From 61abf780d177b69e79f507390eea6ef49ec78d4d Mon Sep 17 00:00:00 2001
From: mathuo <6710312+mathuo@users.noreply.github.com>
Date: Sun, 5 May 2024 13:44:21 +0100
Subject: [PATCH] feat: improve onDidLayoutChange events

---
 .../dockview/dockviewComponent.spec.ts        | 54 +++++++++++++++++++
 .../src/__tests__/events.spec.ts              | 36 +++++++++++++
 .../src/gridview/baseComponentGridview.ts     | 13 ++---
 3 files changed, 94 insertions(+), 9 deletions(-)

diff --git a/packages/dockview-core/src/__tests__/dockview/dockviewComponent.spec.ts b/packages/dockview-core/src/__tests__/dockview/dockviewComponent.spec.ts
index 17497364f..b429a32be 100644
--- a/packages/dockview-core/src/__tests__/dockview/dockviewComponent.spec.ts
+++ b/packages/dockview-core/src/__tests__/dockview/dockviewComponent.spec.ts
@@ -5331,4 +5331,58 @@ describe('dockviewComponent', () => {
             expect(addGroupCount).toBe(2);
         });
     });
+
+    test('that `onDidLayoutChange` only subscribes to events after initial subscription time', () => {
+        jest.useFakeTimers();
+
+        const container = document.createElement('div');
+
+        const dockview = new DockviewComponent({
+            parentElement: container,
+            createComponent(options) {
+                switch (options.name) {
+                    case 'default':
+                        return new PanelContentPartTest(
+                            options.id,
+                            options.name
+                        );
+                    default:
+                        throw new Error(`unsupported`);
+                }
+            },
+        });
+        const api = new DockviewApi(dockview);
+
+        dockview.layout(1000, 1000);
+
+        let a = 0;
+
+        api.onDidLayoutChange((e) => {
+            a++;
+        });
+
+        api.addPanel({
+            id: 'panel_1',
+            component: 'default',
+        });
+        api.addPanel({
+            id: 'panel_2',
+            component: 'default',
+        });
+        api.addPanel({
+            id: 'panel_3',
+            component: 'default',
+        });
+
+        let b = 0;
+
+        api.onDidLayoutChange((e) => {
+            b++;
+        });
+
+        jest.runAllTicks();
+
+        expect(a).toBe(1);
+        expect(b).toBe(0);
+    });
 });
diff --git a/packages/dockview-core/src/__tests__/events.spec.ts b/packages/dockview-core/src/__tests__/events.spec.ts
index 532390a07..af05c3f28 100644
--- a/packages/dockview-core/src/__tests__/events.spec.ts
+++ b/packages/dockview-core/src/__tests__/events.spec.ts
@@ -1,4 +1,5 @@
 import {
+    AsapEvent,
     Emitter,
     Event,
     addDisposableListener,
@@ -82,6 +83,41 @@ describe('events', () => {
         });
     });
 
+    describe('asapEvent', () => {
+        test('that asapEvents fire once per event-loop-cycle', () => {
+            jest.useFakeTimers();
+
+            const event = new AsapEvent();
+
+            let preFireCount = 0;
+            let postFireCount = 0;
+
+            event.onEvent(() => {
+                preFireCount++;
+            });
+
+            for (let i = 0; i < 100; i++) {
+                event.fire();
+            }
+
+            /**
+             * check that subscribing after the events have fired but before the event-loop cycle completes
+             * results in no event fires.
+             */
+            event.onEvent((e) => {
+                postFireCount++;
+            });
+
+            expect(preFireCount).toBe(0);
+            expect(postFireCount).toBe(0);
+
+            jest.runAllTimers();
+
+            expect(preFireCount).toBe(1);
+            expect(postFireCount).toBe(0);
+        });
+    });
+
     it('should emit a value when any event fires', () => {
         const emitter1 = new Emitter<number>();
         const emitter2 = new Emitter<number>();
diff --git a/packages/dockview-core/src/gridview/baseComponentGridview.ts b/packages/dockview-core/src/gridview/baseComponentGridview.ts
index e6e572786..1e9c3102a 100644
--- a/packages/dockview-core/src/gridview/baseComponentGridview.ts
+++ b/packages/dockview-core/src/gridview/baseComponentGridview.ts
@@ -76,11 +76,8 @@ export abstract class BaseGrid<T extends IGridPanelView>
     private readonly _id = nextLayoutId.next();
     protected readonly _groups = new Map<string, IValueDisposable<T>>();
     protected readonly gridview: Gridview;
-    //
-    protected _activeGroup: T | undefined;
 
-    private _onDidLayoutChange = new Emitter<void>();
-    readonly onDidLayoutChange = this._onDidLayoutChange.event;
+    protected _activeGroup: T | undefined;
 
     private readonly _onDidRemove = new Emitter<T>();
     readonly onDidRemove: Event<T> = this._onDidRemove.event;
@@ -93,6 +90,8 @@ export abstract class BaseGrid<T extends IGridPanelView>
         this._onDidActiveChange.event;
 
     protected readonly _bufferOnDidLayoutChange = new AsapEvent();
+    readonly onDidLayoutChange: Event<void> =
+        this._bufferOnDidLayoutChange.onEvent;
 
     get id(): string {
         return this._id;
@@ -172,9 +171,6 @@ export abstract class BaseGrid<T extends IGridPanelView>
             )(() => {
                 this._bufferOnDidLayoutChange.fire();
             }),
-            this._bufferOnDidLayoutChange.onEvent(() => {
-                this._onDidLayoutChange.fire();
-            }),
             this._bufferOnDidLayoutChange
         );
     }
@@ -187,7 +183,7 @@ export abstract class BaseGrid<T extends IGridPanelView>
 
     public setVisible(panel: T, visible: boolean): void {
         this.gridview.setViewVisible(getGridLocation(panel.element), visible);
-        this._onDidLayoutChange.fire();
+        this._bufferOnDidLayoutChange.fire();
     }
 
     public isVisible(panel: T): boolean {
@@ -330,7 +326,6 @@ export abstract class BaseGrid<T extends IGridPanelView>
         this._onDidActiveChange.dispose();
         this._onDidAdd.dispose();
         this._onDidRemove.dispose();
-        this._onDidLayoutChange.dispose();
 
         for (const group of this.groups) {
             group.dispose();