feat(viewport): add view port service

projects/ng-sortgrid/src/lib/helpers/view-port.helper.service.ts

@@ -0,0 +1,32 @@
+import {ViewPortService} from './view-port.service';
+import {beforeEach} from '@angular/core/testing/src/testing_internal';
+
+describe('Viewport helper', () => {
+
+  let sut: ViewPortService;
+  const documentMock = {
+    defaultView: {
+      innerHeight: 0,
+      innerWidth: 0
+    },
+  };
+
+  beforeEach(() => sut = new ViewPortService(documentMock));
+
+  it('should detect when we drag over the top viewport', () => {
+    const element = {
+      getBoundingClientRect: () => ({top: -100, left: 0, bottom: 0, right: 0})
+    } as any;
+    const viewPortOverflow = sut.isOutOfViewport(element);
+    expect(viewPortOverflow.top).toBeTruthy();
+  });
+
+  it('should detect when we drag over the bottom viewport', () => {
+    spyOn(window, 'innerHeight').and.returnValue(0);
+    const element = {
+      getBoundingClientRect: () => ({top: 0, left: 0, bottom: 100, right: 0})
+    } as any;
+    const viewPortOverflow = sut.isOutOfViewport(element);
+    expect(viewPortOverflow.bottom).toBeTruthy();
+  });
+});

projects/ng-sortgrid/src/lib/helpers/view-port.service.ts

@@ -0,0 +1,28 @@
+import {Inject, Injectable} from '@angular/core';
+import {DOCUMENT} from '@angular/common';
+
+export interface ViewPortOverflow {
+  top: boolean;
+  bottom: boolean;
+}
+
+@Injectable({
+  providedIn: 'root'
+})
+export class ViewPortService {
+
+  private window: WindowProxy;
+
+  constructor(@Inject(DOCUMENT) private document) {
+    this.window = document.defaultView;
+  }
+
+  public isOutOfViewport(element: HTMLElement): ViewPortOverflow {
+
+    const bounding = element.getBoundingClientRect();
+    return {
+      top: bounding.top < 0,
+      bottom: bounding.bottom > (this.window.innerHeight || document.documentElement.clientHeight)
+    };
+  }
+}

projects/ng-sortgrid/src/lib/ngsg-item.directive.spec.ts

@@ -27,6 +27,12 @@ describe('NgsgItemDirective', () => {
     'setItems'
   ]);
   const ngsgEventService = new NgsgEventsService();
+  const viewPortService = {
+    isOutOfViewport: () => ({
+      top: false,
+      bottom: false
+    })
+  } as any;
 
   beforeEach(() => {
     sut = new NgsgItemDirective(
@@ -35,7 +41,8 @@ describe('NgsgItemDirective', () => {
       ngsgSelectionService,
       ngsgReflectService,
       ngsgStore,
-      ngsgEventService
+      ngsgEventService,
+      viewPortService
     );
   });
 

projects/ng-sortgrid/src/lib/ngsg-item.directive.ts

@@ -5,21 +5,21 @@ import {
   EventEmitter,
   HostListener,
   Input,
-  NgZone, OnChanges, OnDestroy,
+  OnChanges,
+  OnDestroy,
   OnInit,
-  Output, SimpleChanges
+  Output,
+  SimpleChanges
 } from '@angular/core';
 
 import {NgsgReflectService} from './ngsg-reflect.service';
 import {NgsgStoreService} from './ngsg-store.service';
 import {NgsgSortService} from './ngsg-sort.service';
 import {NgsgSelectionService} from './ngsg-selection.service';
-import {NgsgClassService} from './ngsg-class.service';
-import {NgsgElementsHelper} from './ngsg-elements.helper';
 import {NgsgEventsService} from './ngsg-events.service';
 import {Subject} from 'rxjs';
 import {takeUntil} from 'rxjs/operators';
-import {group} from '@angular/animations';
+import {ViewPortService} from './helpers/view-port.service';
 
 const selector = '[ngSortgridItem]';
 
@@ -31,6 +31,7 @@ export class NgsgItemDirective implements OnInit, OnChanges, AfterViewInit, OnDe
   @Output() sorted = new EventEmitter<any>();
 
   private selected = false;
+  private SCROLLSPEED = 100;
   private destroy$ = new Subject();
 
   constructor(
@@ -39,7 +40,8 @@ export class NgsgItemDirective implements OnInit, OnChanges, AfterViewInit, OnDe
     private selectionService: NgsgSelectionService,
     private reflectService: NgsgReflectService,
     private ngsgStore: NgsgStoreService,
-    private ngsgEventService: NgsgEventsService
+    private ngsgEventService: NgsgEventsService,
+    private viewPortService: ViewPortService
   ) {
   }
 
@@ -88,6 +90,15 @@ export class NgsgItemDirective implements OnInit, OnChanges, AfterViewInit, OnDe
 
   @HostListener('dragover', ['$event'])
   dragOver(event): boolean {
+
+    if (this.viewPortService.isOutOfViewport(event.target).top) {
+      window.scrollBy({top: -this.SCROLLSPEED, behavior: 'smooth'});
+    }
+
+    if (this.viewPortService.isOutOfViewport(event.target).bottom) {
+      window.scrollBy({top: this.SCROLLSPEED, behavior: 'smooth'});
+    }
+
     if (event.preventDefault) {
       // Necessary. Allows us to drop.
       event.preventDefault();