File indexing completed on 2025-03-16 08:11:27

 /*
    This file is part of Konsole, an X terminal.
 
    SPDX-FileCopyrightText: 2007-2008 Robert Knight <robert.knight@gmail.com>
    SPDX-FileCopyrightText: 1997, 1998 Lars Doelle <lars.doelle@on-line.de>
 
    SPDX-License-Identifier: GPL-2.0-or-later
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
    02110-1301  USA.
    */
 
 // Own
 #include "Screen.h"
 
 // Standard
 #include <cctype>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <unistd.h>
 
 // Qt
 #include <QDate>
 #include <QTextStream>
 
 // KDE
 // #include <kdebug.h>
 
 // Konsole
 #include "TerminalCharacterDecoder.h"
 #include "konsole_wcwidth.h"
 
 using namespace Konsole;
 
 // FIXME: this is emulation specific. Use false for xterm, true for ANSI.
 // FIXME: see if we can get this from terminfo.
 #define BS_CLEARS false
 
 // Macro to convert x,y position on screen to position within an image.
 //
 // Originally the image was stored as one large contiguous block of
 // memory, so a position within the image could be represented as an
 // offset from the beginning of the block.  For efficiency reasons this
 // is no longer the case.
 // Many internal parts of this class still use this representation for parameters and so on,
 // notably moveImage() and clearImage().
 // This macro converts from an X,Y position into an image offset.
 #ifndef loc
 #define loc(X, Y) ((Y)*columns + (X))
 #endif
 
 Character Screen::defaultChar =
     Character(' ', CharacterColor(COLOR_SPACE_DEFAULT, DEFAULT_FORE_COLOR), CharacterColor(COLOR_SPACE_DEFAULT, DEFAULT_BACK_COLOR), DEFAULT_RENDITION);
 
 // #define REVERSE_WRAPPED_LINES  // for wrapped line debug
 
 Screen::Screen(int l, int c)
     : lines(l)
     , columns(c)
     , screenLines(lines + 1)
     , _scrolledLines(0)
     , _droppedLines(0)
     , history(std::make_unique<HistoryScrollNone>())
     , cuX(0)
     , cuY(0)
     , currentRendition(0)
     , _topMargin(0)
     , _bottomMargin(0)
     , selBegin(0)
     , selTopLeft(0)
     , selBottomRight(0)
     , blockSelectionMode(false)
     , effectiveForeground(CharacterColor())
     , effectiveBackground(CharacterColor())
     , effectiveRendition(0)
     , lastPos(-1)
 {
     lineProperties.resize(lines + 1);
     for (int i = 0; i < lines + 1; i++)
         lineProperties[i] = LINE_DEFAULT;
 
     initTabStops();
     clearSelection();
     reset();
 }
 
 /*! Destructor
  */
 
 Screen::~Screen()
 {
 }
 
 void Screen::cursorUp(int n)
 //=CUU
 {
     if (n == 0)
         n = 1; // Default
     int stop = cuY < _topMargin ? 0 : _topMargin;
     cuX = qMin(columns - 1, cuX); // nowrap!
     cuY = qMax(stop, cuY - n);
 }
 
 void Screen::cursorDown(int n)
 //=CUD
 {
     if (n == 0)
         n = 1; // Default
     int stop = cuY > _bottomMargin ? lines - 1 : _bottomMargin;
     cuX = qMin(columns - 1, cuX); // nowrap!
     cuY = qMin(stop, cuY + n);
 }
 
 void Screen::cursorLeft(int n)
 //=CUB
 {
     if (n == 0)
         n = 1; // Default
     cuX = qMin(columns - 1, cuX); // nowrap!
     cuX = qMax(0, cuX - n);
 }
 
 void Screen::cursorRight(int n)
 //=CUF
 {
     if (n == 0)
         n = 1; // Default
     cuX = qMin(columns - 1, cuX + n);
 }
 
 void Screen::setMargins(int top, int bot)
 //=STBM
 {
     if (top == 0)
         top = 1; // Default
     if (bot == 0)
         bot = lines; // Default
     top = top - 1; // Adjust to internal lineno
     bot = bot - 1; // Adjust to internal lineno
     if (!(0 <= top && top < bot && bot < lines)) { // Debug()<<" setRegion("<<top<<","<<bot<<") : bad range.";
         return; // Default error action: ignore
     }
     _topMargin = top;
     _bottomMargin = bot;
     cuX = 0;
     cuY = getMode(MODE_Origin) ? top : 0;
 }
 
 int Screen::topMargin() const
 {
     return _topMargin;
 }
 int Screen::bottomMargin() const
 {
     return _bottomMargin;
 }
 
 void Screen::index()
 //=IND
 {
     if (cuY == _bottomMargin)
         scrollUp(1);
     else if (cuY < lines - 1)
         cuY += 1;
 }
 
 void Screen::reverseIndex()
 //=RI
 {
     if (cuY == _topMargin)
         scrollDown(_topMargin, 1);
     else if (cuY > 0)
         cuY -= 1;
 }
 
 void Screen::nextLine()
 //=NEL
 {
     toStartOfLine();
     index();
 }
 
 void Screen::eraseChars(int n)
 {
     if (n == 0)
         n = 1; // Default
     int p = qMax(0, qMin(cuX + n - 1, columns - 1));
     clearImage(loc(cuX, cuY), loc(p, cuY), ' ');
 }
 
 void Screen::deleteChars(int n)
 {
     Q_ASSERT(n >= 0);
 
     // always delete at least one char
     if (n == 0)
         n = 1;
 
     // if cursor is beyond the end of the line there is nothing to do
     if (cuX >= screenLines[cuY].size())
         return;
 
     if (cuX + n > screenLines[cuY].size())
         n = screenLines[cuY].size() - cuX;
 
     Q_ASSERT(n >= 0);
     Q_ASSERT(cuX + n <= screenLines[cuY].size());
 
     screenLines[cuY].remove(cuX, n);
 }
 
 void Screen::insertChars(int n)
 {
     if (n == 0)
         n = 1; // Default
 
     if (screenLines[cuY].size() < cuX)
         screenLines[cuY].resize(cuX);
 
     screenLines[cuY].insert(cuX, n, ' ');
 
     if (screenLines[cuY].size() > columns)
         screenLines[cuY].resize(columns);
 }
 
 void Screen::repeatChars(int count)
 //=REP
 {
     if (count == 0) {
         count = 1;
     }
     /**
      * From ECMA-48 version 5, section 8.3.103
      * If the character preceding REP is a control function or part of a
      * control function, the effect of REP is not defined by this Standard.
      *
      * So, a "normal" program should always use REP immediately after a visible
      * character (those other than escape sequences). So, lastDrawnChar can be
      * safely used.
      */
     for (int i = 0; i < count; i++) {
         displayCharacter(lastDrawnChar);
     }
 }
 
 void Screen::deleteLines(int n)
 {
     if (n == 0)
         n = 1; // Default
     scrollUp(cuY, n);
 }
 
 void Screen::insertLines(int n)
 {
     if (n == 0)
         n = 1; // Default
     scrollDown(cuY, n);
 }
 
 void Screen::setMode(int m)
 {
     currentModes[m] = true;
     switch (m) {
     case MODE_Origin:
         cuX = 0;
         cuY = _topMargin;
         break; // FIXME: home
     }
 }
 
 void Screen::resetMode(int m)
 {
     currentModes[m] = false;
     switch (m) {
     case MODE_Origin:
         cuX = 0;
         cuY = 0;
         break; // FIXME: home
     }
 }
 
 void Screen::saveMode(int m)
 {
     savedModes[m] = currentModes[m];
 }
 
 void Screen::restoreMode(int m)
 {
     currentModes[m] = savedModes[m];
 }
 
 bool Screen::getMode(int m) const
 {
     return currentModes[m];
 }
 
 void Screen::saveCursor()
 {
     savedState.cursorColumn = cuX;
     savedState.cursorLine = cuY;
     savedState.rendition = currentRendition;
     savedState.foreground = currentForeground;
     savedState.background = currentBackground;
 }
 
 void Screen::restoreCursor()
 {
     cuX = qMin(savedState.cursorColumn, columns - 1);
     cuY = qMin(savedState.cursorLine, lines - 1);
     currentRendition = savedState.rendition;
     currentForeground = savedState.foreground;
     currentBackground = savedState.background;
     updateEffectiveRendition();
 }
 
 void Screen::resizeImage(int new_lines, int new_columns)
 {
     if ((new_lines == lines) && (new_columns == columns))
         return;
 
     if (cuY > new_lines - 1) { // attempt to preserve focus and lines
         _bottomMargin = lines - 1; // FIXME: margin lost
         for (int i = 0; i < cuY - (new_lines - 1); i++) {
             addHistLine();
             scrollUp(0, 1);
         }
     }
 
     // create new screen lines and copy from old to new
 
     auto newScreenLines = QVector<ImageLine>(new_lines + 1);
     for (int i = 0; i < qMin(lines, new_lines + 1); i++)
         newScreenLines[i] = screenLines[i];
     for (int i = lines; (i > 0) && (i < new_lines + 1); i++)
         newScreenLines[i].resize(new_columns);
 
     lineProperties.resize(new_lines + 1);
     for (int i = lines; (i > 0) && (i < new_lines + 1); i++)
         lineProperties[i] = LINE_DEFAULT;
 
     clearSelection();
 
     screenLines.clear();
     screenLines = std::move(newScreenLines);
 
     lines = new_lines;
     columns = new_columns;
     cuX = qMin(cuX, columns - 1);
     cuY = qMin(cuY, lines - 1);
 
     // FIXME: try to keep values, evtl.
     _topMargin = 0;
     _bottomMargin = lines - 1;
     initTabStops();
     clearSelection();
 }
 
 void Screen::setDefaultMargins()
 {
     _topMargin = 0;
     _bottomMargin = lines - 1;
 }
 
 /*
    Clarifying rendition here and in the display.
 
    currently, the display's color table is
    0       1       2 .. 9    10 .. 17
    dft_fg, dft_bg, dim 0..7, intensive 0..7
 
    currentForeground, currentBackground contain values 0..8;
    - 0    = default color
    - 1..8 = ansi specified color
 
    re_fg, re_bg contain values 0..17
    due to the TerminalDisplay's color table
 
    rendition attributes are
 
    attr           widget screen
    -------------- ------ ------
    RE_UNDERLINE     XX     XX    affects foreground only
    RE_BLINK         XX     XX    affects foreground only
    RE_BOLD          XX     XX    affects foreground only
    RE_REVERSE       --     XX
    RE_TRANSPARENT   XX     --    affects background only
    RE_INTENSIVE     XX     --    affects foreground only
 
    Note that RE_BOLD is used in both widget
    and screen rendition. Since xterm/vt102
    is to poor to distinguish between bold
    (which is a font attribute) and intensive
    (which is a color attribute), we translate
    this and RE_BOLD in falls eventually appart
    into RE_BOLD and RE_INTENSIVE.
    */
 
 void Screen::reverseRendition(Character &p) const
 {
     CharacterColor f = p.foregroundColor;
     CharacterColor b = p.backgroundColor;
 
     p.foregroundColor = b;
     p.backgroundColor = f; // p->r &= ~RE_TRANSPARENT;
 }
 
 void Screen::updateEffectiveRendition()
 {
     effectiveRendition = currentRendition;
     if (currentRendition & RE_REVERSE) {
         effectiveForeground = currentBackground;
         effectiveBackground = currentForeground;
     } else {
         effectiveForeground = currentForeground;
         effectiveBackground = currentBackground;
     }
 
     if (currentRendition & RE_BOLD)
         effectiveForeground.setIntensive();
 }
 
 void Screen::copyFromHistory(std::span<Character> dest, int startLine, int count) const
 {
     Q_ASSERT(startLine >= 0 && count > 0 && startLine + count <= history->getLines());
 
     for (int line = startLine; line < startLine + count; line++) {
         const int length = qMin(columns, history->getLineLen(line));
         const int destLineOffset = (line - startLine) * columns;
 
         history->getCells(line, 0, length, dest.subspan(destLineOffset));
 
         for (int column = length; column < columns; column++)
             dest[destLineOffset + column] = defaultChar;
 
         // invert selected text
         if (selBegin != -1) {
             for (int column = 0; column < columns; column++) {
                 if (isSelected(column, line)) {
                     reverseRendition(dest[destLineOffset + column]);
                 }
             }
         }
     }
 }
 
 void Screen::copyFromScreen(std::span<Character> dest, int startLine, int count) const
 {
     Q_ASSERT(startLine >= 0 && count > 0 && startLine + count <= lines);
 
     for (int line = startLine; line < (startLine + count); line++) {
         int srcLineStartIndex = line * columns;
         int destLineStartIndex = (line - startLine) * columns;
 
         for (int column = 0; column < columns; column++) {
             int srcIndex = srcLineStartIndex + column;
             int destIndex = destLineStartIndex + column;
 
             dest[destIndex] = screenLines[srcIndex / columns].value(srcIndex % columns, defaultChar);
 
             // invert selected text
             if (selBegin != -1 && isSelected(column, line + history->getLines()))
                 reverseRendition(dest[destIndex]);
         }
     }
 }
 
 void Screen::getImage(std::span<Character> dest, int size, int startLine, int endLine) const
 {
     Q_ASSERT(startLine >= 0);
     Q_ASSERT(endLine >= startLine && endLine < history->getLines() + lines);
 
     const int mergedLines = endLine - startLine + 1;
 
     Q_ASSERT(size >= mergedLines * columns);
     Q_UNUSED(size);
 
     const int linesInHistoryBuffer = qBound(0, history->getLines() - startLine, mergedLines);
     const int linesInScreenBuffer = mergedLines - linesInHistoryBuffer;
 
     // copy lines from history buffer
     if (linesInHistoryBuffer > 0)
         copyFromHistory(dest, startLine, linesInHistoryBuffer);
 
     // copy lines from screen buffer
     if (linesInScreenBuffer > 0)
         copyFromScreen(dest.subspan(linesInHistoryBuffer * columns), startLine + linesInHistoryBuffer - history->getLines(), linesInScreenBuffer);
 
     // invert display when in screen mode
     if (getMode(MODE_Screen)) {
         for (int i = 0; i < mergedLines * columns; i++)
             reverseRendition(dest[i]); // for reverse display
     }
 
     // mark the character at the current cursor position
     int cursorIndex = loc(cuX, cuY + linesInHistoryBuffer);
     if (getMode(MODE_Cursor) && cursorIndex < columns * mergedLines)
         dest[cursorIndex].rendition |= RE_CURSOR;
 }
 
 QVector<LineProperty> Screen::getLineProperties(int startLine, int endLine) const
 {
     Q_ASSERT(startLine >= 0);
     Q_ASSERT(endLine >= startLine && endLine < history->getLines() + lines);
 
     const int mergedLines = endLine - startLine + 1;
     const int linesInHistory = qBound(0, history->getLines() - startLine, mergedLines);
     const int linesInScreen = mergedLines - linesInHistory;
 
     QVector<LineProperty> result(mergedLines);
     int index = 0;
 
     // copy properties for lines in history
     for (int line = startLine; line < startLine + linesInHistory; line++) {
         // TODO Support for line properties other than wrapped lines
         if (history->isWrappedLine(line)) {
             result[index] = (LineProperty)(result[index] | LINE_WRAPPED);
         }
         index++;
     }
 
     // copy properties for lines in screen buffer
     const int firstScreenLine = startLine + linesInHistory - history->getLines();
     for (int line = firstScreenLine; line < firstScreenLine + linesInScreen; line++) {
         result[index] = lineProperties[line];
         index++;
     }
 
     return result;
 }
 
 void Screen::reset(bool clearScreen)
 {
     setMode(MODE_Wrap);
     saveMode(MODE_Wrap); // wrap at end of margin
     resetMode(MODE_Origin);
     saveMode(MODE_Origin); // position refere to [1,1]
     resetMode(MODE_Insert);
     saveMode(MODE_Insert); // overstroke
     setMode(MODE_Cursor); // cursor visible
     resetMode(MODE_Screen); // screen not inverse
     resetMode(MODE_NewLine);
 
     _topMargin = 0;
     _bottomMargin = lines - 1;
 
     setDefaultRendition();
     saveCursor();
 
     if (clearScreen)
         clear();
 }
 
 void Screen::clear()
 {
     clearEntireScreen();
     home();
 }
 
 void Screen::backspace()
 {
     cuX = qMin(columns - 1, cuX); // nowrap!
     cuX = qMax(0, cuX - 1);
 
     if (screenLines[cuY].size() < cuX + 1)
         screenLines[cuY].resize(cuX + 1);
 
     if (BS_CLEARS)
         screenLines[cuY][cuX].character = u' ';
 }
 
 void Screen::tab(int n)
 {
     // note that TAB is a format effector (does not write ' ');
     if (n == 0)
         n = 1;
     while ((n > 0) && (cuX < columns - 1)) {
         cursorRight(1);
         while ((cuX < columns - 1) && !tabStops[cuX])
             cursorRight(1);
         n--;
     }
 }
 
 void Screen::backtab(int n)
 {
     // note that TAB is a format effector (does not write ' ');
     if (n == 0)
         n = 1;
     while ((n > 0) && (cuX > 0)) {
         cursorLeft(1);
         while ((cuX > 0) && !tabStops[cuX])
             cursorLeft(1);
         n--;
     }
 }
 
 void Screen::clearTabStops()
 {
     for (int i = 0; i < columns; i++)
         tabStops[i] = false;
 }
 
 void Screen::changeTabStop(bool set)
 {
     if (cuX >= columns)
         return;
     tabStops[cuX] = set;
 }
 
 void Screen::initTabStops()
 {
     tabStops.resize(columns);
 
     // Arrg! The 1st tabstop has to be one longer than the other.
     // i.e. the kids start counting from 0 instead of 1.
     // Other programs might behave correctly. Be aware.
     for (int i = 0; i < columns; i++)
         tabStops[i] = (i % 8 == 0 && i != 0);
 }
 
 void Screen::newLine()
 {
     if (getMode(MODE_NewLine))
         toStartOfLine();
     index();
 }
 
 void Screen::checkSelection(int from, int to)
 {
     if (selBegin == -1)
         return;
     int scr_TL = loc(0, history->getLines());
     // Clear entire selection if it overlaps region [from, to]
     if ((selBottomRight >= (from + scr_TL)) && (selTopLeft <= (to + scr_TL)))
         clearSelection();
 }
 
 void Screen::displayCharacter(QChar c)
 {
     // Note that VT100 does wrapping BEFORE putting the character.
     // This has impact on the assumption of valid cursor positions.
     // We indicate the fact that a newline has to be triggered by
     // putting the cursor one right to the last column of the screen.
 
     int w = konsole_wcwidth(c);
     if (w <= 0)
         return;
 
     if (cuX + w > columns) {
         if (getMode(MODE_Wrap)) {
             lineProperties[cuY] = (LineProperty)(lineProperties[cuY] | LINE_WRAPPED);
             nextLine();
         } else
             cuX = columns - w;
     }
 
     // ensure current line vector has enough elements
     int size = screenLines[cuY].size();
     if (size < cuX + w) {
         screenLines[cuY].resize(cuX + w);
     }
 
     if (getMode(MODE_Insert))
         insertChars(w);
 
     lastPos = loc(cuX, cuY);
 
     // check if selection is still valid.
     checkSelection(lastPos, lastPos);
 
     Character &currentChar = screenLines[cuY][cuX];
 
     currentChar.character = c;
     currentChar.foregroundColor = effectiveForeground;
     currentChar.backgroundColor = effectiveBackground;
     currentChar.rendition = effectiveRendition;
 
     lastDrawnChar = c;
 
     int i = 0;
     int newCursorX = cuX + w--;
     while (w) {
         i++;
 
         if (screenLines[cuY].size() < cuX + i + 1)
             screenLines[cuY].resize(cuX + i + 1);
 
         Character &ch = screenLines[cuY][cuX + i];
         ch.character = QChar(0);
         ch.foregroundColor = effectiveForeground;
         ch.backgroundColor = effectiveBackground;
         ch.rendition = effectiveRendition;
 
         w--;
     }
     cuX = newCursorX;
 }
 
 void Screen::compose(const QString & /*compose*/)
 {
     Q_ASSERT(0 /*Not implemented yet*/);
 
     /*  if (lastPos == -1)
         return;
 
         QChar c(image[lastPos].character);
         compose.prepend(c);
     //compose.compose(); ### FIXME!
     image[lastPos].character = compose[0].unicode();*/
 }
 
 int Screen::scrolledLines() const
 {
     return _scrolledLines;
 }
 int Screen::droppedLines() const
 {
     return _droppedLines;
 }
 void Screen::resetDroppedLines()
 {
     _droppedLines = 0;
 }
 void Screen::resetScrolledLines()
 {
     _scrolledLines = 0;
 }
 
 void Screen::scrollUp(int n)
 {
     if (n == 0)
         n = 1; // Default
     if (_topMargin == 0)
         addHistLine(); // history.history
     scrollUp(_topMargin, n);
 }
 
 QRect Screen::lastScrolledRegion() const
 {
     return _lastScrolledRegion;
 }
 
 void Screen::scrollUp(int from, int n)
 {
     if (n <= 0)
         return;
     if (from > _bottomMargin)
         return;
     if (from + n > _bottomMargin)
         n = _bottomMargin + 1 - from;
 
     _scrolledLines -= n;
     _lastScrolledRegion = QRect(0, _topMargin, columns - 1, (_bottomMargin - _topMargin));
 
     // FIXME: make sure `topMargin', `bottomMargin', `from', `n' is in bounds.
     moveImage(loc(0, from), loc(0, from + n), loc(columns, _bottomMargin));
     clearImage(loc(0, _bottomMargin - n + 1), loc(columns - 1, _bottomMargin), ' ');
 }
 
 void Screen::scrollDown(int n)
 {
     if (n == 0)
         n = 1; // Default
     scrollDown(_topMargin, n);
 }
 
 void Screen::scrollDown(int from, int n)
 {
     _scrolledLines += n;
 
     // FIXME: make sure `topMargin', `bottomMargin', `from', `n' is in bounds.
     if (n <= 0)
         return;
     if (from > _bottomMargin)
         return;
     if (from + n > _bottomMargin)
         n = _bottomMargin - from;
     moveImage(loc(0, from + n), loc(0, from), loc(columns - 1, _bottomMargin - n));
     clearImage(loc(0, from), loc(columns - 1, from + n - 1), ' ');
 }
 
 void Screen::setCursorYX(int y, int x)
 {
     setCursorY(y);
     setCursorX(x);
 }
 
 void Screen::setCursorX(int x)
 {
     if (x == 0)
         x = 1; // Default
     x -= 1; // Adjust
     cuX = qMax(0, qMin(columns - 1, x));
 }
 
 void Screen::setCursorY(int y)
 {
     if (y == 0)
         y = 1; // Default
     y -= 1; // Adjust
     cuY = qMax(0, qMin(lines - 1, y + (getMode(MODE_Origin) ? _topMargin : 0)));
 }
 
 void Screen::home()
 {
     cuX = 0;
     cuY = 0;
 }
 
 void Screen::toStartOfLine()
 {
     cuX = 0;
 }
 
 int Screen::getCursorX() const
 {
     return cuX;
 }
 
 int Screen::getCursorY() const
 {
     return cuY;
 }
 
 void Screen::clearImage(int loca, int loce, char c)
 {
     int scr_TL = loc(0, history->getLines());
     // FIXME: check positions
 
     // Clear entire selection if it overlaps region to be moved...
     if ((selBottomRight > (loca + scr_TL)) && (selTopLeft < (loce + scr_TL))) {
         clearSelection();
     }
 
     int topLine = loca / columns;
     int bottomLine = loce / columns;
 
     Character clearCh(c, currentForeground, currentBackground, DEFAULT_RENDITION);
 
     // if the character being used to clear the area is the same as the
     // default character, the affected lines can simply be shrunk.
     bool isDefaultCh = (clearCh == Character());
 
     for (int y = topLine; y <= bottomLine; y++) {
         lineProperties[y] = 0;
 
         int endCol = (y == bottomLine) ? loce % columns : columns - 1;
         int startCol = (y == topLine) ? loca % columns : 0;
 
         QVector<Character> &line = screenLines[y];
 
         if (isDefaultCh && endCol == columns - 1) {
             line.resize(startCol);
         } else {
             if (line.size() < endCol + 1)
                 line.resize(endCol + 1);
 
             Character *data = line.data();
             for (int i = startCol; i <= endCol; i++)
                 data[i] = clearCh;
         }
     }
 }
 
 void Screen::moveImage(int dest, int sourceBegin, int sourceEnd)
 {
     Q_ASSERT(sourceBegin <= sourceEnd);
 
     int lines = (sourceEnd - sourceBegin) / columns;
 
     // move screen image and line properties:
     // the source and destination areas of the image may overlap,
     // so it matters that we do the copy in the right order -
     // forwards if dest < sourceBegin or backwards otherwise.
     //(search the web for 'memmove implementation' for details)
     if (dest < sourceBegin) {
         for (int i = 0; i <= lines; i++) {
             screenLines[(dest / columns) + i] = screenLines[(sourceBegin / columns) + i];
             lineProperties[(dest / columns) + i] = lineProperties[(sourceBegin / columns) + i];
         }
     } else {
         for (int i = lines; i >= 0; i--) {
             screenLines[(dest / columns) + i] = screenLines[(sourceBegin / columns) + i];
             lineProperties[(dest / columns) + i] = lineProperties[(sourceBegin / columns) + i];
         }
     }
 
     if (lastPos != -1) {
         int diff = dest - sourceBegin; // Scroll by this amount
         lastPos += diff;
         if ((lastPos < 0) || (lastPos >= (lines * columns)))
             lastPos = -1;
     }
 
     // Adjust selection to follow scroll.
     if (selBegin != -1) {
         bool beginIsTL = (selBegin == selTopLeft);
         int diff = dest - sourceBegin; // Scroll by this amount
         int scr_TL = loc(0, history->getLines());
         int srca = sourceBegin + scr_TL; // Translate index from screen to global
         int srce = sourceEnd + scr_TL; // Translate index from screen to global
         int desta = srca + diff;
         int deste = srce + diff;
 
         if ((selTopLeft >= srca) && (selTopLeft <= srce))
             selTopLeft += diff;
         else if ((selTopLeft >= desta) && (selTopLeft <= deste))
             selBottomRight = -1; // Clear selection (see below)
 
         if ((selBottomRight >= srca) && (selBottomRight <= srce))
             selBottomRight += diff;
         else if ((selBottomRight >= desta) && (selBottomRight <= deste))
             selBottomRight = -1; // Clear selection (see below)
 
         if (selBottomRight < 0) {
             clearSelection();
         } else {
             if (selTopLeft < 0)
                 selTopLeft = 0;
         }
 
         if (beginIsTL)
             selBegin = selTopLeft;
         else
             selBegin = selBottomRight;
     }
 }
 
 void Screen::clearToEndOfScreen()
 {
     clearImage(loc(cuX, cuY), loc(columns - 1, lines - 1), ' ');
 }
 
 void Screen::clearToBeginOfScreen()
 {
     clearImage(loc(0, 0), loc(cuX, cuY), ' ');
 }
 
 void Screen::clearEntireScreen()
 {
     // Add entire screen to history
     for (int i = 0; i < (lines - 1); i++) {
         addHistLine();
         scrollUp(0, 1);
     }
 
     clearImage(loc(0, 0), loc(columns - 1, lines - 1), ' ');
 }
 
 /*! fill screen with 'E'
   This is to aid screen alignment
   */
 
 void Screen::helpAlign()
 {
     clearImage(loc(0, 0), loc(columns - 1, lines - 1), 'E');
 }
 
 void Screen::clearToEndOfLine()
 {
     clearImage(loc(cuX, cuY), loc(columns - 1, cuY), ' ');
 }
 
 void Screen::clearToBeginOfLine()
 {
     clearImage(loc(0, cuY), loc(cuX, cuY), ' ');
 }
 
 void Screen::clearEntireLine()
 {
     clearImage(loc(0, cuY), loc(columns - 1, cuY), ' ');
 }
 
 void Screen::setRendition(int re)
 {
     currentRendition |= re;
     updateEffectiveRendition();
 }
 
 void Screen::resetRendition(int re)
 {
     currentRendition &= ~re;
     updateEffectiveRendition();
 }
 
 void Screen::setDefaultRendition()
 {
     setForeColor(COLOR_SPACE_DEFAULT, DEFAULT_FORE_COLOR);
     setBackColor(COLOR_SPACE_DEFAULT, DEFAULT_BACK_COLOR);
     currentRendition = DEFAULT_RENDITION;
     updateEffectiveRendition();
 }
 
 void Screen::setForeColor(int space, int color)
 {
     currentForeground = CharacterColor(space, color);
 
     if (currentForeground.isValid())
         updateEffectiveRendition();
     else
         setForeColor(COLOR_SPACE_DEFAULT, DEFAULT_FORE_COLOR);
 }
 
 void Screen::setBackColor(int space, int color)
 {
     currentBackground = CharacterColor(space, color);
 
     if (currentBackground.isValid())
         updateEffectiveRendition();
     else
         setBackColor(COLOR_SPACE_DEFAULT, DEFAULT_BACK_COLOR);
 }
 
 void Screen::clearSelection()
 {
     selBottomRight = -1;
     selTopLeft = -1;
     selBegin = -1;
 }
 
 void Screen::getSelectionStart(int &column, int &line) const
 {
     if (selTopLeft != -1) {
         column = selTopLeft % columns;
         line = selTopLeft / columns;
     } else {
         column = cuX + getHistLines();
         line = cuY + getHistLines();
     }
 }
 void Screen::getSelectionEnd(int &column, int &line) const
 {
     if (selBottomRight != -1) {
         column = selBottomRight % columns;
         line = selBottomRight / columns;
     } else {
         column = cuX + getHistLines();
         line = cuY + getHistLines();
     }
 }
 void Screen::setSelectionStart(const int x, const int y, const bool mode)
 {
     selBegin = loc(x, y);
     /* FIXME, HACK to correct for x too far to the right... */
     if (x == columns)
         selBegin--;
 
     selBottomRight = selBegin;
     selTopLeft = selBegin;
     blockSelectionMode = mode;
 }
 
 void Screen::setSelectionEnd(const int x, const int y)
 {
     if (selBegin == -1)
         return;
 
     int endPos = loc(x, y);
 
     if (endPos < selBegin) {
         selTopLeft = endPos;
         selBottomRight = selBegin;
     } else {
         /* FIXME, HACK to correct for x too far to the right... */
         if (x == columns)
             endPos--;
 
         selTopLeft = selBegin;
         selBottomRight = endPos;
     }
 
     // Normalize the selection in column mode
     if (blockSelectionMode) {
         int topRow = selTopLeft / columns;
         int topColumn = selTopLeft % columns;
         int bottomRow = selBottomRight / columns;
         int bottomColumn = selBottomRight % columns;
 
         selTopLeft = loc(qMin(topColumn, bottomColumn), topRow);
         selBottomRight = loc(qMax(topColumn, bottomColumn), bottomRow);
     }
 }
 
 bool Screen::isSelected(const int x, const int y) const
 {
     bool columnInSelection = true;
     if (blockSelectionMode) {
         columnInSelection = x >= (selTopLeft % columns) && x <= (selBottomRight % columns);
     }
 
     int pos = loc(x, y);
     return pos >= selTopLeft && pos <= selBottomRight && columnInSelection;
 }
 
 QString Screen::selectedText(bool preserveLineBreaks) const
 {
     QString result;
     QTextStream stream(&result, QIODevice::ReadWrite);
 
     PlainTextDecoder decoder;
     decoder.begin(&stream);
     writeSelectionToStream(&decoder, preserveLineBreaks);
     decoder.end();
 
     return result;
 }
 
 bool Screen::isSelectionValid() const
 {
     return selTopLeft >= 0 && selBottomRight >= 0;
 }
 
 void Screen::writeSelectionToStream(TerminalCharacterDecoder *decoder, bool preserveLineBreaks) const
 {
     if (!isSelectionValid())
         return;
     writeToStream(decoder, selTopLeft, selBottomRight, preserveLineBreaks);
 }
 
 void Screen::writeToStream(TerminalCharacterDecoder *decoder, int startIndex, int endIndex, bool preserveLineBreaks) const
 {
     int top = startIndex / columns;
     int left = startIndex % columns;
 
     int bottom = endIndex / columns;
     int right = endIndex % columns;
 
     Q_ASSERT(top >= 0 && left >= 0 && bottom >= 0 && right >= 0);
 
     for (int y = top; y <= bottom; y++) {
         int start = 0;
         if (y == top || blockSelectionMode)
             start = left;
 
         int count = -1;
         if (y == bottom || blockSelectionMode)
             count = right - start + 1;
 
         const bool appendNewLine = (y != bottom);
         int copied = copyLineToStream(y, start, count, decoder, appendNewLine, preserveLineBreaks);
 
         // if the selection goes beyond the end of the last line then
         // append a new line character.
         //
         // this makes it possible to 'select' a trailing new line character after
         // the text on a line.
         if (y == bottom && copied < count) {
             Character newLineChar('\n');
             decoder->decodeLine(std::span(&newLineChar, 1), 0);
         }
     }
 }
 
 int Screen::copyLineToStream(int line, int start, int count, TerminalCharacterDecoder *decoder, bool appendNewLine, bool preserveLineBreaks) const
 {
     // buffer to hold characters for decoding
     // the buffer is static to avoid initialising every
     // element on each call to copyLineToStream
     //(which is unnecessary since all elements will be overwritten anyway)
     static const int MAX_CHARS = 1024;
     static std::array<Character, MAX_CHARS> characterBuffer;
 
     Q_ASSERT(count < MAX_CHARS);
 
     LineProperty currentLineProperties = 0;
 
     // determine if the line is in the history buffer or the screen image
     if (line < history->getLines()) {
         const int lineLength = history->getLineLen(line);
 
         // ensure that start position is before end of line
         start = qMin(start, qMax(0, lineLength - 1));
 
         // retrieve line from history buffer.  It is assumed
         // that the history buffer does not store trailing white space
         // at the end of the line, so it does not need to be trimmed here
         if (count == -1) {
             count = lineLength - start;
         } else {
             count = qMin(start + count, lineLength) - start;
         }
 
         // safety checks
         Q_ASSERT(start >= 0);
         Q_ASSERT(count >= 0);
         Q_ASSERT((start + count) <= history->getLineLen(line));
 
         history->getCells(line, start, count, characterBuffer);
 
         if (history->isWrappedLine(line))
             currentLineProperties |= LINE_WRAPPED;
     } else {
         if (count == -1)
             count = columns - start;
 
         Q_ASSERT(count >= 0);
 
         const int screenLine = line - history->getLines();
 
         auto data = screenLines[screenLine].data();
         int length = screenLines[screenLine].size();
 
         // retrieve line from screen image
         for (int i = start; i < qMin(start + count, length); i++) {
             characterBuffer[i - start] = data[i];
         }
 
         // count cannot be any greater than length
         count = qBound(0, length - start, count);
 
         Q_ASSERT(screenLine < lineProperties.size());
         currentLineProperties |= lineProperties[screenLine];
     }
 
     // add new line character at end
     const bool omitLineBreak = (currentLineProperties & LINE_WRAPPED) || !preserveLineBreaks;
 
     if (!omitLineBreak && appendNewLine && (count + 1 < MAX_CHARS)) {
         characterBuffer[count] = '\n';
         count++;
     }
 
     // decode line and write to text stream
     decoder->decodeLine(std::span(characterBuffer).subspan(0, count), currentLineProperties);
 
     return count;
 }
 
 void Screen::writeLinesToStream(TerminalCharacterDecoder *decoder, int fromLine, int toLine) const
 {
     writeToStream(decoder, loc(0, fromLine), loc(columns - 1, toLine));
 }
 
 void Screen::addHistLine()
 {
     // add line to history buffer
     // we have to take care about scrolling, too...
 
     if (hasScroll()) {
         int oldHistLines = history->getLines();
 
         history->addCellsVector(screenLines[0]);
         history->addLine(lineProperties[0] & LINE_WRAPPED);
 
         int newHistLines = history->getLines();
 
         bool beginIsTL = (selBegin == selTopLeft);
 
         // If the history is full, increment the count
         // of dropped lines
         if (newHistLines == oldHistLines)
             _droppedLines++;
 
         // Adjust selection for the new point of reference
         if (newHistLines > oldHistLines) {
             if (selBegin != -1) {
                 selTopLeft += columns;
                 selBottomRight += columns;
             }
         }
 
         if (selBegin != -1) {
             // Scroll selection in history up
             int top_BR = loc(0, 1 + newHistLines);
 
             if (selTopLeft < top_BR)
                 selTopLeft -= columns;
 
             if (selBottomRight < top_BR)
                 selBottomRight -= columns;
 
             if (selBottomRight < 0)
                 clearSelection();
             else {
                 if (selTopLeft < 0)
                     selTopLeft = 0;
             }
 
             if (beginIsTL)
                 selBegin = selTopLeft;
             else
                 selBegin = selBottomRight;
         }
     }
 }
 
 int Screen::getHistLines() const
 {
     return history->getLines();
 }
 
 void Screen::setScroll(const HistoryType &t, bool copyPreviousScroll)
 {
     clearSelection();
 
     if (copyPreviousScroll)
         history = t.scroll(std::move(history));
     else {
         auto oldScroll = std::move(history);
         history = t.scroll(nullptr);
     }
 }
 
 bool Screen::hasScroll() const
 {
     return history->hasScroll();
 }
 
 const HistoryType &Screen::getScroll() const
 {
     return history->getType();
 }
 
 void Screen::setLineProperty(LineProperty property, bool enable)
 {
     if (enable)
         lineProperties[cuY] = (LineProperty)(lineProperties[cuY] | property);
     else
         lineProperties[cuY] = (LineProperty)(lineProperties[cuY] & ~property);
 }
 void Screen::fillWithDefaultChar(std::span<Character> dest, int count)
 {
     for (int i = 0; i < count; i++)
         dest[i] = defaultChar;
 }