jesseduffield.lazygit/pkg/gui
Stefan Haller 9e23111172 Render async content into an off-screen buffer and swap it in
A cmd/pty re-render used to overwrite the displayed buffer from the top
down as lines arrived, relying on keeping the previous render's view-line
tail to avoid a blank frame. That left the view showing a mixture of old
and new content while loading, and any reader (draw, clicks, the
view-line mapping) could observe a half-written buffer at the wrong
scroll.

Instead, build the new content in a second, off-screen viewBuffer: until
the task has read enough to paint, writes go there and the displayed
buffer — and so everything every reader sees — is left untouched. Once the
task reaches its first-paint point (InitialRefreshAfter, or EOF for short
content) it swaps the off-screen buffer in atomically, so the view jumps
straight from the previous render to the new one with no intermediate
frame. Subsequent lines append to the now-displayed buffer.

Swapping at the first-paint point means the displayed buffer is only a
viewport tall when it appears and then grows as the rest streams in toward
the count needed for an accurate scrollbar. The scrollbar is sized from the
displayed buffer's height, so left to itself the thumb would shrink and
snap back during that growth (most visibly: the files panel's periodic
refresh making the thumb jump while scrolled down). The total height the
scrollbar needs is a strictly later quantity than the viewport-fill paint,
so no single early swap can have both right. FreezeScrollbarHeight therefore
records the view's height when a load begins and the scrollbar is held there
— growing only if the new content turns out taller — until the load ends; a
synchronous render superseding the load releases it. This mirrors the layout
clamp, which already ignores the partial content height while a view loads.

With the swap doing a wholesale replace, refreshViewLinesIfNeeded can
truncate the view lines to the current buffer: there is no longer a
half-loaded shorter buffer whose tail we must keep showing, so a stale
tail never forms. clear()/Reset() abandon any in-progress off-screen
render so a synchronous SetContent after a stopped task writes to the
display.

The swap holds writeMutex for now; it could later move to the main thread.
Flicker behaviour still needs interactive verification (LAZYGIT_SLOW_RENDER
+ a real diff renderer).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-15 15:30:27 +02:00
..
context Scroll the selection into view by default 2026-08-14 08:04:13 +02:00
controllers Auto-select the conflicted commit when stopping in rebase 2026-08-15 15:24:36 +02:00
filetree Add a function SetStatusFilterPreservingSelection 2026-08-15 14:58:27 +02:00
mergeconflicts Recognize conflict markers that have no label 2026-08-08 12:43:42 +02:00
modes Make Commit.Hash a getter for an unexported hash field 2025-04-29 14:57:15 +02:00
patch_exploring Rework the custom pager config (rename to diff renderer) 2026-07-31 08:42:51 +02:00
popup Decouple hiding the working tree state from blocking input 2026-08-05 17:29:20 +02:00
presentation Show a Github PR's combined checks state in branches list and main view 2026-08-02 13:06:21 +02:00
services/custom_commands Remove the RefreshMode field 2026-07-17 12:32:32 +02:00
status Render the app status in a single background render loop 2026-07-17 15:55:01 +02:00
style Modernize all codes 2025-11-15 10:46:23 +01:00
types Scroll the selection into view by default 2026-08-14 08:04:13 +02:00
background.go Let OnUIThreadAndWait's error be about the wait, not about f 2026-08-12 11:04:53 +02:00
command_log_panel.go Adapt links 2026-07-31 08:42:51 +02:00
context.go Bump gocui (and tcell) 2025-12-23 16:49:16 +01:00
context_config.go Remove some unused code 2025-07-08 15:14:45 +02:00
controllers.go Redesign the 'w' worktree-creation flow 2026-07-03 18:53:05 +02:00
dummies.go Move NewDummyCommon to pkg/common 2025-05-06 09:43:26 +02:00
editors.go Capture suggestions inputs on the UI thread 2026-07-17 12:35:54 +02:00
extras_panel.go Rename Key to Keys in Binding, KeybindingsOpts, and MenuItem 2026-05-25 15:18:18 +02:00
global_handlers.go Read lines based on scroll position instead of a fixed per-notch delta 2026-07-09 09:32:35 +02:00
gui.go Remember how to get back to a repo we entered a submodule from 2026-08-08 11:15:01 +02:00
gui_common.go Scroll the selection into view by default 2026-08-14 08:04:13 +02:00
gui_driver.go Only react to focus reports that change whether we're focused 2026-08-15 11:26:58 +02:00
information_panel.go Rename ModeStatus.Description to InfoLabel 2025-08-14 17:59:38 +02:00
keybindings.go Fold remaining alt bindings into their main fields 2026-05-25 15:32:47 +02:00
layout.go Don't scroll a view up to fill blank space while its content is loading 2026-08-15 15:30:27 +02:00
main_panels.go Reset other main views' scroll after copying content, not before 2026-08-15 15:30:27 +02:00
menu_panel.go Remove the scroll calls that are now redundant 2026-08-14 08:04:13 +02:00
options_map.go Cleanup: filter out empty keybindings earlier 2026-05-28 19:26:43 +02:00
pty.go Render async content into an off-screen buffer and swap it in 2026-08-15 15:30:27 +02:00
pty_test.go Prevent stale index.lock files from diffs rendered through a pty on Windows 2026-08-04 06:53:53 +02:00
recent_repos_panel.go Remove unused field gui.IsNewRepo 2024-12-01 10:44:26 +01:00
side_panels.go Assign the transient contexts' initial windows from the side panel config 2026-07-17 12:07:24 +02:00
side_panels_test.go Assign the transient contexts' initial windows from the side panel config 2026-07-17 12:07:24 +02:00
tasks_adapter.go Render async content into an off-screen buffer and swap it in 2026-08-15 15:30:27 +02:00
tasks_adapter_test.go Never hand NewCmdTask a nil reader when a command fails to start 2026-07-23 17:31:26 +02:00
test_mode.go Dump goroutine stacks when the test watchdog fires 2026-07-20 14:26:25 +02:00
test_timeout_norace.go Scale the integration test watchdog up under the race detector 2026-07-20 14:26:25 +02:00
test_timeout_race.go Scale the integration test watchdog up under the race detector 2026-07-20 14:26:25 +02:00
view_helpers.go Scroll the selection into view by default 2026-08-14 08:04:13 +02:00
views.go Clear tab strips on views that are no longer tabs 2026-06-23 14:15:18 +02:00