Programming exercises: Remember scrolling position when switching between files in the online editor

[chrisknedl]

Checklist

General

• I tested all changes and their related features with all corresponding user types on a test server.
• This is a small issue that I tested locally and was confirmed by another developer on a test server.
• Language: I followed the guidelines for inclusive, diversity-sensitive, and appreciative language.
• I chose a title conforming to the naming conventions for pull requests.

Client

• Important: I implemented the changes with a very good performance, prevented too many (unnecessary) REST calls and made sure the UI is responsive, even with large data (e.g. using paging).
• I strictly followed the client coding and design guidelines.
• I added multiple integration tests (Jest) related to the features (with a high test coverage), while following the test guidelines.
• I documented the TypeScript code using JSDoc style.

Motivation and Context

Closes #8402.

Description

The scrollTop attribute is added to the editor file session. It stores the absolute distance from the top of the viewport to the beginning of the file. This makes it possible to restore the scroll positions of files that have been previously looked at in a straightforward way.

Steps for Testing

Prerequisites:

• 1 Instructor
• 1 programming exercise with online editor and manual assessment

1. Open the code editor
2. Scroll down in one of the files in the editor (if necessary, add some text so that you can actually scroll down)
3. Switch to a different file, and go back to the file where you scrolled down
4. It should still show the lines that it showed before switching
   -> Try different files and different scrolling positions
5. Manually assess a programming exercise submission via the assessment dashboard
6. Add inline comments by clicking on the '+' sign on the left of the code editor
7. Repeat steps 2 - 4 for the assessment editor. It should still remember the scroll position correctly.

Testserver States

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Review Progress

Code Review

• Code Review 1
• Code Review 2

Manual Tests

• Test 1
• Test 2

Test Coverage

Client

Class/File	Line Coverage	Confirmation (assert/expect)
code-editor-monaco.component.ts	93.53%	✅
monaco-editor.component.ts	94.87%	✅

Summary by CodeRabbit

• New Features

  • The code editor now remembers and restores the vertical scroll position when navigating between files.
  • New methods added to control the scroll position of the editor externally.

• Bug Fixes

  • Updated tests to ensure the scroll position is correctly managed and verified during file selection and other operations.

• Tests

  • Enhanced test suite to include scenarios for the new scroll position functionality.

[coderabbitai]

Walkthrough

The pull request addresses the issue of maintaining scroll positions when switching between files in the Monaco code editor. The changes involve updating the FileSession type to include a scrollTop property, which tracks the vertical scroll position for each file. New methods are introduced in the CodeEditorMonacoComponent and MonacoEditorComponent to manage and restore scroll positions when navigating between files, ensuring that users can return to their previous scroll location in each file.

Changes

File	Change Summary
src/main/webapp/app/exercises/programming/shared/code-editor/monaco/code-editor-monaco.component.ts	- Updated FileSession type to include scrollTop - Added switchToSelectedFile method - Modified ngOnChanges, selectFileInEditor, and onFileTextChanged to handle scroll position
src/main/webapp/app/shared/monaco-editor/monaco-editor.component.ts	- Added getScrollTop() method - Added setScrollTop(scrollTop: number) method
src/test/javascript/spec/component/code-editor/code-editor-monaco.component.spec.ts	- Updated test cases to include scrollTop property - Added test to verify scroll position persistence

Assessment against linked issues

Objective	Addressed	Explanation
Persist scrolling position when switching files [#8402]	✅
Maintain scroll state across different files	✅
Support scroll position tracking in online editor	✅

Possibly related PRs

• Communication: Remember last scroll position when switching conversations #9614: Enhances scroll position handling in ConversationMessagesComponent
• Plagiarism checks: Fix scrolling issue on side-by-side viewer for modeling #9748: Addresses scrolling issues in the modeling editor
• Communication: Fix scrolling error for long messages #9997: Fixes scrolling error for long messages

Suggested labels

bugfix, ready to merge

Suggested reviewers

• az108
• JohannesStoehr
• coolchock
• egekurt123
• b-fein
• Jan-Thurner

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

src/main/webapp/app/exercises/programming/shared/code-editor/monaco/code-editor-monaco.component.ts (1)

220-224: Consider simplifying the scroll position access.

The null coalescing operator is unnecessary since the scrollTop property is guaranteed to exist in the FileSession type.

-        this.editor().setScrollTop(this.fileSession()[this.selectedFile()!].scrollTop ?? 0);
+        this.editor().setScrollTop(this.fileSession()[selectedFileName].scrollTop);

Also, consider using the selectedFileName parameter instead of this.selectedFile()! for consistency and to avoid the non-null assertion.

📜 Review details

Configuration used: .coderabbit.yaml
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 0d0a9e9 and ff52315.

📒 Files selected for processing (3)

• src/main/webapp/app/exercises/programming/shared/code-editor/monaco/code-editor-monaco.component.ts (4 hunks)
• src/main/webapp/app/shared/monaco-editor/monaco-editor.component.ts (1 hunks)
• src/test/javascript/spec/component/code-editor/code-editor-monaco.component.spec.ts (13 hunks)

🧰 Additional context used

📓 Path-based instructions (3)

src/main/webapp/app/shared/monaco-editor/monaco-editor.component.ts (1)

Pattern src/main/webapp/**/*.ts: angular_style:https://angular.io/guide/styleguide;methods_in_html:false;lazy_loading:true;code_reuse:true;tests:meaningful;types:PascalCase;enums:PascalCase;funcs:camelCase;props:camelCase;no_priv_prefix:true;strings:single_quotes;localize:true;btns:functionality;links:navigation;icons_text:newline;labels:associate;code_style:arrow_funcs,curly_braces,open_braces_same_line,indent_4;memory_leak_prevention:true;routes:naming_schema;chart_framework:ngx-charts;responsive_layout:true

src/test/javascript/spec/component/code-editor/code-editor-monaco.component.spec.ts (1)

Pattern src/test/javascript/spec/**/*.ts: jest: true; mock: NgMocks; bad_practices: avoid_full_module_import; perf_improvements: mock_irrelevant_deps; service_testing: mock_http_for_logic; no_schema: avoid_NO_ERRORS_SCHEMA; expectation_specificity: true; solutions: {boolean: toBeTrue/False, reference: toBe, existence: toBeNull/NotNull, undefined: toBeUndefined, class_obj: toContainEntries/toEqual, spy_calls: {not_called: not.toHaveBeenCalled, once: toHaveBeenCalledOnce, with_value: toHaveBeenCalledWith|toHaveBeenCalledExactlyOnceWith}}

src/main/webapp/app/exercises/programming/shared/code-editor/monaco/code-editor-monaco.component.ts (1)

Pattern src/main/webapp/**/*.ts: angular_style:https://angular.io/guide/styleguide;methods_in_html:false;lazy_loading:true;code_reuse:true;tests:meaningful;types:PascalCase;enums:PascalCase;funcs:camelCase;props:camelCase;no_priv_prefix:true;strings:single_quotes;localize:true;btns:functionality;links:navigation;icons_text:newline;labels:associate;code_style:arrow_funcs,curly_braces,open_braces_same_line,indent_4;memory_leak_prevention:true;routes:naming_schema;chart_framework:ngx-charts;responsive_layout:true

🔇 Additional comments (7)

src/test/javascript/spec/component/code-editor/code-editor-monaco.component.spec.ts (1)

485-497: LGTM! Comprehensive test coverage for scroll position functionality.

The new test case effectively verifies that the scroll position is preserved when switching between files. The test setup is clear and the assertions are precise.

src/main/webapp/app/shared/monaco-editor/monaco-editor.component.ts (1)

192-198: LGTM: Clean implementation of scroll position management.

The new methods provide a clean interface for managing scroll positions in the Monaco editor, properly exposing the underlying Monaco editor's scroll functionality.

src/main/webapp/app/exercises/programming/shared/code-editor/monaco/code-editor-monaco.component.ts (5)

45-45: LGTM: Well-structured type definition.

The FileSession type has been properly extended to include the scrollTop property for tracking scroll positions.

---

160-164: LGTM: Proper scroll position preservation.

The implementation correctly saves the scroll position before switching files, with appropriate null checks for safety.

---

204-207: LGTM: Clean initialization of new file sessions.

New file sessions are properly initialized with default values, including a scroll position of 0.

---

229-234: LGTM: Proper scroll position preservation during content updates.

The implementation correctly preserves the scroll position when updating file content.

---

425-425: LGTM: Proper initialization of new files.

New files are correctly initialized with default values, including a scroll position of 0.

[b-fein]

Code looks good.

Also tested for the manual assessment scenario with many inline feedbacks for the files. They were always rendered in the correct location and the scroll position remained correct when switching back to a file. 👍

Good job, very nice improvement!

[SimonEntholzer]

Works on Ts2, scroll position is stored code editor files for students and during assessment

[sawys777]

Tested on TS3, everything works as described.

[HawKhiem]

Tested on TS1. Everything works as expected

[Cathy0123456789]

Tested on TS1. Works as described, scroll positions are maintained in both scenarios