feat(Ruler): introduce Ruler service

Closes #1089

Closes #1253

modules/angular2/src/dom/browser_adapter.dart

@@ -176,6 +176,7 @@ class BrowserDomAdapter extends GenericBrowserDomAdapter {
       document.implementation.createHtmlDocument('fakeTitle');
 
   HtmlDocument defaultDoc() => document;
+  Rectangle getBoundingClientRect(el) => el.getBoundingClientRect();
   String getTitle() => document.title;
   void setTitle(String newTitle) {
     document.title = newTitle;

modules/angular2/src/dom/browser_adapter.es6

@@ -228,6 +228,9 @@ export class BrowserDomAdapter extends GenericBrowserDomAdapter {
   defaultDoc() {
     return document;
   }
+  getBoundingClientRect(el) {
+    return el.getBoundingClientRect();
+  }
   getTitle() {
     return document.title;
   }

modules/angular2/src/dom/dom_adapter.js

@@ -210,6 +210,9 @@ export class DomAdapter {
   defaultDoc() {
     throw _abstract();
   }
+  getBoundingClientRect(el) {
+    throw _abstract();
+  }
   getTitle() {
     throw _abstract();
   }

modules/angular2/src/dom/parse5_adapter.cjs

@@ -377,6 +377,9 @@ export class Parse5DomAdapter extends DomAdapter {
     }
     return defDoc;
   }
+  getBoundingClientRect(el) {
+    return {left: 0, top: 0, width: 0, height: 0};
+  }
   getTitle() {
     return this.defaultDoc().title || "";
   }

modules/angular2/src/services/ruler.js

@@ -0,0 +1,34 @@
+import {Promise, PromiseWrapper} from 'angular2/src/facade/async';
+import {DomAdapter} from 'angular2/src/dom/dom_adapter';
+import {NgElement} from 'angular2/src/core/dom/element';
+
+export class Rectangle {
+  left;
+  right;
+  top;
+  bottom;
+  height;
+  width;
+  constructor(left, top, width, height) {
+    this.left = left;
+    this.right = left + width;
+    this.top = top;
+    this.bottom = top + height;
+    this.height = height;
+    this.width = width;
+  }
+}
+
+export class Ruler {
+  domAdapter: DomAdapter;
+  constructor(domAdapter: DomAdapter) {
+    this.domAdapter = domAdapter;
+  }
+
+  measure(el:NgElement): Promise<Rectangle> {
+    var clntRect = this.domAdapter.getBoundingClientRect(el.domElement);
+
+    //even if getBoundingClientRect is synchronous we use async API in preparation for further changes
+    return PromiseWrapper.resolve(new Rectangle(clntRect.left, clntRect.top, clntRect.width, clntRect.height));
+  }
+}

modules/angular2/test/services/rectangle_mock.dart

@@ -0,0 +1,6 @@
+import 'dart:html';
+
+Rectangle createRectangle(left, top, width, height) {
+  return new Rectangle(left, top, width, height);
+}
+

modules/angular2/test/services/rectangle_mock.es6

@@ -0,0 +1,3 @@
+export function createRectangle(left, top, width, height) {
+  return {left, top, width, height};
+}

modules/angular2/test/services/ruler_spec.js

@@ -0,0 +1,57 @@
+import {AsyncTestCompleter, inject, ddescribe, describe, it, iit, xit, expect, SpyObject} from 'angular2/test_lib';
+
+import {DOM, DomAdapter} from 'angular2/src/dom/dom_adapter';
+import {NgElement} from 'angular2/src/core/dom/element';
+
+import {Ruler, Rectangle} from 'angular2/src/services/ruler';
+import {createRectangle} from './rectangle_mock';
+
+class DomAdapterMock extends DomAdapter {
+  rect;
+  constructor(rect) {
+    super();
+    this.rect = rect;
+  }
+
+  getBoundingClientRect(elm) {
+    return this.rect;
+  }
+}
+
+function assertDimensions(rect: Rectangle, left, right, top, bottom, width, height) {
+  expect(rect.left).toEqual(left);
+  expect(rect.right).toEqual(right);
+  expect(rect.top).toEqual(top);
+  expect(rect.bottom).toEqual(bottom);
+  expect(rect.width).toEqual(width);
+  expect(rect.height).toEqual(height);
+}
+
+export function main() {
+
+  describe('ruler service', () => {
+
+    it('should allow measuring NgElements',
+      inject([AsyncTestCompleter], (async) => {
+        var ruler = new Ruler(new DomAdapterMock(createRectangle(10, 20, 200, 100)));
+
+        ruler.measure(new NgElement(null)).then((rect) => {
+          assertDimensions(rect, 10, 210, 20, 120, 200, 100);
+          async.done();
+        });
+      }));
+
+
+    it('should return 0 for all rectangle values while measuring elements in a document fragment',
+      inject([AsyncTestCompleter], (async) => {
+        var ruler = new Ruler(DOM);
+
+        ruler.measure(new NgElement(DOM.createElement('div'))).then((rect) => {
+          //here we are using an element created in a doc fragment so all the measures will come back as 0
+          assertDimensions(rect, 0, 0, 0, 0, 0, 0);
+          async.done();
+        });
+    }));
+
+  });
+}