bump version to 0.11

* feat: add ability to cycle preset widths in reverse

* tests: add tests for cycling widths in reverse

.github/ISSUE_TEMPLATE/3-feature_request.md

@@ -0,0 +1,22 @@
+---
+name: Feature request
+about: Request a feature
+title: "[Feature]"
+labels: ''
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.
+
+These sections are just guidelines, feel free to remove them.

README.md

@@ -22,6 +22,13 @@ Karousel requires the following QML modules:
 - Doesn't support windows on all desktops
 - Doesn't support windows on multiple activities
 
+## Installation
+First install the _org.kde.notification_ QML module (_qml-module-org-kde-notifications_ package on Ubuntu).
+
+Then download the [latest release](https://github.com/peterfajdiga/karousel/releases/latest) and extract it into _~/.local/share/kwin/scripts/_.
+
+Or clone the repo and run `make install` (requires node and tsc).
+
 ## Key bindings
 The key bindings can be configured in KDE System Settings among KWin's own keyboard shortcuts.
 Here's the default ones:
@@ -32,12 +39,16 @@ Here's the default ones:
 | Meta+D                   | Move focus right (Clashes with default KDE shortcuts, may require manual remapping)                                            |
 | Meta+W                   | Move focus up (Clashes with default KDE shortcuts, may require manual remapping)                                               |
 | Meta+S                   | Move focus down (Clashes with default KDE shortcuts, may require manual remapping)                                             |
+| (unassigned)             | Move focus to the next window in grid                                                                                          |
+| (unassigned)             | Move focus to the previous window in grid                                                                                      |
 | Meta+Home                | Move focus to start                                                                                                            |
 | Meta+End                 | Move focus to end                                                                                                              |
 | Meta+Shift+A             | Move window left (Moves window out of and into columns)                                                                        |
 | Meta+Shift+D             | Move window right (Moves window out of and into columns)                                                                       |
 | Meta+Shift+W             | Move window up                                                                                                                 |
 | Meta+Shift+S             | Move window down                                                                                                               |
+| (unassigned)             | Move window to the next position in grid                                                                                       |
+| (unassigned)             | Move window to the previous position in grid                                                                                   |
 | Meta+Shift+Home          | Move window to start                                                                                                           |
 | Meta+Shift+End           | Move window to end                                                                                                             |
 | Meta+X                   | Toggle stacked layout for focused column (One window in the column visible, others shaded; not supported on Wayland)           |
@@ -47,7 +58,10 @@ Here's the default ones:
 | Meta+Ctrl+Shift+End      | Move column to end                                                                                                             |
 | Meta+Ctrl++              | Increase column width                                                                                                          |
 | Meta+Ctrl+-              | Decrease column width                                                                                                          |
+| Meta+R                   | Cycle through preset column widths                                                                                             |
 | Meta+Ctrl+X              | Equalize widths of visible columns                                                                                             |
+| Meta+Ctrl+A              | Squeeze left column onto the screen (Clashes with default KDE shortcuts, may require manual remapping)                         |
+| Meta+Ctrl+D              | Squeeze right column onto the screen                                                                                           |
 | Meta+Alt+Return          | Center focused window (Scrolls so that the focused window is centered in the screen)                                           |
 | Meta+Alt+A               | Scroll one column to the left                                                                                                  |
 | Meta+Alt+D               | Scroll one column to the right                                                                                                 |

package/metadata.json

@@ -9,7 +9,7 @@
             "Name": "Peter Fajdiga"
         }],
         "Id": "karousel",
-        "Version": "0.10",
+        "Version": "0.11",
         "License": "GPLv3",
         "Website": "https://github.com/peterfajdiga/karousel",
         "BugReportUrl": "https://github.com/peterfajdiga/karousel/issues"

src/lib/behavior/PresetWidths.ts

@@ -11,6 +11,12 @@ class PresetWidths {
         return nextIndex >= 0 ? widths[nextIndex] : widths[0];
     }
 
+    public prev(currentWidth: number, minWidth: number, maxWidth: number) {
+        const widths = this.getWidths(minWidth, maxWidth).reverse();
+        const nextIndex = widths.findIndex(width => width < currentWidth);
+        return nextIndex >= 0 ? widths[nextIndex] : widths[0];
+    }
+
     public getWidths(minWidth: number, maxWidth: number) {
         const widths = this.presets.map(f => clamp(f(maxWidth), minWidth, maxWidth));
         widths.sort((a, b) => a - b);

src/lib/behavior/columnResizer/ContextualResizer.ts

@@ -9,7 +9,7 @@ class ContextualResizer {
         const visibleRange = desktop.getCurrentVisibleRange();
         const minWidth = column.getMinWidth();
         const maxWidth = column.getMaxWidth();
-        if(!column.isVisible(visibleRange, true) || column.getWidth() >= maxWidth) {
+        if(!Range.contains(visibleRange, column) || column.getWidth() >= maxWidth) {
             return;
         }
 
@@ -46,7 +46,7 @@ class ContextualResizer {
         const visibleRange = desktop.getCurrentVisibleRange();
         const minWidth = column.getMinWidth();
         const maxWidth = column.getMaxWidth();
-        if(!column.isVisible(visibleRange, true) || column.getWidth() <= minWidth) {
+        if(!Range.contains(visibleRange, column) || column.getWidth() <= minWidth) {
             return;
         }
 

src/lib/keyBindings/Actions.ts

@@ -189,6 +189,11 @@ class Actions {
         column.setWidth(nextWidth, true);
     }
 
+    public readonly cyclePresetWidthsReverse = (cm: ClientManager, dm: DesktopManager, window: Window, column: Column, grid: Grid) => {
+        const nextWidth = this.config.presetWidths.prev(column.getWidth(), column.getMinWidth(), column.getMaxWidth());
+        column.setWidth(nextWidth, true);
+    }
+
     public readonly columnsWidthEqualize = (cm: ClientManager, dm: DesktopManager) => {
         const desktop = dm.getCurrentDesktop();
         const visibleRange = desktop.getCurrentVisibleRange();
@@ -202,7 +207,7 @@ class Actions {
         );
         visibleColumns.forEach((column, index) => column.setWidth(widths[index], true));
 
-        desktop.scrollCenterRange(Desktop.RangeImpl.fromRanges(
+        desktop.scrollCenterRange(Range.fromRanges(
             visibleColumns[0],
             visibleColumns[visibleColumns.length - 1],
         ));
@@ -210,7 +215,7 @@ class Actions {
 
     public readonly columnsSqueezeLeft = (cm: ClientManager, dm: DesktopManager, window: Window, focusedColumn: Column, grid: Grid) => {
         const visibleRange = grid.desktop.getCurrentVisibleRange();
-        if (!focusedColumn.isVisible(visibleRange, true)) {
+        if (!Range.contains(visibleRange, focusedColumn)) {
             return;
         }
 
@@ -237,7 +242,7 @@ class Actions {
 
     public readonly columnsSqueezeRight = (cm: ClientManager, dm: DesktopManager, window: Window, focusedColumn: Column, grid: Grid) => {
         const visibleRange = grid.desktop.getCurrentVisibleRange();
-        if (!focusedColumn.isVisible(visibleRange, true)) {
+        if (!Range.contains(visibleRange, focusedColumn)) {
             return;
         }
 
@@ -279,7 +284,7 @@ class Actions {
 
         const widths = fillSpace(availableSpace - gapsWidth, columnConstraints);
         columns.forEach((column, index) => column.setWidth(widths[index], true));
-        desktop.scrollCenterRange(Desktop.RangeImpl.fromRanges(firstColumn, lastColumn));
+        desktop.scrollCenterRange(Range.fromRanges(firstColumn, lastColumn));
         return true;
     }
 
@@ -292,8 +297,7 @@ class Actions {
     }
 
     private readonly gridScroll = (desktopManager: DesktopManager, amount: number) => {
-        const grid = desktopManager.getCurrentDesktop().grid;
-        grid.desktop.adjustScroll(amount, false);
+        desktopManager.getCurrentDesktop().adjustScroll(amount, false);
     }
 
     public readonly gridScrollStart = (cm: ClientManager, dm: DesktopManager) => {
@@ -410,7 +414,10 @@ class Actions {
 namespace Actions {
     export type Config = {
         manualScrollStep: number;
-        presetWidths: { next: (currentWidth: number, minWidth: number, maxWidth: number) => number };
+        presetWidths: {
+            next: (currentWidth: number, minWidth: number, maxWidth: number) => number;
+            prev: (currentWidth: number, minWidth: number, maxWidth: number) => number
+};
         columnResizer: ColumnResizer;
     };
 

src/lib/keyBindings/definition.ts

@@ -152,6 +152,12 @@ function getKeyBindings(world: World, actions: Actions): KeyBinding[] {
             defaultKeySequence: "Meta+R",
             action: () => world.doIfTiledFocused(actions.cyclePresetWidths),
         },
+        {
+            name: "cycle-preset-widths-reverse",
+            description: "Cycle through preset column widths in reverse",
+            defaultKeySequence: "Meta+Shift+R",
+            action: () => world.doIfTiledFocused(actions.cyclePresetWidthsReverse),
+        },
         {
             name: "columns-width-equalize",
             description: "Equalize widths of visible columns",

src/lib/layout/Column.ts

@@ -21,7 +21,7 @@ class Column {
         if (targetGrid === this.grid) {
             this.grid.moveColumn(this, leftColumn);
         } else {
-            this.grid.onColumnRemoved(this, false);
+            this.grid.onColumnRemoved(this, this.isFocused());
             this.grid = targetGrid;
             targetGrid.onColumnAdded(this, leftColumn);
             for (const window of this.windows.iterator()) {
@@ -203,9 +203,17 @@ class Column {
         window.focus();
     }
 
+    public isFocused() {
+        const lastFocusedWindow = this.grid.getLastFocusedWindow();
+        if (lastFocusedWindow === null) {
+            return false;
+        }
+        return lastFocusedWindow.column === this && lastFocusedWindow.isFocused();
+    }
+
     public arrange(x: number, visibleRange: Range, forceOpaque: boolean) {
         if (this.grid.config.offScreenOpacity < 1.0 && !forceOpaque) {
-            const opacity = this.isVisible(visibleRange, true) ? 100 : this.grid.config.offScreenOpacity;
+            const opacity = Range.contains(visibleRange, this) ? 100 : this.grid.config.offScreenOpacity;
             for (const window of this.windows.iterator()) {
                 window.client.kwinClient.opacity = opacity;
             }
@@ -267,16 +275,6 @@ class Column {
         return true;
     }
 
-    public isVisible(visibleRange: Desktop.Range, fullyVisible: boolean) {
-        if (fullyVisible) {
-            return this.getLeft() >= visibleRange.getLeft() &&
-                this.getRight() <= visibleRange.getRight();
-        } else {
-            return this.getRight() + this.grid.config.gapsInnerHorizontal > visibleRange.getLeft() &&
-                this.getLeft() - this.grid.config.gapsInnerHorizontal < visibleRange.getRight();
-        }
-    }
-
     public onWindowAdded(window: Window, bottom: boolean) {
         if (bottom) {
             this.windows.insertEnd(window);

src/lib/layout/Desktop.ts

@@ -55,7 +55,7 @@ class Desktop {
         )
     }
 
-    public scrollIntoView(range: Desktop.Range) {
+    public scrollIntoView(range: Range) {
         const left = range.getLeft();
         const right = range.getRight();
         const initialVisibleRange = this.getCurrentVisibleRange();
@@ -72,7 +72,7 @@ class Desktop {
         this.setScroll(targetScrollX, false);
     }
 
-    public scrollCenterRange(range: Desktop.Range) {
+    public scrollCenterRange(range: Range) {
         const windowCenter = range.getLeft() + range.getWidth() / 2;
         const screenCenter = this.scrollX + this.tilingArea.width / 2;
         this.adjustScroll(Math.round(windowCenter - screenCenter), true);
@@ -95,13 +95,13 @@ class Desktop {
     }
 
     public scrollToColumn(column: Column) {
-        if (this.dirtyScroll || !column.isVisible(this.getCurrentVisibleRange(), true)) {
+        if (this.dirtyScroll || !Range.contains(this.getCurrentVisibleRange(), column)) {
             this.config.scroller.scrollToColumn(this, column);
         }
     }
 
     private getVisibleRange(scrollX: number) {
-        return new Desktop.RangeImpl(scrollX, this.tilingArea.width);
+        return Range.create(scrollX, this.tilingArea.width);
     }
 
     public getCurrentVisibleRange() {
@@ -135,6 +135,10 @@ class Desktop {
         this.dirty = false;
     }
 
+    public forceArrange() {
+        this.dirty = true;
+    }
+
     public onLayoutChanged() {
         this.dirty = true;
         this.dirtyScroll = true;
@@ -161,40 +165,6 @@ namespace Desktop {
         clamper: Desktop.Clamper;
     };
 
-    export type Range = {
-        getLeft(): number;
-        getRight(): number;
-        getWidth(): number;
-    };
-
-    export class RangeImpl {
-        private readonly x: number;
-        private readonly width: number;
-
-        constructor(x: number, width: number) {
-            this.x = x;
-            this.width = width;
-        }
-
-        public getLeft() {
-            return this.x;
-        }
-
-        public getRight() {
-            return this.x + this.width;
-        }
-
-        public getWidth() {
-            return this.width;
-        }
-
-        public static fromRanges(leftRange: Range, rightRange: Range) {
-            const left = leftRange.getLeft();
-            const right = rightRange.getRight();
-            return new RangeImpl(left, right - left);
-        }
-    }
-
     export class ColumnRange {
         private left: Column;
         private right: Column;
@@ -206,7 +176,7 @@ namespace Desktop {
             this.width = initialColumn.getWidth();
         }
 
-        public addNeighbors(visibleRange: Desktop.Range, gap: number) {
+        public addNeighbors(visibleRange: Range, gap: number) {
             const grid = this.left.grid;
 
             const columnRange = this;

src/lib/layout/Grid.ts

@@ -1,5 +1,3 @@
-import Range = Desktop.Range;
-
 class Grid {
     public readonly desktop: Desktop;
     public readonly config: LayoutConfig;
@@ -106,19 +104,19 @@ class Grid {
         this.width = x - this.config.gapsInnerHorizontal;
     }
 
-    public getLeftmostVisibleColumn(visibleRange: Desktop.Range, fullyVisible: boolean) {
+    public getLeftmostVisibleColumn(visibleRange: Range, fullyVisible: boolean) {
         for (const column of this.columns.iterator()) {
-            if (column.isVisible(visibleRange, fullyVisible)) {
+            if (Range.contains(visibleRange, column)) {
                 return column;
             }
         }
         return null;
     }
 
-    public getRightmostVisibleColumn(visibleRange: Desktop.Range, fullyVisible: boolean) {
+    public getRightmostVisibleColumn(visibleRange: Range, fullyVisible: boolean) {
         let last = null;
         for (const column of this.columns.iterator()) {
-            if (column.isVisible(visibleRange, fullyVisible)) {
+            if (Range.contains(visibleRange, column)) {
                 last = column;
             } else if (last !== null) {
                 break;
@@ -127,29 +125,14 @@ class Grid {
         return last;
     }
 
-    public *getVisibleColumns(visibleRange: Desktop.Range, fullyVisible: boolean) {
+    public *getVisibleColumns(visibleRange: Range, fullyVisible: boolean) {
         for (const column of this.columns.iterator()) {
-            if (column.isVisible(visibleRange, fullyVisible)) {
+            if (Range.contains(visibleRange, column)) {
                 yield column;
             }
         }
     }
 
-    public getVisibleColumnsWidth(visibleRange: Desktop.Range, fullyVisible: boolean) {
-        let width = 0;
-        let nVisible = 0;
-        for (const column of this.getVisibleColumns(visibleRange, fullyVisible)) {
-            width += column.getWidth();
-            nVisible++;
-        }
-
-        if (nVisible > 0) {
-            width += (nVisible-1) * this.config.gapsInnerHorizontal;
-        }
-
-        return width;
-    }
-
     public arrange(x: number, visibleRange: Range) {
         for (const column of this.columns.iterator()) {
             column.arrange(x, visibleRange, this.userResize);

src/lib/layout/Range.ts

@@ -0,0 +1,41 @@
+type Range = {
+    getLeft(): number;
+    getRight(): number;
+    getWidth(): number;
+};
+
+namespace Range {
+    export function create(x: number, width: number) {
+        return new Basic(x, width);
+    }
+
+    export function fromRanges(leftRange: Range, rightRange: Range) {
+        const left = leftRange.getLeft();
+        const right = rightRange.getRight();
+        return new Basic(left, right - left);
+    }
+
+    export function contains(parent: Range, child: Range) {
+        return child.getLeft() >= parent.getLeft() &&
+            child.getRight() <= parent.getRight();
+    }
+
+    class Basic {
+        constructor(
+            private readonly x: number,
+            private readonly width: number,
+        ) {}
+
+        public getLeft() {
+            return this.x;
+        }
+
+        public getRight() {
+            return this.x + this.width;
+        }
+
+        public getWidth() {
+            return this.width;
+        }
+    }
+}

src/lib/layout/Window.ts

@@ -21,7 +21,7 @@ class Window {
         if (targetColumn === this.column) {
             return;
         }
-        this.column.onWindowRemoved(this, false);
+        this.column.onWindowRemoved(this, this.isFocused() && targetColumn.grid !== this.column.grid);
         this.column = targetColumn;
         targetColumn.onWindowAdded(this, bottom);
     }
@@ -66,6 +66,14 @@ class Window {
     }
 
     public onFocused() {
+        if (this.column.grid.config.reMaximize && (
+            this.focusedState.maximizedMode !== MaximizedMode.Unmaximized ||
+            this.focusedState.fullScreen
+        )) {
+            // We need to maximize/fullscreen this window, but we can't do it here.
+            // We need to do it in `arrange` to ensure it happens after placement.
+            this.column.grid.desktop.forceArrange();
+        }
         this.column.onWindowFocused(this);
     }
 
@@ -75,7 +83,6 @@ class Window {
         }
         this.client.setFullScreen(false);
         this.client.setMaximize(false, false);
-        this.column.grid.desktop.onLayoutChanged();
     }
 
     public onMaximizedChanged(maximizedMode: MaximizedMode) {

src/lib/utils/fillSpace.ts

@@ -26,38 +26,38 @@ function fillSpace(availableSpace: number, items: { min: number, max: number }[]
     }
 
     function buildRanges(items: { min: number, max: number }[]) {
-        const landmarks = buildLandmarks(items);
-        if (landmarks.length === 1) {
+        const fenceposts = extractFenceposts(items);
+        if (fenceposts.length === 1) {
             return [{
-                start: landmarks[0].value,
-                end: landmarks[0].value,
+                start: fenceposts[0].value,
+                end: fenceposts[0].value,
                 n: items.length,
             }];
         }
 
         const ranges: Range[] = [];
         let n = 0;
-        for (let i = 1; i < landmarks.length; i++) {
-            const startLandmark = landmarks[i-1];
-            const endLandmark = landmarks[i];
-            n = n - startLandmark.nMax + startLandmark.nMin;
+        for (let i = 1; i < fenceposts.length; i++) {
+            const startFencepost = fenceposts[i-1];
+            const endFencepost = fenceposts[i];
+            n = n - startFencepost.nMax + startFencepost.nMin;
             ranges.push({
-                start: startLandmark.value,
-                end: endLandmark.value,
+                start: startFencepost.value,
+                end: endFencepost.value,
                 n: n,
             });
         }
         return ranges;
     }
 
-    function buildLandmarks(items: { min: number, max: number }[]) {
-        const landmarks = new Map<number, Landmark>();
+    function extractFenceposts(items: { min: number, max: number }[]) {
+        const fenceposts = new Map<number, Fencepost>();
         for (const item of items) {
-            mapGetOrInit(landmarks, item.min, { value: item.min, nMin: 0, nMax: 0 }).nMin++;
-            mapGetOrInit(landmarks, item.max, { value: item.max, nMin: 0, nMax: 0 }).nMax++;
+            mapGetOrInit(fenceposts, item.min, { value: item.min, nMin: 0, nMax: 0 }).nMin++;
+            mapGetOrInit(fenceposts, item.max, { value: item.max, nMin: 0, nMax: 0 }).nMax++;
         }
 
-        const array = Array.from(landmarks.values());
+        const array = Array.from(fenceposts.values());
         array.sort((a, b) => a.value - b.value);
         return array;
     }
@@ -90,7 +90,7 @@ function fillSpace(availableSpace: number, items: { min: number, max: number }[]
         n: number,
     };
 
-    type Landmark = {
+    type Fencepost = {
         value: number,
         nMin: number,
         nMax: number,

src/lib/world/World.ts

@@ -11,6 +11,7 @@ class World {
 
         let presetWidths = {
             next: (currentWidth: number, minWidth: number, maxWidth: number) => currentWidth,
+            prev: (currentWidth: number, minWidth: number, maxWidth: number) => currentWidth,
             getWidths: (minWidth: number, maxWidth: number): number[] => [],
         };
         try {

src/lib/world/clientState/Floating.ts

@@ -18,9 +18,6 @@ namespace ClientState {
 
         public destroy(passFocus: boolean) {
             this.signalManager.destroy();
-            if (this.config.floatingKeepAbove) {
-                this.client.kwinClient.keepAbove = false;
-            }
         }
 
         // TODO: move to `Tiled.restoreClientAfterTiling`

src/lib/world/clientState/Pinned.ts

@@ -19,9 +19,6 @@ namespace ClientState {
 
         public destroy(passFocus: boolean) {
             this.signalManager.destroy();
-            if (this.config.floatingKeepAbove) {
-                this.kwinClient.keepAbove = true;
-            }
             this.pinManager.removeClient(this.kwinClient);
             for (const desktop of this.desktopManager.getDesktopsForClient(this.kwinClient)) {
                 desktop.onPinsChanged();

src/lib/world/clientState/Tiled.ts

@@ -204,6 +204,7 @@ namespace ClientState {
             if (config.tiledKeepBelow) {
                 client.kwinClient.keepBelow = true;
             }
+            client.kwinClient.keepAbove = false;
             client.setFullScreen(false);
             if (client.kwinClient.tile !== null) {
                 client.setMaximize(false, true); // disable quick tile mode

src/tests/flows/centerFocused.ts

@@ -0,0 +1,23 @@
+tests.register("Center focused", 1, () => {
+    const config = getDefaultConfig();
+    const { qtMock, workspaceMock, world } = init(config);
+
+    const [client0, client1, client2] = workspaceMock.createClientsWithWidths(300, 152, 300);
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.hasClient(client0));
+        Assert.assert(clientManager.hasClient(client1));
+        Assert.assert(clientManager.hasClient(client2));
+    });
+    Assert.assert(workspaceMock.activeWindow === client2);
+    Assert.columnsFillTilingArea([client0, client1, client2]);
+
+    qtMock.fireShortcut("karousel-grid-scroll-focused");
+    Assert.centered(config, screen, client2);
+    Assert.fullyVisible(client1.frameGeometry);
+    Assert.fullyVisible(client2.frameGeometry);
+
+    qtMock.fireShortcut("karousel-focus-left");
+    Assert.centered(config, screen, client2, { message: "No scrolling should have occured" });
+    Assert.fullyVisible(client1.frameGeometry);
+    Assert.fullyVisible(client2.frameGeometry);
+});

src/tests/flows/layering.ts

@@ -0,0 +1,191 @@
+tests.register("tiledKeepBelow", 10, () => {
+    const config = getDefaultConfig();
+    config.tiledKeepBelow = true;
+    config.floatingKeepAbove = false;
+    const { qtMock, workspaceMock, world } = init(config);
+
+    const pinGeometry = new MockQmlRect(0, 0, 200, screen.height);
+
+    const [client] = workspaceMock.createClients(1);
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) !== null);
+    });
+    Assert.assert(client.keepBelow);
+    Assert.assert(!client.keepAbove);
+
+    qtMock.fireShortcut("karousel-window-toggle-floating");
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) === null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(!client.keepAbove);
+
+    client.pin(pinGeometry);
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) === null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(!client.keepAbove);
+
+    client.unpin();
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) === null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(!client.keepAbove);
+
+    qtMock.fireShortcut("karousel-window-toggle-floating");
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) !== null);
+    });
+    Assert.assert(client.keepBelow);
+    Assert.assert(!client.keepAbove);
+
+    client.pin(pinGeometry);
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) === null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(!client.keepAbove);
+
+    qtMock.fireShortcut("karousel-window-toggle-floating");
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) !== null);
+    });
+    Assert.assert(client.keepBelow);
+    Assert.assert(!client.keepAbove);
+});
+
+tests.register("floatingKeepAbove", 10, () => {
+    const config = getDefaultConfig();
+    config.tiledKeepBelow = false;
+    config.floatingKeepAbove = true;
+    const { qtMock, workspaceMock, world } = init(config);
+
+    const pinGeometry = new MockQmlRect(0, 0, 200, screen.height);
+
+    const [client] = workspaceMock.createClients(1);
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) !== null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(!client.keepAbove);
+
+    qtMock.fireShortcut("karousel-window-toggle-floating");
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) === null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(client.keepAbove);
+
+    client.pin(pinGeometry);
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) === null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(client.keepAbove);
+
+    client.unpin();
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) === null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(client.keepAbove);
+
+    qtMock.fireShortcut("karousel-window-toggle-floating");
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) !== null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(!client.keepAbove);
+
+    client.pin(pinGeometry);
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) === null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(client.keepAbove);
+
+    qtMock.fireShortcut("karousel-window-toggle-floating");
+    world.do((clientManager, desktopManager) => {
+        Assert.assert(clientManager.findTiledWindow(client) !== null);
+    });
+    Assert.assert(!client.keepBelow);
+    Assert.assert(!client.keepAbove);
+});
+
+tests.register("No layering", 10, () => {
+    const config = getDefaultConfig();
+    config.tiledKeepBelow = false;
+    config.floatingKeepAbove = false;
+    // In this mode, Karousel shouldn't change keepBelow or keepAbove.
+    // Except when tiling a window, keepAbove should still be cleared.
+
+    const pinGeometry = new MockQmlRect(0, 0, 200, screen.height);
+
+    const testCases = [
+        { keepBelow: false, keepAbove: false },
+        { keepBelow: false, keepAbove: true },
+        { keepBelow: true,  keepAbove: false },
+        { keepBelow: true,  keepAbove: true },
+    ];
+
+    for (const testCase of testCases) {
+        const assertOptions = { message: JSON.stringify(testCase) };
+
+        const { qtMock, workspaceMock, world } = init(config);
+
+        const [client] = workspaceMock.createClients(1);
+        client.keepBelow = testCase.keepBelow;
+        client.keepAbove = testCase.keepAbove;
+
+        world.do((clientManager, desktopManager) => {
+            Assert.assert(clientManager.findTiledWindow(client) !== null, assertOptions);
+        });
+        Assert.equal(client.keepBelow, testCase.keepBelow, assertOptions);
+        Assert.equal(client.keepAbove, testCase.keepAbove, assertOptions);
+
+        qtMock.fireShortcut("karousel-window-toggle-floating");
+        world.do((clientManager, desktopManager) => {
+            Assert.assert(clientManager.findTiledWindow(client) === null, assertOptions);
+        });
+        Assert.equal(client.keepBelow, testCase.keepBelow, assertOptions);
+        Assert.equal(client.keepAbove, testCase.keepAbove, assertOptions);
+
+        client.pin(pinGeometry);
+        world.do((clientManager, desktopManager) => {
+            Assert.assert(clientManager.findTiledWindow(client) === null, assertOptions);
+        });
+        Assert.equal(client.keepBelow, testCase.keepBelow, assertOptions);
+        Assert.equal(client.keepAbove, testCase.keepAbove, assertOptions);
+
+        client.unpin();
+        world.do((clientManager, desktopManager) => {
+            Assert.assert(clientManager.findTiledWindow(client) === null, assertOptions);
+        });
+        Assert.equal(client.keepBelow, testCase.keepBelow, assertOptions);
+        Assert.equal(client.keepAbove, testCase.keepAbove, assertOptions);
+
+        qtMock.fireShortcut("karousel-window-toggle-floating");
+        world.do((clientManager, desktopManager) => {
+            Assert.assert(clientManager.findTiledWindow(client) !== null, assertOptions);
+        });
+        Assert.equal(client.keepBelow, testCase.keepBelow, assertOptions);
+        Assert.assert(!client.keepAbove, assertOptions);
+        client.keepAbove = testCase.keepAbove;
+
+        client.pin(pinGeometry);
+        world.do((clientManager, desktopManager) => {
+            Assert.assert(clientManager.findTiledWindow(client) === null, assertOptions);
+        });
+        Assert.equal(client.keepBelow, testCase.keepBelow, assertOptions);
+        Assert.equal(client.keepAbove, testCase.keepAbove, assertOptions);
+
+        qtMock.fireShortcut("karousel-window-toggle-floating");
+        world.do((clientManager, desktopManager) => {
+            Assert.assert(clientManager.findTiledWindow(client) !== null, assertOptions);
+        });
+        Assert.equal(client.keepBelow, testCase.keepBelow, assertOptions);
+        Assert.assert(!client.keepAbove, assertOptions);
+    }
+});

src/tests/flows/layout.ts

@@ -12,7 +12,7 @@ tests.register("Focus and move windows", 1, () => {
 
     function testLayout(shortcutName: string, grid: KwinClient[][]) {
         qtMock.fireShortcut(shortcutName);
-        Assert.grid(config, screen, grid, { skip: 1 });
+        Assert.grid(config, screen, 100, grid, true, { skip: 1 });
     }
 
     function testFocus(shortcutName: string, expectedFocus: KwinClient) {

src/tests/flows/lazyScroller.ts

@@ -0,0 +1,47 @@
+tests.register("LazyScroller", 20, () => {
+    const config = getDefaultConfig();
+    config.scrollingLazy = true;
+    config.scrollingCentered = false;
+    config.scrollingGrouped = false;
+    const { qtMock, workspaceMock, world } = init(config);
+
+    const [client1] = workspaceMock.createClientsWithWidths(300);
+    Assert.grid(config, screen, 300, [[client1]], true);
+
+    const [client2] = workspaceMock.createClientsWithWidths(300);
+    Assert.grid(config, screen, 300, [[client1], [client2]], true);
+
+    const [client3] = workspaceMock.createClientsWithWidths(300);
+    Assert.grid(config, screen, 300, [[client1], [client2], [client3]], false);
+    Assert.equal(client3.frameGeometry.right, tilingArea.right);
+
+    runOneOf(
+        () => workspaceMock.activeWindow = client2,
+        () => qtMock.fireShortcut("karousel-focus-2"),
+        () => qtMock.fireShortcut("karousel-focus-left"),
+    );
+    Assert.grid(config, screen, 300, [[client1], [client2], [client3]], false);
+    Assert.equal(client3.frameGeometry.right, tilingArea.right);
+
+    runOneOf(
+        () => workspaceMock.activeWindow = client1,
+        () => qtMock.fireShortcut("karousel-focus-1"),
+        () => qtMock.fireShortcut("karousel-focus-left"),
+        () => qtMock.fireShortcut("karousel-focus-start"),
+    );
+    workspaceMock.activeWindow = client1;
+    Assert.grid(config, screen, 300, [[client1], [client2], [client3]], false);
+    Assert.equal(client1.frameGeometry.left, tilingArea.left);
+
+    qtMock.fireShortcut("karousel-grid-scroll-focused");
+    Assert.grid(config, screen, 300, [[client1], [client2], [client3]], false);
+    Assert.grid(config, screen, 300, [[client1]], true);
+
+    runOneOf(
+        () => workspaceMock.activeWindow = client2,
+        () => qtMock.fireShortcut("karousel-focus-2"),
+        () => qtMock.fireShortcut("karousel-focus-right"),
+    );
+    Assert.grid(config, screen, 300, [[client1], [client2], [client3]], false);
+    Assert.equal(client1.frameGeometry.left, tilingArea.left);
+});

src/tests/flows/passFocus.ts

@@ -0,0 +1,40 @@
+tests.register("Pass focus", 20, () => {
+    const config = getDefaultConfig();
+    const { qtMock, workspaceMock, world } = init(config);
+
+    const [client0, client1a, client1b, client1c, client4, client5, client6] = workspaceMock.createClients(7);
+    workspaceMock.activeWindow = client1b;
+    qtMock.fireShortcut("karousel-window-move-left");
+    workspaceMock.activeWindow = client1c;
+    qtMock.fireShortcut("karousel-window-move-left");
+    workspaceMock.activeWindow = client1b;
+    workspaceMock.activeWindow = client5;
+
+    function removeWindow(client: MockKwinClient) {
+        runOneOf(
+            () => workspaceMock.removeWindow(client),
+            () => client.desktops = [workspaceMock.desktops[1]],
+        );
+    }
+
+    removeWindow(client5);
+    Assert.equal(workspaceMock.activeWindow, client4);
+
+    qtMock.fireShortcut("karousel-column-move-to-desktop-2");
+    Assert.equal(workspaceMock.activeWindow, client1b);
+
+    removeWindow(client1b);
+    Assert.equal(workspaceMock.activeWindow, client1a);
+
+    removeWindow(client1a);
+    Assert.equal(workspaceMock.activeWindow, client1c);
+
+    removeWindow(client1c);
+    Assert.equal(workspaceMock.activeWindow, client0);
+
+    removeWindow(client0);
+    Assert.equal(workspaceMock.activeWindow, client6);
+
+    removeWindow(client6);
+    Assert.equal(workspaceMock.activeWindow, null);
+});

src/tests/flows/pinning.ts

@@ -6,34 +6,34 @@ tests.register("Pin", 20, () => {
     const screenHalfRight = new MockQmlRect(screen.width/2, 0, screen.width/2, screen.height);
 
     const [pinned, tiled1, tiled2] = workspaceMock.createClients(3);
-    Assert.grid(config, screen, [ [pinned], [tiled1], [tiled2] ]);
+    Assert.grid(config, screen, 100, [ [pinned], [tiled1], [tiled2] ], true);
 
     pinned.pin(screenHalfLeft);
     Assert.equalRects(pinned.frameGeometry, screenHalfLeft);
-    Assert.grid(config, screenHalfRight, [ [tiled1], [tiled2] ]);
+    Assert.grid(config, screenHalfRight, 100, [ [tiled1], [tiled2] ], true);
 
     pinned.pin(screenHalfRight);
     Assert.equalRects(pinned.frameGeometry, screenHalfRight);
-    Assert.grid(config, screenHalfLeft, [ [tiled1], [tiled2] ]);
+    Assert.grid(config, screenHalfLeft, 100, [ [tiled1], [tiled2] ], true);
 
     pinned.unpin();
     Assert.equalRects(pinned.frameGeometry, screenHalfRight);
-    Assert.grid(config, screen, [ [tiled1], [tiled2] ]);
+    Assert.grid(config, screen, 100, [ [tiled1], [tiled2] ], true);
 
     pinned.pin(screenHalfRight);
     Assert.equalRects(pinned.frameGeometry, screenHalfRight);
-    Assert.grid(config, screenHalfLeft, [ [tiled1], [tiled2] ]);
+    Assert.grid(config, screenHalfLeft, 100, [ [tiled1], [tiled2] ], true);
 
     pinned.minimized = true;
-    Assert.grid(config, screen, [ [tiled1], [tiled2] ]);
+    Assert.grid(config, screen, 100, [ [tiled1], [tiled2] ], true);
 
     pinned.minimized = false;
     Assert.equalRects(pinned.frameGeometry, screenHalfRight);
-    Assert.grid(config, screenHalfLeft, [ [tiled1], [tiled2] ]);
+    Assert.grid(config, screenHalfLeft, 100, [ [tiled1], [tiled2] ], true);
 
     workspaceMock.activeWindow = pinned;
     qtMock.fireShortcut("karousel-window-toggle-floating");
     Assert.assert(pinned.tile === null);
     pinned.frameGeometry = new MockQmlRect(10, 20, 100, 200); // This is needed because the window's preferredWidth can change when pinning, because frameGeometryChanged can fire before tileChanged. TODO: Ensure pinned window keeps its preferredWidth.
-    Assert.grid(config, screen, [ [tiled1], [tiled2], [pinned] ]);
+    Assert.grid(config, screen, 100, [ [tiled1], [tiled2], [pinned] ], true);
 });

src/tests/flows/presetWidths.ts

@@ -25,6 +25,12 @@ tests.register("Preset Widths default", 1, () => {
 
     qtMock.fireShortcut("karousel-cycle-preset-widths");
     Assert.equalRects(kwinClient.frameGeometry, getRect(halfWidth));
+
+    qtMock.fireShortcut("karousel-cycle-preset-widths-reverse");
+    Assert.equalRects(kwinClient.frameGeometry, getRect(maxWidth));
+
+    qtMock.fireShortcut("karousel-cycle-preset-widths-reverse");
+    Assert.equalRects(kwinClient.frameGeometry, getRect(halfWidth));
 });
 
 tests.register("Preset Widths custom", 1, () => {
@@ -61,6 +67,15 @@ tests.register("Preset Widths custom", 1, () => {
 
     qtMock.fireShortcut("karousel-cycle-preset-widths");
     Assert.equalRects(kwinClient.frameGeometry, getRect(250));
+
+    qtMock.fireShortcut("karousel-cycle-preset-widths-reverse");
+    Assert.equalRects(kwinClient.frameGeometry, getRect(100));
+
+    qtMock.fireShortcut("karousel-cycle-preset-widths-reverse");
+    Assert.equalRects(kwinClient.frameGeometry, getRect(500));
+
+    qtMock.fireShortcut("karousel-cycle-preset-widths-reverse");
+    Assert.equalRects(kwinClient.frameGeometry, getRect(halfWidth));
 });
 
 tests.register("Preset Widths fill screen uniform", 1, () => {

src/tests/utils/Assert.ts

@@ -126,23 +126,29 @@ namespace Assert {
     export function grid(
         config: Config,
         screen: QmlRect,
+        columnWidth: number,
         grid: KwinClient[][],
+        centered: boolean,
         { message, skip=0 }: Options = {},
     ) {
-        // assumes uniformly sized windows within columns of width 100
+        const nColumns = grid.length;
+        const columnHeight = screen.height - config.gapsOuterTop - config.gapsOuterBottom;
+        const columnsWidth = nColumns * columnWidth + (nColumns-1) * config.gapsInnerHorizontal;
+        const startX = centered ?
+            screen.x + (screen.width - columnsWidth) / 2 :
+            grid[0][0].frameGeometry.x;
+
+        // assumes uniformly sized windows within columns of uniform width
         function getRectInGrid(column: number, window: number, nColumns: number, nWindows: number) {
-            const columnHeight = screen.height - config.gapsOuterTop - config.gapsOuterBottom;
-            const columnsWidth = nColumns * 100 + (nColumns-1) * config.gapsInnerHorizontal;
             const windowHeight = (columnHeight - config.gapsInnerVertical * (nWindows-1)) / nWindows;
             return new MockQmlRect(
-                screen.x + column * (100 + config.gapsInnerHorizontal) + (screen.width-columnsWidth) / 2,
+                startX + column * (columnWidth + config.gapsInnerHorizontal),
                 screen.y + config.gapsOuterTop + (windowHeight + config.gapsInnerVertical) * window,
-                100,
+                columnWidth,
                 (columnHeight - config.gapsInnerVertical * (nWindows-1)) / nWindows,
             );
         }
 
-        const nColumns = grid.length;
         for (let iColumn = 0; iColumn < nColumns; iColumn++) {
             const column = grid[iColumn];
             const nWindows = column.length;
@@ -157,6 +163,22 @@ namespace Assert {
         }
     }
 
+    export function centered(
+        config: Config,
+        screen: QmlRect,
+        client:KwinClient,
+        { message, skip=0 }: Options = {},
+    ) {
+        grid(
+            config,
+            screen,
+            client.frameGeometry.width,
+            [[client]],
+            true,
+            { message: appendMessage("Window not centered", message), skip: skip+1 },
+        );
+    }
+
     export function fullyVisible(
         rect: QmlRect,
         { message, skip=0 }: Options = {},

src/tests/utils/mocks/MockKwinClient.ts

@@ -4,7 +4,7 @@ class MockKwinClient {
     private static readonly borderThickness = 10;
 
     public readonly shadeable: boolean = false;
-    public readonly caption = "App";
+    public caption = "App";
     public minSize: Readonly<QmlSize> = new MockQmlSize(0, 0);
     public readonly transient: boolean;
     public readonly move: boolean = false;
@@ -21,30 +21,32 @@ class MockKwinClient {
     public readonly popupWindow: boolean = false;
     public readonly pid = 1;
 
+    private _maximizedVertically: boolean = false;
+    private _maximizedHorizontally: boolean = false;
     private _fullScreen: boolean = false;
     public activities: string[] = [];
     public skipSwitcher: boolean = false;
     public keepAbove: boolean = false;
     public keepBelow: boolean = false;
     public shade: boolean = false;
-    public _minimized: boolean = false;
-    public desktops: KwinDesktop[] = [];
-    public _tile: Tile|null = null;
+    private _minimized: boolean = false;
+    private _desktops: KwinDesktop[] = [];
+    private _tile: Tile|null = null;
     public opacity: number = 1.0;
 
-    public readonly fullScreenChanged = new MockQSignal();
-    public readonly desktopsChanged = new MockQSignal();
-    public readonly activitiesChanged = new MockQSignal();
-    public readonly minimizedChanged = new MockQSignal();
+    public readonly fullScreenChanged = new MockQSignal<[]>();
+    public readonly desktopsChanged = new MockQSignal<[]>();
+    public readonly activitiesChanged = new MockQSignal<[]>();
+    public readonly minimizedChanged = new MockQSignal<[]>();
     public readonly maximizedAboutToChange = new MockQSignal<[MaximizedMode]>();
-    public readonly captionChanged = new MockQSignal();
-    public readonly tileChanged = new MockQSignal();
-    public readonly interactiveMoveResizeStarted = new MockQSignal();
-    public readonly interactiveMoveResizeFinished = new MockQSignal();
+    public readonly captionChanged = new MockQSignal<[]>();
+    public readonly tileChanged = new MockQSignal<[]>();
+    public readonly interactiveMoveResizeStarted = new MockQSignal<[]>();
+    public readonly interactiveMoveResizeFinished = new MockQSignal<[]>();
     public readonly frameGeometryChanged = new MockQSignal<[oldGeometry: QmlRect]>();
 
     private windowedFrameGeometry: MockQmlRect;
-    private windowed: boolean = false;
+    private windowed: boolean = true;
     private hasBorder: boolean = true;
 
     constructor(
@@ -53,11 +55,18 @@ class MockKwinClient {
     ) {
         this.windowedFrameGeometry = _frameGeometry.clone();
         this.transient = transientFor !== null;
+        this._desktops = [Workspace.currentDesktop];
     }
 
     setMaximize(vertically: boolean, horizontally: boolean) {
         this.windowed = !(vertically || horizontally);
 
+        if (vertically === this._maximizedVertically && horizontally === this._maximizedHorizontally) {
+            return;
+        }
+        this._maximizedVertically = vertically;
+        this._maximizedHorizontally = horizontally;
+
         this.maximizedAboutToChange.fire(
             vertically ? (
                 horizontally ? MaximizedMode.Maximized : MaximizedMode.Vertically
@@ -167,6 +176,18 @@ class MockKwinClient {
         this.minimizedChanged.fire();
     }
 
+    public get desktops() {
+        return this._desktops;
+    }
+
+    public set desktops(desktops: KwinDesktop[]) {
+        this._desktops = desktops;
+        this.desktopsChanged.fire();
+        if (Workspace.activeWindow === this && !desktops.includes(Workspace.currentDesktop)) {
+            Workspace.activeWindow = null;
+        };
+    }
+
     public get tile() {
         return this._tile;
     }
@@ -189,4 +210,8 @@ class MockKwinClient {
     public getFrameGeometryCopy() {
         return this._frameGeometry.clone();
     }
+
+    public toString() {
+        return `MockKwinClient("${this.caption}")`;
+    }
 }

src/tests/utils/mocks/MockQmlTimer.ts

@@ -2,7 +2,7 @@ class MockQmlTimer {
     public readonly __brand = "QmlObject";
 
     public interval = 0;
-    public readonly triggered = new MockQSignal();
+    public readonly triggered = new MockQSignal<[]>();
 
     public restart() {
         // no need to wait in tests, just fire immediately

src/tests/utils/mocks/MockShortcutHandler.ts

@@ -1,7 +1,7 @@
 class MockShortcutHandler {
     public readonly __brand = "QmlObject";
 
-    public readonly activated: MockQSignal<[]> = new MockQSignal();
+    public readonly activated: MockQSignal<[]> = new MockQSignal<[]>();
 
     public destroy() {}
 }

src/tests/utils/mocks/MockWorkspace.ts

@@ -9,7 +9,7 @@ class MockWorkspace {
     public currentDesktop = this.desktops[0];
     public currentActivity = this.activities[0];
     public activeScreen: Output = { __brand: "Output" };
-    public windows = [];
+    public readonly windows: MockKwinClient[] = [];
     public cursorPos = new MockQmlPoint(0, 0);
 
     private _activeWindow: KwinClient|null = null;
@@ -30,6 +30,7 @@ class MockWorkspace {
 
     public createWindows(...kwinClients: MockKwinClient[]) {
         for (const kwinClient of kwinClients) {
+            this.windows.push(kwinClient);
             this.windowAdded.fire(kwinClient);
             this.activeWindow = kwinClient;
         }
@@ -41,6 +42,7 @@ class MockWorkspace {
 
     public createClientsWithFrames(...frames: MockQmlRect[]) {
         const clients = frames.map(rect => new MockKwinClient(rect));
+        clients.forEach((client, index) => client.caption = `Client ${index}`);
         this.createWindows(...clients);
         return clients;
     }
@@ -49,6 +51,17 @@ class MockWorkspace {
         return this.createClientsWithFrames(...widths.map(width => new MockQmlRect(randomInt(100), randomInt(100), width, 100+randomInt(400))));
     }
 
+    public removeWindow(window: MockKwinClient) {
+        runReorder(
+            () => this.windows.splice(this.windows.indexOf(window), 1),
+            () => this.windowRemoved.fire(window),
+        );
+        if (window === this.activeWindow) {
+            const windows = this.windows.filter(w => w.desktops.includes(this.currentDesktop));
+            Workspace.activeWindow = windows.length > 0 ? randomItem(windows) : null;
+        };
+    }
+
     public resizeWindow(window: MockKwinClient, edgeResize: boolean, leftEdge: boolean, topEdge: boolean, ...deltas: QmlSize[]) {
         const frame = window.getFrameGeometryCopy();
         if (edgeResize) {

src/tests/utils/random.ts

@@ -26,6 +26,12 @@ function randomInt(n: number) {
     return Math.floor(Math.random() * n);
 }
 
+function randomItem(items: any[]) {
+    Assert.assert(items.length > 0);
+    const index = randomInt(items.length);
+    return items[index];
+}
+
 function shuffle(items: any[]) {
     for (let n = items.length; n > 1; n--) {
         const i = n-1;