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Use Erase-in-Line more carefully

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Instead of erasing a whole line before writing a line, simply write the
line.  At the end of the line, issue a CSI 0K to erase from the cursor to
the end of the line.  The erasing serves two purposes:

 * It can clear characters beyond the right end of the terminal, which
   have been obscured by a terminal resize.

 * It sets the background color for the trailing whitespace.

Doing the erasing like so has two benefits:

 * It's more correct.  Previously, the trailing whitespace was colored
   arbitrarily.  Now, it is correctly colored to the last color on the
   line.

 * It should eliminate a lot of flicker.
This commit is contained in:
Ryan Prichard 2015-10-14 04:39:52 -05:00
parent d4a5d0f5a0
commit efb10c4fcf
1 changed files with 18 additions and 4 deletions
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22
agent/Terminal.cc
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@ -309,12 +309,9 @@ void Terminal::sendLine(int line, CHAR_INFO *lineData, int width)
hideTerminalCursor();
moveTerminalToLine(line);
// Erase in Line -- erase entire line.
if (!m_consoleMode)
m_output->write(CSI"2K");
m_termLine.clear();
int trimmedLineLength = 0;
bool alreadyErasedLine = false;
int cellCount = 1;
for (int i = 0; i < width; i += cellCount) {
@ -331,6 +328,19 @@ void Terminal::sendLine(int line, CHAR_INFO *lineData, int width)
if (ch == ' ') {
m_termLine.push_back(' ');
} else {
if (i + cellCount == width) {
// We'd like to erase the line after outputting all non-blank
// characters, but this doesn't work if the last cell in the
// line is non-blank. At the point, the cursor is positioned
// just past the end of the line, but in many terminals,
// issuing a CSI 0K at that point also erases the last cell in
// the line. Work around this behavior by issuing the erase
// one character early in that case.
if (!m_consoleMode) {
m_termLine.append(CSI"0K"); // Erase from cursor to EOL
}
alreadyErasedLine = true;
}
ch = fixConsolePopupBoxArt(ch);
char enc[4];
int enclen = encodeUtf8(enc, ch);
@ -344,6 +354,10 @@ void Terminal::sendLine(int line, CHAR_INFO *lineData, int width)
}
m_output->write(m_termLine.data(), trimmedLineLength);
if (!alreadyErasedLine && !m_consoleMode) {
m_output->write(CSI"0K"); // Erase from cursor to EOL
}
}
void Terminal::finishOutput(const std::pair<int, int> &newCursorPos)