feat(overlay): support custom offsets

src/lib/core/overlay/overlay-directives.spec.ts

@@ -1,5 +1,6 @@
 import {ComponentFixture, TestBed} from '@angular/core/testing';
 import {Component, ViewChild} from '@angular/core';
+import {By} from '@angular/platform-browser';
 import {ConnectedOverlayDirective, OverlayModule} from './overlay-directives';
 import {OverlayContainer} from './overlay-container';
 import {ConnectedPositionStrategy} from './position/connected-position-strategy';
@@ -121,6 +122,36 @@ describe('Overlay directives', () => {
       expect(fixture.componentInstance.backdropClicked).toBe(true);
     });
 
+    it('should set the offsetX', () => {
+      const trigger = fixture.debugElement.query(By.css('button')).nativeElement;
+      const startX = trigger.getBoundingClientRect().left;
+
+      fixture.componentInstance.offsetX = 5;
+      fixture.componentInstance.isOpen = true;
+      fixture.detectChanges();
+
+      // expected x value is the starting x + offset x
+      const expectedX = startX + 5;
+      const pane = overlayContainerElement.children[0] as HTMLElement;
+      expect(pane.style.transform).toContain(`translateX(${expectedX}px)`);
+    });
+
+    it('should set the offsetY', () => {
+      const trigger = fixture.debugElement.query(By.css('button')).nativeElement;
+      trigger.style.position = 'absolute';
+      trigger.style.top = '30px';
+      trigger.style.height = '20px';
+
+      fixture.componentInstance.offsetY = 45;
+      fixture.componentInstance.isOpen = true;
+      fixture.detectChanges();
+
+      // expected y value is the starting y + trigger height + offset y
+      // 30 + 20 + 45 = 95px
+      const pane = overlayContainerElement.children[0] as HTMLElement;
+      expect(pane.style.transform).toContain(`translateY(95px)`);
+    });
+
   });
 
 });
@@ -131,14 +162,16 @@ describe('Overlay directives', () => {
   <button overlay-origin #trigger="overlayOrigin">Toggle menu</button>
   <template connected-overlay [origin]="trigger" [open]="isOpen" [width]="width" [height]="height"
             [hasBackdrop]="hasBackdrop" backdropClass="md-test-class" 
-            (backdropClick)="backdropClicked=true">
+            (backdropClick)="backdropClicked=true" [offsetX]="offsetX" [offsetY]="offsetY">
     <p>Menu content</p>
   </template>`,
 })
 class ConnectedOverlayDirectiveTest {
   isOpen = false;
   width: number | string;
   height: number | string;
+  offsetX: number = 0;
+  offsetY: number = 0;
   hasBackdrop: boolean;
   backdropClicked = false;
 

src/lib/core/overlay/overlay-directives.ts

@@ -67,6 +67,12 @@ export class ConnectedOverlayDirective implements OnDestroy {
   @Input() origin: OverlayOrigin;
   @Input() positions: ConnectionPositionPair[];
 
+  /** The offset in pixels for the overlay connection point on the x-axis */
+  @Input() offsetX: number = 0;
+
+  /** The offset in pixels for the overlay connection point on the y-axis */
+  @Input() offsetY: number = 0;
+
   /** The width of the overlay panel. */
   @Input() width: number | string;
 
@@ -150,20 +156,27 @@ export class ConnectedOverlayDirective implements OnDestroy {
       overlayConfig.backdropClass = this.backdropClass;
     }
 
-    overlayConfig.positionStrategy = this._getPosition();
+    overlayConfig.positionStrategy = this._setUpPosition();
 
     overlayConfig.direction = this.dir;
 
     return overlayConfig;
   }
 
+  /** Sets up the position strategy with its initial configuration. */
+  private _setUpPosition(): ConnectedPositionStrategy {
+    return this._getPosition()
+      .withDirection(this.dir)
+      .withOffsetX(this.offsetX)
+      .withOffsetY(this.offsetY);
+  }
+
   /** Returns the position of the overlay to be set on the overlay config */
   private _getPosition(): ConnectedPositionStrategy {
     return this._overlay.position().connectedTo(
       this.origin.elementRef,
       {originX: this.positions[0].overlayX, originY: this.positions[0].originY},
-      {overlayX: this.positions[0].overlayX, overlayY: this.positions[0].overlayY})
-      .setDirection(this.dir);
+      {overlayX: this.positions[0].overlayX, overlayY: this.positions[0].overlayY});
   }
 
   /** Attaches the overlay and subscribes to backdrop clicks if backdrop exists */

src/lib/core/overlay/position/connected-position-strategy.spec.ts

@@ -215,14 +215,45 @@ describe('ConnectedPositionStrategy', () => {
         fakeElementRef,
         {originX: 'start', originY: 'bottom'},
         {overlayX: 'start', overlayY: 'top'})
-        .setDirection('rtl');
+        .withDirection('rtl');
 
       strategy.apply(overlayElement);
 
       let overlayRect = overlayElement.getBoundingClientRect();
       expect(overlayRect.top).toBe(originRect.bottom);
       expect(overlayRect.right).toBe(originRect.right);
     });
+
+    it('should position a panel with the x offset provided', () => {
+      originRect = originElement.getBoundingClientRect();
+      strategy = positionBuilder.connectedTo(
+        fakeElementRef,
+        {originX: 'start', originY: 'top'},
+        {overlayX: 'start', overlayY: 'top'});
+
+      strategy.withOffsetX(10);
+      strategy.apply(overlayElement);
+
+      let overlayRect = overlayElement.getBoundingClientRect();
+      expect(overlayRect.top).toBe(originRect.top);
+      expect(overlayRect.left).toBe(originRect.left + 10);
+    });
+
+    it('should position a panel with the y offset provided', () => {
+      originRect = originElement.getBoundingClientRect();
+      strategy = positionBuilder.connectedTo(
+        fakeElementRef,
+        {originX: 'start', originY: 'top'},
+        {overlayX: 'start', overlayY: 'top'});
+
+      strategy.withOffsetY(50);
+      strategy.apply(overlayElement);
+
+      let overlayRect = overlayElement.getBoundingClientRect();
+      expect(overlayRect.top).toBe(originRect.top + 50);
+      expect(overlayRect.left).toBe(originRect.left);
+    });
+
   });
 
 

src/lib/core/overlay/position/connected-position-strategy.ts

@@ -11,14 +11,20 @@ import {
 
 /**
  * A strategy for positioning overlays. Using this strategy, an overlay is given an
- * implict position relative some origin element. The relative position is defined in terms of
+ * implicit position relative some origin element. The relative position is defined in terms of
  * a point on the origin element that is connected to a point on the overlay element. For example,
  * a basic dropdown is connecting the bottom-left corner of the origin to the top-left corner
  * of the overlay.
  */
 export class ConnectedPositionStrategy implements PositionStrategy {
   private _dir = 'ltr';
 
+  /** The offset in pixels for the overlay connection point on the x-axis */
+  private _offsetX: number = 0;
+
+  /** The offset in pixels for the overlay connection point on the y-axis */
+  private _offsetY: number = 0;
+
   /** Whether the we're dealing with an RTL context */
   get _isRtl() {
     return this._dir === 'rtl';
@@ -89,11 +95,23 @@ export class ConnectedPositionStrategy implements PositionStrategy {
   }
 
   /** Sets the layout direction so the overlay's position can be adjusted to match. */
-  setDirection(dir: 'ltr' | 'rtl') {
+  withDirection(dir: 'ltr' | 'rtl'): ConnectedPositionStrategy {
     this._dir = dir;
     return this;
   }
 
+  /** Sets an offset for the overlay's connection point on the x-axis */
+  withOffsetX(offset: number): ConnectedPositionStrategy {
+    this._offsetX = offset;
+    return this;
+  }
+
+  /** Sets an offset for the overlay's connection point on the y-axis */
+  withOffsetY(offset: number): ConnectedPositionStrategy {
+    this._offsetY = offset;
+    return this;
+  }
+
   /**
    * Gets the horizontal (x) "start" dimension based on whether the overlay is in an RTL context.
    * @param rect
@@ -168,8 +186,8 @@ export class ConnectedPositionStrategy implements PositionStrategy {
     }
 
     return {
-      x: originPoint.x + overlayStartX,
-      y: originPoint.y + overlayStartY
+      x: originPoint.x + overlayStartX + this._offsetX,
+      y: originPoint.y + overlayStartY + this._offsetY
     };
   }