// vs/workbench/browser/parts/activitybar/activitybarPart.ts

export class ActivitybarPart extends Part implements IActivityBarService {
  // 获取到注册到 activitybarPart 的视图
  private getViewContainers(): readonly ViewContainer[] {
    return this.viewDescriptorService.getViewContainersByLocation(this.location)
  }

  override createContentArea(parent: HTMLElement): HTMLElement {
    // View Containers action bar
    this.compositeBarContainer = this.compositeBar.create(this.content)
  }
}

// vs/workbench/browser/parts/compositeBar.ts
export class CompositeBar extends Widget implements ICompositeBar {
  create(parent: HTMLElement): HTMLElement {
    this.compositeSwitcherBar = this._register(
      new ActionBar(actionBarDiv, {
        actionViewItemProvider: (action) => {
          return item && this.instantiationService.createInstance(CompositeActionViewItem)
        },
      })
    )
  }
}

// vs/workbench/browser/parts/compositeBarActions.ts
export class CompositeActionViewItem extends ActivityActionViewItem {}