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Bugfix: fix overshoot with wide characters #569 #668

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Bugfix: fix overshoot with wide characters #569 #668

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c2056ac
Bugfix: fix overshoot with wide characters
6f7665 Sep 28, 2026
e435136
Move fix outside of overloaded operator
6f7665 Oct 5, 2026
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39 changes: 39 additions & 0 deletions src/curses/window.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1347,6 +1347,44 @@ void Window::scroll(Scroll where)
scrollok(m_window, 0);
}

bool Window::isInsideWideChar() const
{
const int y = getcury(m_window);
const int x = getcurx(m_window);
const int max_cols = getWidth();
int i = 0;
for (; (i + x) < max_cols; i++)
{
cchar_t cell{};
wchar_t characters[CCHARW_MAX]{};
attr_t attributes{};
short colorPair{};
if (mvwin_wch(m_window,y,x + i,&cell) == OK && getcchar(&cell,characters,&attributes,&colorPair,nullptr) != ERR)
{
//check if it is not 2 col wide
if (wcwidth(characters[0]) != 2)
{
//it is not a 2 col wide char, break
break;
}
}
}
wmove(m_window, y, x);
if ((i % 2) == 1) {
return true;
}
return false;
}

void Window::fixWideChar() {
if (isInsideWideChar()) {
const int y = getcury(m_window);
const int x = getcurx(m_window);
wmove(m_window, y, x - 1);
waddstr(m_window, " ");
wmove(m_window, y, x);
}
}

Window &Window::operator<<(const Color &c)
{
Expand Down Expand Up @@ -1498,6 +1536,7 @@ Window &Window::operator<<(double d)

Window &Window::operator<<(const std::string &s)
{
fixWideChar();
waddnstr(m_window, s.c_str(), s.length());
return *this;
}
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7 changes: 7 additions & 0 deletions src/curses/window.h
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Original file line number Diff line number Diff line change
Expand Up @@ -450,6 +450,13 @@ struct Window
/// Scrolls the window by amount of lines given in its parameter
/// @param where indicates how many lines it has to scroll
virtual void scroll(Scroll where);

/// This checks if the current position is in the middle of a wide character
/// Can be used to fix line overshoot with Japanese characters
bool isInsideWideChar() const;

/// This fixes rendering issues when printing on top of wide characters
void fixWideChar();

Window &operator<<(TermManip tm);
Window &operator<<(const Color &color);
Expand Down