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eyelockDavid Collieclaudemigueldeicaza
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Translate selections when rows move in place (#616)
* Translate selections when lines are scrolled in place A selection is anchored to absolute buffer rows. When a scroll pushes lines into the scrollback that is safe: the rows stay valid and yDisp advances. But when an application sets a scroll region that does not start at the top of the screen (DECSTBM), Terminal.scroll shifts the lines within the region instead, leaving yDisp untouched. The selection anchors are then left pointing at whatever text scrolled into those rows, so the highlight sits over the wrong text and copying returns it. Full-screen TUIs hit this constantly: GitHub Copilot CLI, for example, reserves its tab bar and prompt rows and scrolls the transcript between them with ESC[4;34r followed by a linefeed, so any selection made while output is streaming silently drifts onto other lines. Selections now register with their terminal and are translated when lines shift in place, and are cleared when they scroll out of the region. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * Cover the remaining in-place row movements Selections also need translating when rows move without going through the scrollback on the other paths that shift lines in place: - reverseIndex (ESC M) shifts rows down within the scroll region - cmdInsertLines (CSI L) pushes rows below the cursor down - cmdDeleteLines (CSI M) pulls rows below the cursor up Margin mode (DECSLRM) shifts only the columns between the margins, and a selection cannot be represented as partially shifted, so on those paths an overlapping selection is cleared instead. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * Complete selection translation for row scrolling --------- Co-authored-by: David Collie <support@eyelock.net> Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com> Co-authored-by: Miguel de Icaza <miguel@gnome.org>
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‎Sources/SwiftTerm/SelectionService.swift‎

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Original file line numberDiff line numberDiff line change
@@ -24,6 +24,104 @@ class SelectionService: CustomDebugStringConvertible {
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end = Position(col: 0, row: 0)
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pivot = Position(col: 0, row: 0)
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hasSelectionRange = false
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terminal.register (selection: self)
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}
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/**
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* Translates the selection when the terminal shifts lines in place, which
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* happens when an application scrolls a region set with DECSTBM that does
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* not start at the top of the screen. Those scrolls do not push lines into
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* the scrollback, so `yDisp` does not move and the absolute rows the
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* selection is anchored to end up holding different text.
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*
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* Rows outside the scrolled region keep their position. A selection is
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* dropped if it scrolls out of the region or crosses a region boundary.
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* In those cases, the original text is gone or is no longer contiguous.
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*/
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func adjustForInPlaceScroll (top: Int, bottom: Int, lines: Int)
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{
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guard active, lines != 0 else {
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return
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}
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let (first, last) = Position.compare (start, end) == .before ? (start, end) : (end, start)
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let intersectsRegion = first.row <= bottom && last.row >= top
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guard intersectsRegion else {
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return
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}
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guard first.row >= top && last.row <= bottom else {
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selectNone ()
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return
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}
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func translate (_ position: Position) -> Position? {
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guard position.row >= top && position.row <= bottom else {
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return position
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}
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let newRow = position.row - lines
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guard newRow >= top && newRow <= bottom else {
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return nil
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}
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return Position (col: position.col, row: newRow)
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}
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guard let newStart = translate (start), let newEnd = translate (end) else {
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selectNone ()
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return
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}
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let newPivot: Position?
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if let pivot, pivot == start || pivot == end {
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guard let translatedPivot = translate (pivot) else {
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selectNone ()
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return
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}
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newPivot = translatedPivot
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} else {
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newPivot = pivot
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}
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let newWordSelectionAnchor: (start: Position, end: Position)?
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if let wordSelectionAnchor {
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guard let translatedStart = translate (wordSelectionAnchor.start),
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let translatedEnd = translate (wordSelectionAnchor.end) else {
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selectNone ()
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return
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}
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newWordSelectionAnchor = (translatedStart, translatedEnd)
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} else {
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newWordSelectionAnchor = nil
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}
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start = newStart
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end = newEnd
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pivot = newPivot
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wordSelectionAnchor = newWordSelectionAnchor
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terminal.tdel?.selectionChanged (source: terminal)
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}
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/**
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* Clears the selection if it overlaps a region whose contents were shifted
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* only within a range of columns, which happens when margin mode narrows
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* the scrolled area (DECSLRM). A selection cannot be represented as
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* partially shifted, so the honest answer is to drop it.
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*/
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func invalidateForColumnRestrictedScroll (top: Int, bottom: Int, left: Int, right: Int)
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{
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guard active else {
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return
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}
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let (first, last) = Position.compare (start, end) == .before ? (start, end) : (end, start)
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guard first.row <= bottom && last.row >= top else {
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return
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}
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// A single-row selection that sits entirely outside the margin columns
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// is unaffected; anything spanning rows crosses them by definition.
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if first.row == last.row && (last.col < left || first.col > right) {
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return
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}
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selectNone ()
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}
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/**

‎Sources/SwiftTerm/Terminal.swift‎

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Original file line numberDiff line numberDiff line change
@@ -333,6 +333,41 @@ open class Terminal {
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/// Setup(isReset:) method should be called to apply changes
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public var options: TerminalOptions
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// Selection services attached to this terminal. Held weakly: the views own
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// them. They are notified when lines are shifted in place so they can
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// translate their anchors (see `adjustForInPlaceScroll`).
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private struct WeakSelection {
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weak var value: SelectionService?
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}
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private var selections: [WeakSelection] = []
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func register (selection: SelectionService)
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{
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selections.removeAll { $0.value == nil }
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guard !selections.contains (where: { $0.value === selection }) else {
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return
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}
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selections.append (WeakSelection (value: selection))
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}
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/// Notifies attached selections that `lines` rows were shifted up in place
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/// within the absolute row range `top...bottom`.
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func selectionsAdjustForInPlaceScroll (top: Int, bottom: Int, lines: Int)
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{
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for entry in selections {
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entry.value?.adjustForInPlaceScroll (top: top, bottom: bottom, lines: lines)
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}
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}
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/// Notifies attached selections that rows `top...bottom` were shifted only
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/// within the columns `left...right` (margin mode).
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func selectionsInvalidateForColumnRestrictedScroll (top: Int, bottom: Int, left: Int, right: Int)
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{
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for entry in selections {
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entry.value?.invalidateForColumnRestrictedScroll (top: top, bottom: bottom, left: left, right: right)
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}
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}
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// The current buffers
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var normalBuffer, altBuffer: Buffer
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/**
@@ -2525,8 +2560,11 @@ open class Terminal {
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let last = buffer.lines [row]
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last.fill (with: CharData (attribute: ea), atCol: buffer.marginLeft, len: columnCount)
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}
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selectionsInvalidateForColumnRestrictedScroll (top: row, bottom: row + rowCount, left: buffer.marginLeft, right: buffer.marginRight)
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}
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} else {
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let inserted = p
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for _ in 0..<p {
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p -= 1
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// test: echo -e '\e[44m\e[1L\e[0m'
@@ -2536,6 +2574,9 @@ open class Terminal {
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let newLine = buffer.getBlankLine (attribute: ea)
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buffer.lines.splice (start: row, deleteCount: 0, items: [newLine], change: { line in updateRange (line) })
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}
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// Rows below the cursor moved down in place.
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selectionsAdjustForInPlaceScroll (top: row, bottom: scrollBottomAbsolute - 1, lines: -inserted)
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}
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// this.maxRange();
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updateRange (startLine: buffer.y, endLine: buffer.scrollBottom)
@@ -4765,6 +4806,8 @@ open class Terminal {
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let last = buffer.lines [row]
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last.fill (with: CharData (attribute: da), atCol: buffer.marginLeft, len: columnCount)
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}
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selectionsInvalidateForColumnRestrictedScroll (top: row, bottom: row + rowCount, left: buffer.marginLeft, right: buffer.marginRight)
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} else {
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for _ in 0..<p {
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buffer.lines.splice (start: buffer.yBase + buffer.scrollBottom, deleteCount: 1,
@@ -4773,6 +4816,10 @@ open class Terminal {
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items: [buffer.getBlankLine (attribute: da)],
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change: { line in updateRange (line) })
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}
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let top = buffer.yBase + buffer.scrollTop
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let bottom = buffer.yBase + buffer.scrollBottom
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selectionsAdjustForInPlaceScroll (top: top, bottom: bottom, lines: -p)
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}
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// this.maxRange();
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refreshScrolledRegion(top: buffer.scrollTop, bottom: buffer.scrollBottom, canBlit: false)
@@ -4801,6 +4848,8 @@ open class Terminal {
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let last = buffer.lines [row+rowCount]
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last.fill (with: CharData (attribute: da), atCol: buffer.marginLeft, len: columnCount)
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}
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selectionsInvalidateForColumnRestrictedScroll (top: row, bottom: row + rowCount, left: buffer.marginLeft, right: buffer.marginRight)
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} else {
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for _ in 0..<p {
48064855
buffer.lines.splice (start: buffer.yBase + buffer.scrollTop, deleteCount: 1,
@@ -4809,6 +4858,10 @@ open class Terminal {
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items: [buffer.getBlankLine (attribute: da)],
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change: { line in updateRange (line) })
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}
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let top = buffer.yBase + buffer.scrollTop
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let bottom = buffer.yBase + buffer.scrollBottom
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selectionsAdjustForInPlaceScroll (top: top, bottom: bottom, lines: p)
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}
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// this.maxRange();
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refreshScrolledRegion(top: buffer.scrollTop, bottom: buffer.scrollBottom, canBlit: false)
@@ -4872,6 +4925,8 @@ open class Terminal {
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let last = buffer.lines [row+rowCount]
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last.fill (with: CharData (attribute: ea), atCol: buffer.marginLeft, len: columnCount)
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}
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selectionsInvalidateForColumnRestrictedScroll (top: row, bottom: row + rowCount, left: buffer.marginLeft, right: buffer.marginRight)
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}
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} else {
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if buffer.y >= buffer.scrollTop && buffer.y <= buffer.scrollBottom {
@@ -4883,6 +4938,9 @@ open class Terminal {
48834938
items: [buffer.getBlankLine (attribute: ea)],
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change: { line in updateRange (line)})
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}
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// Rows below the cursor moved up in place.
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selectionsAdjustForInPlaceScroll (top: row, bottom: j, lines: p)
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}
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}
48884946

@@ -5351,6 +5409,8 @@ open class Terminal {
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bottomLine.isWrapped = false
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buffer.clearImagesFromLine(at: bottomRow)
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bottomLine.renderMode = .single
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selectionsInvalidateForColumnRestrictedScroll (top: topRow, bottom: bottomRow, left: bMarginLeft, right: bMarginRight)
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} else if scrollTop == 0 {
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// Determine whether the buffer is going to be trimmed after insertion.
53565416
let willBufferBeTrimmed = lines.isFull
@@ -5381,6 +5441,10 @@ open class Terminal {
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buffer.linesTop += 1
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}
53835443

5444+
// Recycling removes the first buffer row and shifts every
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// remaining row up without changing yDisp.
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selectionsAdjustForInPlaceScroll (top: 0, bottom: lines.count - 1, lines: 1)
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53845448
// When the buffer is full and the user has scrolled up, keep the text
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// stable unless ydisp is right at the top
53865450
if userScrolling {
@@ -5405,6 +5469,10 @@ open class Terminal {
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}
54065470
}
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lines [bottomRow] = BufferLine (from: newLine)
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5473+
// The rows moved but yDisp did not, so any selection anchored to
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// absolute rows in this region now points at different text.
5475+
selectionsAdjustForInPlaceScroll (top: topRow, bottom: bottomRow, lines: 1)
54085476
}
54095477

54105478
// Move the viewport to the bottom of the buffer unless the user is
@@ -5844,13 +5912,18 @@ open class Terminal {
58445912
topLine.isWrapped = false
58455913
buffer.clearImagesFromLine(at: topRow)
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topLine.renderMode = .single
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5916+
selectionsInvalidateForColumnRestrictedScroll (top: topRow, bottom: bottomRow, left: buffer.marginLeft, right: buffer.marginRight)
58475917
} else {
58485918
// Full-width scrolling - use original shiftElements approach
58495919
let scrollRegionHeight = buffer.scrollBottom - buffer.scrollTop
58505920
if !buffer.lines.shiftElements (start: topRow, count: scrollRegionHeight, offset: 1) {
58515921
print ("Assertion on reverseIndex, state was: y=\(buffer.y) scrollTop=\(buffer.scrollTop) yDisp=\(buffer.yDisp) linesTop=\(buffer.linesTop) isAlternate=\(isCurrentBufferAlternate)")
58525922
}
58535923
buffer.lines [topRow] = buffer.getBlankLine (attribute: eraseAttr ())
5924+
5925+
// Lines moved down in place; translate selections with them.
5926+
selectionsAdjustForInPlaceScroll (top: topRow, bottom: bottomRow, lines: -1)
58545927
}
58555928
refreshScrolledRegion(top: buffer.scrollTop, bottom: buffer.scrollBottom, canBlit: false)
58565929
}

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