Objective

Add an optional smooth cursor movement animation to make cursor position
changes easier to follow, especially during larger jumps and
multi-cursor editing.

Related to #4991.

Solution

• Add a new cursor_animation.enabled editor setting, disabled by
  default.
• Animate local bar and block cursors using a damped spring while
  preserving momentum during rapid cursor movement.
• Support multiple local cursors independently.
• Continue using the cursor color provided by the active theme.
• Snap immediately when scrolling, resizing, or other viewport changes
  would make interpolation misleading.
• Respect the reduce_motion setting.
• Request animation frames only while an enabled cursor animation is
  active.

Enabling the feature causes additional editor redraws while the cursor
is moving, so it is opt-in and the performance cost is mentioned in the
setting documentation.

Attribution

The cursor spring physics and four-corner deformation algorithm are
adapted from
vscode-neovide-cursor,
which is available under the MIT License and inspired by Neovide.

The implementation adapts the algorithm to Zed's editor and GPUI
architecture, including viewport handling, selection state
reconciliation, multi-cursor support, theme integration, and
reduced-motion behavior. The attribution and license information are
also retained in the source file.

Testing

Automated checks run on Windows:

• cargo fmt --all --check
• cargo test -p editor cursor_animation --lib
  • 15 cursor animation tests passed.

The tests cover:

• Spring convergence.
• Short and long cursor movements.
• Mid-animation retargeting and momentum preservation.
• Multiple independent cursors.
• Selection replacement and state cleanup.
• Viewport and scroll changes.
• Invalid or unusually large timing values.
• Supported cursor shapes.

To test manually:

1. Add the following to the settings file:

   "cursor_animation": {
     "enabled": true
   }

2. Move the cursor using typing, arrow keys, mouse clicks, and
   multi-cursor actions.

3. Toggle the setting off and confirm that cursor rendering immediately
   returns to its normal behavior.

Manual testing was performed on Windows and Linux using a release build
from this exact PR branch.

Verified that:

• Cursor animation is disabled by default.
• Enabling cursor_animation.enabled is hot-reloaded without restarting
  Zed.
• Disabling the setting immediately restores the original cursor
  behavior.
• Cursor movement remains responsive during typing, keyboard navigation,
  and mouse navigation.

This exact PR branch has not yet been manually tested on macOS.

Self-Review Checklist:

• I've reviewed my own diff for quality, security, and reliability
• Unsafe blocks (if any) have justifying comments
• The content adheres to Zed's UI standards
  (UX/UI
  and
  icon
  guidelines)
• Tests cover the new/changed behavior
• Performance impact has been considered and is acceptable

Showcase

Release Notes:

• Added an optional cursor movement animation setting.

Co-authored-by: Christopher Biscardi chris@christopherbiscardi.com