Added scroll interaction on the ruler & minor style improvement

[kyasbal]

This PR adds the wheel event handling on ruler component to make interaction on timeline component have backward-compatibility. This also includes minor style improvement especially around user interactions.

[gemini-code-assist]

Summary of Changes

Hello @kyasbal, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the timeline component by introducing scroll-based interaction on the ruler, which improves user experience and maintains backward compatibility for timeline navigation. Concurrently, it refines several UI elements through minor style improvements, focusing on color consistency, clearer user hints, and more robust border rendering, making the interface more intuitive and visually cohesive.

Highlights

• Ruler Scroll Interaction: Implemented wheel event handling on the timeline ruler component to enable scrolling for timeline interaction, ensuring backward compatibility. This includes emitting scroll events and managing a scalingMode state based on mouse entry/exit on the ruler.
• Dynamic Timeline Hint Message: Updated the timeline corner indicator to dynamically display context-sensitive hints for scaling or moving time. The message now changes based on whether the user is in scaling mode, providing clearer guidance.
• Styling Refinements and Consistency: Refactored color definitions in style-model.ts to use direct RGBA arrays for highlight tints and updated SCSS to leverage Angular Material color palettes for better consistency. Additionally, a new mixin was introduced for more robust dashed border rendering, and minor adjustments were made to element styling, such as removing a box-shadow and adding default left borders to subresources.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request successfully adds wheel event handling on the ruler component for backward compatibility and introduces several nice style improvements. The implementation for the new scroll interaction is well-done, using runOutsideAngular for performance and properly cleaning up event listeners. The style enhancements, such as using Material theme colors and refactoring CSS into a mixin, improve the codebase.

I've found one high-severity issue regarding a contradictory UI hint that could confuse users, and one medium-severity suggestion to improve code readability by replacing magic numbers with named constants. After addressing these points, the PR should be in great shape.