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feat(core): 每缓冲区滚动边距 (#41) #249

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Merged
JavaZeroo merged 3 commits into from
Oct 30, 2026
Merged

feat(core): 每缓冲区滚动边距 (#41) #249

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5197adc
feat(core): keep the scroll margins per buffer refs #41
JavaZeroo Oct 30, 2026
832b167
fix(core): only the bottom margin scrolls on a line feed refs #41
JavaZeroo Oct 30, 2026
6e41200
test(core): pin the 175 byte margin source result refs #41
JavaZeroo Oct 30, 2026
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37 changes: 35 additions & 2 deletions experiments/core/edit_csi_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -91,14 +91,30 @@ int main() {
row_text(margin.screen, 2).empty() && row_text(margin.screen, 3) == "d",
"DL ignored the scroll margins");

// Margins belong to the buffer: a 1049 switch keeps each buffer's region.
{
Parser buffers(4, 10, 10, termforge::ParseMode::recovery);
buffers.feed("\x1b[2;3r");
require(buffers.screen.region_top() == 1 && buffers.screen.region_bottom() == 2,
"primary region was not set");
buffers.feed("\x1b[?1049h");
require(buffers.screen.region_top() == 0 && buffers.screen.region_bottom() == 3,
"alternate buffer inherited the primary region");
buffers.feed("\x1b[1;2r");
require(buffers.screen.region_top() == 0 && buffers.screen.region_bottom() == 1,
"alternate region was not set");
buffers.feed("\x1b[?1049l");
require(buffers.screen.region_top() == 1 && buffers.screen.region_bottom() == 2,
"primary region was lost across the switch");
}
// A resize drops the margins: scrolling afterwards reaches history again.
{
Parser resized(4, 10, 10, termforge::ParseMode::recovery);
resized.feed("a\r\nb\r\nc\r\nd");
resized.feed("\x1b[2;3r");
require(resized.screen.scroll_bottom() == 2, "test setup lost the region");
require(resized.screen.region_bottom() == 2, "test setup lost the region");
resized.screen.resize(4, 12);
require(resized.screen.scroll_bottom() == 3, "resize kept the stale region bottom");
require(resized.screen.region_bottom() == 3, "resize kept the stale region bottom");
resized.feed("\x1b[4;1H");
resized.feed("\n");
require(resized.screen.scrollback_lines() > 0,
Expand Down Expand Up @@ -148,6 +164,23 @@ int main() {
require(row_text(insert.screen, 0) == "abcdQ" && row_text(insert.screen, 1).empty(),
"text after a cancelled ICH wrap did not stay on the row");
}
// The 175-byte margin source from experiments/shell/margin_checks.py, with
// its lone line feeds translated to CRLF the way a console does on output.
// The core must land on the "required" screen, not the ConPTY "observed" one.
{
Parser margin(24, 80, 100, termforge::ParseMode::recovery);
margin.feed("\x1b[2J\x1b[HTOP_FIXED\r\nREGION_A\r\nREGION_B\r\nBOTTOM_FIXED\r\n\x1b[2;3r");
margin.feed("\x1b[?1049hALT_OUTSIDE\r\n\x1b[4;1HALT_A\r\nALT_B\x1b[4;5r\x1b[5;1H\r\nALT_C\r\nALT_D");
margin.feed("\x1b[?1049l");
margin.feed("\x1b[3;1H\r\nREGION_C\r\nREGION_D\x1b[6;1HTF_MARGIN_DONE\r\n");
const std::string expected[] = {"TOP_FIXED", "REGION_C", "REGION_D", "BOTTOM_FIXED", "",
"TF_MARGIN_DONE"};
for (int index = 0; index < 6; ++index)
require(row_text(margin.screen, index) == expected[index],
"margin source produced the ConPTY-observed screen");
require(margin.screen.row == 6 && margin.screen.column == 0,
"margin source cursor mismatch");
}
std::puts("edit csi contracts passed");
return 0;
} catch (const std::exception& error) {
Expand Down
48 changes: 29 additions & 19 deletions experiments/core/screen.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -64,8 +64,13 @@ class Screen {
// True only while the retained sequence is known to be ordered by id.
// False is the safe fallback: lookups scan instead of bisecting.
bool ordered_ = true;
// DECSTBM margins belong to the frame: the primary and alternate buffers
// keep their own scrolling region across a 1049 switch.
int scroll_top = 0;
int scroll_bottom = -1;
template<class State> void swap(State& other) noexcept {
std::swap(row, other.row); std::swap(column, other.column);
std::swap(scroll_top, other.scroll_top); std::swap(scroll_bottom, other.scroll_bottom);
std::swap(last_row, other.last_row); std::swap(last_column, other.last_column);
std::swap(wrap_pending, other.wrap_pending); std::swap(discarded, other.discarded);
std::swap(style, other.style);
Expand All @@ -81,18 +86,19 @@ class Screen {
std::deque<Line> history;
int columns_;
uint64_t next_id_ = 1;
int scroll_top_ = 0;
// Negative means "the bottom row", which keeps full-screen scrolling on the
// history path after a resize changes the height.
int scroll_bottom_ = -1;
// DECSTBM margins travel with the buffer through active_state_copy/swap.
// Negative bottom means "the last row", which survives a height change.
int scroll_top = 0;
int scroll_bottom = -1;
uint64_t buffer_epoch_ = 0;
uint64_t order_revision_ = 0;
bool ordered_ = true;
int last_row = -1, last_column = -1;
ScreenBuffer active_buffer_ = ScreenBuffer::primary;
std::optional<FrameState> inactive_;
FrameState active_state_copy() const {
return {row, column, last_row, last_column, wrap_pending, discarded, style, lines, history, ordered_};
return {row, column, last_row, last_column, wrap_pending, discarded, style, lines, history, ordered_,
scroll_top, scroll_bottom};
}
void swap_active(FrameState& state) noexcept {
state.swap(*this);
Expand Down Expand Up @@ -382,16 +388,18 @@ class Screen {
if (hidden) inactive_->swap(*hidden);
columns_ = columns; next_id_ = identity;
// The reference terminal drops the scrolling margins on resize, so a
// stale bottom could point past the new height.
scroll_top_ = 0; scroll_bottom_ = -1;
// stale bottom could point past the new height. Both frames reset.
scroll_top = 0; scroll_bottom = -1;
if (inactive_) { inactive_->scroll_top = 0; inactive_->scroll_bottom = -1; }
advance_order(ordered_);
}
void invalidate_attachment() { last_row = last_column = -1; }
void move(int r, int c) {
row = std::clamp(r, 0, height() - 1); column = std::clamp(c, 0, width() - 1);
wrap_pending = false; invalidate_attachment();
}
int scroll_bottom() const { return scroll_bottom_ < 0 ? height() - 1 : scroll_bottom_; }
int region_bottom() const { return scroll_bottom < 0 ? height() - 1 : scroll_bottom; }
int region_top() const { return scroll_top; }
// DECSTBM: rows inside [top, bottom] scroll together. The list itself keeps
// whole rows only, so a partial region scroll shifts entries in place; rows
// that leave a full-screen region still reach history.
Expand All @@ -401,7 +409,7 @@ class Screen {
// An invalid region is ignored rather than rejected: the reference
// terminal logs and returns, leaving the previous margins in place.
if (bottom - top < 1) return;
scroll_top_ = top; scroll_bottom_ = bottom;
scroll_top = top; scroll_bottom = bottom;
// DECSTBM homes the cursor to the screen origin, matching the reference
// terminal (vendor/alacritty_terminal/src/term/mod.rs: goto(0, 0)).
move(0, 0);
Expand All @@ -414,17 +422,19 @@ class Screen {
// A newly allocated bottom row is known before moving its predecessor.
previous.next_id = automatic ? (row + 1 < height() ? lines[row + 1].id : next_id_) : 0;
wrap_pending = false; invalidate_attachment();
if (row + 1 < height() && row < scroll_bottom()) { ++row; return; }
if (row < scroll_bottom() || scroll_top_ > 0 || scroll_bottom() < height() - 1) {
// Scrolling inside a region (or inside a movement that stops early)
// moves rows up within the margins and blanks the last region row.
for (int r = scroll_top_; r < scroll_bottom(); ++r) lines[r] = std::move(lines[r + 1]);
lines[scroll_bottom()] = make_line(width(), Cell{}, next_id_);
row = scroll_bottom();
const int bottom = region_bottom();
// Only the bottom margin scrolls; rows above it move down normally and
// rows below it must not disturb the region at all.
if (row < bottom) { ++row; return; }
if (row > bottom) { if (row + 1 < height()) ++row; return; }
if (region_top() > 0 || bottom < height() - 1) {
// Scrolling inside the margins moves rows up and blanks the last one.
for (int r = region_top(); r < bottom; ++r) lines[r] = std::move(lines[r + 1]);
lines[bottom] = make_line(width(), Cell{}, next_id_);
row = bottom;
advance_order(ordered_);
return;
}
if (row < height() - 1) { ++row; return; }
const auto limit = active_history_limit();
if (limit) {
history.push_back(std::move(lines.front()));
Expand Down Expand Up @@ -472,7 +482,7 @@ class Screen {
}
void insert_lines(int count) {
if (count < 1) throw InputError("invalid insert line count");
const int bottom = scroll_bottom();
const int bottom = region_bottom();
const int insert = (std::min)(count, bottom + 1 - row);
if (insert <= 0) { wrap_pending = false; return; }
// Rows pushed past the bottom margin leave the screen; their identities
Expand All @@ -484,7 +494,7 @@ class Screen {
}
void delete_lines(int count) {
if (count < 1) throw InputError("invalid delete line count");
const int bottom = scroll_bottom();
const int bottom = region_bottom();
const int remove = (std::min)(count, bottom + 1 - row);
if (remove <= 0) { wrap_pending = false; return; }
for (int r = row; r <= bottom - remove; ++r) lines[r] = std::move(lines[r + remove]);
Expand Down