Root cause of the ~1GB 'Unknown' memory on large files: with word wrap
on (the default), VisibleByteRange used the previously-shaped
GlyphLayout.VisualLineStarts to bound the visible byte range. That layout
only covers the visible window (~50 lines), not the whole document, so
whenever the viewport's line count exceeded the window's visual-line count
the range fell back to end=fileLen. The text shaper then laid out the ENTIRE
file each frame; its internal line/glyph buffers grow to the largest layout
ever shaped and are never released (document.reset() keeps the backing cap),
so memory ballooned to the file size (~1.1 GB for 10 MB) and OOM-killed the
process under scroll.
Fix: always derive the visible range from the real-line LineIndex (or the
heuristic estimate before it is ready). Word wrap needs no separate path:
each real line yields >= 1 visual line, so shaping viewportHeight/lineHeight
real lines always fills the viewport, and the range can never collapse to the
whole file.
Also fixed the pre-existing LineIndex storage mismatch: EditorLayout read
TheState.Editor.LineIndex (never set; SetLineIndex had zero callers) for
maxScroll and scrollByteOffset, so it always used the huge pre-index estimate.
It now reads cb.LineIndex, the single source of truth; the dead
EditorState.LineIndex field and SetLineIndex are removed.
On-device (emulator/SwiftShader), a 10 MB file now uses ~150 MB PSS / ~230 MB
RSS at steady state and stays flat under scroll (was 1.13 GB PSS / 1.5 GB RSS,
growing, OOM-killed). go test -race ./... green.
- Viewport: swallow the opening tap/scroll (justOpenedAt window) and
re-clamp ScrollOffset to [0,MaxScroll] in EditorLayout so a short file
never opens past its content (blank viewport).
- Chunked buffer: replace the fixed i*chunkSize slot model (which drifted
after length-changing edits and could re-read stale disk for shifted
tail chunks) with an ordered chunk slice + prefix-sum byte offsets.
In-range files now load fully on open (SetContent), so there is no lazy
load and no stale-disk re-read. Edits splice only the affected chunk(s).
- Size guard: files > MaxEditableFileSize (50 MB) show a 'too large to
edit' notice instead of loading; the browser still lists them. Edit
handlers (KeyDown/ReplaceRange) are no-ops for too-large files.
- Tests: rewrite chunked_buffer_test.go for prefix-sum correctness (insert/
delete across chunk boundaries, rune->byte after edit); fix the large-file
e2e expectation to the shift-correct ground truth.
The IME commit path (swipe-to-type, autocorrect replacement) sends a
key.EditEvent with a Range that the editor ignored, causing the replaced
region to be duplicated. Add Logic.HandleReplaceRange which deletes the
rune range [start,end) and inserts text, converting rune indices to byte
offsets (string path: utf8.DecodeRuneInString; chunked path: leading-byte
scan). HandleKeyDown now routes key.EditEvent through it.
Also fixes two pre-existing ChunkedBuffer correctness bugs the tests
exposed:
- Delete mis-computed the per-chunk end using a shrinking 'remaining'
instead of the absolute end, corrupting multi-chunk deletes.
- FullContent derived its chunk bound solely from fileLen, truncating
in-memory chunks grown past the old bound by an insert.
Adds ime_range_test.go covering insert/replace/delete, unicode, chunked,
and swapped bounds. go test -race ./... green.
- JNI: open_file_in_termux via ACTION_SEND intent (text/plain + file:// uri),
global context ref kept from registerFragment
- impl_android.go: OpenFile(path) attaches current thread if needed
- NewLogic takes openfunc; State.open + ui.OpenFile now func(string)
- ChunkedBuffer.VisibleByteRange: word-wrap path using
GlyphLayout.VisualLineStarts (+byteOffset, lineHeight, visual index param)
- GlyphLayout gains LineHeight; drawWrappedText records VisualLineStarts
- WordWrap default true; State.ByteOffset tracks first visible line
- types: VisualLineIndex
- scroll_fix_test.go (new)
- debug prints left in place (WIP; cleanup in later phase)
- Fix ChunkedBuffer.Insert to always update file length.
- Fix UpdateLineIndexAfterEdit to not shift the first line offset.
- Remove redundant ReadFileTask dispatch in HandleBrowserTap.
- Add end-to-end test for typing at start of buffer.
