Add horizontal scrolling to IDE component on small viewports (#897)

* added horizontal scroll to editor content

* added horizontal scroll to editor tabs

* scroll to active tab when active tab changes

* mock scrollIntoView

* update snapshots

* add changeset

* only scroll in inline direction

* remove debug line

.changeset/thirty-swans-yawn.md

@@ -0,0 +1,5 @@
+---
+'@primer/react-brand': patch
+---
+
+Added horizontal scrolling to `IDE` component when viewed on small viewports

packages/react/src/IDE/IDE.module.css

@@ -1,4 +1,5 @@
 .IDE__inner {
+  --brand-IDE-lineNumber-width: 45px;
   background: var(--brand-IDE-default-bgColor);
   border: var(--brand-borderWidth-thin) solid var(--brand-IDE-borderColor);
 }
@@ -170,10 +171,11 @@
 }
 
 .IDE--default .IDE__Editor {
-  margin-left: var(--base-size-20);
+  padding-left: var(--base-size-20);
 }
 
 .IDE__Editor-tabs {
+  overflow-x: auto;
   display: inline-flex;
   background: var(--brand-IDE-default-editor-tabs-bgColor);
 }
@@ -187,6 +189,7 @@
 }
 
 .IDE__Editor-tab {
+  flex-shrink: 0;
   display: flex;
   padding: var(--base-size-8) var(--base-size-12);
   align-items: center;
@@ -262,6 +265,7 @@ img.IDE__Editor-tab-icon {
 .IDE__Editor-content {
   height: 100%;
   padding-top: var(--base-size-16);
+  overflow-x: auto;
 }
 
 .IDE--default .IDE__Editor-content {
@@ -281,6 +285,14 @@ img.IDE__Editor-tab-icon {
   margin: 0;
 }
 
+.IDE__Editor-content-wrapper {
+  display: flex;
+}
+
+.IDE__Editor-content-inner {
+  flex: 1;
+}
+
 .IDE__Editor--small .IDE__Editor-pane,
 .IDE__Editor--small .IDE__Editor-lineNumbers {
   font-size: calc(var(--base-size-12) - 1px) !important; /* workaround dotcom specificity */
@@ -300,18 +312,19 @@ img.IDE__Editor-tab-icon {
 }
 
 .IDE__Editor-pane--suggested {
+  margin-left: calc(-1 * var(--base-size-64));
+  padding-left: calc((var(--base-size-64) * 2) - var(--brand-IDE-lineNumber-width)) !important;
   background-color: var(--brand-IDE-autoSuggestLine-bgColor);
 }
 
 .IDE__Editor-lineNumbers {
-  position: absolute;
   z-index: 1;
   font-family: var(--brand-fontStack-monospace);
   font-weight: var(--brand-text-weight-200);
   font-feature-settings: 'liga' 0, 'calt' 0;
   font-variation-settings: normal;
   letter-spacing: 0;
-  width: 45px;
+  flex: 0 0 var(--brand-IDE-lineNumber-width);
 }
 
 .IDE__Editor-lineNumber {
@@ -341,20 +354,17 @@ img.IDE__Editor-tab-icon {
 .IDE__Editor pre {
   color: var(--brand-color-text-default);
   font-family: var(--brand-fontStack-monospace);
-  padding-left: var(--base-size-64);
+  padding-left: calc(var(--base-size-64) - var(--brand-IDE-lineNumber-width));
 }
 
 pre.IDE__Chat-copilot-indicator {
   background-color: var(--brand-IDE-autoSuggest-bgColor);
   padding-left: 0;
-  position: absolute;
   display: inline-flex;
   padding: var(--base-size-8) var(--base-size-24);
   border-radius: var(--brand-borderRadius-small);
   gap: var(--base-size-16);
-  margin: 0;
-  margin-left: 60px;
-  margin-top: var(--base-size-4);
+  margin: var(--base-size-4) 0 0 var(--base-size-16);
 
   box-shadow: -9px 10px 39px 0px rgba(0, 0, 0, 0.25);
 }

packages/react/src/IDE/IDE.module.css.d.ts

@@ -23,6 +23,8 @@ declare const styles: {
   readonly "IDE__Editor-tab-icon": string;
   readonly "IDE__Editor-content": string;
   readonly "IDE__Editor-pane": string;
+  readonly "IDE__Editor-content-wrapper": string;
+  readonly "IDE__Editor-content-inner": string;
   readonly "IDE__Editor--small": string;
   readonly "IDE__Editor-lineNumbers": string;
   readonly "IDE__Editor--medium": string;

packages/react/src/IDE/IDE.test.tsx

@@ -39,7 +39,14 @@ describe('IDE', () => {
     {name: 'File 3', alternativeText: 'Alt for File 3', code: 'Code for File 3'},
   ]
 
-  afterEach(cleanup)
+  beforeEach(() => {
+    Element.prototype.scrollIntoView = jest.fn()
+  })
+
+  afterEach(() => {
+    cleanup()
+    jest.clearAllMocks()
+  })
 
   it('renders main elements correctly into the document', () => {
     const {getByTestId} = render(

packages/react/src/IDE/IDE.tsx

@@ -16,7 +16,7 @@ import React, {
 
 import {Avatar, Button, Text, TextInput} from '..'
 import type {BaseProps} from '../component-helpers'
-import {useTabs} from '../hooks/useTabs'
+import {useTabs, type OnTabActivate} from '../hooks/useTabs'
 
 /**
  * Design tokens
@@ -404,9 +404,13 @@ const _Editor = memo(
         setTimeouts(prev => [...prev, animationEndTimeout])
       }, [hasAnimated, isAnimating])
 
-      const onTabActivate = useCallback(() => {
-        resetAnimation()
-      }, [resetAnimation])
+      const onTabActivate = useCallback<OnTabActivate>(
+        (_, activeTabRef) => {
+          activeTabRef?.scrollIntoView({behavior: 'smooth', block: 'nearest', inline: 'start'})
+          resetAnimation()
+        },
+        [resetAnimation],
+      )
 
       const tabs = useTabs({
         defaultTab: activeTab.toString(),
@@ -454,7 +458,7 @@ const _Editor = memo(
             {files.map((file, fileIndex) => (
               <div {...tabs.getTabPanelProps(fileIndex.toString())} key={file.name}>
                 <span className="visually-hidden">{file.alternativeText}</span>
-                <div aria-hidden="true">
+                <div className={styles['IDE__Editor-content-wrapper']} aria-hidden="true">
                   {showLineNumbers && (
                     <div className={styles['IDE__Editor-lineNumbers']}>
                       {(Array.isArray(file.code) ? file.code : file.code.split('\n')).map((_, index) => (
@@ -467,6 +471,7 @@ const _Editor = memo(
                   <div
                     ref={tabs.activeTab === fileIndex.toString() ? presRef : null}
                     data-testid={testIds.editorContent}
+                    className={styles['IDE__Editor-content-inner']}
                   >
                     {Array.isArray(file.code) ? (
                       (file.code as string[]).map((line, index) => {

packages/react/src/hooks/useTabs.ts

@@ -1,27 +1,27 @@
 import {useCallback, useState, useRef, type HTMLAttributes, type KeyboardEvent} from 'react'
 import {useId} from '../hooks/useId'
 
-type TabOrientation = 'horizontal' | 'vertical'
+export type OnTabActivate = (id: string, activeTabRef?: HTMLElement) => void
 
-type UseTabsOptions = {
+export type UseTabsOptions = {
   defaultTab?: string
   autoActivate?: boolean
-  onTabActivate?: (id: string) => void
-  orientation?: TabOrientation
+  onTabActivate?: OnTabActivate
+  orientation?: 'horizontal' | 'vertical'
 }
 
-type TabState = {
+export type TabState = {
   activeTab: string | null
   focusedTab: string | null
   tabs: Set<string>
 }
 
-type TabListProps = {
+export type TabListProps = {
   label?: string
   labelledBy?: string
 }
 
-type UseTabs = {
+export type UseTabs = {
   activeTab: string | null
   focusedTab: string | null
   activateTab: (id: string) => void
@@ -50,7 +50,7 @@ export const useTabs = ({
         const nextState = updater(prev)
 
         if (nextState.activeTab && nextState.activeTab !== prev.activeTab) {
-          onTabActivate?.(nextState.activeTab)
+          onTabActivate?.(nextState.activeTab, tabRefs.current.get(nextState.activeTab))
         }
 
         return nextState