chore(overlay): add attach method to PositionStrategy interface

Author: jelbourn

src/cdk/overlay/overlay-ref.ts

@@ -45,6 +45,10 @@ export class OverlayRef implements PortalHost {
   attach(portal: Portal<any>): any {
     let attachResult = this._portalHost.attach(portal);
 
+    if (this._state.positionStrategy) {
+      this._state.positionStrategy.attach(this);
+    }
+
     // Update the pane element with the given state configuration.
     this._updateStackingOrder();
     this.updateSize();

src/cdk/overlay/overlay.spec.ts

@@ -537,6 +537,7 @@ class FakePositionStrategy implements PositionStrategy {
     return Promise.resolve(null);
   }
 
+  attach() {}
   dispose() {}
 }
 

src/cdk/overlay/position/connected-position-strategy.ts

@@ -18,6 +18,8 @@ import {
 import {Subject} from 'rxjs/Subject';
 import {Observable} from 'rxjs/Observable';
 import {Scrollable} from '../scroll/scrollable';
+import {OverlayRef} from '../overlay-ref';
+
 
 /**
  * Container to hold the bounding positions of a particular element with respect to the viewport,
@@ -39,6 +41,9 @@ type ElementBoundingPositions = {
  * of the overlay.
  */
 export class ConnectedPositionStrategy implements PositionStrategy {
+  /** The overlay to which this strategy is attached. */
+  private _overlayRef: OverlayRef;
+
   private _dir = 'ltr';
 
   /** The offset in pixels for the overlay connection point on the x-axis */
@@ -89,9 +94,11 @@ export class ConnectedPositionStrategy implements PositionStrategy {
     return this._preferredPositions;
   }
 
-  /**
-   * To be used to for any cleanup after the element gets destroyed.
-   */
+  attach(overlayRef: OverlayRef): void {
+    this._overlayRef = overlayRef;
+  }
+
+  /** To be used to for any cleanup after the element gets destroyed. */
   dispose() { }
 
   /**

src/cdk/overlay/position/global-position-strategy.ts

@@ -7,6 +7,7 @@
  */
 
 import {PositionStrategy} from './position-strategy';
+import {OverlayRef} from '../overlay-ref';
 
 
 /**
@@ -16,6 +17,9 @@ import {PositionStrategy} from './position-strategy';
  * element to become blurry.
  */
 export class GlobalPositionStrategy implements PositionStrategy {
+  /** The overlay to which this strategy is attached. */
+  private _overlayRef: OverlayRef;
+
   private _cssPosition: string = 'static';
   private _topOffset: string = '';
   private _bottomOffset: string = '';
@@ -29,6 +33,10 @@ export class GlobalPositionStrategy implements PositionStrategy {
   /* A lazily-created wrapper for the overlay element that is used as a flex container.  */
   private _wrapper: HTMLElement | null = null;
 
+  attach(overlayRef: OverlayRef): void {
+    this._overlayRef = overlayRef;
+  }
+
   /**
    * Sets the top position of the overlay. Clears any previously set vertical position.
    * @param value New top offset.

src/cdk/overlay/position/position-strategy.ts

@@ -6,9 +6,15 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {OverlayRef} from '../overlay-ref';
+
+
 /** Strategy for setting the position on an overlay. */
 export interface PositionStrategy {
 
+  /** Attaches this position strategy to an overlay. */
+  attach(overlay: OverlayRef): void;
+
   /** Updates the position of the overlay element. */
   apply(element: Element): void;