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Work around OS escape code limitation.
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See #546.  When "Wrap text output on resize" is unchecked (or when
Window Width != Screen Buffer Width) then escape codes for cursor
positioning and insert/delete characters and clearing text and etc only
affect the part of the terminal display that's within the visible area
(the CONSOLE_SCREEN_BUFFER_INFO::srWindow area).

That results in jitter and some text getting displayed inaccurately.

There's only so much Clink can do to compensate for the problem, but
this change tries to mitigate it as much as possible.  However, the
visible area jitters around.  There's nothing Clink can do about that;
the behavior is built into the OS console APIs.
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@chrisant996
chrisant996 committed Jan 16, 2024
1 parent b4a9b2a commit a714527
Showing 1 changed file with 130 additions and 12 deletions.
142 changes: 130 additions & 12 deletions clink/lib/src/display_readline.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -131,6 +131,18 @@ static bool is_autowrap_bug_present()
#pragma warning(pop)
}

//------------------------------------------------------------------------------
static HANDLE is_horizpos_workaround_needed()
{
HANDLE h = GetStdHandle(STD_OUTPUT_HANDLE);
CONSOLE_SCREEN_BUFFER_INFO csbi;
if (!GetConsoleScreenBufferInfo(h, &csbi))
return nullptr;
if (csbi.srWindow.Left == 0 && csbi.srWindow.Right == csbi.dwSize.X - 1)
return nullptr;
return h;
}

//------------------------------------------------------------------------------
static void clear_to_end_of_screen()
{
Expand Down Expand Up @@ -275,6 +287,69 @@ int32 prompt_contains_problem_codes(const char* prompt, std::vector<prompt_probl



//------------------------------------------------------------------------------
class preserve_window_scroll_position
{
public:
preserve_window_scroll_position(HANDLE h);
~preserve_window_scroll_position();
private:
static int32 s_nested;
static char* s_saved_rl_term_clreol;
static HANDLE s_h;
static CONSOLE_SCREEN_BUFFER_INFO s_window;
};

//------------------------------------------------------------------------------
int32 preserve_window_scroll_position::s_nested = 0;
char* preserve_window_scroll_position::s_saved_rl_term_clreol = nullptr;
HANDLE preserve_window_scroll_position::s_h = nullptr;
CONSOLE_SCREEN_BUFFER_INFO preserve_window_scroll_position::s_window;

//------------------------------------------------------------------------------
preserve_window_scroll_position::preserve_window_scroll_position(HANDLE h)
{
assertimplies(!s_nested, !s_h);
++s_nested;
if (!s_h && h)
{
s_h = h;
s_saved_rl_term_clreol = _rl_term_clreol;
_rl_term_clreol = nullptr;
display_accumulator::flush();
GetConsoleScreenBufferInfo(s_h, &s_window);
}
}

//------------------------------------------------------------------------------
preserve_window_scroll_position::~preserve_window_scroll_position()
{
assert(s_nested > 0);
if (s_h)
{
display_accumulator::flush();
CONSOLE_SCREEN_BUFFER_INFO cursor;
GetConsoleScreenBufferInfo(s_h, &cursor);
if (cursor.srWindow.Right - cursor.srWindow.Left == s_window.srWindow.Right - s_window.srWindow.Left &&
cursor.srWindow.Bottom - cursor.srWindow.Top == s_window.srWindow.Bottom - s_window.srWindow.Top &&
cursor.dwCursorPosition.X >= cursor.srWindow.Left &&
cursor.dwCursorPosition.X <= cursor.srWindow.Right &&
cursor.dwCursorPosition.Y >= cursor.srWindow.Top &&
cursor.dwCursorPosition.Y <= cursor.srWindow.Bottom)
SetConsoleWindowInfo(s_h, true, &s_window.srWindow);
}
--s_nested;
if (!s_nested)
{
if (s_h)
_rl_term_clreol = s_saved_rl_term_clreol;
s_h = nullptr;
s_saved_rl_term_clreol = nullptr;
}
}



//------------------------------------------------------------------------------
struct display_line
{
Expand Down Expand Up @@ -1358,11 +1433,13 @@ class display_manager

private:
void update_line(int32 i, const display_line* o, const display_line* d, bool has_rprompt);
void clear_comment_row_internal();
void move_to_column(uint32 col, bool force=false);
void move_to_row(int32 row);
void shift_cols(uint32 col, int32 delta);
void print(const char* chars, uint32 len);
void print_rprompt(const char* s);
void init_horizpos_workaround();
void detect_pending_wrap();
void finish_pending_wrap();

Expand All @@ -1377,6 +1454,7 @@ class display_manager
bool m_horz_scroll = false;

const bool m_autowrap_bug;
HANDLE m_horizpos_workaround = nullptr;
bool m_pending_wrap = false;
const display_lines* m_pending_wrap_display = nullptr;
};
Expand Down Expand Up @@ -1439,11 +1517,14 @@ void display_manager::on_new_line()
//------------------------------------------------------------------------------
void display_manager::end_prompt_lf()
{
init_horizpos_workaround();
preserve_window_scroll_position preserve(m_horizpos_workaround);

// FUTURE: When in a scrolling mode (vert or horz), reprint the entire
// prompt and input line without the scroll constraints?

// Erase comment row if present.
clear_comment_row();
clear_comment_row_internal();

// If the cursor is the only thing on an otherwise-blank last line,
// compensate so we don't print an extra CRLF.
Expand Down Expand Up @@ -1476,7 +1557,7 @@ void display_manager::end_prompt_lf()
const uint32 len = d->m_len - index;
const uint32 wc = clink_wcswidth(d->m_chars + index, len);
move_to_column(_rl_screenwidth - wc);
_rl_clear_to_eol(0);
_rl_clear_to_eol(wc);
rl_puts_face_func(d->m_chars + index, d->m_faces + index, len);
}
else if (m_top == m_last_prompt_line_botlin && count <= 1)
Expand Down Expand Up @@ -1509,6 +1590,9 @@ void display_manager::display()
if (!_rl_echoing_p)
return;

init_horizpos_workaround();
preserve_window_scroll_position preserve(m_horizpos_workaround);

#ifdef REPORT_REDISPLAY
++s_calls;
#endif
Expand Down Expand Up @@ -1793,7 +1877,7 @@ void display_manager::display()
{
move_to_row(old_botlin + 1);
move_to_column(0);
_rl_clear_to_eol(_rl_screenwidth); // BUGBUG: assumes _rl_term_clreol.
_rl_clear_to_eol(_rl_screenwidth);
}

// Update each display line for the line buffer.
Expand Down Expand Up @@ -1822,12 +1906,13 @@ void display_manager::display()
for (int32 i = new_botlin; i++ < old_botlin;)
{
move_to_row(i);
_rl_clear_to_eol(_rl_screenwidth); // BUGBUG: assumes _rl_term_clreol.
_rl_clear_to_eol(_rl_screenwidth);
}
}

// Update current cursor position.
assert(_rl_last_c_pos < _rl_screenwidth);
assertimplies(m_horizpos_workaround, _rl_last_c_pos <= _rl_screenwidth);
assertimplies(!m_horizpos_workaround, _rl_last_c_pos < _rl_screenwidth);

// Finally update the bottom line counter.
_rl_vis_botlin = new_botlin;
Expand Down Expand Up @@ -1925,7 +2010,8 @@ void display_manager::display()
}
}

print("\x1b[m\x1b[K", 6);
print("\x1b[m", 3);
_rl_clear_to_eol(_rl_screenwidth - _rl_last_c_pos);

if (reset_col)
{
Expand Down Expand Up @@ -2069,18 +2155,30 @@ bool display_manager::has_comment_row() const
}

//------------------------------------------------------------------------------
void display_manager::clear_comment_row()
void display_manager::clear_comment_row_internal()
{
if (*m_curr.get_comment_row())
{
_rl_move_vert(_rl_vis_botlin + 1);
_rl_cr();
_rl_last_c_pos = 0;
_rl_clear_to_eol(0);
_rl_clear_to_eol(_rl_screenwidth);
m_curr.clear_comment_row();
}
}

//------------------------------------------------------------------------------
void display_manager::clear_comment_row()
{
if (*m_curr.get_comment_row())
{
init_horizpos_workaround();
preserve_window_scroll_position preserve(m_horizpos_workaround);

clear_comment_row_internal();
}
}

//------------------------------------------------------------------------------
void display_manager::update_line(int32 i, const display_line* o, const display_line* d, bool has_rprompt)
{
Expand All @@ -2103,12 +2201,12 @@ void display_manager::update_line(int32 i, const display_line* o, const display_
return;
}

bool use_eol_opt = !has_rprompt && d->m_toeol;
bool use_eol_opt = !m_horizpos_workaround && !has_rprompt && d->m_toeol;

// Optimize updating when the new starting column is less than or equal to
// the old starting column. Can't optimize in the other direction unless
// update_line(0) happens before displaying the prompt string.
if (o && d->m_x <= o->m_x)
if (!m_horizpos_workaround && o && d->m_x <= o->m_x)
{
const char* oc = o->m_chars;
const char* of = o->m_faces;
Expand Down Expand Up @@ -2236,7 +2334,7 @@ void display_manager::update_line(int32 i, const display_line* o, const display_
{
if (use_eol_opt)
{
rl_fwrite_function(_rl_out_stream, "\x1b[K", 3);
_rl_clear_to_eol(_rl_screenwidth - rcol);
}
else
{
Expand Down Expand Up @@ -2273,7 +2371,18 @@ void display_manager::move_to_column(uint32 col, bool force)
if (col == _rl_last_c_pos && !force)
return;

if (col)
if (m_horizpos_workaround)
{
display_accumulator::flush();

CONSOLE_SCREEN_BUFFER_INFO csbi;
GetConsoleScreenBufferInfo(m_horizpos_workaround, &csbi);
csbi.dwCursorPosition.X = col;

preserve_window_scroll_position preserve(m_horizpos_workaround);
SetConsoleCursorPosition(m_horizpos_workaround, csbi.dwCursorPosition);
}
else if (col)
{
char *buffer = tgoto(_rl_term_ch, 0, col + 1);
tputs(buffer);
Expand All @@ -2295,6 +2404,7 @@ void display_manager::move_to_row(int32 row)
if (row == _rl_last_v_pos)
return;

preserve_window_scroll_position preserve(m_horizpos_workaround);
_rl_move_vert(row);
}

Expand All @@ -2308,6 +2418,7 @@ void display_manager::shift_cols(uint32 col, int32 delta)
if (m_pending_wrap)
finish_pending_wrap();

assert(!m_horizpos_workaround);
assert(delta < _rl_screenwidth - col);
if (_rl_term_IC)
{
Expand Down Expand Up @@ -2336,6 +2447,7 @@ void display_manager::shift_cols(uint32 col, int32 delta)
if (m_pending_wrap)
finish_pending_wrap();

assert(!m_horizpos_workaround);
assert(-delta < _rl_screenwidth - col);
if (_rl_term_DC && *_rl_term_DC)
{
Expand Down Expand Up @@ -2391,6 +2503,12 @@ void display_manager::print_rprompt(const char* s)
detect_pending_wrap();
}

//------------------------------------------------------------------------------
void display_manager::init_horizpos_workaround()
{
m_horizpos_workaround = is_horizpos_workaround_needed();
}

//------------------------------------------------------------------------------
void display_manager::detect_pending_wrap()
{
Expand Down

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