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Fix handling of surrogate pairs in ircview and inputeditor #2569

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merged 3 commits into from
Nov 28, 2023
Merged

Fix handling of surrogate pairs in ircview and inputeditor #2569

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57b7b2d
Ircview: consider surrogate pairs when calculating block widths, wrap…
ctrlaltca Nov 23, 2023
5b50866
InputEditor: consider surrogate pairs when moving cursor, deleting a …
ctrlaltca Nov 23, 2023
a71cf80
Ircview: Fix out of bound memory read when a line ends with a tab; fi…
ctrlaltca Nov 23, 2023
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148 changes: 66 additions & 82 deletions src/kvirc/ui/KviInputEditor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1748,6 +1748,9 @@ void KviInputEditor::focusOutEvent(QFocusEvent * e)
e->accept();
}

#define INPUT_ISHIGHSURROGATE(c) ((c).unicode() >= 0xD800 && (c).unicode() <= 0xDBFF)
#define INPUT_ISLOWSURROGATE(c) ((c).unicode() >= 0xDC00 && (c).unicode() <= 0xDFFF)

void KviInputEditor::internalCursorRight(bool bShift)
{
if(m_iCursorPosition >= ((int)(m_szTextBuffer.length())))
Expand All @@ -1757,34 +1760,42 @@ void KviInputEditor::internalCursorRight(bool bShift)
return;
}

int iNewCursorPosition = m_iCursorPosition;
if(INPUT_ISHIGHSURROGATE(m_szTextBuffer.at(iNewCursorPosition)))
{
// avoid to position the cursor in the middle of a surrogate pair
iNewCursorPosition += 2;
} else {
iNewCursorPosition++;
}

//Grow the selection if needed
if(bShift)
{
if((m_iSelectionBegin != -1) && (m_iSelectionEnd != -1))
{
if(m_iSelectionEnd <= m_iCursorPosition)
m_iSelectionEnd = m_iCursorPosition + 1;
m_iSelectionEnd = iNewCursorPosition;
else if(m_iSelectionBegin >= m_iCursorPosition)
m_iSelectionBegin = m_iCursorPosition + 1;
m_iSelectionBegin = iNewCursorPosition;
else
{
m_iSelectionBegin = m_iCursorPosition;
m_iSelectionEnd = m_iCursorPosition + 1;
m_iSelectionEnd = iNewCursorPosition;
}
}
else
{
m_iSelectionBegin = m_iCursorPosition;
m_iSelectionEnd = m_iCursorPosition + 1;
m_iSelectionEnd = iNewCursorPosition;
}
m_iCursorPosition++;
}
else
{
m_iCursorPosition++;
clearSelection();
}

m_iCursorPosition = iNewCursorPosition;
m_p->bTextBlocksDirty = true;
ensureCursorVisible();
}
Expand All @@ -1798,33 +1809,39 @@ void KviInputEditor::internalCursorLeft(bool bShift)
return;
}

int iNewCursorPosition = m_iCursorPosition - 1;
if(INPUT_ISLOWSURROGATE(m_szTextBuffer.at(iNewCursorPosition)))
{
// avoid to position the cursor in the middle of a surrogate pair
iNewCursorPosition--;
}

if(bShift)
{
if((m_iSelectionBegin != -1) && (m_iSelectionEnd != -1))
{
if(m_iSelectionBegin >= m_iCursorPosition)
m_iSelectionBegin = m_iCursorPosition - 1;
m_iSelectionBegin = iNewCursorPosition;
else if(m_iSelectionEnd <= m_iCursorPosition)
m_iSelectionEnd = m_iCursorPosition - 1;
m_iSelectionEnd = iNewCursorPosition;
else
{
m_iSelectionEnd = m_iCursorPosition;
m_iSelectionBegin = m_iCursorPosition - 1;
m_iSelectionBegin = iNewCursorPosition;
}
}
else
{
m_iSelectionEnd = m_iCursorPosition;
m_iSelectionBegin = m_iCursorPosition - 1;
m_iSelectionBegin = iNewCursorPosition;
}
m_iCursorPosition--;
}
else
{
m_iCursorPosition--;
clearSelection();
}

m_iCursorPosition = iNewCursorPosition;
m_p->bTextBlocksDirty = true;
ensureCursorVisible();
}
Expand Down Expand Up @@ -2516,82 +2533,35 @@ int KviInputEditor::charIndexFromXPosition(qreal fXPos)
if(!pBlock)
return iCurChar;

// This is very tricky. Qt does not provide a simple means to figure out the cursor position
// from an x position on the text. We use QFontMetrics::elidedText() to guess it.

// Additionally Qt::ElideNone does not work as expected (see QTBUG-40315): it just ignores clipping altogether.
// So we use Qt::ElideRight here but we must take into account the width of the elision

qreal fWidth = fXPos - fCurX;

qreal fCurWidth = 0, fCharWidth = 0;
QFontMetrics * fm = getLastFontMetrics(font());

QString szPart = fm->elidedText(pBlock->szText, Qt::ElideRight, fWidth + m_p->fFontElisionWidth);

if(szPart.endsWith(m_p->szFontElision))
szPart.truncate(szPart.length() - 1); // kill the elision

// OK, now we have a good starting point

qreal fPrevWidth = fm->horizontalAdvance(szPart);
int iBlockLength = pBlock->szText.length();
int iCurPosInBlock = 0;
const QChar * p = pBlock->szText.unicode();

if(fPrevWidth <= fWidth)
{
// move up adding characters
for(;;)
{
int iPartLength = szPart.length();
if(iPartLength == iBlockLength)
return iCurChar + iBlockLength;

szPart = pBlock->szText.left(iPartLength + 1);

qreal fNextWidth = fm->horizontalAdvance(szPart);

if(fNextWidth >= fWidth)
{
// gotcha.
qreal fMiddle = (fPrevWidth + fNextWidth) / 2.0;

if(fWidth < fMiddle)
return iCurChar + iPartLength;

return iCurChar + iPartLength + 1;
}

fPrevWidth = fNextWidth;
}
}
else
while(iCurPosInBlock < iBlockLength)
{
// move down removing characters
for(;;)
if(INPUT_ISHIGHSURROGATE(*p) && iCurPosInBlock < iBlockLength - 1)
{
int iPartLength = szPart.length();
if(iPartLength == 0)
return iCurChar;

szPart = pBlock->szText.left(iPartLength - 1);

qreal fNextWidth = fm->horizontalAdvance(szPart);

if(fNextWidth <= fWidth)
{
// gotcha.
qreal fMiddle = (fPrevWidth + fNextWidth) / 2.0;

if(fWidth < fMiddle)
return iCurChar + iPartLength - 1;

return iCurChar + iPartLength;
}

fPrevWidth = fNextWidth;
// extract and calculate width of both chars together
fCharWidth = fm->horizontalAdvance(QString(p, 2));
if(fCurWidth + fCharWidth >= fWidth)
break;
fCurWidth += fCharWidth;
iCurPosInBlock += 2;
p += 2;
} else {
fCharWidth = fm->horizontalAdvance(*p);
if(fCurWidth + fCharWidth >= fWidth)
break;
fCurWidth += fCharWidth;
iCurPosInBlock++;
p++;
}
}

Q_ASSERT(false); // not reached
return iCurChar + iCurPosInBlock;
}

qreal KviInputEditor::xPositionFromCharIndex(int iChIdx)
Expand Down Expand Up @@ -3328,8 +3298,16 @@ void KviInputEditor::backspaceHit()
else if(m_iCursorPosition > 0)
{
m_iCursorPosition--;
addUndo(new EditCommand(EditCommand::RemoveText, m_szTextBuffer.mid(m_iCursorPosition, 1), m_iCursorPosition));
m_szTextBuffer.remove(m_iCursorPosition, 1);
int iDeletedSize = 1;
if(INPUT_ISLOWSURROGATE(m_szTextBuffer.at(m_iCursorPosition)) && m_iCursorPosition > 0)
{
// avoid splitting in the middle of a surrogate pair
m_iCursorPosition--;
iDeletedSize++;
}

addUndo(new EditCommand(EditCommand::RemoveText, m_szTextBuffer.mid(m_iCursorPosition, iDeletedSize), m_iCursorPosition));
m_szTextBuffer.remove(m_iCursorPosition, iDeletedSize);
m_p->bTextBlocksDirty = true;
}

Expand All @@ -3351,7 +3329,13 @@ void KviInputEditor::deleteHit()

if(m_iCursorPosition < m_szTextBuffer.length())
{
m_szTextBuffer.remove(m_iCursorPosition, 1);
if(INPUT_ISHIGHSURROGATE(m_szTextBuffer.at(m_iCursorPosition)) && m_iCursorPosition < m_szTextBuffer.length() - 1)
{
m_szTextBuffer.remove(m_iCursorPosition, 2);
} else {
m_szTextBuffer.remove(m_iCursorPosition, 1);
}

m_p->bTextBlocksDirty = true;
clearSelection();
ensureCursorVisible();
Expand Down
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