[gnome-shell/wip/exalm/gestures2: 7/10] workspaceAnimation: Use a workspace strip

[Alexander Mikhaylenko <alexm src gnome org>]

commit a782cf336c681b599b3da9368248c6688e76eb14
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Sat Jun 20 22:01:25 2020 +0500

    workspaceAnimation: Use a workspace strip
    
    Currently, the workspace swipe transition only has one workspace in each
    direction. This works until you try to do multiple swipes in quick
    succession. The second swipe would continue the existing transition, which
    only has 2 or 3 workspaces in it, and will hit a wall.
    
    To prevent this, take all workspaces and arrange them into a column or row,
    depending on the layout, and use that as a transition.
    
    For the transition that happens when focusing a window on another workspace
    (for example, via Alt+Tab), still use only two workspaces instead of all of
    them.
    
    Since we don't support layouts other than single rows/columns anymore,
    diagonal transitions aren't supported anymore, and will be shown as
    horizontal or vertical instead.
    
    Since nw alt-tab and gesture transitions are different, don't allow to do
    both at once, that is, disable swipe tracker when a programmatic transition
    is going. This will also conveniently cancel a gesture transition if a
    programmatic one is initiated while a gesture is in progress.
    
    Fixes https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/2612

 js/ui/workspaceAnimation.js | 268 ++++++++++++++++++--------------------------
 1 file changed, 112 insertions(+), 156 deletions(-)
---
diff --git a/js/ui/workspaceAnimation.js b/js/ui/workspaceAnimation.js
index e01371c49c..4f89da464f 100644
--- a/js/ui/workspaceAnimation.js
+++ b/js/ui/workspaceAnimation.js
@@ -26,6 +26,10 @@ class WorkspaceGroup extends Clutter.Actor {
             this._syncStacking.bind(this));
     }
 
+    get workspace() {
+        return this._workspace;
+    }
+
     _shouldShowWindow(window) {
         if (!window.showing_on_its_workspace())
             return false;
@@ -123,7 +127,7 @@ var WorkspaceAnimationController = class {
         Main.overview.connect('showing', () => {
             if (this._switchData) {
                 if (this._switchData.gestureActivated)
-                    this._switchWorkspaceStop();
+                    this._finishWorkspaceSwitch(this._switchData);
                 this._swipeTracker.enabled = false;
             }
         });
@@ -139,57 +143,25 @@ var WorkspaceAnimationController = class {
         this._swipeTracker = swipeTracker;
     }
 
-    _getPositionForDirection(direction, fromWs, toWs) {
-        let xDest = 0, yDest = 0;
-
-        const oldWsIsFullscreen = fromWs.list_windows().some(w => w.is_fullscreen());
-        const newWsIsFullscreen = toWs.list_windows().some(w => w.is_fullscreen());
-
-        // We have to shift windows up or down by the height of the panel to prevent having a
-        // visible gap between the windows while switching workspaces. Since fullscreen windows
-        // hide the panel, they don't need to be shifted up or down.
-        const shiftHeight = Main.panel.height;
-
-        if (direction === Meta.MotionDirection.UP ||
-            direction === Meta.MotionDirection.UP_LEFT ||
-            direction === Meta.MotionDirection.UP_RIGHT)
-            yDest = -global.screen_height + (oldWsIsFullscreen ? 0 : shiftHeight);
-        else if (direction === Meta.MotionDirection.DOWN ||
-            direction === Meta.MotionDirection.DOWN_LEFT ||
-            direction === Meta.MotionDirection.DOWN_RIGHT)
-            yDest = global.screen_height - (newWsIsFullscreen ? 0 : shiftHeight);
-
-        if (direction === Meta.MotionDirection.LEFT ||
-            direction === Meta.MotionDirection.UP_LEFT ||
-            direction === Meta.MotionDirection.DOWN_LEFT)
-            xDest = -global.screen_width;
-        else if (direction === Meta.MotionDirection.RIGHT ||
-                 direction === Meta.MotionDirection.UP_RIGHT ||
-                 direction === Meta.MotionDirection.DOWN_RIGHT)
-            xDest = global.screen_width;
-
-        return [xDest, yDest];
-    }
-
-    _prepareWorkspaceSwitch(from, to, direction) {
+    _prepareWorkspaceSwitch(workspaceIndices) {
         if (this._switchData)
             return;
 
         const workspaceManager = global.workspace_manager;
-        const curWs = workspaceManager.get_workspace_by_index(from);
+        const vertical = workspaceManager.layout_rows === -1;
+        const nWorkspaces = workspaceManager.get_n_workspaces();
+        const activeWorkspaceIndex = workspaceManager.get_active_workspace_index();
 
         const switchData = {};
 
         this._switchData = switchData;
-        switchData.curGroup = new WorkspaceGroup(curWs, this.movingWindow);
         switchData.movingWindowBin = new Clutter.Actor();
         switchData.movingWindow = null;
-        switchData.surroundings = {};
+        switchData.workspaceGroups = [];
         switchData.gestureActivated = false;
         switchData.inProgress = false;
 
         switchData.container = new Clutter.Actor();
-        switchData.container.add_child(switchData.curGroup);
         switchData.backgroundGroup = new Clutter.Actor();
 
         for (const monitor of Main.layoutManager.monitors)
@@ -199,28 +171,44 @@ var WorkspaceAnimationController = class {
         Main.uiGroup.insert_child_above(switchData.container, switchData.backgroundGroup);
         Main.uiGroup.insert_child_above(switchData.movingWindowBin, switchData.container);
 
-        for (const dir of Object.values(Meta.MotionDirection)) {
-            let ws = null;
+        let x = 0;
+        let y = 0;
+
+        if (!workspaceIndices)
+            workspaceIndices = [...Array(nWorkspaces).keys()];
 
-            if (to < 0)
-                ws = curWs.get_neighbor(dir);
-            else if (dir === direction)
-                ws = workspaceManager.get_workspace_by_index(to);
+        for (const i of workspaceIndices) {
+            const ws = workspaceManager.get_workspace_by_index(i);
+            const fullscreen = ws.list_windows().some(w => w.is_fullscreen());
 
-            if (ws === null || ws === curWs) {
-                switchData.surroundings[dir] = null;
-                continue;
+            if (y > 0 && vertical && !fullscreen) {
+                // We have to shift windows up or down by the height of the panel to prevent having a
+                // visible gap between the windows while switching workspaces. Since fullscreen windows
+                // hide the panel, they don't need to be shifted up or down.
+                y -= Main.panel.height;
             }
 
-            const [x, y] = this._getPositionForDirection(dir, curWs, ws);
             const group = new WorkspaceGroup(ws, this.movingWindow);
-            switchData.surroundings[dir] = group;
+
+            switchData.workspaceGroups.push(group);
             switchData.container.add_child(group);
             switchData.container.set_child_above_sibling(group, null);
-
             group.set_position(x, y);
+
+            if (vertical)
+                y += global.screen_height;
+            else if (Clutter.get_default_text_direction() === Clutter.TextDirection.RTL)
+                x -= global.screen_width;
+            else
+                x += global.screen_width;
         }
 
+        const activeGroup = this._findWorkspaceGroupByIndex(activeWorkspaceIndex);
+        if (vertical)
+            switchData.container.y = -activeGroup.y;
+        else
+            switchData.container.x = -activeGroup.x;
+
         if (this.movingWindow) {
             const windowActor = this.movingWindow.get_compositor_private();
 
@@ -257,79 +245,73 @@ var WorkspaceAnimationController = class {
     }
 
     animateSwitch(from, to, direction, onComplete) {
-        this._prepareWorkspaceSwitch(from, to, direction);
-        this._switchData.inProgress = true;
+        this._swipeTracker.enabled = false;
+
+        let workspaceIndices = [];
+
+        switch (direction) {
+        case Meta.MotionDirection.UP:
+        case Meta.MotionDirection.LEFT:
+        case Meta.MotionDirection.UP_LEFT:
+        case Meta.MotionDirection.UP_RIGHT:
+            workspaceIndices = [to, from];
+            break;
+
+        case Meta.MotionDirection.DOWN:
+        case Meta.MotionDirection.RIGHT:
+        case Meta.MotionDirection.DOWN_LEFT:
+        case Meta.MotionDirection.DOWN_RIGHT:
+            workspaceIndices = [from, to];
+            break;
+        }
 
-        const workspaceManager = global.workspace_manager;
-        const fromWs = workspaceManager.get_workspace_by_index(from);
-        const toWs = workspaceManager.get_workspace_by_index(to);
+        if (Clutter.get_default_text_direction() === Clutter.TextDirection.RTL &&
+            direction !== Meta.MotionDirection.UP &&
+            direction !== Meta.MotionDirection.DOWN)
+            workspaceIndices.reverse();
 
-        let [xDest, yDest] = this._getPositionForDirection(direction, fromWs, toWs);
+        this._prepareWorkspaceSwitch(workspaceIndices);
+        this._switchData.inProgress = true;
+
+        const fromGroup = this._findWorkspaceGroupByIndex(from);
+        const toGroup = this._findWorkspaceGroupByIndex(to);
 
-        /* @direction is the direction that the "camera" moves, so the
-         * screen contents have to move one screen's worth in the
-         * opposite direction.
-         */
-        xDest = -xDest;
-        yDest = -yDest;
+        this._switchData.container.x = -fromGroup.x;
+        this._switchData.container.y = -fromGroup.y;
 
         this._switchData.container.ease({
-            x: xDest,
-            y: yDest,
+            x: -toGroup.x,
+            y: -toGroup.y,
             duration: WINDOW_ANIMATION_TIME,
             mode: Clutter.AnimationMode.EASE_OUT_CUBIC,
             onComplete: () => {
                 this._finishWorkspaceSwitch(this._switchData);
                 onComplete();
+                this._swipeTracker.enabled = true;
             },
         });
     }
 
-    _directionForProgress(progress) {
-        if (global.workspace_manager.layout_rows === -1) {
-            return progress > 0
-                ? Meta.MotionDirection.DOWN
-                : Meta.MotionDirection.UP;
-        } else if (Clutter.get_default_text_direction() === Clutter.TextDirection.RTL) {
-            return progress > 0
-                ? Meta.MotionDirection.LEFT
-                : Meta.MotionDirection.RIGHT;
-        } else {
-            return progress > 0
-                ? Meta.MotionDirection.RIGHT
-                : Meta.MotionDirection.LEFT;
-        }
-    }
-
-    _getProgressRange() {
-        if (!this._switchData)
-            return [0, 0];
-
-        let lower = 0;
-        let upper = 0;
-
-        const horiz = global.workspace_manager.layout_rows !== -1;
-        let baseDistance;
-        if (horiz)
-            baseDistance = global.screen_width;
+    _getProgressForWorkspace(workspaceGroup) {
+        if (global.workspace_manager.layout_rows === -1)
+            return workspaceGroup.y / global.screen_height;
+        else if (Clutter.get_default_text_direction() === Clutter.TextDirection.RTL)
+            return -workspaceGroup.x / global.screen_width;
         else
-            baseDistance = global.screen_height;
-
-        let direction = this._directionForProgress(-1);
-        let group = this._switchData.surroundings[direction];
-        if (group !== null) {
-            const distance = horiz ? group.x : group.y;
-            lower = -Math.abs(distance) / baseDistance;
-        }
+            return workspaceGroup.x / global.screen_width;
+    }
 
-        direction = this._directionForProgress(1);
-        group = this._switchData.surroundings[direction];
-        if (group !== null) {
-            const distance = horiz ? group.x : group.y;
-            upper = Math.abs(distance) / baseDistance;
-        }
+    _findWorkspaceGroupByIndex(index) {
+        return this._switchData.workspaceGroups.find(g => g.workspace.index() === index);
+    }
 
-        return [lower, upper];
+    _findClosestWorkspaceGroup(progress) {
+        const distances = this._switchData.workspaceGroups.map(g => {
+            const workspaceProgress = this._getProgressForWorkspace(g);
+            return Math.abs(workspaceProgress - progress);
+        });
+        const index = distances.indexOf(Math.min(...distances));
+        return this._switchData.workspaceGroups[index];
     }
 
     _switchWorkspaceBegin(tracker, monitor) {
@@ -343,15 +325,10 @@ var WorkspaceAnimationController = class {
             ? Clutter.Orientation.HORIZONTAL
             : Clutter.Orientation.VERTICAL;
 
-        const activeWorkspace = workspaceManager.get_active_workspace();
-
-        let baseDistance;
-        if (horiz)
-            baseDistance = global.screen_width;
-        else
-            baseDistance = global.screen_height;
+        const baseDistance = horiz ? global.screen_width : global.screen_height;
 
         let progress;
+        let cancelProgress;
         if (this._switchData && this._switchData.gestureActivated) {
             this._switchData.container.remove_all_transitions();
             if (!horiz)
@@ -360,41 +337,36 @@ var WorkspaceAnimationController = class {
                 progress = this._switchData.container.x / baseDistance;
             else
                 progress = -this._switchData.container.x / baseDistance;
-        } else {
-            this._prepareWorkspaceSwitch(activeWorkspace.index(), -1);
-            progress = 0;
-        }
 
-        const points = [];
-        const [lower, upper] = this._getProgressRange();
+            const wsGroup = this._findClosestWorkspaceGroup(progress);
+            cancelProgress = this._getProgressForWorkspaceGroup(wsGroup);
+        } else {
+            this._prepareWorkspaceSwitch();
 
-        if (lower !== 0)
-            points.push(lower);
+            const activeIndex = workspaceManager.get_active_workspace_index();
+            const wsGroup = this._findWorkspaceGroupByIndex(activeIndex);
 
-        points.push(0);
+            progress = cancelProgress = this._getProgressForWorkspace(wsGroup);
+        }
 
-        if (upper !== 0)
-            points.push(upper);
+        const points = this._switchData.workspaceGroups.map(this._getProgressForWorkspace);
 
-        tracker.confirmSwipe(baseDistance, points, progress, 0);
+        tracker.confirmSwipe(baseDistance, points, progress, cancelProgress);
     }
 
     _switchWorkspaceUpdate(tracker, progress) {
         if (!this._switchData)
             return;
 
-        const direction = this._directionForProgress(progress);
-        const group = this._switchData.surroundings[direction];
         let xPos = 0;
         let yPos = 0;
-        if (group) {
-            if (global.workspace_manager.layout_rows === -1)
-                yPos = -Math.round(progress * global.screen_height);
-            else if (Clutter.get_default_text_direction() === Clutter.TextDirection.RTL)
-                xPos = Math.round(progress * global.screen_width);
-            else
-                xPos = -Math.round(progress * global.screen_width);
-        }
+
+        if (global.workspace_manager.layout_rows === -1)
+            yPos = -Math.round(progress * global.screen_height);
+        else if (Clutter.get_default_text_direction() === Clutter.TextDirection.RTL)
+            xPos = Math.round(progress * global.screen_width);
+        else
+            xPos = -Math.round(progress * global.screen_width);
 
         this._switchData.container.set_position(xPos, yPos);
     }
@@ -403,40 +375,24 @@ var WorkspaceAnimationController = class {
         if (!this._switchData)
             return;
 
-        const workspaceManager = global.workspace_manager;
-        const activeWorkspace = workspaceManager.get_active_workspace();
-        let newWs = activeWorkspace;
-        let xDest = 0;
-        let yDest = 0;
-        if (endProgress !== 0) {
-            const direction = this._directionForProgress(endProgress);
-            newWs = activeWorkspace.get_neighbor(direction);
-            xDest = -this._switchData.surroundings[direction].x;
-            yDest = -this._switchData.surroundings[direction].y;
-        }
+        const newGroup = this._findClosestWorkspaceGroup(endProgress);
 
         const switchData = this._switchData;
         switchData.gestureActivated = true;
 
         this._switchData.container.ease({
-            x: xDest,
-            y: yDest,
+            x: -newGroup.x,
+            y: -newGroup.y,
             duration,
             mode: Clutter.AnimationMode.EASE_OUT_CUBIC,
             onComplete: () => {
-                if (!newWs.active)
-                    newWs.activate(global.get_current_time());
+                if (!newGroup.workspace.active)
+                    newGroup.workspace.activate(global.get_current_time());
                 this._finishWorkspaceSwitch(switchData);
             },
         });
     }
 
-    _switchWorkspaceStop() {
-        this._switchData.container.x = 0;
-        this._switchData.container.y = 0;
-        this._finishWorkspaceSwitch(this._switchData);
-    }
-
     get gestureActive() {
         return this._switchData !== null && this._switchData.gestureActivated;
     }