Antonio Scandurra
f576ec7a15
Fixes #44997 ## Summary Optimizes editor rendering when an editor is partially clipped by a parent container (e.g., a `List`). The editor now only lays out and renders lines that are actually visible within the viewport, rather than all lines in the document. ## Problem When an `AutoHeight` editor with thousands of lines is placed inside a scrollable `List` (such as in the Agent Panel thread view), the editor would lay out **all** lines during prepaint, even though only a small portion was visible. Profiling showed that ~50% of frame time was spent in `EditorElement::prepaint` → `LineWithInvisibles::from_chunks`, processing thousands of invisible lines. ## Solution Calculate the intersection of the editor's bounds with the current content mask (which represents the visible viewport after all parent clipping). Use this to determine: 1. `clipped_top_in_lines` - how many lines are clipped above the viewport 2. `visible_height_in_lines` - how many lines are actually visible Then adjust `start_row` and `end_row` to only include visible lines. The parent container handles positioning, so `scroll_position` remains unchanged for paint calculations. ## Example For a 3000-line editor where only 50 lines are visible: - **Before**: Lay out and render 3000 lines - **After**: Lay out and render ~50 lines ## Testing Verified the following scenarios work correctly: - Editor fully visible (no clipping) - Editor clipped from top - Editor clipped from bottom - Editor completely outside viewport (renders nothing) - Fractional line clipping at boundaries - Scrollable editors with internal scroll state inside a clipped container Release Notes: - Improved agent panel performance when rendering large diffs.
Zed
Welcome to Zed, a high-performance, multiplayer code editor from the creators of Atom and Tree-sitter.
Installation
On macOS, Linux, and Windows you can download Zed directly or install Zed via your local package manager (macOS/Linux/Windows).
Other platforms are not yet available:
- Web (tracking issue)
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