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// Copyright (c) 2015 Ryan Prichard
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//
// ConsoleLine
//
// This data structure keep tracks of the previous CHAR_INFO content of an
// output line and determines when a line has changed. Detecting line changes
// is made complicated by terminal resizing.
//
#include "ConsoleLine.h"
#include <algorithm>
#include "../shared/WinptyAssert.h"
static CHAR_INFO blankChar(WORD attributes)
{
// N.B.: As long as we write to UnicodeChar rather than AsciiChar, there
// are no padding bytes that could contain uninitialized bytes. This fact
// is important for efficient comparison.
CHAR_INFO ret;
ret.Attributes = attributes;
ret.Char.UnicodeChar = L' ';
return ret;
}
static bool isLineBlank(const CHAR_INFO *line, int length, WORD attributes)
{
for (int col = 0; col < length; ++col) {
if (line[col].Attributes != attributes ||
line[col].Char.UnicodeChar != L' ') {
return false;
}
}
return true;
}
static inline bool areLinesEqual(
const CHAR_INFO *line1,
const CHAR_INFO *line2,
int length)
{
return memcmp(line1, line2, sizeof(CHAR_INFO) * length) == 0;
}
ConsoleLine::ConsoleLine() : m_prevLength(0)
{
}
void ConsoleLine::reset()
{
m_prevLength = 0;
m_prevData.clear();
}
// Determines whether the given line is sufficiently different from the
// previously seen line as to justify reoutputting the line. The function
// also sets the `ConsoleLine` to the given line, exactly as if `setLine` had
// been called.
bool ConsoleLine::detectChangeAndSetLine(const CHAR_INFO *const line, const int newLength)
{
ASSERT(newLength >= 1);
ASSERT(m_prevLength <= static_cast<int>(m_prevData.size()));
if (newLength == m_prevLength) {
bool equalLines = areLinesEqual(m_prevData.data(), line, newLength);
if (!equalLines) {
setLine(line, newLength);
}
return !equalLines;
} else {
if (m_prevLength == 0) {
setLine(line, newLength);
return true;
}
ASSERT(m_prevLength >= 1);
const WORD prevBlank = m_prevData[m_prevLength - 1].Attributes;
const WORD newBlank = line[newLength - 1].Attributes;
bool equalLines = false;
if (newLength < m_prevLength) {
// The line has become shorter. The lines are equal if the common
// part is equal, and if the newly truncated characters were blank.
equalLines =
areLinesEqual(m_prevData.data(), line, newLength) &&
isLineBlank(m_prevData.data() + newLength,
m_prevLength - newLength,
newBlank);
} else {
//
// The line has become longer. The lines are equal if the common
// part is equal, and if both the extra characters and any
// potentially reexposed characters are blank.
//
// Two of the most relevant terminals for winpty--mintty and
// jediterm--don't (currently) erase the obscured content when a
// line is cleared, so we should anticipate its existence when
// making a terminal wider and reoutput the line. See:
//
// * https://github.com/mintty/mintty/issues/480
// * https://github.com/JetBrains/jediterm/issues/118
//
ASSERT(newLength > m_prevLength);
equalLines =
areLinesEqual(m_prevData.data(), line, m_prevLength) &&
isLineBlank(m_prevData.data() + m_prevLength,
std::min<int>(m_prevData.size(), newLength) - m_prevLength,
prevBlank) &&
isLineBlank(line + m_prevLength,
newLength - m_prevLength,
prevBlank);
}
setLine(line, newLength);
return !equalLines;
}
}
void ConsoleLine::setLine(const CHAR_INFO *const line, const int newLength)
{
if (static_cast<int>(m_prevData.size()) < newLength) {
m_prevData.resize(newLength);
}
memcpy(m_prevData.data(), line, sizeof(CHAR_INFO) * newLength);
m_prevLength = newLength;
}
void ConsoleLine::blank(WORD attributes)
{
m_prevData.resize(1);
m_prevData[0] = blankChar(attributes);
m_prevLength = 1;
}
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