# Objective

When using column Git blame with avatars enabled, blame entries whose
author name is the longest in the buffer can exceed the blame border.

For example, line 10 of `crates/vim/src/visual.rs` is displayed as
follows:

<img width="998" height="121" alt="issue"
src="https://github.com/user-attachments/assets/eff3e1ff-bd1c-42af-ae9b-da8efb0a7c22"
/>

The blame contents exceeds the width.

The root cause is in the blame width calculation:

https://github.com/zed-industries/zed/blob/0c51c7fd2481859e9da5c490ef8e41ddbcf1a341/crates/editor/src/editor.rs#L11583-L11598
The calculation accounts for the commit SHA, author name, and timestamp.
Other elements, including spacing, margins, and the avatar, are
represented by the fixed `SPACING_WIDTH` constant.

For typical fonts, `ch_advance` is approximately `0.5rem` to `0.6rem`,
so `SPACING_WIDTH` provides approximately `2rem` to `2.4rem` for
non-text content. However, the avatar itself occupies `1rem`:

https://github.com/zed-industries/zed/blob/0c51c7fd2481859e9da5c490ef8e41ddbcf1a341/crates/ui/src/components/avatar.rs#L81
When avatars are displayed, the entry also contains three `0.5rem` gaps
and also one `0.5rem` right margin:

https://github.com/zed-industries/zed/blob/0c51c7fd2481859e9da5c490ef8e41ddbcf1a341/crates/git_ui/src/blame_ui.rs#L170-L188

This requires approximately `3.0rem`, which can exceed the space
provided by `SPACING_WIDTH`. When an entry contains both the longest
author name in the buffer and a long timestamp, its content can
therefore exceed the blame border.

## Solution

The simplest fix would be to increase `SPACING_WIDTH`, but that would
still rely on an approximate conversion between editor character widths
and UI dimensions.

Instead, this PR adds a method to the blame renderer for calculating the
non-text width of a blame entry. The editor uses this value together
with the measured text width when calculating the final blame width.

## Testing

Tested locally. A before-and-after comparison is included below.

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

## Showcase

| Before | After |
| :--: | :--: | 
| <img width="551" height="94" alt="Before"
src="https://github.com/user-attachments/assets/b6741a41-6531-4fae-adaa-f9ae0b298e0f"
/> |<img width="566" height="93" alt="After"
src="https://github.com/user-attachments/assets/e8d75d2a-6b07-43f6-b2a8-bfb76d118611"
/> |

Release Notes:

- Fixed Git blame entries overflowing the gutter when avatars are
displayed.