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Load ancestor columns on demand and retain recent ones #121

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Load ancestor columns on demand and retain recent ones #121

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f52d2b2
Load ancestor columns near the viewport
k-kostin Nov 13, 2026
0e0e8b4
Retain recently shown columns within a bounded budget
k-kostin Nov 13, 2026
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173 changes: 133 additions & 40 deletions src/FolderColumns.qml
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,38 @@ Item {
// column, and the rest stay as they are instead of reloading (which
// flashed).
ListModel { id: trail }
property bool complete: false
property bool syncingTrail: false
property var recentColumns: []
// Two expanded viewports, including partial columns at their edges.
readonly property int columnLimit: 2 * (Math.ceil(flick.width / (columnWidth + 1)) + 3)
onColumnLimitChanged: updateColumns()

function updateColumns() {
if (!complete || syncingTrail) return
const paths = []
const near = []
for (let i = 0; i < trail.count; ++i) {
const path = trail.get(i).path
paths.push(path)
const x = row.x + (view.LayoutMirroring.enabled
? (trail.count - i) * (columnWidth + 1) + (inside.visible ? inside.width : 0)
: i * (columnWidth + 1))
if (trail.count <= columnLimit || (x + columnWidth > flick.contentX - columnWidth
&& x < flick.contentX + flick.width + columnWidth))
near.push(path)
}
// Protect the whole current area before evicting old ones. Updating
// individual Loaders in binding order could evict a neighbour first.
const older = recentColumns.filter(path => paths.indexOf(path) >= 0 && near.indexOf(path) < 0)
const spare = Math.max(0, columnLimit - near.length)
const keep = older.slice(Math.max(0, older.length - spare)).concat(near)
if (keep.length !== recentColumns.length || keep.some((path, i) => path !== recentColumns[i]))
recentColumns = keep
}

function syncTrail() {
syncingTrail = true
const want = []
for (let i = 0; i + 1 < crumbs.length; ++i)
want.push({ path: crumbs[i].path, next: crumbs[i + 1].name })
Expand All @@ -43,16 +74,25 @@ Item {
trail.setProperty(i, "next", want[i].next)
if (trail.count > same)
trail.remove(same, trail.count - same)
for (let i = same; i < want.length; ++i)
trail.append(want[i])
if (same < want.length)
trail.append(want.slice(same))
syncingTrail = false
revealEnd()
}
onCrumbsChanged: syncTrail()
Component.onCompleted: syncTrail()
Component.onCompleted: {
syncTrail()
complete = true
revealEnd()
}
readonly property var selected: here.currentIndex >= 0 ? (backend.folder.count, backend.folder.get(here.currentIndex)) : ({})

// Keeps the newest columns in view as the trail grows: on the left,
// when mirrored.
function revealEnd() { flick.contentX = view.LayoutMirroring.enabled ? 0 : Math.max(0, flick.contentWidth - flick.width) }
function revealEnd() {
flick.contentX = view.LayoutMirroring.enabled ? 0 : Math.max(0, flick.contentWidth - flick.width)
updateColumns()
}
LayoutMirroring.onEnabledChanged: revealEnd()
function enter() {
if (view.selected.isDir && (insideFolder.loading || insideFolder.count > 0 || insideFolder.error.length > 0))
Expand All @@ -73,6 +113,7 @@ Item {
contentWidth: Math.max(width, row.width)
contentHeight: height
boundsBehavior: Flickable.StopAtBounds
onContentXChanged: view.updateColumns()
onContentWidthChanged: view.revealEnd()
onWidthChanged: view.revealEnd()
ScrollBar.horizontal: FolioScrollBar { }
Expand All @@ -82,7 +123,11 @@ Item {
// A Row isn't placed by its Flickable, so it's moved to the right
// edge by hand when mirrored.
x: LayoutMirroring.enabled ? parent.width - width : 0
// Known before Row's first layout, so RTL and revealEnd select
// the right initial area without loading a transient first one.
width: (trail.count + 1) * (view.columnWidth + 1) + (inside.visible ? inside.width : 0)
height: flick.height
onXChanged: view.updateColumns()

// The folders on the way here, each showing which way the trail goes.
Repeater {
Expand All @@ -91,47 +136,95 @@ Item {
id: ancestor
required property string path
required property string next
width: view.columnWidth + 1
height: row.height
property real scrollY: NaN
onNextChanged: {
scrollY = NaN
if (columnLoader && columnLoader.item) columnLoader.item.revealNext()
}
Connections {
target: backend.folder
function onShowHiddenChanged() { ancestor.scrollY = NaN }
function onSortModeChanged() { ancestor.scrollY = NaN }
}
Connections {
target: translator
function onChanged() { ancestor.scrollY = NaN }
}

ListView {
id: column
Loader {
id: columnLoader
property Item dragSource: null
width: view.columnWidth
height: parent.height
clip: true
acceptedButtons: Qt.NoButton
boundsBehavior: Flickable.StopAtBounds
ScrollBar.vertical: FolioScrollBar { }
model: FolderModel {
id: folder
path: ancestor.path
showHidden: backend.folder.showHidden
sortMode: backend.folder.sortMode
onLoaded: column.revealNext()
}
// Names sort by the language's alphabet.
Connections {
target: translator
function onChanged() { folder.reload() }
}
function revealNext() { positionViewAtIndex(Math.max(0, folder.indexOf(ancestor.next)), ListView.Contain) }
ColumnDrop { items: column; folder: ancestor.path }
TapHandler {
acceptedButtons: Qt.RightButton
onTapped: (point) => {
const index = column.indexAt(point.position.x + column.contentX, point.position.y + column.contentY)
view.contextMenu(index >= 0 ? folder.get(index) : null, ancestor.path, point.scenePosition)
// Recently shown columns stay alive within the shared
// budget. A drag keeps its source until it finishes.
active: dragSource !== null || view.recentColumns.indexOf(ancestor.path) >= 0
sourceComponent: ListView {
id: column
width: view.columnWidth
height: parent.height
clip: true
acceptedButtons: Qt.NoButton
boundsBehavior: Flickable.StopAtBounds
ScrollBar.vertical: FolioScrollBar { }
model: FolderModel {
id: folder
path: ancestor.path
showHidden: backend.folder.showHidden
sortMode: backend.folder.sortMode
onLoaded: if (column.complete) column.revealNext()
}
// Names sort by the language's alphabet.
Connections {
target: translator
function onChanged() { folder.reload() }
}
property bool complete: false
property bool positioned: false
property bool restoring: false
Connections {
target: folder
function onModelAboutToBeReset() { column.positioned = false }
}
function revealNext() {
const saved = ancestor.scrollY
restoring = true
forceLayout()
if (Number.isFinite(saved))
contentY = originY + Math.max(0, Math.min(saved, contentHeight - height))
else
positionViewAtIndex(Math.max(0, folder.indexOf(ancestor.next)), ListView.Contain)
restoring = false
positioned = true
if (Number.isFinite(saved)) ancestor.scrollY = contentY - originY
}
Component.onCompleted: {
complete = true
if (folder.count > 0 || !folder.loading) revealNext()
}
onContentYChanged: if (complete && positioned && !restoring && columnLoader.active) ancestor.scrollY = contentY - originY
ColumnDrop { items: column; folder: ancestor.path }
TapHandler {
acceptedButtons: Qt.RightButton
onTapped: (point) => {
const index = column.indexAt(point.position.x + column.contentX, point.position.y + column.contentY)
view.contextMenu(index >= 0 ? folder.get(index) : null, ancestor.path, point.scenePosition)
}
}
delegate: FileRow {
id: entry
width: column.width
chevron: true
trail: name === ancestor.next
Drag.onActiveChanged: {
if (Drag.active) columnLoader.dragSource = entry
else if (columnLoader.dragSource === entry) columnLoader.dragSource = null
}
onClicked: isDir ? backend.navigate(path) : backend.showItem(path)
onActivated: backend.open(path)
}
}
Connections {
target: ancestor
function onNextChanged() { column.revealNext() }
}
delegate: FileRow {
width: column.width
chevron: true
trail: name === ancestor.next
onClicked: isDir ? backend.navigate(path) : backend.showItem(path)
onActivated: backend.open(path)
}
}
Separator { }
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