feat(tooltip): intoduce disabled flag

Closes #2253

Author: medinarkhov

src/tooltip/tooltip-config.spec.ts

@@ -7,5 +7,6 @@ describe('ngb-tooltip-config', () => {
     expect(config.placement).toBe('top');
     expect(config.triggers).toBe('hover');
     expect(config.container).toBeUndefined();
+    expect(config.disableTooltip).toBe(false);
   });
 });

src/tooltip/tooltip-config.ts

@@ -11,4 +11,5 @@ export class NgbTooltipConfig {
   placement: PlacementArray = 'top';
   triggers = 'hover';
   container: string;
+  disableTooltip = false;
 }

src/tooltip/tooltip.spec.ts

@@ -136,6 +136,17 @@ describe('ngb-tooltip', () => {
       expect(getWindow(fixture.nativeElement)).toBeNull();
     });
 
+    it('should not open a tooltip if [disableTooltip] flag', () => {
+      const fixture = createTestComponent(`<div [ngbTooltip]="Disabled!" [disableTooltip]="true"></div>`);
+      const directive = fixture.debugElement.query(By.directive(NgbTooltip));
+
+      directive.triggerEventHandler('mouseenter', {});
+      fixture.detectChanges();
+      const windowEl = getWindow(fixture.nativeElement);
+
+      expect(windowEl).toBeNull();
+    });
+
     it('should allow re-opening previously closed tooltips', () => {
       const fixture = createTestComponent(`<div ngbTooltip="Great tip!"></div>`);
       const directive = fixture.debugElement.query(By.directive(NgbTooltip));

src/tooltip/tooltip.ts

@@ -101,6 +101,10 @@ export class NgbTooltip implements OnInit, OnDestroy {
    * Currently only supports "body".
    */
   @Input() container: string;
+  /**
+   * A flag indicating if a given tooltip is disabled and should not be displayed.
+   */
+  @Input() disableTooltip: boolean;
   /**
    * Emits an event when the tooltip is shown
    */
@@ -124,6 +128,7 @@ export class NgbTooltip implements OnInit, OnDestroy {
     this.placement = config.placement;
     this.triggers = config.triggers;
     this.container = config.container;
+    this.disableTooltip = config.disableTooltip;
     this._popupService = new PopupService<NgbTooltipWindow>(
         NgbTooltipWindow, injector, viewContainerRef, _renderer, componentFactoryResolver);
 
@@ -155,7 +160,7 @@ export class NgbTooltip implements OnInit, OnDestroy {
    * The context is an optional value to be injected into the tooltip template when it is created.
    */
   open(context?: any) {
-    if (!this._windowRef && this._ngbTooltip) {
+    if (!this._windowRef && this._ngbTooltip && !this.disableTooltip) {
       this._windowRef = this._popupService.open(this._ngbTooltip, context);
       this._windowRef.instance.id = this._ngbTooltipWindowId;