfNeeded,
 };
 
 function findCurrentNetworkChan(name) {
@@ -141,3 +142,8 @@ function requestIdleCallback(callback, timeout) {
 		callback();
 	}
 }
+
+// Force handling preview display
+function togglePreviewMoreButtonsIfNeeded() {
+	window.requestAnimationFrame(() => $(window).trigger("resize"));
+}

client/views/msg_preview.tpl

@@ -23,10 +23,31 @@
 				<img src="{{thumb}}" decoding="async" alt="" class="thumb">
 			</a>
 		{{/if}}
-		<a class="toggle-text" href="{{link}}" target="_blank" rel="noopener">
-			<div class="head" title="{{head}}">{{head}}</div>
-			<div class="body" title="{{body}}">{{body}}</div>
-		</a>
+		<div class="toggle-text">
+			<div class="head">
+				<div class="overflowable">
+					<a href="{{link}}" target="_blank" rel="noopener" title="{{head}}">
+						{{head}}
+					</a>
+				</div>
+
+				<button class="more"
+					aria-expanded="false"
+					aria-label="More"
+					data-closed-text="More"
+					data-opened-text="Less"
+				>
+					<span class="more-caret"></span>
+				</button>
+			</div>
+
+			<div class="body overflowable">
+				<a href="{{link}}" target="_blank" rel="noopener" title="{{body}}">
+					{{body}}
+				</a>
+			</div>
+			</a>
+		</div>
 	{{/equal}}
 	{{#equal type "error"}}
 		{{#equal error "image-too-big"}}
@@ -38,12 +59,24 @@
 			</em>
 		{{/equal}}
 		{{#equal error "message"}}
-			<em>
-				There was an error loading preview for this link.
-				<a href="{{link}}" target="_blank" rel="noopener">Click here</a>
-				to open it in a new window.
-				<small class="prefetch-error">({{message}})</small>
-			</em>
+			<div>
+				<em>
+					A preview could not be loaded.
+					<a href="{{link}}" target="_blank" rel="noopener">Click here</a>
+					to open it in a new window.
+				</em>
+				<br>
+				<pre class="prefetch-error">{{message}}</pre>
+			</div>
+
+			<button class="more"
+				aria-expanded="false"
+				aria-label="More"
+				data-closed-text="More"
+				data-opened-text="Less"
+			>
+				<span class="more-caret"></span>
+			</button>
 		{{/equal}}
 	{{/equal}}
 </div>