From 6c2672100d43784d390f6f6fbc632afa7a63d251 Mon Sep 17 00:00:00 2001
From: GCHQ-Developer-847
 <111882109+GCHQ-Developer-847@users.noreply.github.com>
Date: Fri, 7 Feb 2025 15:04:35 +0000
Subject: [PATCH] fix(canary-web-components): update tree view to improve FOUC

Update tree view to prevent FOUC - set tree items visibility to hidden until loaded when inherited
props from tree view used. Removed timeouts on truncation - tree view now truncates when ready
rather than waiting 0.1 seconds to help reduce flashing.
---
 .../components/ic-tree-item/ic-tree-item.tsx  | 11 +++---
 .../__snapshots__/ic-tree-item.spec.ts.snap   | 34 ++++++++---------
 .../components/ic-tree-view/ic-tree-view.css  | 10 +++++
 .../ic-tree-view/ic-tree-view.stories.mdx     |  4 +-
 .../components/ic-tree-view/ic-tree-view.tsx  | 38 +++++++++++++++----
 .../__snapshots__/ic-tree-view.spec.ts.snap   | 32 ++++++++++------
 6 files changed, 85 insertions(+), 44 deletions(-)

diff --git a/packages/canary-web-components/src/components/ic-tree-item/ic-tree-item.tsx b/packages/canary-web-components/src/components/ic-tree-item/ic-tree-item.tsx
index 98ba5860ea..c549ef8c0f 100644
--- a/packages/canary-web-components/src/components/ic-tree-item/ic-tree-item.tsx
+++ b/packages/canary-web-components/src/components/ic-tree-item/ic-tree-item.tsx
@@ -141,9 +141,7 @@ export class TreeItem {
 
   componentWillLoad(): void {
     removeDisabledFalse(this.disabled, this.el);
-  }
 
-  componentDidLoad(): void {
     this.childTreeItems = Array.from((this.el as HTMLElement).children).filter(
       (child) => child.tagName === this.treeItemTag
     ) as HTMLIcTreeItemElement[];
@@ -151,15 +149,13 @@ export class TreeItem {
     if (this.childTreeItems.length > 0) {
       this.isParent = true;
     }
+  }
 
+  componentDidLoad(): void {
     this.setTreeItemPadding();
 
     this.updateAriaLabel();
 
-    setTimeout(() => {
-      this.truncateTreeItem && this.truncateTreeItemLabel(this.el);
-    }, 100);
-
     !isSlotUsed(this.el, "label") &&
       onComponentRequiredPropUndefined(
         [{ prop: this.label, propName: "label" }],
@@ -175,6 +171,9 @@ export class TreeItem {
   }
 
   componentDidUpdate(): void {
+    // Runs on second render - when truncateTreeItem prop has now been applied in the DOM
+    this.truncateTreeItem && this.truncateTreeItemLabel(this.el);
+
     if (this.hasParentExpanded) {
       this.childTreeItems.forEach((child: HTMLIcTreeItemElement) => {
         child.truncateTreeItem && this.truncateTreeItemLabel(child);
diff --git a/packages/canary-web-components/src/components/ic-tree-item/test/basic/__snapshots__/ic-tree-item.spec.ts.snap b/packages/canary-web-components/src/components/ic-tree-item/test/basic/__snapshots__/ic-tree-item.spec.ts.snap
index 533fd3c441..1671c58653 100644
--- a/packages/canary-web-components/src/components/ic-tree-item/test/basic/__snapshots__/ic-tree-item.spec.ts.snap
+++ b/packages/canary-web-components/src/components/ic-tree-item/test/basic/__snapshots__/ic-tree-item.spec.ts.snap
@@ -1,9 +1,9 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 exports[`ic-tree-item component should render 1`] = `
-<ic-tree-item aria-disabled="false" class="ic-tree-item-dark" id="ic-tree-item-0" label="Item 1">
+<ic-tree-item id="ic-tree-item-0" label="Item 1">
   <mock:shadow-root>
-    <div class="ic-tree-item-single tree-item-content" tabindex="0">
+    <div aria-disabled="false" aria-live="polite" class="tree-item-content" tabindex="0">
       <ic-typography class="tree-item-label">
         Item 1
       </ic-typography>
@@ -13,7 +13,7 @@ exports[`ic-tree-item component should render 1`] = `
 `;
 
 exports[`ic-tree-item component should render disabled 1`] = `
-<ic-tree-item class="ic-tree-item-dark ic-tree-item-disabled" disabled="true" id="ic-tree-item-0" label="Item 1">
+<ic-tree-item class="ic-tree-item-disabled" disabled="true" id="ic-tree-item-6" label="Item 1">
   <mock:shadow-root>
     <div aria-disabled="true" aria-live="polite" class="tree-item-content" tabindex="-1">
       <ic-typography class="tree-item-label">
@@ -25,7 +25,7 @@ exports[`ic-tree-item component should render disabled 1`] = `
 `;
 
 exports[`ic-tree-item component should render disabled: disabled-removed 1`] = `
-<ic-tree-item class="ic-tree-item-dark" id="ic-tree-item-0" label="Item 1">
+<ic-tree-item id="ic-tree-item-6" label="Item 1">
   <mock:shadow-root>
     <div aria-disabled="false" aria-live="polite" class="tree-item-content" tabindex="0">
       <ic-typography class="tree-item-label">
@@ -37,9 +37,9 @@ exports[`ic-tree-item component should render disabled: disabled-removed 1`] = `
 `;
 
 exports[`ic-tree-item component should render selected 1`] = `
-<ic-tree-item aria-disabled="false" class="ic-tree-item-dark ic-tree-item-selected" id="ic-tree-item-7" label="Item 1" selected="true">
+<ic-tree-item class="ic-tree-item-selected" id="ic-tree-item-7" label="Item 1" selected="true">
   <mock:shadow-root>
-    <div class="ic-tree-item-single tree-item-content" tabindex="0">
+    <div aria-disabled="false" aria-live="polite" class="tree-item-content" tabindex="0">
       <ic-typography class="tree-item-label">
         Item 1
       </ic-typography>
@@ -49,9 +49,9 @@ exports[`ic-tree-item component should render selected 1`] = `
 `;
 
 exports[`ic-tree-item component should render with child tree items 1`] = `
-<ic-tree-item aria-disabled="false" class="ic-tree-item-dark" id="ic-tree-item-2" label="Item 1">
+<ic-tree-item id="ic-tree-item-2" label="Item 1">
   <mock:shadow-root>
-    <div class="tree-item-content" tabindex="0">
+    <div aria-disabled="false" aria-live="polite" class="tree-item-content" tabindex="0">
       <span aria-hidden="true" class="arrow-dropdown">
         svg
       </span>
@@ -60,18 +60,18 @@ exports[`ic-tree-item component should render with child tree items 1`] = `
       </ic-typography>
     </div>
   </mock:shadow-root>
-  <ic-tree-item aria-disabled="false" class="ic-tree-item-dark" id="ic-tree-item-3" label="Item 1.1">
+  <ic-tree-item id="ic-tree-item-3" label="Item 1.1">
     <mock:shadow-root>
-      <div class="ic-tree-item-single tree-item-content" tabindex="0">
+      <div aria-disabled="false" aria-live="polite" class="ic-tree-item-single tree-item-content" tabindex="0" style="padding-left: calc(var(--ic-space-xs) + 48px;">
         <ic-typography class="tree-item-label">
           Item 1.1
         </ic-typography>
       </div>
     </mock:shadow-root>
   </ic-tree-item>
-  <ic-tree-item aria-disabled="false" class="ic-tree-item-dark" id="ic-tree-item-4" label="Item 1.2">
+  <ic-tree-item id="ic-tree-item-4" label="Item 1.2">
     <mock:shadow-root>
-      <div class="ic-tree-item-single tree-item-content" tabindex="0">
+      <div aria-disabled="false" aria-live="polite" class="ic-tree-item-single tree-item-content" tabindex="0" style="padding-left: calc(var(--ic-space-xs) + 48px;">
         <ic-typography class="tree-item-label">
           Item 1.2
         </ic-typography>
@@ -82,9 +82,9 @@ exports[`ic-tree-item component should render with child tree items 1`] = `
 `;
 
 exports[`ic-tree-item component should render with icon 1`] = `
-<ic-tree-item aria-disabled="false" class="ic-tree-item-dark" id="ic-tree-item-1" label="Item 1">
+<ic-tree-item id="ic-tree-item-1" label="Item 1">
   <mock:shadow-root>
-    <div class="ic-tree-item-single tree-item-content" tabindex="0">
+    <div aria-disabled="false" aria-live="polite" class="tree-item-content" tabindex="0">
       <div class="icon-container">
         <slot name="icon"></slot>
       </div>
@@ -101,7 +101,7 @@ exports[`ic-tree-item component should render with icon 1`] = `
 `;
 
 exports[`ic-tree-item component should render with router item slot 1`] = `
-<ic-tree-item aria-disabled="false" class="ic-tree-item-dark" id="ic-tree-item-5" label="Item 1">
+<ic-tree-item id="ic-tree-item-5" label="Item 1">
   <mock:shadow-root>
     <slot name="router-item"></slot>
   </mock:shadow-root>
@@ -112,9 +112,9 @@ exports[`ic-tree-item component should render with router item slot 1`] = `
 `;
 
 exports[`ic-tree-item component should render with slotted label 1`] = `
-<ic-tree-item aria-disabled="false" class="ic-tree-item-dark" id="ic-tree-item-8">
+<ic-tree-item id="ic-tree-item-8">
   <mock:shadow-root>
-    <div class="ic-tree-item-single tree-item-content" tabindex="0">
+    <div aria-disabled="false" aria-live="polite" class="tree-item-content" tabindex="0">
       <ic-typography class="ic-typography-body tree-item-label">
         <mock:shadow-root>
           <slot></slot>
diff --git a/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.css b/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.css
index 6bf7441361..c6d5045f2b 100644
--- a/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.css
+++ b/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.css
@@ -42,6 +42,7 @@
 
 .icon-container {
   width: var(--ic-space-lg);
+  min-width: var(--ic-space-lg);
   height: var(--ic-space-lg);
   margin: 0 var(--ic-space-xs) 0 0;
 }
@@ -60,6 +61,15 @@
   overflow: hidden;
 }
 
+/* Ensures truncation works - accounts for text width increase as component hydrates */
+.tree-view-header.with-padding {
+  padding-right: var(--ic-space-xs);
+}
+
+.tree-items-container-hidden {
+  visibility: hidden;
+}
+
 ::slotted([slot="icon"]) {
   fill: var(--ic-tree-view-icon);
 }
diff --git a/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.stories.mdx b/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.stories.mdx
index 9fbf66e437..c10ccd0c94 100644
--- a/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.stories.mdx
+++ b/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.stories.mdx
@@ -597,7 +597,7 @@ An example with truncated tree items. When the heading/label exceeds the width o
               d="M10,4H4C2.89,4 2,4.89 2,6V18A2,2 0 0,0 4,20H20A2,2 0 0,0 22,18V8C22,6.89 21.1,6 20,6H12L10,4Z"
             />
           </svg>
-          <ic-tree-item label="Coffee">
+          <ic-tree-item label="Coffee" expanded="true">
             <svg
               slot="icon"
               xmlns="http://www.w3.org/2000/svg"
@@ -613,7 +613,7 @@ An example with truncated tree items. When the heading/label exceeds the width o
             ></ic-tree-item>
             <ic-tree-item label="Espresso"></ic-tree-item>
           </ic-tree-item>
-          <ic-tree-item label="Tea">
+          <ic-tree-item label="Tea" expanded="true">
             <ic-tree-item label="Earl Grey"></ic-tree-item>
             <ic-tree-item
               label="Earl Grey with truncation false"
diff --git a/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.tsx b/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.tsx
index 7e1abe443d..476b23e509 100644
--- a/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.tsx
+++ b/packages/canary-web-components/src/components/ic-tree-view/ic-tree-view.tsx
@@ -31,6 +31,7 @@ export class TreeView {
   private treeViewId = `ic-tree-view-${treeViewIds++}`;
   private treeItemTag = "IC-TREE-ITEM";
   private hostMutationObserver: MutationObserver = null;
+  private isLoaded = false;
 
   @Element() el: HTMLIcTreeViewElement;
 
@@ -106,9 +107,7 @@ export class TreeView {
     this.watchThemeHandler();
     this.watchTruncateTreeItemsHandler();
 
-    setTimeout(() => {
-      this.truncateHeading && this.truncateTreeViewHeading();
-    }, 100);
+    this.truncateHeading && this.truncateTreeViewHeading();
 
     this.addSlotChangeListener();
 
@@ -118,6 +117,8 @@ export class TreeView {
     this.hostMutationObserver.observe(this.el, {
       childList: true,
     });
+
+    this.isLoaded = true;
   }
 
   @Listen("icTreeItemSelected")
@@ -294,7 +295,15 @@ export class TreeView {
   };
 
   render() {
-    const { heading, size, theme } = this;
+    const {
+      focusInset,
+      heading,
+      isLoaded,
+      size,
+      theme,
+      truncateHeading,
+      truncateTreeItems,
+    } = this;
 
     return (
       <Host
@@ -302,7 +311,7 @@ export class TreeView {
         class={{
           [`ic-tree-view-${size}`]: size !== "medium",
           [`ic-theme-${theme}`]: theme !== "inherit",
-          "ic-tree-view-truncate": this.truncateHeading,
+          "ic-tree-view-truncate": truncateHeading,
         }}
         onKeyDown={this.handleKeyDown}
         aria-label={this.isHeadingDefined() ? heading : null}
@@ -314,7 +323,13 @@ export class TreeView {
                 <slot name="icon" />
               </div>
             )}
-            <ic-typography variant="subtitle-large" class="tree-view-header">
+            <ic-typography
+              variant="subtitle-large"
+              class={{
+                "tree-view-header": true,
+                "with-padding": this.truncateHeading && !isLoaded,
+              }}
+            >
               {isSlotUsed(this.el, "heading") ? (
                 <slot name="heading" />
               ) : (
@@ -323,7 +338,16 @@ export class TreeView {
             </ic-typography>
           </div>
         )}
-        <slot></slot>
+        <div
+          // Hide tree items until fully loaded with props passed down from tree view - prevents FOUC
+          class={{
+            "tree-items-container-hidden":
+              (focusInset || size !== "medium" || truncateTreeItems) &&
+              !isLoaded,
+          }}
+        >
+          <slot></slot>
+        </div>
       </Host>
     );
   }
diff --git a/packages/canary-web-components/src/components/ic-tree-view/test/basic/__snapshots__/ic-tree-view.spec.ts.snap b/packages/canary-web-components/src/components/ic-tree-view/test/basic/__snapshots__/ic-tree-view.spec.ts.snap
index 4c3e24b538..f86899f4df 100644
--- a/packages/canary-web-components/src/components/ic-tree-view/test/basic/__snapshots__/ic-tree-view.spec.ts.snap
+++ b/packages/canary-web-components/src/components/ic-tree-view/test/basic/__snapshots__/ic-tree-view.spec.ts.snap
@@ -1,20 +1,22 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 exports[`ic-tree-view component should render 1`] = `
-<ic-tree-view class="ic-tree-view-dark" context-id="ic-tree-view-0" heading="Heading">
+<ic-tree-view aria-label="Heading" context-id="ic-tree-view-0" heading="Heading">
   <mock:shadow-root>
     <div class="heading-area-container">
       <ic-typography class="tree-view-header" variant="subtitle-large">
         Heading
       </ic-typography>
     </div>
-    <slot></slot>
+    <div>
+      <slot></slot>
+    </div>
   </mock:shadow-root>
 </ic-tree-view>
 `;
 
 exports[`ic-tree-view component should render with icon 1`] = `
-<ic-tree-view class="ic-tree-view-dark" context-id="ic-tree-view-1" heading="Heading">
+<ic-tree-view aria-label="Heading" context-id="ic-tree-view-1" heading="Heading">
   <mock:shadow-root>
     <div class="heading-area-container">
       <div class="icon-container">
@@ -24,7 +26,9 @@ exports[`ic-tree-view component should render with icon 1`] = `
         Heading
       </ic-typography>
     </div>
-    <slot></slot>
+    <div>
+      <slot></slot>
+    </div>
   </mock:shadow-root>
   <svg fill="#000000" height="24px" slot="icon" viewBox="0 0 24 24" width="24px" xmlns="http://www.w3.org/2000/svg">
     <path d="M0 0h24v24H0V0z" fill="none"></path>
@@ -34,7 +38,7 @@ exports[`ic-tree-view component should render with icon 1`] = `
 `;
 
 exports[`ic-tree-view component should render with slotted heading 1`] = `
-<ic-tree-view class="ic-tree-view-dark" context-id="ic-tree-view-3">
+<ic-tree-view context-id="ic-tree-view-3">
   <mock:shadow-root>
     <div class="heading-area-container">
       <ic-typography class="ic-typography-subtitle-large tree-view-header">
@@ -44,7 +48,9 @@ exports[`ic-tree-view component should render with slotted heading 1`] = `
         <slot name="heading"></slot>
       </ic-typography>
     </div>
-    <slot></slot>
+    <div>
+      <slot></slot>
+    </div>
   </mock:shadow-root>
   <ic-typography class="ic-typography-subtitle-large" slot="heading" variant="subtitle-large">
     <mock:shadow-root>
@@ -56,27 +62,29 @@ exports[`ic-tree-view component should render with slotted heading 1`] = `
 `;
 
 exports[`ic-tree-view component should render with tree items 1`] = `
-<ic-tree-view class="ic-tree-view-dark" context-id="ic-tree-view-2" heading="Heading">
+<ic-tree-view aria-label="Heading" context-id="ic-tree-view-2" heading="Heading">
   <mock:shadow-root>
     <div class="heading-area-container">
       <ic-typography class="tree-view-header" variant="subtitle-large">
         Heading
       </ic-typography>
     </div>
-    <slot></slot>
+    <div>
+      <slot></slot>
+    </div>
   </mock:shadow-root>
-  <ic-tree-item aria-disabled="false" class="ic-tree-item-dark" context-id="ic-tree-view-2" id="ic-tree-item-0" label="Item 1">
+  <ic-tree-item context-id="ic-tree-view-2" id="ic-tree-item-0" label="Item 1">
     <mock:shadow-root>
-      <div class="ic-tree-item-single tree-item-content" tabindex="0">
+      <div aria-disabled="false" aria-live="polite" class="tree-item-content" tabindex="0">
         <ic-typography class="tree-item-label">
           Item 1
         </ic-typography>
       </div>
     </mock:shadow-root>
   </ic-tree-item>
-  <ic-tree-item aria-disabled="false" class="ic-tree-item-dark" context-id="ic-tree-view-2" id="ic-tree-item-1" label="Item 2">
+  <ic-tree-item context-id="ic-tree-view-2" id="ic-tree-item-1" label="Item 2">
     <mock:shadow-root>
-      <div class="ic-tree-item-single tree-item-content" tabindex="0">
+      <div aria-disabled="false" aria-live="polite" class="tree-item-content" tabindex="0">
         <ic-typography class="tree-item-label">
           Item 2
         </ic-typography>